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ASME Conference Presenter Attendance Policy and Archival Proceedings

2018;():V001T00A001. doi:10.1115/DMD2018-NS.
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This online compilation of papers from the 2018 Design of Medical Devices Conference (DMD2018) represents the archival version of the Conference Proceedings. According to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference by an author of the paper, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

Cardiovascular

2018;():V001T01A001. doi:10.1115/DMD2018-6801.
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Importance of repeatable and reproducible measurements in medicine cannot be understated [1]. In this investigation, we quantified repeatability (intra-observer variability) and reproducibility (inter-observer variability) while measuring peripheral arterial tonometry (PAT) signals from finger tips of healthy subjects using piezoelectric transducers. Although numerous techniques for measuring PAT have been described in literature, the repeatability and reproducibility of these measurements, and the variability in multiple probes have not been established. We hypothesize that: (1) PAT measurements would be repeatable when measured by a single operator at each time point, (2) readings would be reproducible when measured by multiple operators, and (3) there would be minimal variation between multiple probes.

Commentary by Dr. Valentin Fuster
2018;():V001T01A002. doi:10.1115/DMD2018-6805.
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Patients with peripheral arterial disease (PAD) have compromised blood flow to their extremities as a result of arterial narrowing. PAD is often associated with impairment in endothelial function which is exaggerated by injury from processes related to cardiovascular risk factors such as ageing, hypertension, hyperlipidemia, diabetes, smoking, and obesity [1]. Furthermore, patients with diabetes often have calcified arteries making standard non-invasive testing non diagnostic [2]. With increase in diabetes prevalence and concomitant PAD, a new non-invasive assessment method of arterial function that has the potential to reflect both arterial tone and response to ischemia reperfusion may be valuable. We have developed a peripheral arterial tonometry (PAT) system (previously described, [3]) that is capable of measuring pulsatility in peripheral digits. We complemented our system with simultaneous peripheral temperature measurements that could not only add value in understanding PAD, but also aid in clinical diagnoses. In this investigation, we characterized our system on healthy individuals before using it on patients suffering from arterial disease in future investigations.

Commentary by Dr. Valentin Fuster
2018;():V001T01A003. doi:10.1115/DMD2018-6835.
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Congestive heart failure (CHF) remains one of the most costly diseases in the industrialized world, both in terms of healthcare dollars and the loss of human life. Despite great strides made in the treatment of CHF using mechanical ventricular assist devices (VADs), several longstanding difficulties associated with pumping blood continue to limit their long-term use. Among the most troublesome have been the increased risk of infection associated with the use of percutaneous drivelines and the persistent risk of clot formation at the blood-device interface. Development of a completely self-contained, non-blood-contacting VAD for long-term use would therefore be an important advance in circulatory support technology. Toward that end, we have developed a muscle-powered co-pulsation VAD (Figure 1) that avoids both these problems by using an internal muscle energy converter (MEC) to drive a non-blood-contacting direct cardiac compression sleeve (DCCS) for long-term circulatory support.

Topics: Design , Robotics , Muscle
Commentary by Dr. Valentin Fuster
2018;():V001T01A004. doi:10.1115/DMD2018-6847.
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For more than 27 years, implanted vagus nerve stimulation (VNS) devices, with electric current outputs in the 1 to 3.5 mA range, have been developed for many health care applications, including epilepsy and heart disease [1]. Mechanical compression approaches for VNS were administered under surgical conditions, using forceps, in the 1800’s [2]. Outcomes such as Electrocardiogram (ECG) data, blood pressure (BP), and heart rate (HR) were evaluated. Also, non-invasive (NI) mechanical compression of the vagus nerve for various nervous system disorders using hand, thumb, finger and belt pressure was popular in the 1800’s [3]. Cyberonics (now LivaNova) received the first FDA clearance for a surgically implanted electrical VNS device to treat refractory epilepsy in 1997.

Topics: Pressure , Blood
Commentary by Dr. Valentin Fuster
2018;():V001T01A005. doi:10.1115/DMD2018-6860.
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Mitral subvalvular apparatus plays an important role in mitral and ventricular dynamics by preserving annuloventricular continuity, known to be fundamental for ventricular function. While some proposed mitral valve prostheses designs do attempt to account for this relationship by using papillary flaps, they are not adjustable and do not mimic the native saddle shaped mitral annulus. Unfortunately, these designs are not versatile as their papillary flap lengths cannot be altered and the prostheses are unsuitable for percutaneous implantation.

We address these issues through the design of a novel semistented and chorded mitral valve that better mimics the native mitral annulus, leaflets and chordae function and can be made from off-the-shelf biomaterials with the potential to be implanted percutaneously. We also propose a novel and reliable method to set the chordal lengths individually. Finally, we demonstrate the hydrodynamic performance of the valve, showing that it meets the minimum performance requirements stipulated by the international standard ISO 5840-3:2013.

Commentary by Dr. Valentin Fuster
2018;():V001T01A006. doi:10.1115/DMD2018-6869.
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Atherosclerosis is a chronic progressive cardiovascular disease that results from plaque formation in the arteries. It is one of the leading causes of death and loss of healthy life in modern world. Atherosclerosis lesions consist of sub-endothelial accumulations of cholesterol and inflammatory cells [1]. However, not all lesions progress to the final stage to cause catastrophic ischemic cardiovascular events [2]. Early identification and treatment of high-risk plaques before they rupture, and precipitate adverse events constitutes a major challenge in cardiology today. Numerous investigations have confirmed that atherosclerosis is an inflammatory disease [3] [4] [5]. This confirmation has opened the treatment of this disease to many novel anti-inflammatory therapeutics. The use of nanoparticle-nanomedicines has gained popularity over recent years. Initially approved as anticancer treatment therapeutics [6], nanomedicine also holds promise for anti-inflammatory treatment, personalized medicine, target-specific treatment, and imaging of atherosclerotic disease [7]. The primary aim of this collaborative work is to develop and validate a novel strategy for catheter-directed local treatment of high-risk plaque using anti-inflammatory nanoparticles. Preselected drugs with the highest anti-inflammatory efficacy will be incorporated into a novel liposome nanocarrier, and delivered in-vivo through a specially designed catheter to high-risk atherosclerotic plaques. The catheter has specially designed perfusion pores that inject drug into the blood stream in such a controlled manner that the streamlines carry the nanoparticles to the stenotic arterial wall. Once the particles make it to the arterial wall, they can be absorbed into the inflamed tissue. In this paper, we discuss the design and development of an atraumatic drug delivery catheter for the administration of lipid nanoparticles.

Commentary by Dr. Valentin Fuster
2018;():V001T01A007. doi:10.1115/DMD2018-6875.
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Thrombogenicity testing continues to be a critical requirement for regulatory approval of blood-contacting medical devices and the ISO guidelines have recently been updates [1]. This new guideline ascribes value to both in vivo and in vitro testing including both the non-anticoagulated venous implant (NAVI) model, and the new methods for in vitro testing. One challenge with the animal-blood-based in vitro assays that have been validated and used for submissions is that they still may not accurately translate to clinical safety or predict the risk for thrombogenic potential in humans. We have previously described a model using minimally heparinized ovine blood and are continuing to improve the overall methodology [2,3]. In addition, we have transferred these methods to a human blood assay which therefore has enhanced potential for prediction of clinical risk. As with the ovine model, the key characteristics of a successful in vitro method include fresh blood, low levels of anticoagulation, flow conditions and minimization of air/blood interfaces. This human model integrates freshly harvested human blood containing minimal levels of heparin with variable flow from a unidirectional peristaltic pump and unlike many of the human blood assays, it can accommodate larger devices and higher flow rates than previously described [1,4]. Control materials which were optimized in the ovine model were also used to reproducibly elicit positive and negative thrombogenic responses. We feel that this model can be used for validation of the ovine model with cross comparisons of a number of legally marketed comparator devices. Alternatively, if the human blood methodology can be streamlined and performed cost effectively on a regular and basis, this assay could supplant the current ovine model and allow a highly predictive preclinical test for thrombogenicity of devices.

Commentary by Dr. Valentin Fuster
2018;():V001T01A008. doi:10.1115/DMD2018-6877.
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Medical device developers can often be limited in pre-clinical experimental testing of new products because of procedural complexities and safety concerns to the animal or patient. Though animal or human cadavers can be used for these types of studies thereby eliminating the need for safety precautions, the functional capabilities of the tissue can be lost. As a novel way to provide such functional device/tissue assessment, the Visible Heart® (VH®) Laboratory has developed reanimation methodologies1 that allow the four chambers of the heart to contract naturally ex vivo. Swine hearts are routinely reanimated using this methodology with a clear perfusate which allows for direct endoscopic visualization of functional cardiac anatomy and importantly the device/tissue interface. For the past two decades, these capabilities have been useful for testing early device prototypes and developing educational and procedural videos. More specifically, this approach provides the added convenience of manipulating catheters into the ex vivo prep and visually studying their behavior for validation experiments of new medical devices. Further, multimodal imaging comparative assessments using both 4D echocardiography and fluoroscopy have been routinely performed. Yet, as imaging modalities continue to develop and are utilized for device placements or post-procedure evaluations, we hope to expand VH® capabilities.

Topics: Imaging
Commentary by Dr. Valentin Fuster
2018;():V001T01A009. doi:10.1115/DMD2018-6887.
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The applications of sensing and localization are becoming more sophisticated in many invasive and non-invasive surgical procedures and there is great interest to apply them to the human heart. Ideally, such tools could be indispensable for allowing physicians to spatially understand relative tissue morphologies and their associated electrical conduction. Yet today there remains a steep divide between the creation of spatial environment models and the contextual understandings of adjacent features. To begin to address this, we explore the problem of anatomical perception by applying deep learning to the identification of internal cardiac anatomy images.

Topics: Anatomy
Commentary by Dr. Valentin Fuster
2018;():V001T01A010. doi:10.1115/DMD2018-6891.
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There currently exist many cardiac assist devices for the clinical treatment of congestive heart failure, which affects nearly 5 million Americans and costs the United States health care system nearly $32 billion annually [1]. The majority of these clinical devices help to improve cardiac perfusion by utilizing a blood pump — either pulsatile or continuous flow — cannulated to the circulatory system to create a parallel bypass for blood flow. These devices are typically very effective in the short term (days to months) but are typically limited by problems associated with chronic use [2]. Some of the most prevalent complications stem from the need for long-term system anticoagulation, invasive implant surgeries, catastrophic wear and tear of mechanical parts or drivelines, and infections at the percutaneous driveline site. Therefore, there is a great medical need to develop new or improve existing technologies to minimize and/or eliminate these adverse events.

Commentary by Dr. Valentin Fuster
2018;():V001T01A011. doi:10.1115/DMD2018-6905.
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Primary care physicians (PCPs) often lack the skills to distinguish the common innocent Still’s murmur from far less frequent but potentially serious pathological heart murmurs. This leads to approximately 800,000 children being referred to pediatric cardiologists each year for evaluation of heart murmurs in the United States [1–2]. The murmur is ultimately diagnosed as an innocent Still’s murmur in approximately 78% of these children (Children’s National Health System data). These unnecessary referrals and associated tests cost the healthcare system over half a billion annually, and are a source of avoidable anxiety for children and families while waiting to see a pediatric cardiologist.

Commentary by Dr. Valentin Fuster
2018;():V001T01A012. doi:10.1115/DMD2018-6907.
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In 2017, the American Heart Association reported that one third of deaths in the United States, and 31% of deaths worldwide, are attributed to cardiovascular disease (CVD) [1]. A risk factor pervasive across most types of CVD is chronic high blood pressure, or hypertension [2].

Commentary by Dr. Valentin Fuster
2018;():V001T01A013. doi:10.1115/DMD2018-6912.
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Peripheral Artery Disease (PAD) is a widespread and often undiagnosed condition associated with increased incidence of serious cardiovascular events. Current diagnostic tests for PAD may not be adequate for screening the large at-risk population. A new skin blood flow measurement technique using RF heating in the millimeter wave band, with simultaneous surface temperature measurement offers a potential method for screening individuals at risk for PAD quickly and easily. The feasibility of a transducer design incorporating a microstrip antenna and one or more infrared temperature sensors was evaluated in vitro, using a phantom skin material and a custom flow chamber. Results demonstrate the ability to heat the unperfused phantom by up to 7°C in less than 60 s, depending on antenna separation distance from the target surface. At a distance of 2 mm, preliminary results indicate the rate of temperature increase is sensitive to flowrate. These results suggest a possible method for noninvasive screening of individuals for PAD that is quick, easy and inexpensive.

Commentary by Dr. Valentin Fuster
2018;():V001T01A014. doi:10.1115/DMD2018-6919.
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Aortic aneurysm is a common disorder which is due to weakening of the aortic wall [1]. Aneurysm rupture is a potentially life threatening complication [2]. The stent graft implantation is one of the potential alternatives for treating patients at high risk for an open surgical procedure. The short-term outcome for stent implantation is promising; however, as with any medical procedure, this has potential limitations such as side branch occlusion, device malfunctions, dilatation at the proximal portion and the so called ‘endoleak’. An endoleak is the persistent blood flow into and within the aneurysmal sac after endovascular repair (i.e. the blood leaks around the endograft which is supposed to have sealed off the entry of blood around it and can be classified into 5 categories[3]). Type I (inadequate seal) and III (graft mechanical failure) endoleaks, characterized by direct communication between systemic and aneurysm sac compartments, pose higher risk of aneurysm rupture and are therefore aggressively treated [4]. Despite advances in the treatment of aneurysm, we believe that there is a still great need for a medical device that can improve patient outcomes.

Commentary by Dr. Valentin Fuster
2018;():V001T01A015. doi:10.1115/DMD2018-6930.
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Hypothermia (brain temperature < 35°C) shows great promise to minimize neural damage in patients with cardiopulmonary arrest and traumatic head injuries.[1, 2] However, cooling the whole body below 33–34°C can induce severe complications.[3] Arrhythmia, infection and primary coagulopathy are the most commonly noted complications.[3] We have developed a Selective Brain Cooling (SBC) approach which can be initiated early after injury, induces rapid cooling and maintains the target brain temperature over an extended period of time before slowly rewarming without significantly affecting the core body temperature.[4] In our experiments, brain temperature was measured invasively by inserting a thermocouple probe into the brain parenchyma, which measured brain temperature accurately but is invasive, making it unsuitable for most patients. Invasive intracranial probe also can have complications such as intracranial hemorrhage or hematoma and infection.[5] Accordingly, the clinical adaptation of our SBC technique requires a reliable, non-invasive and accurate method for measuring local brain temperature so that cooling and rewarming rate can be controlled during targeted temperature management.

Commentary by Dr. Valentin Fuster
2018;():V001T01A016. doi:10.1115/DMD2018-6948.
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Sleep apnea is characterized by abnormal interruptions in breathing during sleep due to partial or complete airway obstructions affecting middle-aged men and women on an estimated ∼4% of the population [1]. While the disorder is clinically manageable to relieve patients, the challenge occurs with diagnosis, with many patients going undiagnosed leading to further complications such as ischemic heart diseases, stroke etc. Sleep apnea also significantly affects the quality of day to day life causing sleepiness and fatigue. Polysomnography (PSG) technique is currently a used for detecting sleep apnea which is a comprehensive sleep test to diagnose sleep disorders by recording brain waves, the oxygen level in the blood, heart rate, breathing, eye and leg movements during the study. However, PSG test is very expensive, requires patients to stay overnight and is known to cause inconvenience to the patients.

Topics: Entropy , Sleep
Commentary by Dr. Valentin Fuster
2018;():V001T01A017. doi:10.1115/DMD2018-6949.
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Thermal ablation is rapidly becoming a standard of care for the treatment of atrial fibrillation (AF), a cardiac disorder characterized by irregular heart rhythm and estimated to impact more than 33 million people worldwide [1]. AtriCure is a company that specializes in epicardial ablation for AF and here we describe the development of a numerical model to study the performance of the Isolator® Synergy™ Clamp bipolar radiofrequency (RF) device. The clamp device features two jaws with embedded electrode pairs, which are used to secure the tissue by clamping across the left atrium (as shown in Figure 1). Energy is applied between the bipolar electrodes at approximately 460 kHz through an impedance-based control algorithm and is additionally duty-cycled between the pairs to further distribute the heating. Patient anatomies vary greatly and measured impedance will depend on atrial wall thickness, epicardial fat, electrode-tissue engagement, and structural variations. Further, tissue conductivity (inversely related to impedance) increases as the tissue is heated, leading to a complicated process, where the heat generation depends on the impedance, which in turn is a strong function of temperature. Energy delivery continues until a phase change in the tissue’s water content occurs, producing a sharp increase in impedance and termination of the ablation. Therefore, since tissue impedance and heating drive the device’s performance, a majority of the effort described here focuses on the validation work done to ensure the model is based on an accurate description of the tissue properties and response. While previous modeling of RF ablation often does include temperature-dependence of tissue properties, the referenced values vary notably and rarely include direct validation of modeling results to benchtop data. Variations in anatomy and fat content can dramatically impact the energy delivery and patient-to-patient treatment efficacy, so an accurate description of the tissue response is critical to understanding the limitations of current energy delivery algorithms and provides an invaluable tool in designing more efficacious ablation devices and algorithms.

Commentary by Dr. Valentin Fuster
2018;():V001T01A018. doi:10.1115/DMD2018-6963.
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Atrial Fibrillation (AF) is a common disease that may occur in the heart, especially as we age. AF is due to non-normal myocardial ectopic foci that then causes an uncoordinated atrium contraction. This effectively reduces the atrial kick to the ventricles, which can account for up to 20% of ventricular filling. While not an immediately fatal disease, it can cause reduced quality of life for patients and also puts them at increased risk for stroke. AF as a disease, is expected to affect over 50 million people in the United States alone by 2050 [1].

Commentary by Dr. Valentin Fuster
2018;():V001T01A019. doi:10.1115/DMD2018-6968.
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Medical imaging is one of common area that nowadays researchers uses human body images for clinical or medical science [1] [2]. Currently most of the diagnoses are performed by doctors after manual inspection of real time frames of the video generated by the respective medical imaging systems. In this paper, we propose to use digital image processing techniques in detection and categorization of the clogs in the arteries (stenosis/blockage) by using the frames generated from the X-ray angiography [3][4]. Utilized image pre-processing methods includes selecting a line of Interest (LOI) on blocked vessel and further selection of the region of interest (ROI) on that area, then automatically cropping the region of interest followed by Gaussian filtering for smoothing. In the post processing, three alternative methods are proposed to measure the stenosis in the vessel. The first method applies thresholding (Local) to extract the vessel of interest. The extracted vessel is analyzed for the calculation of the stenosis in percentage [5]. The second method utilizes segmentation (both edge-based and region-based) of the vessel tissue over the extracted pixels of ROI. The final method uses K-means clustering to differentiate between the vessel regions and non-vessel regions. Among the proposed methods K-means clustering based method outperforms the thresholding and segmentation methods.

Commentary by Dr. Valentin Fuster

Neuroengineering

2018;():V001T02A001. doi:10.1115/DMD2018-6899.
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Microinjection of genetic components and dye into organotypic slices provides excellent single cell resolution for unraveling biological complexities, but is extremely difficult and time consuming to perform manually resulting in low yield and low use in the developmental biology field. We developed a computer vision guided platform to inject specimen with mRNA, and/or dye and investigated the efficiency of the process using organotypic slices of the mouse developing neocortex. We demonstrate that the system significantly increases yield of injection relative to manual use by an order of magnitude, allows for cell tracking over 0, 24, and 48 hours post injection in culture, and enables mRNA translation of injected product. The autoinjector platform thus can open the door to new types of experiments including investigating effects of mRNA concentration, and composition on cell fate, and tracking these effects on cell reprogramming and lineage.

Commentary by Dr. Valentin Fuster
2018;():V001T02A002. doi:10.1115/DMD2018-6901.
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We are engineering neurotechnologies for large-scale cellular resolution activity mapping of the mammalian cortex. We have developed ‘brain windows’ — 3D-printed transparent cranial prostheses for chronic, optical access to the whole cortex. Using compatible imaging methodologies, we have demonstrated the pan-cortical activity map at multiple spatial scales — cellular to the mesoscale.

Topics: Prostheses
Commentary by Dr. Valentin Fuster
2018;():V001T02A003. doi:10.1115/DMD2018-6951.
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Electrical stimulation of neural tissue is a promising therapy for a variety of neurological diseases. For example, electrical stimulation of deep thalamic nuclei has been used extensively to treat symptoms of Parkinson’s disease, and there is growing interest in treating other conditions including epilepsy and depression with similar techniques. However, the mechanisms of electrical brain stimulation for disease therapy are not fully understood [1].

Commentary by Dr. Valentin Fuster
2018;():V001T02A004. doi:10.1115/DMD2018-6959.
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The tools and techniques available for systems neuroscientists for neural recording and stimulation during behavior have become plentiful in the last decade. The tools for implementing these techniques in vivo, however, have not advanced respectively. The use of these techniques requires the removal of sections of skull tissue without damaging the underlying tissue, which is a very delicate procedure requiring significant training. Automating a part of the tissue removal processes would potentially enable more precise procedures to be performed, and it could democratize these procedres for widespread adoption by neuroscience lab groups. Here, we describe the ‘Craniobot’, a microsurgery platform that combines automated skull surface profiling with a computer numerical controlled (CNC) milling machine to perform a variety of microsurgical procedures in mice. Surface profiling by the Craniobot has micrometer precision, and the surface profiling information can be used to perform milling operations with relatively quick, allowing high throughput. We have used the Craniobot to perform skull thinning, small to large craniotomies, as well as drilling pilot holes for anchoring cranial implants. The Craniobot is implemented using open source and customizable machining practices and can be built with of the shelf parts for under $1000.

Topics: Surgery , Computers
Commentary by Dr. Valentin Fuster

Orthopedics and Rehabilitation

2018;():V001T03A001. doi:10.1115/DMD2018-6804.
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The goal of this study was to construct a design methodology for a prosthesis which causes less stress shielding and meets fatigue requirements. Stress shielding is the reduction in bone stresses due to the introduction of an implant. Implants may become loose when stress shielding is present because bone resorption occurs as the bone adapts to the reduced bone stresses. Topology and lattice optimization were performed using OptiStruct to design a hip prosthesis where stress shielding and prosthesis fatigue were considered. The optimized design reduced stress shielding by 50+% when compared to a conventional generic implant, and the fatigue life met the ISO standards. Additionally, manufacturability was considered in the design process and a Ti-6Al-4V prototype was printed with an EOS selective laser melting machine.

Commentary by Dr. Valentin Fuster
2018;():V001T03A002. doi:10.1115/DMD2018-6809.
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Obstructive sleep apnea (OSA) is a condition characterized by temporary diminutions or cessations of breathing caused by repetitive collapse of the upper airway (UA) during sleep [1]. OSA is a common disorder — the American Academy of Sleep Medicine estimates the condition affects 29.4 million Americans — in which the muscles that hold the airway open weaken, resulting in partial or complete UA collapse during inspiration [2]. These pauses in breathing lead to blood oxygen desaturation and induce neurological arousal resulting in sleep disruption and fragmentation. The cycle of airway collapse and arousal can repeat hundreds of times per night.

Topics: Sleep
Commentary by Dr. Valentin Fuster
2018;():V001T03A003. doi:10.1115/DMD2018-6816.
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Nearly half of individuals with stroke experience some form of long-term disability and stroke is one of the main causes of wheelchair use in the United States [1]. Early rehabilitation in the acute phase of stroke has been shown critical to promoting motor plasticity and patient outcomes. However, research shows that only 32% of the time during inpatient rehabilitation is spent in active therapy, while the rest of the time is spent on other activities around the ward [2]. For walking impairment, it is especially important for patients to experience similar force loading and practice the patterning of gait in order to recover [3]. However, in a typical therapy session focused on gait rehabilitation patients only will take about 300 steps on average. This is far below what has been thought needed for humans to learn how to walk [4].

Commentary by Dr. Valentin Fuster
2018;():V001T03A004. doi:10.1115/DMD2018-6820.
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Natural human ankle motion includes dorsiflexion/plantarflexion (the major contributor to gait) as well as smaller contributions from inversion/eversion and abduction/adduction motions. Many of the commercially available passive prostheses for amputees are either stiff in all these motion directions or are compliant mainly in the dorsiflexion/plantarflexion direction. This can make it difficult for amputees to walk on uneven or sloped surfaces, and leads to increased risk of falling [1–4].

Topics: Prostheses
Commentary by Dr. Valentin Fuster
2018;():V001T03A005. doi:10.1115/DMD2018-6824.
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A quarter of a million people in the United States are affected by spinal cord injury (SCI), which causes loss of sensation and muscle function. Improvements in clinical care have resulted in a lower risk of mortality from initial complications like bedsores or urosepsis, though patients are more susceptible to long term conditions like coronary heart disease [1], which is a leading cause of death for SCI patients [2]. Patients with SCI have sedentary lifestyles, decreased aerobic fitness, and limited levels of oxygen uptake, which contribute to increased rates of cardiovascular complications [2]. To mitigate these factors, SCI patients must perform vigorous aerobic exercise, which can be done through functional electrical stimulation (FES) [3].

Commentary by Dr. Valentin Fuster
2018;():V001T03A006. doi:10.1115/DMD2018-6838.
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In this paper we present a device for improving blood oxygenation in patients with Acute Respiratory Distress Syndrome (ARDS). ARDS is caused by lung-related illness or injury, and can occur in mechanically ventilated ICU patients due to volutrauma or barotrauma. In ARDS, the lower lung is closed resulting in impaired gas exchange, and the upper lung is easily overstretched resulting in injury. The application of continuous negative abdominal pressure (CNAP) assists in opening the lower lung by pulling the diaphragm towards the abdomen. The device, consisting of a rigid arch, a compliant patient interface, and a pressure sensor module, allows for the application of CNAP to a patient suffering from ARDS.

An initial pig trial using the prototype device showed significant improvement in the ratio of oxygen in the blood to the fraction of inspired oxygen, PaO2/FiO2, after five minutes of −5 cmH2O pressure application. Furthermore, preliminary testing on healthy humans indicated the device was comfortable, easy to apply, and formed a consistent airtight seal. Future prototypes will focus on ease of application, rigidity, and adjustability.

Commentary by Dr. Valentin Fuster
2018;():V001T03A007. doi:10.1115/DMD2018-6845.
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Supporting body weight and balance control are foundations of our ability to move and function independently. However, neurological disease, injury, and aging often threaten these prerequisites of functional independence, leading to a decrease in quality of life. In the United States alone, 7.5 million individuals have survived stroke, traumatic brain injury (TBI), or spinal cord injury (SCI), and over a million new patients are diagnosed every year [1–2]. To improve gait function in these patient populations, partial body weight-supported gait training is a widely-used rehabilitation therapy. In general, the therapeutic quality of partial body weight-supported gait training is directly proportional to the amount of time patients are able to tolerate an upright posture (either standing or walking). To achieve an upright posture, therapists must first attach a support system (e.g., gait belt, harness lift system, exoskeleton), then several therapists must assist the patient into a standing position. Depending on the patient’s level of impairment, several therapists may also be needed to support and assist the patient while standing and walking, then again to remove the support system at the end of therapy. Accordingly, multiple therapists are often needed to provide a small quantity of upright physical therapy time with standard support systems. Furthermore, use of standard support systems can be uncomfortable and fatiguing for the patient, further reducing their actual therapeutic treatment time [3].

Commentary by Dr. Valentin Fuster
2018;():V001T03A008. doi:10.1115/DMD2018-6852.
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The American Board of Orthopaedic Surgery has mandated dedicated skills training for first-year orthopedic surgical residents.1 Most residency programs address this requirement with training exercises with cadavers and plastic foam bones. Some programs incorporate one or more simulators in their skills training, including several sophisticated virtual reality simulators and a variety of low-tech simulators. Simulators are helpful because they can provide repeatable educational experiences and quantitative performance assessment. Unfortunately, few simulators have been developed for orthopedic trauma skills training. Even fewer simulators have been developed and validated with more advanced students, such as residents in their 3rd or 4th year of training, and for more complex surgeries. In contrast to the completely virtual surgical simulation using haptic feedback devices and sophisticated renderings of soft tissue deformation, our group has chosen to use physical models, real surgical instruments and position tracking in conjunction with virtual reality.2–4 The physical models provide experience with the surgical tools, and enable more realistic hand movements and haptic cue feedback.

Commentary by Dr. Valentin Fuster
2018;():V001T03A009. doi:10.1115/DMD2018-6853.
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In 1964, Dr. Barrows first introduced the standardized patients, who are individuals trained to imitate the pathological symptoms of the real patients, and involved them in teaching and clinical skills assessment for healthcare education. In recent decades, the application of the virtual patient has been rapidly grown and has been widely used in clinical or educational practice among residents, surgeons, or other medical professionals because the virtual patient is cost-effective and time-efficient [1]. The Food and Drug Administration (FDA) collaborated with the Foundation of Research on Information Technologies in Society (IT’IS Foundation, Zürich, Switzerland) to produce a virtual family, which is a set of anatomical computer-aided design (CAD) models of adults and children [2, 3], and those CAD models are used in electromagnetic, thermal, and computer fluid dynamics simulations. However, the meaning of virtual patients or models has varied across the recent years and more and more researchers tried to categorize the terminology of virtual patients. In general, virtual patients can be classified into seven major types including: case presentation, interactive patient scenarios, virtual patient game, high fidelity software simulation, human standardized patients, high fidelity manikins, and virtual standardized patients [4]. The virtual patients discussed in this study can be classified as interactive patient scenarios, whose application includes clinical reasoning, surgical planning, and disease diagnosis.

Commentary by Dr. Valentin Fuster
2018;():V001T03A010. doi:10.1115/DMD2018-6868.
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A device to quantitatively assess the ulnar collateral ligament of the thumb was developed to facilitate rapid and accurate diagnosis of the ligamentous injury known as Skier’s thumb.

Topics: Wounds
Commentary by Dr. Valentin Fuster
2018;():V001T03A011. doi:10.1115/DMD2018-6889.
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There are 275,000 people in the US who have spinal cord injury (SCI) and there are about 12,500 new cases each year [1]. Among these 18.5% have incomplete paraplegia and 23% have complete paraplegia [1]. The number of patients experiencing mobility impairment caused by SCI is increasing because of accidents and disease [2,3]. Among people with SCI, 51% identified walking as first choice for a technology application [4].

Commentary by Dr. Valentin Fuster
2018;():V001T03A012. doi:10.1115/DMD2018-6894.
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The stiffness and damping of anatomical joints can be modulated by muscle co-contraction, where antagonistic muscles contract simultaneously, increasing both the joint’s stiffness and damping. In a second order system, the mechanical impedance, or simply impedance, is a function of the system’s inertia, damping, and stiffness. The ankle impedance can be defined as the resultant force due to an external motion perturbation. The impedance modulation of the human ankle is required for stable walking. The estimation of the time-varying impedance modulation of the human ankle is the focus of research by different groups [1,2].

Commentary by Dr. Valentin Fuster
2018;():V001T03A013. doi:10.1115/DMD2018-6931.
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Exoskeleton based rehabilitation for post-stroke recovery is being aggressively pursued due to unavailability of adequate number of caregivers and huge investment for the manual treatment [1]. The structural framework for providing different training exercises is not similar for all exoskeletons and there is no standardized protocol for rehabilitation following stroke [2]. Various approaches have been undertaken to come up with customized exoskeleton design for implementing a specific type of exercise. Though a few exoskeletons have proved to be beneficial in terms of clinical outcomes, there is still a long way to go before a useful rehabilitation device becomes acceptable to the users. After reviewing the 46 exoskeletons (commercial or prototypes) [3], two key requirements can be considered for the design of an exoskeleton; the structural parameter which decides the size, weight and the ease of control and the other is the nature of rehabilitation therapy which defines the type and intensity of the exercises performed during training.

Commentary by Dr. Valentin Fuster
2018;():V001T03A014. doi:10.1115/DMD2018-6932.
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The use of video games during exercise, exergaming, has been shown to increase energy expenditure without increasing perceived exertion [1]. This suggests that exergaming may be an effective way to engage a patient during rehabilitation and increase adherence to a rehabilitation regime. Existing exergame systems are designed with able bodied users in mind and often combine hand controlled game play while using lower limbs for aerobic exertion, making current systems inaccessible to individuals with spinal cord injuries and others without lower limb function. Our earlier work on increasing exercise accessibility includes developing an ergometer for supine use for patients who have recently had a flap procedure [2]. The goal of the present project was to create an engaging, interactive video game designed for use during arm ergometry by individuals with spinal cord injury (SCI) in either the supine or seated position.

Topics: Design , Wounds , Spinal cord
Commentary by Dr. Valentin Fuster
2018;():V001T03A015. doi:10.1115/DMD2018-6942.
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Most existing transtibial prostheses are energetically passive. Amputees using passive prostheses exhibit asymmetrical gait patterns [1], consume more metabolic energy [2–3], and walk at lower speed compared with able-bodied individuals [2–3]. As a result, powered transtibial prostheses are gaining increasing popularity. Several studies have shown that powered prostheses can improve the walking performance of the amputees [4–5]. However, most studies only focus on the importance of the ankle joint and few pay attention to the effects of toe joint during walking.

Topics: Prostheses
Commentary by Dr. Valentin Fuster
2018;():V001T03A016. doi:10.1115/DMD2018-6943.
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The human knee is a hinge joint, primarily facilitating locomotion. Knee joint instability, due to ligament injuries (anterior cruciate ligament [ACL], posterior cruciate ligament [PCL], medial collateral ligament [MCL] and lateral collateral ligament [LCL]), is a result of direct or indirect trauma, non-anatomical stresses during pivoting movements about the knee, imbalanced landing during jumping and rapid deceleration during high intensity locomotion [1]. Biomechanical indications of an unstable knee joint include decreased joint integrity, hyper laxity, abrupt locking and catching combined with clicking noises during locomotion. Approximately, two hundred and fifty thousand ACL injuries occur in the United States of America, annually [2].

Topics: Stress
Commentary by Dr. Valentin Fuster
2018;():V001T03A017. doi:10.1115/DMD2018-6945.
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A-priori research show that trans-tibial (TT) amputees display poor gait parameters when walking with passive mechanical ankle-foot prosthetics (AFP’s). This has large implications for the amputee populations in the developing world, who have limited access to advanced prosthetic technologies and instead rely on baseline AFP’s. Analysis of such baseline AFP’s in literature indicates that the predominant issue with these devices are their inability to adequately replicate the mechanics of a normal ankle during the stance phase of a walking gait cycle. This has shown to be a contributory cause of increased energy expenditure, as well as secondary complications such as osteoarthritis and joint deterioration.

This paper presents the design and analysis of a modular low-cost ankle-joint prosthetic (AJP) that serves as an attachment to existing prosthetic feet, with the intention to improve the ankle mechanics thereof. The AJP is modelled to reproduce ankle joint mechanisms, specifically controlled relative angular flexion in the sagittal plane, using only simple mechanical elements (i.e. compression springs instead of electronics). Initial results were positive, indicating that the AJP improves the stance phase mechanics of the baseline AFP in a simulated TT amputee gait cycle. During forefoot dorsiflexion rollover, an 80%–132% (p < 0.001) increase in joint angle and a 42–56% decrease in ankle stiffness (p < 0.001 for all but one participant) is observed. Following heelstrike a 22%–77% (p < 0.001) increase in joint angle is observed. However equipment and methodology errors left the moment response of this phase unverifiable. The overall conclusion of this paper is that the introduction of the AJP to baseline AFP’s supplies evidence of improved rollover shapes, easier phase transitions, and the facilitation of footflat during mid-stance.

Commentary by Dr. Valentin Fuster
2018;():V001T03A018. doi:10.1115/DMD2018-6947.
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The purpose of this report is to propose a new principle of minimally-required-assistance in the design of assistive devices for sensorimotor training in patients with neurological disorders. We illustrate the implementation of the principle in design and development of a novel assistive device for gait training in stroke survivors. Specific aims of this report are three folds including a brief review of literature on gait training after stroke, revision of movement specifics during gait in the context of task-specific training, and design of a novel assistive device for gait training.

Commentary by Dr. Valentin Fuster
2018;():V001T03A019. doi:10.1115/DMD2018-6952.
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The scope of the project was to design a pneumatic cylinder for measuring the resistive and applied force of the flexor pollicis longus (FPL) after anterior interosseous nerve (AIN) surgery. The patient’s distal section of the first phalange, of the thumb, is the area of evaluation. The device is intended for assessing both the quality of the surgery results as well as physical therapy progression. Criteria such as mobility, compact design, accuracy, repeatability, and ease of operation are some of the major requirements. The initial prototype is intended to collect FPL strength data to establish operating conditions.

Topics: Design , Testing
Commentary by Dr. Valentin Fuster
2018;():V001T03A020. doi:10.1115/DMD2018-6961.
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This study is aimed at the design of a novel task-based knee rehabilitation device. The desired trajectories of the knee have been obtained through a vision-based motion capture system. The collected experimental kinematic data has been used as an input to a spatial mechanism synthesis procedure. Parallel mechanisms with single degree-of-freedom (DOF) have been considered to generate the complex 3D motions of the lower leg. An exact workspace synthesis approach is utilized, in which the parameterized forward kinematics equations of each serial chains of the parallel mechanisms are to be converted into implicit equations via elimination. The implicit description of the workspace is made to be a function of the structural parameters of the serial chain, making it easy to relate those parameters to the desired trajectory. The selected mechanism has been verified for the accuracy of its trajectory through CAD modeling and simulations. This design approach reduces alignment and fitting challenges in an exoskeleton as the mechanism does not require alignment of each robotic joint axis with its human counterpart.

Commentary by Dr. Valentin Fuster

Urologic

2018;():V001T04A001. doi:10.1115/DMD2018-6839.
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Through a needs-based approach we sought to reduce instrument drops during endourological surgery. To this end, we designed and validated an endourology equipment organization device: the cord caddy. Iterative computer aided design and fused deposition model prototyping lead to the development of a machined functional prototype to accommodate the wide-variety of cables, cords, wires and equipment used in endourologic cases. Over 20 consecutive endourological surgeries, use of the cord caddy demonstrated that it met most of the design requirements, aside from disposability and basket/ureteroscope storage. Assessment of these requirements was precluded by the inability to test a sterile version of the device at our institution. Future plans include validating a sterile disposable device in the operating room.

Topics: Design , Surgery
Commentary by Dr. Valentin Fuster
2018;():V001T04A002. doi:10.1115/DMD2018-6909.
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The proposed 3D-printed template is a low cost and disposable devise which makes innovative registration-free procedure possible. The accuracy of the targeting is greatly improved due to its MRI-visible feature and precise design of needle insertion channels.

Commentary by Dr. Valentin Fuster

MEMS and Nano

2018;():V001T05A001. doi:10.1115/DMD2018-6811.
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3-D culture has been shown to provide cells with a more physiologically authentic environment than traditional 2-D (planar) culture [1, 2]. 3-D cues allow cells to exhibit more realistic functions and behaviors, e.g., adhesion, spreading, migration, metabolic activity, and differentiation. Knowledge of changes in cell morphology, mechanics, and mobility in response to geometrical cues and topological stimuli is important for understanding normal and pathological cell development [3]. Microfabrication provides unique in vitro approaches to recapitulating in vivo conditions due to the ability to precisely control the cellular microenvironment [4, 5]. Microwell arrays have emerged as robust alternatives to traditional 2D cell culture substrates as they are relatively simple and compatible with existing laboratory techniques and instrumentation [6, 7]. In particular, microwells have been adopted as a biomimetic approach to modeling the unique micro-architecture of the epithelial lining of the gastrointestinal (GI) tract [8–10]. The inner (lumen-facing) surface of the intestine has a convoluted topography consisting of finger-like projections (villi) with deep well-like invaginations (crypts) between them. The dimensions of villi and crypts are on the order of hundreds of microns (100–700 μm in height and 50–250 μm in diameter) [11]. While microwells have proven important in the development of physiologically realistic in vitro models of human intestine, existing methods of ensuring their surface is suitable for cell culture are lacking. Sometimes it is desirable to selectively seed cells within microwells and confine or restrict them to the microwells in which they are seeded. Existing methods of patterning microwells for cell attachment either lack selectivity, meaning cells can adhere and migrate anywhere on the microwell array, i.e., inside microwells or outside of them, or necessitate sophisticated techniques such as micro-contact printing, which requires precise alignment and control to selectively pattern the bottoms of microwells for cell attachment [12, 13].

Commentary by Dr. Valentin Fuster
2018;():V001T05A002. doi:10.1115/DMD2018-6812.
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Herein, we report on the motivation for, design of, and progress toward a microfluidic implementation of a digital potentiometer for various physical and life science applications.

Topics: Microfluidics
Commentary by Dr. Valentin Fuster

Sensors

2018;():V001T06A001. doi:10.1115/DMD2018-6888.
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Device companies commonly install memory chips in a disposable or semi-reusable attachment within a product assembly [1]. Attachment examples include single-use medical diagnostic sensors, reusable monitoring probes, disposable catheters and plug in tools having limited cutting, connection or sterilizing cycles. The memory chip provides information about the attachment to a hosting device that controls or operates the attachment. This stored information may include the attachment’s number of connections or uses, calibration coefficients [2] and the manufacturer or patient identification and date. This attachment data can then be used to enforce product requirements regarding reliability, accuracy, safety and brand [3,4]. For example, the host device can alarm the user, shutdown, or prevent attachment operation when the memory data is outside the product’s validated or tested limits.

Commentary by Dr. Valentin Fuster
2018;():V001T06A002. doi:10.1115/DMD2018-6904.
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Urinary incontinence (UI), defined by the International Continence Society as “the complaint of any involuntary leakage of urine” [1], is believed to affect at least 13 million people in the United States. Around 80% of people affected are women [2,3]. The most common type of UI in women is stress urinary incontinence (SUI) [4]. Although not identified as life-threatening, UI may lead to withdrawal from social situations and reduced life quality.

Commentary by Dr. Valentin Fuster
2018;():V001T06A003. doi:10.1115/DMD2018-6964.
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Wearable environment perception system has the great potential for improving the autonomous control of mobility aids [1]. A visual perception system could provide abundant information of surroundings to assist the task-oriented control such as navigation, obstacle avoidance, object detection, etc., which are essential functions for the wearers who are visually impaired or blind [2, 3, 4]. Moreover, a vision-based terrain sensing is a critical input to the decision-making for the intelligent control system. Especially for the users who find difficulties in manually achieving a seamless control model transition.

Commentary by Dr. Valentin Fuster

Surgical Tools

2018;():V001T07A001. doi:10.1115/DMD2018-6821.
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Most robots for minimally invasive surgery (MIS) are large, bulky devices which mimic the paradigm of manual MIS by manipulating long, rigid instruments from outside the body [1]. Some of these incorporate “wristed” instruments to place some local dexterity at or near the tool tip [2]. In contrast, a small number of MIS robot designs place all of the degrees of freedom inside the patient’s body in order to increase the local dexterity [3].

Topics: Robots , Design , Surgery
Commentary by Dr. Valentin Fuster
2018;():V001T07A002. doi:10.1115/DMD2018-6850.
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A craniotomy is a procedure where a piece of the skull is removed in order to gain access to the brain. This is commonly done to remove brain tumors, treat epilepsy, and to treat traumatic brain injury. Currently, the craniotomy procedure involves drilling one or more burr holes and then using a craniotome to complete the cut. The craniotome consists of a rotating cutting tool and a dura guard, which is intended to prevent the cutting tool from touching the dura. However, even with the dura guard, dural tears occur in approximately 20–30% of craniotomy procedures [1], [2]. There are approximately 160,000 craniotomies performed per year in the United States [3]. Dural tears add time to the craniotomy procedure due to the increased difficulty in suturing the dura and the potential need to use synthetic dura material in order to reclose the dura. Also, if the dura tears while using the craniotome, the brain is no longer protected as the craniotomy is completed. There is a strong desire among neurosurgeons to have an improved tool for craniotomies that reduces the incidence of dural tears.

Commentary by Dr. Valentin Fuster
2018;():V001T07A003. doi:10.1115/DMD2018-6856.
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Shape Memory Alloys (SMAs) are a unique class of smart materials that recover their deformed shapes, caused by a loading condition, through temperature changes [1]. SMAs are employed in a variety of areas including aerospace, automotive, and biomedical fields. Their Pseudoelastic characteristics, shape memory effects, and biocompatibility make them particularly suitable for medical applications.

Commentary by Dr. Valentin Fuster
2018;():V001T07A004. doi:10.1115/DMD2018-6857.
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Since the early discovery in 1951 [1], shape memory alloys (SMAs) have been used in design and development of several innovative engineering systems. SMAs’ unique characteristics have introduced unconventional alternatives in design and development of advanced devices. SMA’s field of applications has covered many areas from aerospace to auto industries, and medical devices [2]. During the past couple of decades, scientists have suggested material models to predict the SMA’s shape memory effect (SME) and its superelastic behavior. The superelastic characteristic of SMAs (its capability to exhibit a large recoverable strain) has been widely used to develop innovative products including biomedical implants such as stents, artificial heart valves, orthodontic wires, frames of indestructible spectacles, etc. However, its actuation capabilities, known as SME, hasn’t been thoroughly expanded. The number of products privileging from SMA’s SME behavior has been very limited. The reason relies on the SMA’s complex material properties that depend on the stress, strain and temperature at every stage of actuation as well as the material’s processing and the thermomechanical loading history.

Commentary by Dr. Valentin Fuster
2018;():V001T07A005. doi:10.1115/DMD2018-6858.
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Lung cancer is the second most common cancer in both men and women globally. More than one million lung cancer cases are diagnosed worldwide each year. The leading cause of cancer death is lung cancer in the United States and worldwide [1]. According to the American Cancer Society, there were an estimated 222,500 new cases of lung cancer and 155,870 deaths from lung cancer in the United States in 2017. Early detection and diagnosis, as well as accurate localization in lung intervention, are the keys to reducing the death rate from lung cancer [1].

Commentary by Dr. Valentin Fuster
2018;():V001T07A006. doi:10.1115/DMD2018-6864.
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In high-frequency (“HF”) monopolar electrosurgery (or radio-frequency ablation), high current density causes heating of tissue adjacent to a surgical instrument. HF current passes through tissue at a frequency sufficiently high to avoid stimulation of muscle, but intentionally causes I2R heating of tissue for the purposes of ablation, dissection, and coagulation. In addition to the surgical tool, a Neutral Electrode (“NE”, often called a “ground pad”, “return electrode”, or simply “pad”) contacts the patient to complete the electrical circuit, as shown in Fig. 1.

Topics: Electrodes
Commentary by Dr. Valentin Fuster
2018;():V001T07A007. doi:10.1115/DMD2018-6867.
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Prostate cancer is the third leading cause of cancer-related death for males in the United States [1]. Over three million Americans with prostate cancer were reported in 2016 [2] marking the prostate cancer as the most prevalent cancer among males in the US. In 2016, 180,890 new cases and 26,120 deaths were reported [1]. The prostate is a male reproductive gland located in the pelvis and surrounded by the rectum posteriorly and the bladder superiorly.

Commentary by Dr. Valentin Fuster
2018;():V001T07A008. doi:10.1115/DMD2018-6871.
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Minimally invasive surgery (MIS) has substantially improved surgery by reducing patient pain, discomfort, and tissue trauma [1]. MIS, however, has shortcomings including limited workspace, reduced surgeon’s dexterity, and poor eye-hand coordination [2]. Robot-assisted minimally invasive surgery (RMIS) has aimed to mitigate these limitations [3]. The da Vinci® Surgical System (Intuitive Surgical, Inc., Sunnyvale, CA) is the-state-of-the-art RMIS, in which the surgeon operates by using the console’s master controllers to maneuver the patient-side robotic arms, where the surgeon’s hand movements are refined through motion scaling and tremor reduction. Over half a million procedures are performed using the da Vinci annually [4].

Topics: Robotics , Surgery
Commentary by Dr. Valentin Fuster
2018;():V001T07A009. doi:10.1115/DMD2018-6890.
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Magnetic resonance (MR) imaging (MRI) has become the preferred method for medical diagnosis due to high resolution images and lack of ionizing radiation. Recently, the potential for using MRI to obtain real-time image feedback for targeted therapeutic procedures such as targeted biopsies and injections has been explored [1]. Some devices designed for intra-MRI use exist and more such devices are currently being developed and researched. Procedures often require precise positional targeting, such as injections and biopsies, and an MRI safe controlled-motion stepper motor is an ideal choice for actuating these mechanical devices. Some such drivers have been developed, but for various reasons, none are considered to be the standard for MRI use at this time. Therefore, a new design combining certain aspects of previous motors has been developed, making use of newer three-dimensional (3D) printers with extreme accuracy. Presented is a small, low-cost plastic four-cylinder piston stepper motor which is actuated by pressurized air. Connected to a plastic gearbox, this motor is capable of driving a rotational shaft at torques of up to 20 N·mm by increments of 3.6 degrees.

Commentary by Dr. Valentin Fuster
2018;():V001T07A010. doi:10.1115/DMD2018-6892.
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Computer-assisted interventions (CAI) — which offer advantages such as increased accuracy, reduction of complications, and decreased intervention time — have increased in prevalence in recent years. A type of CAI called image-guided therapy (IGT) can be used to provide navigation for freehand procedures or guidance for localization of medical devices. Electromagnetic (EM) tracking technology can track instruments such as needle tips inside the patient body without the need for a line-of-sight, allowing for minimally invasive imaging-guided procedures [1–3].

Commentary by Dr. Valentin Fuster
2018;():V001T07A011. doi:10.1115/DMD2018-6911.
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Robot assisted minimally invasive surgery helps overcome some of the limitations like limited dexterity, fulcrum effect, and lack of 3D vision in manual laparoscopic procedures [1]. A Remote Centre of Motion (RCM) mechanism is an essential part of tele-operated surgical robots. An RCM mechanism enables a rigid surgical tool to maintain a kinematic constraint about the insertion point on a patient’s body [2]. It permits a surgical tool to pivot only about the insertion point and prevents tool translation about the insertion point [3]. A parallelogram architecture based RCM mechanism is one of the most commonly used RCM mechanisms in surgical robots [4] due to its simplicity and large usable range of motion. Commercially available surgical robots such as da Vinci™ from Intuitive Surgical Inc. [5] use synchronous transmission [2] based passive RCM mechanism as a substitute for parallelogram based RCM.

Topics: Robotics , Surgery
Commentary by Dr. Valentin Fuster
2018;():V001T07A012. doi:10.1115/DMD2018-6913.
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Tube Thoracostomy (TT) is a surgical procedure involving the insertion of a plastic tube into the patient’s pleural cavity with the purpose of evacuating the air or fluid contents that have abnormally accumulated in this space [1]. Chest tube insertion has been identified as part of a core set of skills needed in a physician’s repertoire when caring for an injured patient [2]. Iatrogenic injuries, traumatic injuries, as well as malignancy, are the likely clinical scenarios were tube thoracotomy may be required. The presentation of these clinical events can be classified into three broad categories: pneumothorax, hemothorax, and pleural effusion, all of which lead to the abnormal accumulation of air, blood, or lymphatic fluid within the pleural space, respectively.

Commentary by Dr. Valentin Fuster

Computer Modeling and Simulation

2018;():V001T08A001. doi:10.1115/DMD2018-6818.
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Obstructive Sleep Apnea (OSA) is a prevalent disease among adults and children (Macey, Woo, Kumar, Cross, & Harper, 2010). Patients with OSA have recurrent episodes of airflow limitation during sleep, which lead to daytime sleepiness and several comorbidities, including cardiovascular diseases (Durán, Esnaola, Rubio, & Iztueta, 2001). During the episode of OSA, the airway is partially occluded (hypopnoeas) or totally blocked (apneas). Since the velopharynx is the narrowest segment of the pharyngeal airway, the local air velocity increases significantly leading to the large decrease in the intraluminal pressure. The relationship between the distribution of the minimum pressure and the anatomical geometry of the airway is thus very important. Hence, understanding the mechanical interaction between the soft palate and air flow is important in investigating OSA pathology.

Commentary by Dr. Valentin Fuster
2018;():V001T08A002. doi:10.1115/DMD2018-6832.
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Colorectal surgery is widely performed to re-establish the bowel, the part of which is removed because of diverticulitis, intestinal polyps, inflammatory bowel and cancer. Stapled anastomosis is a highly standardized technique and considered the standard of care. However, complications like leakage, stenosis and postoperative bleeding cannot be completely avoided [1,2]. There is limited understanding of the impact of staplers on tissue and basic mechanics of tissue stapling. According to the previous research, compression, staple height, tissue thickness, tissue compressibility, and tissue type have an effect on the patient outcomes [3]. Hence, we conducted this prospective study to analyze the effect of staple height on tissue damage and compression pressure. An attempt was made to determine the relationship between the tissue height and the optimal closed staple height.

Commentary by Dr. Valentin Fuster
2018;():V001T08A003. doi:10.1115/DMD2018-6834.
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Fracture toughness is an important mechanical property of materials that describes the failure of material by cracking. Yet, characterizing fracture toughness in soft tissue cutting is still a challenging task as the behavior of the soft tissue may vary under different tissue, cutting and pre-crack conditions [1]. Predicting cutting force has been important to needle biopsy design, surgical planning/training, and other surgical operations. However, in order to obtain accurate predictions, understanding the fracture toughness is crucial. In this study, we present an approach to characterize the fracture toughness directly from cutting experiments of hollow needle cutting soft tissue mimicking materials. Cutting tests are carried out to obtain the dynamic force response of gelatin samples when being cut by non-rotational and rotational hollow needles. The data is used to establish a mixed-mode fracture behavior which is then used to implement a cohesive surface based finite element model. Nearly 1% difference of the axial cutting force between the simulation and experimental results showed that the approach is capable of predicting accurate cutting force in rotational needle biopsy. The approach also has the potential to be used to predict the cutting force in various types of needle biopsy.

Commentary by Dr. Valentin Fuster
2018;():V001T08A004. doi:10.1115/DMD2018-6837.
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Transcatheter closure of ventricular septal defect (VSD) has become an alternative therapy to open-chest surgery because of simple procedure, less invasion, and high safety [1–2]. The most important occluder device of the therapy is double-disc structure which occludes the VSD, with the discs of the occluder clamp the margin of VSD while the waist of the occluder supports the VSD hole (Figure 1(a)). Commercially available occluders are woven by 72 nitinol wires (Figure1(b)) and then formed by heat treatment. However, the implantation of metal occluders in perimembranous part will result in a substantial risk of complete atrioventricular block (cAVB) averaging 3.5%, because of its close proximity to the conduction system, which passes at the posterior border of defects [3]. To improve the biocompatibility, Huang [4] developed biodegradable VSD occluders (Figure 1(c)) which woven by polydioxanone (PDO) wires and can be fully absorbed within 24 weeks after implantation.

Commentary by Dr. Valentin Fuster
2018;():V001T08A005. doi:10.1115/DMD2018-6840.
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Minimally invasive surgery (MIS) requires ports to be placed through the body wall in a manner such that instruments can reach a desired area. Limitations of laparoscopic surgery include maintaining triangulation and ergonomics for the surgeon while allowing access to the anatomy with non-wristed instruments [1]. In robotically-assisted MIS, the surgeon does not stand bedside, and they have wristed instruments that the robot manipulates. Limitations of robotically-assisted MIS include range of motion (ROM) limits and decreased spatial awareness, resulting in the potential for interfering robotic components. As a result, port placement varies between laparoscopic and robotically-assisted surgery.

Topics: Optimization , Surgery
Commentary by Dr. Valentin Fuster
2018;():V001T08A006. doi:10.1115/DMD2018-6866.
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Currently, stent therapy constitutes to over 95% of all endovascular interventions. The biological and clinical complications of stent therapy can now be well controlled with modern techniques and procedures. However, the mechanical failure of stent remains an important clinical problem [1]. While there is a consensus that such failure usually proceeds through mechanical fracture activation due to fatigue, the mechanisms of fracture activation are not well understood. The virtual analysis of fracture is typically conducted using the Finite Element Method (FEM) model regulated by the externally applied criteria of fracture nucleation. Typically, the FEM model must deal with ambiguity of derivatives of displacement at discontinuities and should contain requirements on mesh size to resolve material damage. In this study, we pursue an alternative approach, called peridynamics, to depict the mechanism of fracture activation. Peridynamic damage model does not require special criteria to guide crack or damage growth and naturally accounts for surface roughness that can highly influence fatigue life of stent.

Commentary by Dr. Valentin Fuster
2018;():V001T08A007. doi:10.1115/DMD2018-6872.
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Every year in the United States, 4,500 deaths occur from abdominal aortic aneurysm (AAA) rupture. Aneurysms develop when the arterial wall weakens. Many risk factors can contribute to aneurysm formation, including age, sex, ethnicity, smoking and hypertension [1]. AAAs are the most common form of aneurysm because the aorta experiences the highest wall shear stress (WSS) of any vessels in the human body. These aneurysms are 5–6% prevalent in men and 1–2% in women, both over 65 years of age [2]. In the aorta, high WSS causes plaque formation, but in peripheral arteries where the flow rate is lower, atherosclerosis can also trigger aneurysm formation.

Commentary by Dr. Valentin Fuster
2018;():V001T08A008. doi:10.1115/DMD2018-6873.
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As the medical field continues to increase its effectiveness and scope, computational fluid dynamics (CFD) has become essential to understanding flow mechanics cardiovascular systems. Many simulations and experiments have been conducted to confirm the behavior of blood within veins and arteries, under both Newtonian and non-Newtonian conditions. Traditionally, these simulations have been conducted where blood is represented as a homogeneous fluid. However, blood is a heterogeneous fluid mixture, consisting of fluid plasma and solid components of red blood cells (RBC), white blood cells (WBC), and platelets. The effects of the heterogeneity of blood becomes more influential in blood flows through smaller diameter vessels and high velocity flows, as the addition of particles will create variations in flow speed, shear stress, and fluid displacement due to particle-particle and particle-wall collisions [1].

Commentary by Dr. Valentin Fuster
2018;():V001T08A009. doi:10.1115/DMD2018-6895.
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Advances in technology are making virtual reality (VR) available for many different interests. Inexpensive commercially available hardware can be setup at home [1,2], while corporations are using VR to design mechanical systems and train pilots [3,4]. However, limited application is seen in the medical field.

Commentary by Dr. Valentin Fuster
2018;():V001T08A010. doi:10.1115/DMD2018-6916.
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Transcatheter replacement therapies for the atrioventricular (AV) valves are considered as the next frontier for the treatment of valvular regurgitation. The AV valves, tricuspid and mitral, are the regulators of blood flow from the atria into the ventricles. During diastole, blood flows through the open tricuspid and mitral valves to fill the right and left ventricles, respectively. During systole, the ventricles contract, closing the AV valves, and forcing the blood to exit through their respective ventricular outflow tracts (VOTs) to the arterial circulations. Although the current gold standard for the treatment of valvular regurgitation is surgical replacement or repair, the field of transcatheter therapies is rapidly expanding as new treatment options for patients; especially for those individuals considered to be at greater risks for surgical complications. Market released bioprosthetic devices for replacing the aortic and pulmonary valves have shown great promise and success. However, the advancement of similar therapies for either the mitral and tricuspid valves remain in the early stages of development. This slower progress is attributed to the high complexities and variabilities of the AV valves, which present challenges for both device design and post-implantation functions.

Commentary by Dr. Valentin Fuster
2018;():V001T08A011. doi:10.1115/DMD2018-6928.
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Nowadays, “personalized medicine” is starting to replace the current “one size fits all” approach. The goal is to have the right drug with the right dose for the right patient at the right time and location. Indeed, conventional pulmonary drug delivery devices still have poor efficiencies (<25%) for delivering drugs to the lung tumor sites. Major portions of the aggressive medicine deposit on healthy tissue, which causes severe side effects and induces extra health care expenses. Therefore, a new targeted pulmonary drug delivery method is proposed and evaluated using the Computational Fluid-Particle Dynamics (CFPD) method to achieve the lobe-specific delivery. By controlling the release position and velocity of the drug particles at the mouth inlet, drug deposition efficiency (DE) in a designated lobe can be increased up to 90%. Intersubject variability has also been investigated using the noninvasive in silico tool. Results indicate that the glottis constriction ratio is a key factor to influence the effectiveness of the purposed targeted drug delivery method. Although lobe-specific pulmonary drug delivery can be realized, the actuation flow rate must be lower than 2 L/min, and the glottis constriction ratio has a significant impact on the effectiveness of the targeting method. Also, a design idea using e-cigarette as the prototype is proposed as the next-generation inhaler to accommodate the operational flexibility restrictions.

Commentary by Dr. Valentin Fuster
2018;():V001T08A012. doi:10.1115/DMD2018-6934.
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There has been an increasing amount of interest in the design and preparation of new biomaterials that can be used in the fabrication of medical devices for artificial prostheses or implant applications. The use of molecular modeling and computational chemistry aids in the design of these materials by calculating different structural properties such as molecular energy, geometry optimization, dipole moments, FTIR, UV-vis, NMR, and others. In this study graphene, polyurethane (PU), polymethylmethacrylate (PMMA) and PU/graphene/PMMA composites have been studied using theoretical calculations. For this work, the AMBER and AM1 simulation methods were used. The results indicate the favorable formation of a cross-linked PU/Graphene composite and adsorption of PMMA.

Commentary by Dr. Valentin Fuster
2018;():V001T08A013. doi:10.1115/DMD2018-6935.
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In the present work the physical-chemical and energetic properties of the molecules of hydrogels about chitosan crosslinking with genipin were studied in the adsorption process of Metformine and Glibenclamide. The analysis was done by means of PM6 model in order to obtain the necessary data base to establish their potential use as transdermal controlled release systems. Currently, the drugs (metformine and glibenclamide) are administered orally, however, there are already several oral medications that have been presented as transdermal administration systems (SAT), with great advantages, such as patient comfort and zero order release. Drugs before mentioned, are especially important in chronic diseases such as type 2 diabetes.

Topics: Hydrogels
Commentary by Dr. Valentin Fuster
2018;():V001T08A014. doi:10.1115/DMD2018-6957.
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Stent implantation is widely used to treat blocked lumen. Stents were meshed structure made of polymers and metal alloys, including stainless steel, cobalt chrome and nitinol [1]. Clinical studies had demonstrated that stents helped to scaffold the diseased lesion up to one year when tissue adapted to the stented environment [2]. However, the permanently implanted stents inside artery were associated with complications such as stent fracture, tissue inflammation, in-stent restenosis and thrombosis [3]. Currently, biodegradable stents are attracting more attention due to its potential long-term efficacy in treating blocked lumens. The detailed characterizations of biodegradable stents are essential for the desired clinical outcomes.

Commentary by Dr. Valentin Fuster
2018;():V001T08A015. doi:10.1115/DMD2018-6966.
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Newly developed interactive tutorials and applications which teach human anatomy are often set up as pay-to-play websites. Examples of these include the Visible Body app1 and the 3D Organon Anatomy2. Though these applications can be very educational, they may be costly, thus many students and members of the education community will not access these programs because of the upfront charges. These teaching programs are also frequently anatomically limited because they utilize idealized models, like KineMan3, instead of renderings or imaging data sets obtained from humans (clinical or from cadavers). This characteristic may make them useful study tools, but will not best prepare future doctors, nurses, and other health professionals for true, variable patient anatomies they will encounter in their various practices. Further, such students would likely gain more by studying 3D objects of real human anatomies instead of 2D images. We have designed a strategy to bring 3D human anatomies from real cadavers to the scientific and education communities completely open source (free of charge). Our interactive application is geared toward students of all ages (grade school to medical school) or by anyone interested in learning more about human bone anatomy.

Topics: Bone , Teaching
Commentary by Dr. Valentin Fuster

Human Factors

2018;():V001T09A001. doi:10.1115/DMD2018-6848.
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Anterior cruciate ligaments (ACL) injuries account for a significant proportion of all sports-related injuries. Despite successful completion of a rehabilitation program, about 35% of ACL patients experience re-injury after return to sport, and studies have identified persistent quadriceps strength deficits as a potential cause [1–3]. Deficits in quadriceps strength can be monitored throughout rehabilitation using muscle strength testing. The most common test protocol involves isometric testing of quadriceps strength whereby the knee is extended against a static resistance. In this method, the clinician uses their strength to resist the patient’s motion and subsequently assigns a qualitative value of strength. The highly subjective nature of this test has motivated clinicians to use devices that can more accurately assess quadriceps strength.

Commentary by Dr. Valentin Fuster
2018;():V001T09A002. doi:10.1115/DMD2018-6920.
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Cardiovascular, orthopedic, and interventional radiology procedures using fluoroscopy require healthcare professionals to wear heavy lead garments for radiation protection, sometimes for up to 12 hours per day. Wearing lead garments for prolonged periods of time can lead to musculoskeletal injuries, discomfort, and fatigue. MobiLead is a mobile lead garment frame that was developed to reduce the weight supported by the user in an effort to mitigate these problems. The MobiLead system moves the lower garment load off the user’s body to a structural ground-supported frame and redistributes the upper load from the shoulders to the hips through a torso frame. The system is compact and maximizes the limited space available in operating rooms, while still giving the surgeon adequate mobility for various emergency procedures. Preliminary analysis of device effectiveness was conducted using electromyography and qualitative surgeon user feedback surveys. This paper will discuss the design, fabrication, and testing procedures for this mobile radiation protection system optimizing both support and mobility.

Topics: Stress , Orthopedics
Commentary by Dr. Valentin Fuster
2018;():V001T09A003. doi:10.1115/DMD2018-6956.
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Patients are frequently prescribed a medication that must be administered either by a nasal spray, an inhaler, or a self-injection device. These devices are classified as combination devices by the Food and Drug Administration (FDA) and the Medical Device Regulations (MDR). However, there has been an issue of who and how do these patients get trained. It has long been the stance of the pharmaceutical companies they will not provide training because they provide an Information for Use (IFU) and/or a demo on their website. The issues with either of these means is that neither the FDA, nor the MDR permit them as mitigation for use errors. And, in human factors testing there are considerable numbers of use errors when patients attempt to use the devices.

Commentary by Dr. Valentin Fuster

Wearables

2018;():V001T10A001. doi:10.1115/DMD2018-6806.
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Chronic back pain is a disorder which affects a large portion of the American population at some time during their lifespan. There are many causes for lower back pain and usually can be an indicator of a serious medical condition. This problem plagues the nation and the world leading to an estimated annual cost for back pain treatment amounts to $50 billion. This problem isn’t isolated to just the United States either, the world at large suffers from back pain and unfortunately modern treatment methods are effective but the technology simply hasn’t progressed in decades. The main drawback appears to be the rigidity of the device, which limits flexibility and comfort. The soft pneumatic actuators of this newfound device have the potential to provide the appropriate applications chronic back pain suffers and post-surgery patients.

In this work, the design and development of a soft robotic back orthotic device that has the capability to relieve back pain by assisting patients to fully achieve the upright position and stabilize the lumbosacral spine, is presented. The soft robotic actuators of this device allow the support to be disabled when the patient is in a supported position. Unlike conventional robotic assistive devices, this pneumatically actuated back orthosis provides dynamic support while being lightweight, comfortable, and cost affordable. After testing the device in a laboratory environment, the data overall displays a trend decreasing in EMG activity of the Erector Spinae muscles. This reduced activity leads to a reduction in strain on the patient.

Topics: Design , Robotics , Orthotics
Commentary by Dr. Valentin Fuster
2018;():V001T10A002. doi:10.1115/DMD2018-6808.
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Shoulder overuse syndrome (SOS) is a fatigue-related condition caused by repetitive motion or excessive practice, common amongst wheelchair users. Diagnostic treatment methods for SOS include physiotherapy sessions, kinesiology tapes and few other measures. Many commercial devices available in the market targeting rehabilitation and recovery of shoulder pathologies are expensive and inaccessible for in-home treatment. A detailed survey of the rehabilitative devices for upper limbs is given in [1]. Although, prognostic measures to avoid SOS in wheelchair users such as taking smoother strides and altering wheel stroke mechanics have been suggested [2], [3], there is a clear lack of assistive devices that augment the shoulder joint muscles during wheelchair propulsion.

Topics: Robotics , Wheelchairs
Commentary by Dr. Valentin Fuster
2018;():V001T10A003. doi:10.1115/DMD2018-6822.
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Advances in ankle-foot orthosis (AFO) technology have been trending toward more powerful and lightweight devices. A hydraulic series elastic actuator (HSEA) was explored to design a lightweight powered AFO that meets the high peak power demand of ankle gait. With its excellent power density and its ability to separate the power supply from the actuator using a hose, hydraulic power was used, combined with an SEA that takes advantage of the high-peak and low-average power profile of ankle gait to store energy and release it during the push-off stage of gait. The parameters required for the SEA were determined and validated using simulation. A gait pattern that would require 235W of motor power was able to be tracked using a motor rated at 95W. The actuator weight of the hydraulic ankle-foot orthosis (HAFO) at the ankle was 0.35, which is 43% of an equivalent electromechanical system. A novel design of an HSEA with a clutch capability is proposed for future HAFO applications.

Topics: Actuators , Orthotics
Commentary by Dr. Valentin Fuster
2018;():V001T10A004. doi:10.1115/DMD2018-6874.
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The paper describes a stretchable piezoelectric nanogenerator that is intended to harvest energy. The nanogenerator was fabricated from zinc oxide (ZnO) piezoelectric thin film embedded in polymer materials. The microfabricated nanogenerator has the thickness in the micrometer scale to be attached on the skin and stretched by the natural movements of arms, legs or neck. We expect that energy harvested by this device will be able to power wearable skin sensors.

Topics: Skin
Commentary by Dr. Valentin Fuster
2018;():V001T10A005. doi:10.1115/DMD2018-6884.
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Medical compression garments are used to treat lymphatic disorders or conditions of poor venous return (e.g. orthostatic intolerance). Conventional compression garments, namely elastic compression sleeves and inflatable compression systems, may aid in relief of these conditions but are also limited in usability. Fixed levels of compression in elastic materials may induce challenges in donning/doffing, complicating patient compliance [1]. Compression levels in inflatable systems are customizable, but these garments are also bulky and require a tethered inflation source [2]. We are interested in developing easy-to-don/-doff compression garments using shape memory alloy (SMA) coil actuators that contract with heat from an applied current which can be wrapped around the body to apply compressive forces. More specifically, we use a spring coil formation as described by Holschuh et al. [3]. Further developed in the Wearable Technology Lab at the University of Minnesota, our current SMA compression garment (SMA-CG) design improves upon the work of Duvall et al. [4] presented in previous year’s (2017) Design of Medical Devices Conference, representing a year’s evolution in active compression garment design that integrate actuators made with SMA.

Topics: Compression , Tension
Commentary by Dr. Valentin Fuster
2018;():V001T10A006. doi:10.1115/DMD2018-6886.
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Postural orthostatic tachycardia syndrome (POTS) is a clinical autonomic disorder characterized by a spike in heart rate and syncope in response to orthostasis, symptoms which then dissipate upon recumbency [1]. Additional symptoms include chronic fatigue, bloating, and nausea [2]. POTS predominately affects females (5:1) between the ages of 15 and 50 years [3]. It is estimated 1 to 3 million are affected by POTS in the United States [4]. While there is no known cure, symptom management requires a multifaceted approach, including physical exercise, counter maneuvers, high salt and fluid intake, and medications, including beta blockers and fludrocortisone [3]. Lower body compression is a core component to POTS treatment, especially during prolonged periods of upright posture. Because POTS disproportionately affects young, otherwise healthy females who have high physical and professional demands, compression garments (CG) are critical to allow this population to carry out their activities of daily living [5].

Topics: Compression
Commentary by Dr. Valentin Fuster
2018;():V001T10A007. doi:10.1115/DMD2018-6906.
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Patients with neuromuscular disorders such as Parkinson’s disease (PD), traumatic brain or spinal cord injury, or multiple sclerosis (MS) can develop different levels of abnormal muscle behavior (hypertonia) such as rigidity and spasticity [1], [2]. Hypertonia can affect different parts of the body such as upper or lower extremities. Symptoms include pain, increased muscle tone, spasms, and decreased functional abilities. Hypertonia can interfere with many activities of daily living, greatly affecting the quality of life in patients and causing anxiety, depression, and social isolation [2].

Topics: Stiffness
Commentary by Dr. Valentin Fuster
2018;():V001T10A008. doi:10.1115/DMD2018-6914.
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The thermochromic device is a low-cost 3D-printed bracelet. It has the function of reading body temperature and warns individuals of the potential risk for heat related illnesses. The product is created from a thermochromic resin that is sensitive to temperature. This product can be customized to fit different age groups such as children and elders. Combined with the smartphone application, the device can provide realtime body temperature monitoring and alert to people who are vulnerable to heatstroke.

Commentary by Dr. Valentin Fuster
2018;():V001T10A009. doi:10.1115/DMD2018-6915.
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When considering how to design medical devices considering the needs of the patient and hospital staff may seem sufficient. Hospitalized infants are patients who cannot speak or advocate for their needs; the parents and the hospital staff caring for infant patients have different roles that together are integral to an infant’s recovery. Figure 1 shows how mothers, nurses, and infants form a system of care to promote infant patient healing. In particular caregiver behaviors such as kangaroo care (KC), are dependent upon the involvement of family. KC, defined as bare skin-to-skin contact between an infant and an adult caregiver, is usually done chest-to-chest. The design of wearables for the caregivers holding the infant patient can make KC easier and be part of wearable medical device design that improves infant patient outcomes.

Commentary by Dr. Valentin Fuster
2018;():V001T10A010. doi:10.1115/DMD2018-6918.
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Parkinson’s disease (PD) and essential tremor (ET) are two common but unrelated diseases that cause movement disorders often involving with severe tremor. The two diseases affects tens of millions of people worldwide, but there is no known cure for them. The tremor not only pose difficulty in completing daily tasks but also impair patients’ social confidence. The objective of this project is to develop a wearable tremor reduction device for the upper limb. The device is obviously different from any previous devices because it is compact, lightweight, comfortable to wear and effective. It is expected to help patients manage the tremor symptoms and regain their normal life.

Commentary by Dr. Valentin Fuster
2018;():V001T10A011. doi:10.1115/DMD2018-6921.
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Roboticists have developed a diverse array of powered exoskeletons for human augmentation and rehabilitation over the last few decades. One of the key design objectives is to minimize the discomfort to enhance the user experience. The high inertia and joint misalignment of conventional rigid exoskeletons are two key factors that cause these problems. Different types of control algorithms have been developed to compensate the inertia and render low impedance to the wearers [1–2].

Commentary by Dr. Valentin Fuster
2018;():V001T10A012. doi:10.1115/DMD2018-6922.
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The human hand has extraordinary dexterity with more than 20 degrees of freedom (DOF) actuated by lightweight and efficient biological actuators (i.e., muscles). The average weight of human hand is only 400g [1]. Over the last few decades, research and commercialization effort has been dedicated to the development of novel robotic hands for humanoid or prosthetic application towards dexterous and biomimetic design [2]. However, due to the limitations of existing electric motors in terms of torque density and energy efficiency, the design of humanoid hands has to compromise between dexterity and weight. For example, commercial prosthetic terminal devices i-Limb [3] and Bebionic [4] prioritize the lightweight need (450g) and use 5-DOF motors to under-actuated 11 joints, which is only able to realize a few basic grasp postures. On the other hand, some humanoid robot hand devices like DLR-HIT I & II hands [5] prioritize the dexterity need (15 DOF), but weigh more than four times than their biological counterpart (2200g and 1500g, respectively).

Topics: Density , Torque , Actuators , Design
Commentary by Dr. Valentin Fuster
2018;():V001T10A013. doi:10.1115/DMD2018-6937.
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This study is aimed at exploring the prediction of the various hand gestures based on Force Myography (FMG) signals generated through piezoelectric sensors banded around the forearm for the implementation of a control system in a prosthetic hand. Matlab, Simulink software has been utilized for the analysis and classification. Several classification and recognition models have been considered, and the Tree Decision Learning (TDL) and Support Vector Machine (SVM) have shown high accuracy results. Both of these estimated models generate above ninety five percentage of accuracy in terms of classification. As the classification showed a distinct feature in the signal, a realtime control system based on the threshold value has been implemented in the prosthetic hand. The hand motion has been recorded through Virtual Motion Glove (VMD) to establish dynamic relationship between the FMG data and the different gestures through system identification. The classification of the hand gestures based on FMG signal will provide a useful foundation for future research in the interfacing and utilization of medical devices.

Commentary by Dr. Valentin Fuster
2018;():V001T10A014. doi:10.1115/DMD2018-6953.
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The goal of this study was to develop a wearable olfactory augmentation device (Fig. 1) that provides an intuitive and objective delivery of complex olfactory information via haptic feedback, in the form of cutaneous vibrotactile stimuli, in order to enhance environmental awareness of odor signals. The hypothesis is that displaying olfactory information through the skin enables intuitive and prompt identification of potentially hazardous chemicals and odors before they pose actual threats to the human body. In this work, an olfactory augmentation prototype is designed and manufactured, and experiments are conducted to assess the performance of device components and to improve the functionality of the device.

Commentary by Dr. Valentin Fuster
2018;():V001T10A015. doi:10.1115/DMD2018-6962.
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The field of control of powered lower-leg prostheses has advanced due to the improvements in sensors and computational power. Much effort has been done to improve the capabilities of prostheses, such as mimicking the stiffness, weight, and mobility of a human ankle-foot [1] and autonomously commanding the robotic prosthesis for gait [2].

Topics: Prostheses
Commentary by Dr. Valentin Fuster
2018;():V001T10A016. doi:10.1115/DMD2018-6965.
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Temperature is an important influencer of homeostatic comfort for humans, and its influence extends beyond life-preservation functions into cognitive and emotional effects. To augment metabolic processes in cold climates, many on-body heating solutions are currently available in the commercial market, ranging from chemical heat packs to electrically heated accessories and clothing. These products typically prioritize heating the body core in extreme conditions. By contrast, the experience of thermal comfort in the band around homeostatic comfort temperatures is much more strongly driven by experience of temperature in the body’s periphery: the hands, feet, and face [1]. Thermal sensitivity is highest in the distal extremities and has been established as the best correlate of overall perception of thermal comfort [2], [3]. In the medical context, this is especially significant in treating vasospastic disorders such as Raynaud’s Syndrome, where a spastic vascular response in peripheral vessels results in an over-reaction to cold temperatures proximal to the thermoneutral zone [4].

Commentary by Dr. Valentin Fuster

Special Devices

2018;():V001T11A001. doi:10.1115/DMD2018-6807.
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Parkinson’s disease is a neurodegenerative brain disorder that occurs when a patient’s body stops producing dopamine. This chemical is essential in transferring motor commands between the substantia nigra and the corpus striatum which enables smooth, intentional movement in the body. Because this transmission line is degrading, about 68% of the Parkinson’s population reports falling [1].

Commentary by Dr. Valentin Fuster
2018;():V001T11A002. doi:10.1115/DMD2018-6813.
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Additive Manufacturing or 3D Printing as it is commonly known is increasingly being used in the manufacturing of tissue engineering scaffold. The process allows for just in time production and customization. Hence, optimizing and varying the morphology of the tissue engineering scaffold in accordance to the application is one of the advantages of 3D printing. This paper aims to optimize the surface scaffold morphology by varying the dimensional parameters such as pore size, fibre diameter, orientation of fibres on scaffold and number of layers on the scaffold. The paper makes use of Taguchi’s Design of Experiments to understand and analyse the relationship between the different parameters that influence the morphological and mechanical characteristics of the scaffold.

Commentary by Dr. Valentin Fuster
2018;():V001T11A003. doi:10.1115/DMD2018-6819.
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Episcleral venous pressure (EVP) refers to the pressure in the episcleral veins. It is used by scientists in glaucoma physiology and pharmacology research to study the parameters of aqueous humor dynamics as part of the Goldmann equation [1]. The episcleral veins drain into the superior ophthalmic vein which drains into the cavernous sinus. Our previous work in a pig model [2] shows for the first time that EVP is an excellent non-invasive quantitative marker for intracranial pressure (ICP) estimation (high ICP leads to high intracranial venous pressure and high EVP). Intracranial pressure (ICP) is an important marker of outcomes in traumatic brain injury. There is an unfulfilled civilian and military need for a non-invasive ICP measurement modality. EVP could serve as a quantitative ICP biomarker, measurable by personnel with different skill levels for remote acute triage in battlefields and other urgent situations.

Commentary by Dr. Valentin Fuster
2018;():V001T11A004. doi:10.1115/DMD2018-6859.
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An improved tool for operative vaginal delivery can reduce maternal and fetal trauma during the delivery and recovery processes. When a delivery cannot be completed naturally due to maternal exhaustion or fetal distress, physicians must perform an operative vaginal delivery (OVD), with forceps or a vacuum, or a Cesarean section (C-section). Although C-sections are more prevalent in the United States than OVDs, they require longer maternal hospital stays and recovery time and increase risk of maternal infection and fetal breathing problems [1]. In 2015, the American College of Obstetrics and Gynecology pushed to increase the number of OVDs to limit C-section associated delivery risks [2]. However, the current tools for OVD either have steep learning curves, are unable to be used for all fetal head presentations, or have associated maternal and fetal risks [3][4]. There is a need for an easy to use, safe, and reliable tool for operative vaginal delivery.

Commentary by Dr. Valentin Fuster
2018;():V001T11A005. doi:10.1115/DMD2018-6862.
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The adoption of robotically assisted surgeries is increasing at a dramatic rate. The Da Vinci “was used in 80% of radical prostatectomies performed in the U.S. for 2008, just nine years after the system went on the market” [8]. The Da Vinci is but one of the systems driving the development of more versatile, more cost-effective and more autonomous systems. Robotic systems require real-time, accurate position information of the anatomy and surgical instruments to allow the surgical team to perform critical tasks. For example, Renishaw’s neuromate and Accuray’s CyberKnife both require the precise location of fiducial markers [9]. Others, like Cambridge Medical Robotics’ Versius and Medrobotics’ Flex operators rely upon active imaging or access to direct line of sight [10].

Commentary by Dr. Valentin Fuster
2018;():V001T11A006. doi:10.1115/DMD2018-6870.
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Medical imaging plays an essential role in screening, diagnosis, and pre- and intra-procedural intervention and therapy planning. The prime imaging modalities are Ultrasound (US), Computerized Tomography (CT), Positron Emission Tomography (PET), and Magnetic Resonance Imaging (MRI). Each modality has its advantages and disadvantages, thus, an appropriate one is advised by physicians depending on clinical needs.

Commentary by Dr. Valentin Fuster
2018;():V001T11A007. doi:10.1115/DMD2018-6881.
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Spasticity is a common abnormal muscle behavior associated with neurological disorders and is characterized by speed-dependent increased tone in the affected muscle when induced by passive movement [1]. During the passive stretch of the muscle, additional unique clinical signs that accompany spasticity are (a) sudden increase in muscle tone at a certain joint position (catch angle), called the “catch”, (b) after the “catch”, a quick drop of muscle resistance, called the “release”, where (a) and (b) together are usually referred to as the “catch-release” behavior, and (c) limited range of motion (ROM) [1,2]. With the evolution of spasticity, these symptoms will worsen.

Commentary by Dr. Valentin Fuster
2018;():V001T11A008. doi:10.1115/DMD2018-6883.
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In recent history, the convention that adopting an ‘upright’ seated posture would decrease lumbar strain has shifted. The idea of dynamically varying seated posture is being considered as optimal for reducing lumbar strain and possibly lower back pain [1–2]. Thus, it would seem vital to design a device that helps alert users of the need to change their seated postures in workplace or study environments.

Topics: Design
Commentary by Dr. Valentin Fuster
2018;():V001T11A009. doi:10.1115/DMD2018-6908.
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Acute respiratory distress syndrome (ARDS) arising from trauma, sepsis, pneumonia or other diseases has been acknowledged to be a major clinical problem in respiratory medicine. Hypoxia and hypercapnia arising from ARDS are life-threating particularly in children and elderly people. The reported mortality rate for ARDS is high. Current methods for treating patients who have limited or no lung function are ineffective or insufficient and present additional risks to the patients. In this research, we have explored new methods of infusing phospholipid-coated oxygen microbubbles (OMBs) to the thoracic cavity in order to oxygenate patients suffering from ARDS and hypoxemia. In our previous work, OMBs have been shown to be effective in treating hypoxia in models of LPS lung injury and lung trauma in rats and rabbits. In this study, we have developed a novel thoracic cavity extrapulmonary oxygenation devices using OMBs and test this device in a benchtop test and in vivo experiment on a large animal (pig) right pneumothorax injury model.

Topics: Cavities
Commentary by Dr. Valentin Fuster
2018;():V001T11A010. doi:10.1115/DMD2018-6917.
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Medical devices utilize pumps in several different application domains including medicine dispensing systems, drug and fluid infusion systems, perfusion equipment, and left ventricular assist devices (LVADs). In this paper, we propose a novel pump design for applications where continuous flow at high efficiency is the functional goal, such as in an LVAD.

Commentary by Dr. Valentin Fuster
2018;():V001T11A011. doi:10.1115/DMD2018-6944.
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Anaphylaxis is a severe allergic reaction when a patient is exposed to an antigen to which they have become hypersensitive. Exposure to these antigens results in the release of mediators from mast cells in the body, causing inflammation of critical organ systems. Without immediate treatment, it can lead to patient mortality within 15 minutes. To increase the probability of patient survival, a dose of adrenaline must be administered. There are several routes of administration, but the use of an Adrenaline Auto Injector is the safest, quickest and most efficient route. An Adrenaline Auto-Injector (AAI) is an injection device that delivers adrenaline to the deep muscle tissue of the body, preferably via the vastus lateralis muscle (as the rate of absorption is more effective than other injection sites such as the deltoid, gluteus maximus etc). Adrenaline Auto-Injectors are preferable to syringes, or prefilled syringes as they are easier to use, and can be used by people that are not medically trained. They can also be used in highly stressful situations without much risk of injury.

Topics: Design , Ejectors
Commentary by Dr. Valentin Fuster

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