ASME Conference Presenter Attendance Policy and Archival Proceedings

2018;():V010T00A001. doi:10.1115/IMECE2018-NS10.

This online compilation of papers from the ASME 2018 International Mechanical Engineering Congress and Exposition (IMECE2018) 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presenter attendance policy, if a paper is not presented at the Conference by an author of the paper, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.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

Micro- and Nano-Systems Engineering and Packaging: Applied Mechanics and Materials in Micro- and Nano-Systems

2018;():V010T13A001. doi:10.1115/IMECE2018-86626.

Silicon carbide (SiC) has attracted increasing attention as a material suitable for use with high breakdown voltages and at high temperatures. The effects of residual stress and thermal stress on the electrical properties are therefore a matter of growing concern. To analyze the effects, multi-physics simulation is required. The aim of this study is to present an evaluation method for SiC power modules by electro-thermal-stress coupled analysis. In this analysis, we investigate the relationship among mechanical stress, temperature, and electrical resistance in 4H-SiC MOSFET. To investigate the relationship, we used a four-point bending system that is capable of applying uniaxial stress to the SiC device. We prepared two kinds of test specimens with the uniaxial stress direction of four-point bending coinciding with the 〈112̄0〉 and 〈11̄00〉 direction of SiC. To associate the four-point bending load with the stress components in the SiC device, the four-point bending test was simulated by the finite element method. Tensile or compressive load was applied to two types of test specimens, and the internal stress of the SiC device was determined. To determine the internal stress during operation and mounting, the simple module model was also simulated by the structural analysis method. The internal stress was simulated from mounting temperature to the operating temperature. An electrical circuit and thermal circuit were constructed for the DC-DC converter in the above-described module for the coupled analysis method. The relationship among mechanical stress, temperature, and electrical resistance was incorporated into the additional resistance of the MOSFET in the electrical circuit. When an isotropic stress from −500 to 1400 MPa was applied with the SiC under the oxide film in the one parallel DC-DC converter, the change in the power conversion efficiency was about 0.16%. This indicates that our proposed method is a useful simulation method for SiC power modules.

Commentary by Dr. Valentin Fuster
2018;():V010T13A002. doi:10.1115/IMECE2018-87275.

In recent years, surgical assisting robots and nursing care robots are being introduced to medical and nursing fields due to the rapid increase of the aging society. In order to assure the safety and reliability of these robots, a highly sensitive tactile sensor is necessary to detect the state of contact between these robots and human body. The target specifications of this sensor are spatial resolution of less than 1 mm, and the pressure sensitivity of less than 10 kPa. Since the tactile sensor is expected to be attached on the tip of a surgical assisting robot or the arm of a nursing care robot, it should be small and flexible and highly sensitive to contact pressure.

In this study, high quality MWCNT (Multi-Wall Carbon Nanotube) has been synthesized to develop two types of tactile sensors which consisted of a MWCNT film and the area-arrayed MWCNT bundles. Thermal CVD (Chemical Vapor Deposition) method was applied to the growth of MWCNT and PDMS (Polydimethylsiloxane) was used for a flexible substrate. It was found that MWCNT bundles showed elastic deformation in the compressive strain range from 0% to 60%. The PDMS substrate showed elastic deformation under the application of bending strain of about 20%. In addition, it was confirmed that the detecting resolution of the force was lower than 1 mN, and the obtained gauge factor of the developed sensor was about 3.5.

Commentary by Dr. Valentin Fuster

Micro- and Nano-Systems Engineering and Packaging: Computational Studies on MEMS and Nanostructures

2018;():V010T13A003. doi:10.1115/IMECE2018-86664.

Reverse Osmosis (RO) for the desalination of saline water is associated with tremendous energy costs and low efficiency. Improvements in nanotechnology have led to the development of a variety of nanoporous membranes for water purification. Biomimetic membrane is an emerging new technology for water purification. Consequently, there is still much to study about the function and structure of these kinds of membranes. The purpose of this work was to determine which factors influence membrane performance. The focus was on those factors affecting membranes in pure water. Biomimetic membrane using MoS2 which has a higher rate of ion rejection and higher water permeability was studied through molecular dynamics simulations using reactive force fields (ReaxFF). The behaviour of the membrane before subjecting it to desalination was studied. The effect of water temperature, atmospheric pressure and membrane thickness on performance of membrane was studied. The permeability flux was calculated and compared in different conditions and the relation between these factors was revealed.

Commentary by Dr. Valentin Fuster
2018;():V010T13A004. doi:10.1115/IMECE2018-87622.

In this paper, a two-dimensional Dissipative Particle Dynamics (DPD) technique to simulate the poiseuille flow in a microchannel is developed using an in-house code. The calculated Reynolds number is reduced via adjusting the DPD parameters. The obtained velocity profile is compared with the analytical results and a good agreement is found. The drag force and the drag coefficient on a stationary cylinder exerted by the fluid particles are obtained using the developed DPD code. The calculated drag coefficient exhibits a close match with already published data in the literature.

Commentary by Dr. Valentin Fuster

Micro- and Nano-Systems Engineering and Packaging: Design and Fabrication, Analysis, Processes, and Technology for Micro and Nano Devices and Systems

2018;():V010T13A005. doi:10.1115/IMECE2018-86407.

Very little is known about the fracture behaviors of novel nanomaterials such as carbon nanotubes and graphene due to the difficulty of sample manipulation and in situ detection of their failure mechanism. In the present study, the design and analysis of a Microelectromechanical System (MEMs) device is presented for the tensile testing of single layer graphene. The electrostatically actuated dual parallel plate actuators in the proposed MEMS device enable in situ measurement in a scanning electron microscope by stretching the two ends of a nanostructured sample simultaneously. The elongation in the specimen is obtained by nonlinear finite element analysis using COMSOL, and MATLAB. For the validation of the proposed MEMS device, a lumped model of the system is utilized to analyze the stress-strain behavior of the nanostructured sample under the force generated by the electrodes.

Topics: Sensors , Design , Graphene
Commentary by Dr. Valentin Fuster
2018;():V010T13A006. doi:10.1115/IMECE2018-86528.

As a kind of functional materials, conductive polymer matrix composites filled with carbon nanotube (CNT) has potential application in structural health monitoring. A good formula should have a low percolation threshold and high piezoresistive strain sensitivity, which are always being sought by costly and time-consuming experimental method. Up to date, there is still a lack of numerical models to predict the sharp transition moment in electrical conductivity and mechanical resistance characteristics. This paper aims to establish a three-dimensional (3D) numerical model to observe the conductive network formation, predict the percolation threshold and investigate the piezoresistive characteristics of CNT-filled polymer matrix composites. Additionally, the influence of filler size, filler shape and filler volume fraction on the percolation threshold and piezoresistive characteristics would be investigated. The modeling and numerical simulation method can not only provide theoretical guidance for such a functional composite material, but also could be used in the future study on design and preparation of other conductive composites with two fillers added to improve the piezoresistive strain sensitivity and to decrease the percolation threshold.

Commentary by Dr. Valentin Fuster
2018;():V010T13A007. doi:10.1115/IMECE2018-87007.

The ironless permanent magnet planar motors (IPMPMs) are used in the lithography machine to realize long stroke x, y translation with single mover. The lack of rotation motion limits its use in a wide range of applications. This paper proposes a hybrid model for the IPMPM to realize the rotational motion. Based on the decoupling feature, the influence cause by the x, y translation and the rotation can be expressed by the position functions and 1-d lookup table (LUT) respectively. To the coils with centro-symmetry, the hybrid model can be further simplified. Then simulations about the calculation speed and the model accuracy are conducted. Compared with the 3-d LUT, the hybrid model cost less time with relative high accuracy. Finally the validity of the hybrid model is verified by experiment.

Commentary by Dr. Valentin Fuster
2018;():V010T13A008. doi:10.1115/IMECE2018-87277.

Health monitoring devices using a strain sensor, which shows high sensitivity and large deformability, are strongly demanded due to further aging of society with fewer children. Conventional strain sensors, such as metallic strain gauges and semiconductive strain sensors, however, aren’t applicable to health monitoring because of their low sensitivity and deformability. In this study, fundamental design of area-arrayed graphene nano-ribbon (GNR) strain senor was proposed in order to fabricate next-generation strain sensor. The sensor was consisted of two sections, which are stress concentration section and stress detecting section. This structure can take full advantage of GNR’s properties. Moreover, high quality GNR fabrication process, which is one of the important process in the sensor, was developed by applying CVD (Chemical Vapor Deposition) method. Top-down approach was applied to fabricate the GNR. At first, in order to synthesize a high-quality graphene sheet, acetylene-based LPCVD (low pressure chemical vapor deposition) using a closed Cu foil was employed. After that, graphene was transferred silicon substrate and the quality was evaluated. The high quality graphene was transferred on the soft PDMS substrate and metallic electrodes were fabricated by applying MEMS technology. Area-arrayed fine pin structure was fabricated by using hard PDMS as a stress-concentration section. Finally, both sections were integrated to form a highly sensitive and large deformable pressure sensor. The strain sensitivity of the GNR-base sensor was also evaluated.

Commentary by Dr. Valentin Fuster
2018;():V010T13A009. doi:10.1115/IMECE2018-87928.

The design of a novel micro-propulsion system for small satellites of the nano-satellites class (1–10kg) that is low-cost, non-toxic, non-flammable, and no-pressurized at launch conditions is currently being developed at the University of Arkansas. The goal of the present micro-propulsion system is to achieve milli-Newton thrust levels with specific impulses on the order of 100s. The proposed propellant is the water-propylene glycol. However, little data is available for its fluid and thermal characteristics at the gaseous state, nor the evolution of similar mixtures through micro/nano-channels. This paper will present experimental methods of measuring the mass flow rate of the water-glycol mixtures through micro/nano-channels. A MEMS fluidic chamber fabricated with a nano-channel is used to quantify the mass flow through optical tracking of liquid interfaces confined in the chamber. The dimensions of the channels are designed with the purpose to act as a passive throttling valve that prevent liquid-phase fluids from entering into the nozzle in order to achieve a simple water-based cold-gas propulsion system.

Commentary by Dr. Valentin Fuster
2018;():V010T13A010. doi:10.1115/IMECE2018-88431.

The authors have proposed the formation of dumbbell-shape graphene nanoribbon (GNR) for developing various semi-conductive materials with metallic electrode at both ends. The novel dumbbell-shape structure, which has a center narrow part and wide parts to sandwich the narrow part, can be considered as a composite structure consisting of two single GNRs with different ribbon width. In this study, the electronic band structure of this dumbbell-shape GNR was analyzed by using the first principle calculation method. All the first-principles calculations were performed using DFT. Throughout these calculations, the electronic band structures, densities of states, and orbital distributions of the new dumbbell-shape structure GNR were examined to describe the electronic properties of dumbbell-shape GNRs and predict the performance of strain sensors. The band gap of dumbbell-shape GNRs is different to that of single GNRs. The magnitude of the band gap of the dumbbell-shape GNR depends on the combination of the single GNRs and the difference in the width of narrow part and wide parts. The main change to the band gap is attributed to a change in the orbital distributions of the lowest unoccupied molecular orbitals (LUMO) and the highest occupied molecular orbitals (HOMO). In addition, when a dumbbell-shape GNR undergoes a uniaxial tensile strain, its band gap showed high strain sensitivity as was expected. Therefore, the GNR material with a dumbbell-shape structure has great potential for use in highly sensitive strain sensors.

Commentary by Dr. Valentin Fuster

Micro- and Nano-Systems Engineering and Packaging: General Topics of MEMS/NEMS

2018;():V010T13A011. doi:10.1115/IMECE2018-86310.

With the advent of 3D printing technology growing fast, it is important to determine the properties of objects made by this new process. Since some sensitive products, used in life-sustaining applications, are currently made by 3D printing, the reliability and durability of such components must be closely examined. Mechanical properties of metals may vary with the direction of heat transfer during solidification. This study presents the results of tensile tests, conducted at microscale on samples extracted from 3D printed metals. The implications of the variation of strength with solidification direction on the reliability of such metallic objects are discussed.

Commentary by Dr. Valentin Fuster
2018;():V010T13A012. doi:10.1115/IMECE2018-86436.

Nowadays, many surface sensing mechanisms exist, not all of them can be applied in water-based environment. Most of surface sensing techniques were developed in air-based environment. In order to obtain a potential cell-based biosensor, the sensing method needs to be reliable and repeatable in liquid environment. Therefore, we adapt existing air-based surface acoustic sensor and promote the technology into water-based applications. The goal of this study is to apply surface acoustic waves (SAW) for water-based environment sensing. We will use shear horizontal wave (SH wave) as surface sensing mechanism. SH wave is a type of surface acoustic waves (SAW) which can be used for weight/mass sensing in the air environment. Interdigitated transducers (IDTs) induce the deformation of an ST-cut quartz crystal substrate in AC source and generate waves. With a thin layer of polymer like Parylene and polyimide, the SH wave will be confined between the interface of substrate and polymer layer without suffering the energy loss due to the liquid damping from above. The fundamental frequency of the SAW device is defined by the spacing between the electrodes of IDT. The frequency of interests for this research is below 100 MHz in water-based environment. Due to the stable frequency characteristics of ST-cut quartz in room temperature, this SAW device can be a good candidate for field applications. From an early IDTs design, investigation in material and IDTs configuration is necessary to improve signal quality in order to qualify for liquid phase cell-based bio-sensing applications. A simplified 3D unit cell FEM model is created to study the thickness effects of wave-guide and electrodes. Boundary conditions and assumptions are discussed in the modeling. The simulated eigenfrequency of SH mode is close to the theoretical fundamental frequency of the 64μm wavelength IDTs. The mass damping effects from gold electrodes is more significant than aluminum electrodes.

Topics: Water
Commentary by Dr. Valentin Fuster

Micro- and Nano-Systems Engineering and Packaging: Micro and Nano Devices

2018;():V010T13A013. doi:10.1115/IMECE2018-87245.

The optical properties and device physics of monolayer graphene under light is investigated in this study. In order to understand the change of the electronic behavior of graphene under light, it was necessary to study from the most fundamental layer with high quality. Thus, it became mandatory to develop a highly efficient, low-cost fabrication process for synthesis of high-quality monolayer graphene. The high-quality monolayer graphene was grown on a copper foil using a low-pressure chemical vapor deposition (LP-CVD) method at temperature of 1035°C for 10 minutes. Acetylene was used as the precursor gas for the synthesis of monolayer graphene. Thin Pt/Au films were, then, deposited on a silicon dioxide/silicon (SiO2/Si) substrate using electron beam (EB) lithography which served as source and drain electrodes of a transistor. The synthesized graphene was, then, transferred to a SiO2/Si substrate using PMMA (polymethyl methacrylate)-assisted method.

The quality of the synthesized graphene was validated using Raman spectroscopy. No significant D peak was observed in the Raman spectra of the synthesized graphene. This result validated the high quality of the transferred graphene. Next, the photo-sensitivity of G-FET was investigated under light source of color temperature of 2856 K at room temperature. The electron transfer characteristic of the fabricated G-FET was measured under dark and light illumination conditions. Finally, the graphene-based field effect transistor G-FET demonstrated an external photo responsivity of about 200 μA/W with a maximum photocurrent attained to be 0.2 μA at an incident luminance power of 1 mW. The active detection region of this sample was 1000 × 60 μm2.

Topics: Graphene , Transistors
Commentary by Dr. Valentin Fuster
2018;():V010T13A014. doi:10.1115/IMECE2018-87664.

In this paper, we have introduced a negative Dielectrophoresis based microfluidic system using a novel arrangement of microelectrodes to perform switching of micro objects. Both the experimental and numerical results are presented. Two sets of interdigitated electrodes, extending slightly into the microchannel from each sidewall, are embedded on the bottom of the microchannel. A finite element model in COMSOL Multiphysics 5.2a was developed to demonstrate switching of Red Blood Cells in the microchannel followed by multiple parametric studies to study the effect of several parameters on cell trajectories and optimize the design parameters. To verify numerical results, a PDMS-based microfluidic device on glass wafer was fabricated. The switching of Red Blood Cells in the microfluidic device with a single inlet and three outlets was also demonstrated.

Commentary by Dr. Valentin Fuster

Micro- and Nano-Systems Engineering and Packaging: Microfluidics in Micro- and Nanosystems

2018;():V010T13A015. doi:10.1115/IMECE2018-86384.

In the present work, we realize a study about the influence of viscoelectric effect on the electroosmotic flow of Newtonian fluids in nanochannels formed by two parallel flat plates. In the problem, the channel walls have heterogeneous zeta potentials which follow a sinusoidal distribution; moreover, viscoelectric effects appear into the electric double layers when high zeta potentials are considered at the channel walls, modifying the fluid viscosity and the fluid velocity. To find the solution of flow field, the modified Poisson-Boltzmann, mass conservation and momentum governing equations, are solved numerically. In the results, combined effects from the zeta potential heterogeneities and viscosity changes yields different kind of flow recirculations controlled by the dephasing angle, amplitude and number of waves of the heterogeneities at the walls. The viscoelectric effect produces a decrease in the magnitude of velocity profiles and volumetric flow rate when the high zeta potentials are magnified. Additionally, the heterogeneous zeta potentials at the walls generate an induced pressure on the flow. This investigation extend the knowledge of electroosmotic flows under field effects for future mixing applications.

Topics: Electroosmosis
Commentary by Dr. Valentin Fuster
2018;():V010T13A016. doi:10.1115/IMECE2018-87109.

The characterization of single cells within heterogeneous populations has great impact on both biomedical sciences and cancer research. By investigating cellular compositions on a broad scale, pertinent outliers may be lost in the sample set. Alternatively, an investigation focused on the behavior of specific cells, such as circulating tumor cells (CTCs), will reveal genetic biomarkers or phenotypic characteristics associated with cancer and metastasis. On average, CTC concentration in peripheral blood is extremely low, as few as one to two per billion of healthy blood cells. Consequently, the critical element lacking in many methods of CTC detection is accurate cell capture efficiency at low concentrations. To simulate CTC isolation, researchers usually spike small amounts of tumor cells to healthy blood for separation. However, spiking tumor cells at extremely low concentrations is challenging in a standard laboratory setting. We report our study on an innovative apparatus and method designed for low-cost, precise, and replicable single-cell spiking (SCS). Our SCS method operates solely from capillary aspiration without the reliance on external laboratory equipment. To ensure that our method does not affect the viability of each cell, we investigated the effects of surface membrane tensions induced by aspiration. Finally, we performed affinity-based CTC isolation using human acute lymphoblastic leukemia cells (CCRF-CEM) spiked into healthy whole blood with the SCS technique. The results of the isolation experiments demonstrate the reliability of our method in generating low-concentration cell samples.

Topics: Tumors
Commentary by Dr. Valentin Fuster
2018;():V010T13A017. doi:10.1115/IMECE2018-88629.

The current research work in this paper involves optimizing an orthogonal electrode multifunctional system to transport biofluid. Orthogonal electrode patterned microfluidic device is known to produce high microflow velocity when excited by AC signals. This paper specifically investigates the fluid flow criterion by determining the direction and velocity in the selected electrode pattern actuated with AC signals. During the initial process, experiments were conducted at 100μm spacing between the orthogonal electrodes. The exact setup was placed on a hydrophobic surface to observe the change in the velocity. This process was then repeated with 150μm spacing. Fluid with conductivity 2.36 mS/cm was tested at voltage levels ranging between 5V to 10V at 50 KHz to 1MHZ frequency levels with an increment of 100 KHz. The goal of this research work is to increase microflow velocities by varying the electrode separation distance, flow surface, voltage and frequency. Trivial investigation also done on the possibility of micromixing using this pattern.

Commentary by Dr. Valentin Fuster

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