ASME Conference Presenter Attendance Policy and Archival Proceedings

2018;():V004T00A001. doi:10.1115/DETC2018-NS4.

This online compilation of papers from the ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2018) 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presenter attendance policy, if a paper is not presented at the Conference by an author of the paper, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.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

23rd Design for Manufacturing and the Life Cycle Conference: Conceptual Design and Manufacturability Analysis

2018;():V004T05A001. doi:10.1115/DETC2018-85465.

Conceptual design plays an important role in product development to meet requirements of the product function, cost and other factors. Existing methods of the product conceptual design rely on experience of designers or benchmarking methods to estimate design parameters, which limits the design automation and optimization. This paper improves the benchmarking methods by integrating the kinematics analysis with quality function deployment in design of an upper limb exoskeleton rehabilitation device. Parameters such as velocity, acceleration and displacement of the product are included for rating benchmarking products to evaluate the rehabilitation device based on customer needs. By integrating the benchmarking method and kinematics analysis, products with the best performance can be determined accurately to help designers to improve the existing product or develop a new product. The proposed method is verified in the design of an upper limb rehabilitation device.

Commentary by Dr. Valentin Fuster
2018;():V004T05A002. doi:10.1115/DETC2018-85516.

The selection of biomimetic prototypes mostly depends on the subjective observation of a designer. This research uses TRIZ to explore some inferential steps in bionic design of the heavy machine tool column. Conflict resolution theory of TRIZ is applied to describe improved and deteriorated parameters and a contradiction matrix is used to obtain recommended inventive principles. A reference table of solutions corresponding to the biological phenomenon and TRIZ solutions is formed to expedite retrieving the biomimetic object. Based on the table, herbaceous hollow stem is selected to imitate column structure. Four kinds of plant are chosen from the biological database. To select the best from four candidates, a bionic ideality evaluation index is proposed based on similarity analysis and ideality evaluation theory in TRIZ. Thus, the bionic effect can be described and compared quantitatively. Bionic configuration is then evolved concerning manufacturing requirements. Size optimization of stiffener thicknesses is implemented finally, and satisfactory results of the lightweight effect is obtained.

Commentary by Dr. Valentin Fuster
2018;():V004T05A003. doi:10.1115/DETC2018-85644.

Additive manufacturing (AM) is recognized as a disruptive technology that offers significant potentials for innovative design. Prior experimental studies have revealed that novice designers provided with AM knowledge (AMK) resources can generate a higher quantity and quality of solutions in contrast with the control groups. However, these studies have adopted general evaluation metrics that fall short in correlating AMK with radical or architectural innovation. This deficiency directly affects how AMK should be captured, modeled, and delivered so that novel opportunities may be more efficiently utilized in the ideation stage. To refine the understanding of AMK’s role in stimulating design innovation, an experimental study is conducted with two design projects: (a) a mixer design project, and (b) a hairdryer redesign project. The former of which aims to discover whether AMK inspiration increases the quantity and novelty of working principles (i.e. radical innovation), while the latter examines the influence of AMK on layout and feature novelty (i.e. architectural innovation). The experimental study indicates that AMK does have a positive influence on architectural innovation, but the effects on radical innovation are very limited if the provided AMK is functionally irrelevant to the design problems. Two strategies are proposed to aid the ideation process in maximizing the possibility of identifying AM potentials which facilitate radical innovation. The limitations of this study and future research plans are also discussed.

Commentary by Dr. Valentin Fuster
2018;():V004T05A004. doi:10.1115/DETC2018-85761.

With the rise in popularity of additive manufacturing (AM), relevant design methodologies have become necessary for designers to reap the full benefits from this technology. TRIZ is a problem-solving tool developed to assist with innovative and creative solutions. This paper aims to create a new TRIZ matrix specifically developed for designers using additive manufacturing. The TRIZ matrix offers designers general innovative design solutions to improve specific features of a design while not sacrificing the effectiveness of other features. The proposed matrix can help effective design decision making for additive manufacturing in an early design process as well as a redesign process. Also, a design for additive manufacturing (DfAM) worksheet is provided to enable users to easily find specific design solutions for certain additive manufacturing techniques based on the general solutions derived by the TRIZ matrix. To illustrate the potential of this AM specific TRIZ matrix, case studies are presented.

Commentary by Dr. Valentin Fuster
2018;():V004T05A005. doi:10.1115/DETC2018-86022.

New automated approaches in design often generate nonmanufacturable component geometries. Improved machinability of topology optimized parts, for example, has been under exploration for over a decade with limited success. Recent work is pursuing novel design approaches enabled by developments in voxel-based representation and advanced process technologies. Research reported here suggests a featureless approach for analyzing the machinability of a given geometry using voxels. The input is a tessellated shape, which is converted into a voxel representation. The voxelized shape is then filled in the orthogonal toolpath directions defined by the minimum bounding box to approximate the reach of the cutting tool in each part orientation. The filled shapes are intersected with each other to achieve a solid representation that can be readily accessed by a cutting tool. Overlaying this solid shape against the original tessellated shape will highlight the non-machinable regions of the part when visualized. The volume of non-machinable material can be estimated and used to inform a larger search process for separating and adding part features together to improve component manufacturability.

Commentary by Dr. Valentin Fuster

23rd Design for Manufacturing and the Life Cycle Conference: Design for Manufacturing and Assembly

2018;():V004T05A006. doi:10.1115/DETC2018-85302.

The paper deals with the feasibility of a flexible robotic cell for the disassembly of electronic components. First, the need for an automated process for the end of life management of electronic boards is motivated: the reuse of electronic components represents a potential cost saving opportunity for a class of electronic board producers, other than an effective means to improve the waste management efficiency and the sustainability of the electronics sector. Then, starting from a state of the art survey, a technical implementation of the cell is proposed. Finally, some preliminary tests of the disassembly equipment, aimed at setting the most relevant process parameters, are described.

Commentary by Dr. Valentin Fuster
2018;():V004T05A007. doi:10.1115/DETC2018-85376.

This paper presents a method for a system level design optimization, using currently available commercial tools. A process outlining the optimization steps to be used was created based on performing topology optimization on important components and performing a conceptual topology optimization on the entire system. Using this process, a study was performed on a ceiling structure provided by an industry partner. From the design requirements, three primary areas were targeted for design optimization, the component level optimization of the cross beam component, the component level optimization of a roof attachment bracket, and the system level of the general roof structure. This study produced a design for the ceiling structure that reduced the total mass of the system by 34%, while also reducing the amount of total components in the system by 30%.

Topics: Design , Optimization
Commentary by Dr. Valentin Fuster
2018;():V004T05A008. doi:10.1115/DETC2018-85508.

The accuracy of machine is important to achieving highly accurate shapes. This paper is focused on mechanical design of highly accurate mechanical linkage servo press applicable to (near-)net shape forming. The effects of geometric errors, deformations under heavy loads and ram tilting are analyzed. A top-down design for accuracy approach is proposed: First, accuracy model for identification of inaccuracy-causing factors and their interlinking relations is developed. Then, based on this model, top accuracy index are decomposed and translated into structure design specifications at component level. Both analytic and simulation methods are employed for design for accuracy in aspects of dimensional and geometric tolerance allocation, stiffness synthesis and anti-eccentric load capability. A case study of mechanical design for accuracy of a six-linkage mechanical servo press is also presented to demonstrate and test the proposed design approaches.

Commentary by Dr. Valentin Fuster
2018;():V004T05A009. doi:10.1115/DETC2018-85509.

Machining feature recognition is a key technology in design for manufacturing, inter-operation of neutral format solid models, and reuse of design models in down-streaming applications. Although many approaches have been proposed, the detection and processing of intersection features are still challenging. In this paper, we studied the local property of B-rep model and usage in intersection feature detection. To support hint based reasoning and processing, we proposed a symmetry property definition with relation to edges of solid models. This symmetry property is based on conventional edge convexity, which is an extension of the feature hint theory. The Transformation of global or partial graph matching to local property matching would reduce the complexity in feature matching stages. We implemented a prototype module to evaluate the feasibility of the proposed approach.

Topics: Machining
Commentary by Dr. Valentin Fuster
2018;():V004T05A010. doi:10.1115/DETC2018-85521.

Nowadays the five-axis machine tool is one of the most important foundations of manufacturing industry. To guarantee the accuracy of the complex surface machining, multi-axis linkage performance detection and compensation of five-axis machine tools is necessary. RTCP (Rotation Tool Center Point) is one of the basic essential functions for the five-axis machine tools, which can keep the tool center with the machining trajectory when five axes move synchronously. On the basis of RTCP function, a way to detect multi-axes linkage performance of five-axis machine tools is briefly introduced, and linkage error model is built in accordance with the topological structure of machine tool. Based on the feature of the linkage errors of the five-axis machine tool, the error tracing and compensation method is proposed. Some simulations and experiments that verify the error tracing method could locate the linkage error category are established. Therefore, a new attempt to detect and compensate the linkage error of the five-axis machine tool is provided in this paper.

Commentary by Dr. Valentin Fuster
2018;():V004T05A011. doi:10.1115/DETC2018-85637.

This article addresses the generation and use of manufacturability constraints for design under hybrid additive/subtractive processes. A method for discovering the natural constraints inherent in both additive and subtractive processes is developed; once identified, these guidelines can be converted into mathematical manufacturability constraints to be used in the formulation of design problems. This ability may prove to be useful by enhancing the practicality of designs under realistic hybrid manufacturing conditions, and supporting better integration of classic design-for-manufacturability principles with design and solution methods. A trade-off between design manufacturability and elegance has been noted by many scholars. It is posited that using realistic manufacturing conditions to drive design generation may help manage this trade-off more effectively, focusing exploration efforts on designs that satisfy more comprehensive manufacturability considerations. While this study focuses on two-step AM-SM hybrid processes, the technique extends to other processes, including single-process fabrication. Two case studies are presented here to demonstrate the new constraint generation concept, including formulation of shape and topology optimization problems, comparison of results, and the physical fabrication of hybrid-manufactured products. Ongoing work is aimed at rigorous comparison between candidate constraint generation strategies and the properties of the constraint mapping.

Topics: Manufacturing , Design
Commentary by Dr. Valentin Fuster
2018;():V004T05A012. doi:10.1115/DETC2018-85646.

This study proposes a graph partitioning method to facilitate the idea of physical integration proposed in Axiomatic Design. According to the physical integration concept, the design features should be integrated into a single physical part or a few parts with the aim of reducing the information content, given that the independence of functional requirements is still satisfied. However, no specific method is suggested in the literature for determining the optimal degree of physical integration of a design artifact. This is particularly important with the current advancement in Additive Manufacturing technologies. Since additive manufacturing allows physical elements to be integrated, new methods are needed to help designers evaluate the impact of the physical integration on the design success. The objective of this paper is to develop a framework for determining the best way that functional requirements can be assigned to different parts of a product.

Topics: Design
Commentary by Dr. Valentin Fuster
2018;():V004T05A013. doi:10.1115/DETC2018-85829.

This paper presents a novel design for a test platform to determine the State of Health (SOH) of lithium-ion batteries. The SOH is a key parameter of a battery energy storage system and its estimation remains a challenging issue. The batteries that have been tested are 18650 li-ion cells as they are the most commonly used batteries on the market. The test platform design is detailed from the building of the charging and discharging circuitry to the software. Data acquired from the testing circuitry is stored and displayed in LabView to obtain charging and discharging curves. The resulting graphs are compared to the outcome predicted by the battery datasheets, to verify the platform delivers coherent values. The SOH of the battery is then calculated using a Coulomb Counting method in LabView. The batteries will be discharged through various types of resistive circuits, and the differences in the resulting curves will be discussed. A single battery cell will also be tested over 30 cycles and the decrease in the SOH will be clearly pointed out.

Commentary by Dr. Valentin Fuster
2018;():V004T05A014. doi:10.1115/DETC2018-85864.

Digitization of networked engineered systems is a technology that is increasingly being adopted to respond to changes in the market. Hence, the need for design methods to design a system adaptable to dynamic changes in the market. It is evident through a critical review of literature that current approaches for designing of networked engineering systems are neither agile nor rapidly configurable, and, at design time, usually do not have flexibility in selection and determination of the values of design parameters to lower the overall cost during the execution of networked engineering systems and simultaneously ensure that the product quality is acceptable. Accordingly, in this paper, a method, Design for Dynamic Management, for the realization of networked engineering systems is proposed. The key features of this method, in the context of Design for Dynamic Management, are adaptability and operability in the design of systems. The efficacy of the method is illustrated on a 2-D panel stamping process. Our focus is on the method rather than the results per se.

Commentary by Dr. Valentin Fuster

23rd Design for Manufacturing and the Life Cycle Conference: Design for Sustainable Additive Manufacturing

2018;():V004T05A015. doi:10.1115/DETC2018-85343.

Fused Deposition Modeling (FDM), an Additive Manufacturing (AM) technique, is widely used due to its low-cost and open source. Geometry accuracy and strength performance of the printed parts are closely related to inter-layer bonding between adjacent layers and inter-road bonding in the layer. Because of the limit of layer-based AM, the longitudinal tensile strength of the filaments is much higher than the bonding strength between adjacent filaments, which brings anisotropy of the printed part. While CLFDM is devoted to solve this problem and obtain better geometry accuracy and meanwhile decrease build time by virtue of high continuity of filament, reduced stair-step effect, and lesser number of layers, especially when manufacturing thin and curved parts (shells). However, to the best of our knowledge in the aspects of process modeling of CLFDM, available researches focus mainly on simple curved layer, instead of more intricate ones possessing tiny features, which are more common in manufacturing. Therefore, to realize Solid Freeform Fabrication (SFF), this paper researches CLFDM with VEF (simultaneously changing the direction and the dimension of extruded filament according to manufacturing demand of the curved layer), which would be a fundamental study and a foundation for Advanced Design for Additive Manufacturing (ADFAM), slicing and path planning (extruder path generation) in 3D space. To realize slicing and printing with homogeneous and inhomogeneous extruded filament between consecutive layers and within the layer (flat or curved), models of flat layer FDM and CLFDM with VEF are respectively established. Then, the relationships among key process parameters are analyzed. Finally, graphical simulation of the proposed strategy based on a vase is provided to verify its effectiveness and advantages from a theoretical point of view. In general, variable direction of extruded filament along tangential directions of part surface imparts smoother surfaces, instead of rough exterior appearance resulting from stair-step effects. And variable dimension of extruded filament maximizes material extruded to increase build speed wherever allowed and minimizes deposition size for resolution whenever needed, resulting in curved layer surfaces with uneven layer thickness and having tiny features.

Topics: Modeling
Commentary by Dr. Valentin Fuster
2018;():V004T05A016. doi:10.1115/DETC2018-85489.

Titanium and its alloys are a class of metallic materials having high strength to weight ratio with excellent properties of resistance to temperature, corrosion and oxidation. These properties increase their use in aerospace, chemical and biomedical industries. Electrical discharge machining (EDM), a non-conventional machining process, is the most suitable process for the machining of titanium and its alloys. Generally, tool electrode for EDM application is prepared through various conventional and non-conventional machining processes. The cost of production of EDM electrodes accounts for more than 50% of the cost of the final product. Therefore, additive manufacturing (AM) technology can be suitably applied for direct manufacturing of the complex EDM electrodes. Selective laser sintering (SLS) is one of the appropriate AM processes for preparation of EDM tool electrode. In the present work, machining performance of the AlSi10Mg tool electrode produced through AM process along with copper and brass tool electrodes have been studied considering titanium alloy (Ti6Al4V) as work piece material and commercial grade EDM 30 oil as dielectric fluid. In addition to the tool electrodes, two more EDM parameters such as pulse-on-time (Ton) and discharge current (Ip) have been considered. Four performance measures like material removal rate (MRR), tool wear rate (TWR), average surface roughness (Ra) and surface crack density (SCD) are used to assess the machining performance. In order to reduce the number of experiments, design of experiment (DOE) approach like Taguchi’s L9 orthogonal array is used. Since the performance measures are conflicting in nature, grey relational analysis (GRA) is used to convert four performance measures into an equivalent single performance measure. The best parametric condition is reported for optimal grey relational grade.

Commentary by Dr. Valentin Fuster
2018;():V004T05A017. doi:10.1115/DETC2018-85642.

Despite of its tremendous merits in producing parts with complex geometry and functionally graded materials, additive manufacturing (AM) is inherently an energy expensive process. Prior studies have shown that process parameters, such as printing resolution, printing speed, and printing temperature, are correlated to energy consumption per part. Moreover, part geometric accuracy is another major focus in AM research, and extensive studies have shown that the geometric accuracy of final parts is highly dependent on those process parameters as well. Though both energy consumption and part geometric accuracy heavily depend on the process parameters in AM processes, jointly considering the dual outputs in AM process is not fully investigated. The proposed study aims to obtain a quantitative understanding of the impact of these process parameters on AM energy consumption given part quality requirements, such as geometric accuracy. The study utilizes a MakerGear M2 fused deposition modeling (FDM) 3D printer to complete the designed experiments. By implementing experimental design and statistical regression analysis technologies, the study quantifies the correlation between AM process parameters and energy consumption as well as the final geometric accuracy measure. An optimization framework is proposed to minimize the energy consumption per part. The Kuhn-Tucker non-linear optimization algorithm is used to identify the optimal process parameters. This study is of significance to AM energy consumption in terms of jointly considering energy consumption and final part geometric accuracy in the optimization framework.

Commentary by Dr. Valentin Fuster
2018;():V004T05A018. doi:10.1115/DETC2018-85662.

Additive Manufacturing (AM) provides the advantage of producing complex shapes that are not possible through traditional cutting processes. Along with this line, assembly-based part design in AM creates some opportunities for productivity improvement. This paper proposes an improved optimization algorithm for part separation (OAPS) in assembly-based part design in additive manufacturing. For a given object, previous studies often provide the optimal number of parts resulting from cutting processes and their corresponding orientation to obtain the minimum processing time. During part separation, the cutting plane direction to generate subparts for assembly was often selected randomly in previous studies. The current work addresses the use of random cutting planes for part separation and instead uses the hill climbing optimization technique to generate the cutting planes to separate the parts. The OAPS provides the optimal number of assemblies and the build orientation of the parts for the minimum processing time. Two examples are provided to demonstrate the application of OAPS algorithm.

Commentary by Dr. Valentin Fuster
2018;():V004T05A019. doi:10.1115/DETC2018-85994.

We present an additive manufacturing system for 3D printing large-scale objects using natural bio-composite materials. The process, affine to the Direct Ink Writing method, achieves build rate of 2.5cm3/s using a precision dispensing unit mounted on an industrial six-axis robot. During deposition the composite is wet and exhibits thixotropy. As it loses moisture it hardens and shrinks anisotropically. This paper highlights work on controlling the process settings to print filaments of desired dimensions while constraining the operating point to a region where tensile strength is maximum while shrinkage is minimum. Response surface models relating the controllable process settings such as Robot Linear Velocity, Material Feed Rate and Nozzle Offset, to the geometric and physical properties of an extruded filament, are obtained through Face-centered Central Composite Designed experiments. Unlike traditional applications of this technique which involve identifying a fixed optimal operating point, we use these models to first uncover the possible dimensions of a filament that can be obtained within operating boundaries of our system. Process setting predictions are then made through multi-objective optimization of the mathematical models. An interesting outcome of our study is the ability to produce filaments of different shrinkage and tensile strength properties, by solely changing process settings. As a follow up, we identify the optimal lateral overlap and inter-layer spacing parameters to define toolpaths to print 3D structures. If unoptimized, the material’s anisotropic shrinkage and non-linear compression characteristics cause severe delamination, cross-sectional tapering and warpage. Lastly, we show the linear scalability of our shrinkage model in 3D space which allows us to suitably compensate toolpaths to significantly improve dimensional accuracy of 3D printed artifacts.

Commentary by Dr. Valentin Fuster

23rd Design for Manufacturing and the Life Cycle Conference: Design of Sustainable and Alternative Energy Systems

2018;():V004T05A020. doi:10.1115/DETC2018-85828.

Ocean wave power is a promising renewable energy source for future energy production. It has however been difficult to find a cost-effective solution to convert the wave energy into electricity. The harsh marine environment and the fact that wave power is delivered with high forces at low speeds makes design of durable mechanical structures and efficient energy conversion challenging. The dimensioning forces strongly depend on the wave power concept, the Wave Energy Converter (WEC) implementation and the actual Power Take-Off (PTO) system.

A WEC using a winch as a Power Take-Off system, i.e. a Winch Based Point Absorber (WBPA), could potentially accomplish a low Levelized Cost Of Energy (LCOE) if a key component — a low-cost, durable and efficient winch that can deal with high loads — can be developed.

A key problem for achieving a durable winch is to find a force transmitting solution that can deal with these high loads and handle up to 80 million cycles. In this article we propose a design solution for a force transmitting chain in a WBPA system where elastomeric bearings are used as a means to achieve the relative motion between the links in the chain. With this solution no sliding is present and the angular motion is achieved as a deformation in the elastomeric bearing when the chain is winded on a drum.

The link was designed primarily to minimize the number of joints in the chain: Thereby the maximum allowed relative angle between the links when rolled up over the drum should be as large as possible within practical limits. The angle is to be handled by the elastomeric bearing. A detailed strength analysis of the link has been performed as well as topology optimization to increase the strength to weight ratio.

A test rig for a first proof of concept testing has been developed and the first preliminary test results indicate that this concept with using elastomeric bearings can be a potential solution for a durable chain and should be analyzed further for fatigue conditions and under water operations.

Topics: Chain
Commentary by Dr. Valentin Fuster
2018;():V004T05A021. doi:10.1115/DETC2018-85831.

Hydrogen is a carbon-free fuel expecting to be used in either combustion devices or fuel cells. However, high diffusivity and reactivity of hydrogen may result in potential hazards of flame flash back in conventional combustion systems, which greatly restricts the wide application of hydrogen fuel in engines. In this study, an inherently safe technique of rapidly mixed tubular combustion is adopted to attempt the hydrogen combustion, in which fuel and oxidizer are individually injected into the cylindrical combustor. Two methods of fuel and oxidizer feeding are tested: (1) hydrogen and air are separately injected from fuel and oxidizer inlets, respectively. Measurements are conducted by varying air flow rate and equivalence ratio (Φ), in which a steady tubular flame can only be obtained below Φ = 0.35, above which the flame becomes unsteady. (2) N2 is adopted as the diluent in both H2 and O2 streams. By adding N2 in the fuel stream to approach the same mean injection velocity as that of N2 and O2 mixture in the oxidizer inlet, fuel/oxidizer mixing is much enhanced, and a steady tubular flame has been achieved at Φ = 0.5. Then the oxygen content in the overall mixture of N2 and O2 is gradually reduced from 0.21 to investigate the combustion characteristics. Flame structure, lean extinction limit, flame stability and laminar burning velocity as well as temperature are investigated under various oxygen contents and equivalence ratios. The results provide a useful guide to the safe operation of hydrogen combustion in the rapidly mixed tubular flame burner.

Topics: Combustion , Flames , Hydrogen
Commentary by Dr. Valentin Fuster
2018;():V004T05A022. doi:10.1115/DETC2018-86150.

Recent interest in alternative energy sources, particularly biofuels from biomass, is becoming increasingly evident due to energy security and environmental sustainability concerns, such as depletion of conventional energy reserves and carbon footprint effects, respectively. Existing fuels (e.g., biodiesel and ethanol) are neither sustainable nor cost-competitive. There is a need to integrate the recent advanced manufacturing approaches and machine intelligence (MI) techniques (e.g., machine learning and artificial intelligence), targeted on the midstream segment (i.e., pre-/post-conversion processes) of biomass-to-biofuel supply chains (B2BSC). Thus, a comparative review of the existing MI approaches developed in prior studies is performed herein. This review article, additionally, proposes an MI-based framework to enhance productivity and profitability of existing biofuel production processes through intelligent monitoring and control, optimization, and data-driven decision support tools. It is further concluded that a modernized conversion process utilizing MI techniques is essential to seamlessly capture process-level intricacies and enhance techno-economic resilience and socio-ecological integrity of B2BSC.

Topics: Machinery , Biofuel
Commentary by Dr. Valentin Fuster

23rd Design for Manufacturing and the Life Cycle Conference: Emerging Design for X (Quality, Reliability, Cost, Maintainability, etc.)

2018;():V004T05A023. doi:10.1115/DETC2018-85464.

A sheet of material called bolus is commonly used in the high-energy radiotherapy to treat tumors near the skin surface of patients for a desired dose distribution. The existing method of bolus shaping is a manual process to cut the material into 2D shapes and then wrap them to fit the targeted body surface in clinic. This method cannot cover the bolus on some irregular surfaces such as knee, nose and elbow precisely. The inaccurate coverage will generate air gaps between the bolus and skin. An unfolding method for bolus shaping is introduced in this paper to reduce the air gaps. The shaping process is achieved by planning unfolding strategy to overcome limitations of existing software tools. A case study of bolus shaping for human nose is presented to examine the proposed shaping process. The shaping process includes the surface scanning to obtain point cloud data, 3D surface forming, segmentation and unfolding of the surface. The solution is verified by comparing the 3D model surface and wrapped shape of unfolded patches.

Commentary by Dr. Valentin Fuster
2018;():V004T05A024. doi:10.1115/DETC2018-85583.

Satellite-linked platform terminal transmitters (PTTs) enable biologists to study movements of sea turtles. However, PTTs often fail due to limited battery life, antenna breakage, biofouling, saltwater switch failure, and premature tag detachment. Also, PTTs induce hydrodynamic drag and may bias sea turtle behavior. Advances in technology continue to improve PTTs, however, design opportunities remain so that deployment duration is increased and behavioral biases are limited. We review how PTTs are used to obtain information on sea turtle biology, the current state-of-the-art, review recent innovations and highlight potential areas for design improvements. There remain several areas to focus on design improvements: (1) improve attachment methods so as to stretch as juveniles grow but do not add additional height to tag profile, (2) improve tag profile and attachment location on the turtle carapace to limit hydrodynamic drag, (3) experiment with different energy harvesting options to extend deployment duration, and (4) improve antenna design and material to enhance robustness and transmission quality. Capitalizing on emerging technology that allows for increasing miniaturization will likely create tags that extend deployment duration and induce negligible behavioral biases and will create data that best represents the true biology of sea turtle species in-water.

Topics: Design , Seas , Satellites
Commentary by Dr. Valentin Fuster
2018;():V004T05A025. doi:10.1115/DETC2018-85808.

Cities have been the focus of recent sustainability and climate change mitigation efforts primarily because of unprecedented urban growth and ever-increasing resources consumption. A worrying trend has been the ever-decreasing life of buildings in cities because of premature building obsolescence. Premature building obsolescence has been cited as the major driver of demolition waste which accounts for more than 40% of total waste generated annually. This waste stream poses a bigger challenge as the pressure on natural resources increases with urban growth. A traditional way of looking at the urban sustainability has been from the perspective of the environmental sciences and waste management methods. Analyzing urban areas with design science perspectives could provide novel insights to improve existing resource consumption patterns and transform sustainability growth in cities. This study focuses on the problem of demolition waste arising from the premature building obsolescence in cities. It applies a design research methodology framework for identifying existing problems associated with demolition waste and generating strategies to transform cities into more sustainable urban systems. In the problem clarification phase, a detailed literature review was supported with stakeholder’s interviews to identify the state-of-art for building demolition process and demolition waste. Research was further extended to descriptive study-I phase to carry out a demolition case study and generate support tools to enable transformation in the existing scenario for achieving a desired state. Singapore, a dense city state of South-East Asia has been taken as a case study in this research. Results show that applying design research methods could help open-up a new dimension to solve urban sustainability challenge for built environment. It highlights that material reuse could lead to significant improvement in the built environment sustainability but the challenge associated with realization of material reuse practice needs to be addressed. Descriptive study-I concludes with the strategies on creating a reuse market through entrepreneurial innovation and an alternative material supply chain of secondary materials for regional housing demand. These results highlight the role of design research methods for tackling complex systems level problems in cities.

Commentary by Dr. Valentin Fuster
2018;():V004T05A026. doi:10.1115/DETC2018-86080.

Introducing new technology to an inexpert society can be challenging. Rural communities are often deprived of technology that promotes a higher standard of living. Today there are sustainable energy solutions that, if correctly implemented, could close this gap. The literature indicates that a large number of humanitarian and relief projects failed because the communities were not able to perform the equipment maintenance. This work proposes a method for identifying the capability of a region to perform the necessary maintenance of a new technology. The method works by measuring both the system requirements and region abilities and resources. The proposed technique is devised with a design structure matrix in which each subsystem maintainability is analyzed. The resulting framework generates a comparative analysis that contributes to the decision making process. A case study is performed to evaluate the model on selecting an energy solution for a given community. The results provide designers a better understanding on the dependence of each component maintainability. Furthermore, it provides insights on the effect of region abilities and resources in the maintainability of a system.

Topics: Maintenance
Commentary by Dr. Valentin Fuster
2018;():V004T05A027. doi:10.1115/DETC2018-86187.

Additive manufacturing (AM) continues to rise in popularity due to its various advantages over traditional manufacturing processes. AM interests industry, but achieving repeatable production quality remains problematic for many AM technologies. Thus, modeling the influence of process variables on the production quality in AM can be highly beneficial in creating useful knowledge of the process and product. An approach combining dimensional analysis conceptual modeling, mutual information based analysis, experimental sampling, factors selection, and modeling based on Knowledge-Based Artificial Neural Network (KB-ANN) is proposed for Fused Deposition Modeling (FDM) process. KB-ANN reduces the excessive amount of training samples required in traditional neural networks. The developed KB-ANN’s topology for FDM, integrates existing literature and expert knowledge of the process. The KB-ANN is compared to conventional ANN using prescribed performance metrics. This research presents a methodology to concurrently perform experiments, classify influential factors, limit the effect of noise in the modeled system, and model using KB-ANN. This research can contribute to the qualification efforts of AM technologies.

Commentary by Dr. Valentin Fuster

23rd Design for Manufacturing and the Life Cycle Conference: Life Cycle Decision Making

2018;():V004T05A028. doi:10.1115/DETC2018-85356.

The effects of stress gradient and size effect on fatigue life are investigated based on the distributions of stress at notch root of the notched specimens of GH4169 alloy. The relationship between the life of the notched specimens and the smooth specimens is correlated by introducing the stress gradient effect factor, and a new life model of predicting the notched specimens based on the Walker modification for the mean stress effect is established. In order to improve the prediction precision of life model with the equation parameters having a definite physical significance, the relationships among fatigue parameters, monotonic ultimate tensile strength and reduction of area are established. Three-dimensional elastic finite element (FE) analysis of a vortex reducer is carried out to obtain the data of stress and strain for predicting its life. The results show that there is a high-stress gradient at the edge of the air holes of the vortex reducer, and it is thus a dangerous point for fatigue crack initiation. The prediction result of the vortex reducer is more reasonable if the mean stress, stress gradient and size effect are considered comprehensively. The developed life model can reflect the effects of many factors well, especially the stress concentration. The life of the notched specimens predicted by this model give a high estimation precision, and the prediction life data mainly fall into the scatter band of factor 2.

Commentary by Dr. Valentin Fuster
2018;():V004T05A029. doi:10.1115/DETC2018-85527.

Reducing energy consumption and environmental pollution of road transportation is one of the major challenges to China’s commitment to sustainable development. This paper aims to establish the LCA model of solid oxide fuel cells-based auxiliary power unit (SOFC-APU) for heavy vehicles with Chinese background for analysis of potential environmental benefits of its implementation in China. First, the LCA of the SOFC power using natural gas as the cells’ fuel is performed using eBalance, which is the Chinese LCA software with high quality domestic underlying database, and the results show that the fuel production phase is a major contributor to SOFC-APU’s life-cycle environmental impacts. Then the comparative LCA analysis of SOFC-APU using biomass ethanol from different feedstock planting areas in China is presented and results show that using corn-based ethanol fuel can potentially lower the lifecycle environmental impacts of SOFC-APU by 37.7%.

Commentary by Dr. Valentin Fuster
2018;():V004T05A030. doi:10.1115/DETC2018-85679.

This work aims to develop interventions to reduce automobile idling, where a driver runs the engine unnecessarily while not moving. Idling is a serious problem that wastes fuel, pollutes the air, and releases greenhouse gas emissions. Drivers idle for different reasons, including misconceptions about the time needed to warm up their engines and how much additional fuel is expended by turning the engine off and back on. Information-based interventions, i.e., messages to address idling, may therefore work more effectively to change behavior by correcting such misconceptions than for other types of pro-environmental behaviors where corresponding misconceptions may not exist.

This work incorporates Regulatory Focus Theory, a social-psychological framework which differentiates between promotion- and prevention-focused individuals. Furthermore, messages are framed with respect to idling-relevant concerns that participants identify — finance, health, or the environment.

Participants were asked to express behavioral intention and engagement in response to messages tailored for their regulatory focus and domain of concern. Results revealed that 1) participants prioritized finance and health much more often than the environment; 2) most participant categories responded well to their targeted messages; 3) Promotion/Finance participants seemed especially challenging to motivate, but modifications to their targeted messages led to improved results.

Commentary by Dr. Valentin Fuster
2018;():V004T05A031. doi:10.1115/DETC2018-85694.

The goal of this research is to characterize the effects of use patterns on the environmental sustainability of consumer products, and to enable decision making throughout design processes that encourages product sustainability. Life Cycle Assessments (LCA) are currently used to evaluate the environmental impact of a product, but there can be considerable uncertainty in these analyses, especially relating to the use phase of the product. To better understand this uncertainty, we conducted environmental impact assessments of 20 household products, and employed two uncertainty quantification approaches to accommodate variation in the use phase of these products. The results from each product were then compared to products with similar attributes to find generalizations. This knowledge was integrated into decision trees so designers can better understand the degree to which use-phase uncertainty can affect quantitative measures of environmental impact before performing LCAs. This work enables designers to make more informed decisions about the intended use and use lifetimes of consumer products, potentially leading to a reduced environmental impact of this life cycle phase.

Topics: Sustainability
Commentary by Dr. Valentin Fuster
2018;():V004T05A032. doi:10.1115/DETC2018-86260.

Papercrete, which uses waste paper as an alternative ingredient in concrete, is regarded as one type of mix design for green concrete that provide a new opportunity for waste paper disposal. However, the specific environmental influence of introducing waste paper has not been not clarified. Therefore, to evaluate the environmental contribution and feasibility of papercrete, based on the papercrete unit, the comparison of concrete production coupled with waste paper disposal is conducted according to a Life Cycle Assessment (LCA) analysis.

The system of papercrete production discussed here covers raw material extraction to finished product. Three different treatments for waste paper combined with concrete production are considered in this study. With respect to most environmental indicators, the results indicate that papercrete by introducing waste paper achieves some environmental benefits. The major reasons that environmental indicators of papercrete improve are due to the reduction of natural resource utilization and emissions to air. In detail the environmental impacts of papercrete production acquire a remarkable improvement compared with impact of normal concrete production and the adoption of incineration disposal of waste paper. Nevertheless, the environmental benefits of papercrete production are not significant increased compared with the associated system when waste paper is collected for the manufacture of recycled paper, where most environmental indicators of papercrete production are only slightly increased.

Commentary by Dr. Valentin Fuster

23rd Design for Manufacturing and the Life Cycle Conference: Sustainable Design and Manufacturing

2018;():V004T05A033. doi:10.1115/DETC2018-85093.

Commonality or the use of the same components among products in a product family has been considered an effective approach to designing a product family; however, simultaneous optimization of commonality, product family design, and inventory decisions has not been comprehensively studied. In this paper, we propose a framework to simultaneously optimize commonality, product family design, and inventory decisions by incorporating inventory-related costs in the profit formula. Design of beverage containers is used as an illustrative example to demonstrate the proposed framework.

Topics: Design
Commentary by Dr. Valentin Fuster
2018;():V004T05A034. doi:10.1115/DETC2018-85171.

An attempt has been made to design and analyze Indexing Head a very important component in milling operation under sustainability considerations. The design of each component of indexing head is presented along with solid modeling and finite element analysis. The cost estimation for indexing head for milling operation is also presented. The design and finite element analysis of indexing head should be utilized by manufacturers of this very useful device in milling operation. It is used for cutting gears, spirals, splines, etc. The cost estimated of the manufactured indexing head shows it to be within reasonable limits of market. Finite element analysis of each component is safe. An electronic indexing is suggested as an improvement over the mechanical indexing head. A schematic of electronic indexing is presented. The electronic indexing head can be used with milling machine not provided with indexing head and will be portable. The minimum energy needed to manufacture the indexing head is also estimated.

Commentary by Dr. Valentin Fuster
2018;():V004T05A035. doi:10.1115/DETC2018-85214.

Since the rotary motion of a rolling bearing is implemented by bearing components under geometric constraints, the motion accuracy of an assembled bearing should also be the result of interaction among geometric errors of bearing components. Therefore, it is significant to understand the relationship between the geometric errors of bearing components and motion accuracy of an assembled bearing for the design of high accuracy bearing. Based on quasi-static analytical method, a mathematical model for motion error of cylindrical roller bearings is established considering the roundness error of outer raceway. The motion error of a rolling bearing is affected by the amplitude and harmonic order of the roundness error of outer raceway, number of rollers and the operating conditions such as radial load, rotary speed of outer ring. The effects of above parameters are analyzed. The results show that the motion accuracy of a cylindrical roller bearing degrades with the increase of amplitude of the roundness error of outer raceway and the rotary speed of outer ring. The variation of the radial displacement of outer ring varies periodically with the increase of the harmonic order of the roundness error of outer raceway, and its period is equal to the roller number. With the increase of the roller number, the variation of radial displacement of the outer ring fluctuates. The larger the radial load is, the smaller the variation of radial displacement of outer ring is. The results would be helpful to reduce the production costs by controlling the distribution of machining tolerance of bearing components.

Commentary by Dr. Valentin Fuster
2018;():V004T05A036. doi:10.1115/DETC2018-85215.

The motion error of bearing depends highly on the geometric profile of bearing components. Therefore, it is crucial to establish a correlation between the geometric error of bearing components and the motion error of an assembled bearing, which is required for designing and manufacturing bearings with high accuracy of motion. In this paper, authors derived a geometric compatibility equation for cylindrical roller bearing considering the geometric error of bearing inner raceway. Based on the load balance and the geometric compatibility derived, a mathematical model of motion accuracy is established, and the model is also validated. The effect of geometric error such as the amplitude of roundness error and dimension error of bearing inner raceway, and radial clearance on the bearing motion error is investigated. Results show that the motion error of the bearing increases with the amplitude of the roundness error of inner raceway, and reduces with the increase of radial load. The results indicated that the motion accuracy can be improved by controlling the distribution of machining tolerance of bearing components.

Commentary by Dr. Valentin Fuster
2018;():V004T05A037. doi:10.1115/DETC2018-85369.

In industrialized countries, packaging waste is one of the major issues to deal with, representing around 35% of the total municipal solid waste yearly generated. Therefore, an analysis and an environmental assessment of packaging systems are necessary. This paper aims at analyzing and comparing the environmental performances of two different packaging for domestic hoods. It shows how, through a packaging redesign, it is possible to obtain a reduction of the environmental impacts. This study has been performed in accordance with the international standards ISO 14040/14044, by using attributional Life Cycle Assessment (LCA) from Cradle to Gate. The functional unit has been defined as the packaging of a single household hood. Primary data have been provided by a household hood manufacturer, while secondary data have been obtained from the Ecoinvent database. LCA software SimaPro 8.5 has been used to carry out the life cycle assessment, and ReCiPe method has been chosen for the life cycle impact assessment (LCIA) stage. The results have shown the new packaging model being able to cut down the environmental impacts of approximately 30%. These outcomes may be used by household manufacturers to improve performances and design solutions of their different packaging.

Commentary by Dr. Valentin Fuster
2018;():V004T05A038. doi:10.1115/DETC2018-85422.

This paper studies an interdisciplinary approach for improving smart energy systems, and, in particular, building energy efficiency. Currently, energy audit is the most widely used approach to improve building energy efficiency. Energy audit increases the building energy efficiency by identifying, analyzing and implementing energy saving opportunities in existing buildings. The procedure of existing energy audit approach is relatively standardized, and energy audit professionals usually refer to Energy Conservation Measures (ECMs) checklists to determine opportunities for energy savings. In this context, this paper aims to improve the general energy audit process by integrating, adapting, and extending Design Innovation (DI) techniques which help to identify more energy saving opportunities beyond the existing energy audit checklists and deliver user-centered and disruptive innovative energy-saving solutions which are missing in the traditional energy audit procedure. The motivation, advantages, and the implementation procedure of selected DI approaches are explained separately. To demonstrate the effectiveness of the proposed mechanism, an example of developing a smart energy system for a building testbed is given.

Commentary by Dr. Valentin Fuster
2018;():V004T05A039. doi:10.1115/DETC2018-85518.

LCA predicts the life cycle impacts of product solutions and can help determine what solution is better for the environment. However, LCA is very data dependent and requires in-depth knowledge to explicit relate environmental impacts of product to its design attributes. Current LCA methods are generally still not adapted to designers, who often lack the expertise and time to make LCA efficiently useful to their daily work. This study aims to develop a LCA module integrated with CAD system for machined products. The module employs a feature-based approach for identify, extract and convert life cycle related data in existing product models for LCA modeling and analysis. A coding system for machining feature representation and a rule-based reasoning package to generate manufacturing plans based on feature codes are developed to enable convenient eco-assessment along with CAD modeling of machined products. A step shaft LCA case study is presented to demonstrate the proposed approach.

Commentary by Dr. Valentin Fuster
2018;():V004T05A040. doi:10.1115/DETC2018-85860.

Automation of manufacturing process with robots is an industrial challenge, generally evaluated by the Return On Investment (ROI) that such a transformation could generate. However, the automation has a considerable cost particularly for SMEs, which makes a barrier to access and limits the motivation of facilitating the manual work of the operators, despite of nonergonomic and risky situations. In this study, supported by the European project HORSE, we went through the development of a robotic solution to assist the operator in the manufacturing. This component called programming-by-demonstration is integrated in both main categories of automation: industrial robot and collaborative robot (cobot). Both applications are tested and evaluated in a real manufacturing task (cutting cast pieces from foundry) and evaluated by the industrial end-user. The paper states on the application of the developed component, and concludes with the lesson learned.

Commentary by Dr. Valentin Fuster

12th International Conference on Micro- and Nanosystems: Bio MEMS/NEMS

2018;():V004T08A001. doi:10.1115/DETC2018-85057.

In this study, a three-dimensional bioscaffold printer was developed to fabricate biocompatible scaffolds from water-soluble materials for application in cell studies. A gelatin/sodium alginate solution was used to produce the scaffolds via a fused deposition modelling (FDM) printing method using the modified 3D printer. Modifications and improvements to the material feeding system, printing head, and printing platform were made, with additional optimization of the printing parameters, such as the feed rate, printing rate, and printing head size to investigate the precision and accuracy of two-dimensional and 3D bioscaffold printing. In addition to modifications of the feeding system from the original solid to the new liquid state material, a heating probe and coil were added to maintain the liquid phase. The printing nozzle was also altered to allow for the feed material and a cross-linking agent to mix prior to printing; enabling cross-linked scaffolds to be produced. Furthermore, the printing surface was integrated with a filter to allow for excess fluid to drain from the scaffold after printing and cross-linking. The results of this study revealed that the optimal printing parameters for producing a 2D 15.3 mm × 15.3 mm square was with a printing head-platform distance of 4 mm, material feed rate of 5 mL/min, printing rate of 35 mm/s and a printing head diameter of 0.4 mm. In addition, it was found that the printing speed and the printed image size and resolution are correlated, as such, the smallest dimensions able to be printed is 10.3 mm × 10.3 mm, with a line width of 1 mm. In regards to 3D scaffolds, the printed scaffolds had dimensions of 20 mm × 20.15 mm with a height of 7.5 mm; which were found to support the growth of mouse fibroblast cells.

Commentary by Dr. Valentin Fuster
2018;():V004T08A002. doi:10.1115/DETC2018-85383.

Casimir effect on superharmonic resonance of electrostatically actuated bio-nano-electro-mechanical system (Bio-NEMS) circular plate resonator sensor is investigated. The plate sensor resonator is clamped at the outer end and suspended over a parallel ground plate. The sensor can be used for detecting human viruses. Superharmonic resonance of the second order, frequency near one-fourth the natural frequency of the resonator, is induced using Alternating Current (AC) voltage. The magnitude of the AC voltage is also large enough to be consider hard excitation acting on the resonator. Beside Casimir effect, other external forces (i.e. electrostatic force and viscous air damping) acting on the MEMS resonator create a nonlinear behaviors such as bifurcation and pull-in instability. Hence, numerical models, such as Method of Multiple Scales (MMS) and Reduced Order Model (ROM), are used to predict the frequency-amplitude response for MEMS resonator. MMS transforms the nonlinear partial differential equation of motion into two simpler problems, namely zero-order and first-order. While, ROM, based on the Galerkin procedure which uses the mode shapes of vibration of the resonator as a basis of functions, transforms the nonlinear partial differential equation of motion into a system of ordinary differential equation with respect to dimensionless time. The frequency-amplitude response allows one to observe the behavior of the system for a range of frequencies near the superharmonic resonance. The effects of parameters such as Casimir effect, voltage, and damping on the frequency-amplitude response are reported.

Commentary by Dr. Valentin Fuster
2018;():V004T08A003. doi:10.1115/DETC2018-85484.

This paper presented a MEMS based differential scanning calorimeter (DSC) for biomolecular characterization. In this MEMS based DSC, PDMS (Polydimethylsiloxane) and Flexdyne thin film were used to construct the microfluidic chamber. Polyimide were used to fabricate the flexible substrate and temperature sensitive vanadium oxide was used as the thermistor material. A heating stage was used to heat the sample and reference up at a certain rate. The resolution study and step response characterization indicated the high sensitivity (6.1V/W) of the device. The test with Bovine Serum Albumin (BSA) samples showed clear phase transitions and the data was confirmed to be reasonable by comparing it with the results of commercial DSC’s test. This device used 0.63uL sample amount and could complete the scanning process in 3 minutes, significantly increasing the throughput of the biomolecular thermodynamics study like protein denaturation process compared to the traditional DSC (1 to 2 hours).

Commentary by Dr. Valentin Fuster
2018;():V004T08A004. doi:10.1115/DETC2018-85731.

To convert induced surface stress of a bio-functionalized microcantilever into an electrical signal; U shaped piezoresistive detection technique is mostly preferred over other techniques due to its several advantages. But the inherent disadvantage of this technique is thermal stress sensitivity as a source of noise which reduces its signal to noise ratio [SNR]. Polymer microcantilever has larger stress sensitivity due to its low youngs modulus of elasticity. Varying thickness cantilever satisfy this desired criteria as compared to other configurations of cantilever and has high resonance frequency. Taking all these aspects into consideration, the objectives of proposed study is to design and simulate multilayer varying thickness microcantilever. The numerical analysis is performed using CoventorWare a commercial MEMS design and FEM Multiphysics tool. It is observed that the SNR of the varying thickness microcantilevers design is improved by more than 70%, over normal rectangular design.

Topics: Simulation , Design , Polymers
Commentary by Dr. Valentin Fuster
2018;():V004T08A005. doi:10.1115/DETC2018-86164.

Chronic Venous Insufficiency (CVI) is a disease of the lower limbs that affects millions of people in the United States. CVI results from incompetent venous valves. The purpose of venous valves is to prevent retrograde blood flow to the lower limbs. Valve failure can lead to edema, pain, and ulcers. One solution that has great potential is to create an implantable venous valve that could restore function of the venous system. No prosthetic venous valves are clinically used currently because of problems with biocompatiblility and thrombogenicity caused by high shear rates. This paper presents a prosthetic venous valve that could overcome these difficulties by using carbon-infiltrated carbon nanotubes (CI-CNTs). This material has been proven to be thrombo-resistant, biocompatible due to its non-reactive properties, and durable. The valve was designed to be initially open and to close with physiological pressures. Finite element modeling showed that, with a hydrostatic pressure of 20 mmHg (the minimum hydrostatic pressure in the common femoral vein), it fully closed with a maximum stress of 117 MPa, which is below the ultimate strength of CI-CNTs. A computational fluid dynamics analysis demonstrated the valve would cause a maximum shear rate of 225.1 s−1, which is less than the maximum shear rate in the body. Hence, this valve would be less likely than previous prosthetic valves to develop blood clots. Currently, this is the lowest shear rate reported for a prosthetic venous valve. These results demonstrate that a CI-CNT prosthetic venous valve has the potential to be an effective treatment for CVI.

Commentary by Dr. Valentin Fuster
2018;():V004T08A006. doi:10.1115/DETC2018-86222.

Internalization of pathogens inside pores and channels of fresh produce and formation of polymeric biofilm around their colonies are important phenomena in food safety due to complications they create for removal and inactivation of pathogens. The practical challenges does not allow for monitoring the pathogen-produce interaction in real time and under different ambient conditions. The present work introduces a biomimetic biosensing platform that simulates the actual produce and can detect the presence, growth and internalization of microorganisms and also potential formation of biofilm. The system consists of layers of capacitive electrodes made of polycrystalline silicon which are designed based on a standard foundry process (PolyMUMPs). The electrodes form multiple impedance-based biosensors and can simulate porous medium of the produce surface. As the cells reside on the surface of the top layer or penetrate inside the system, the capacitance value of each electrode pair changes. Monitoring the capacitance change of each biosensor allows us to determine where the microorganisms are and also whether their population is increasing. To demonstrate the applicability of our proposed biosensing system, a comprehensive FEM simulation is performed using ANSYS® APDL. The simulation results show that each pair of electrodes displays a specific pattern of capacitance change when cells reside on the system’s surface, move inside, grow or produce polymeric biofilm, because the electrostatic properties of cells and biofilm polymers are different from those of the solution. Analyzing the capacitance patterns allows us to determine that cells are at which stage of growth or internalization, and how far they have moved inside the system.

Topics: Biomimetics
Commentary by Dr. Valentin Fuster

12th International Conference on Micro- and Nanosystems: Dynamics of MEMS and NEMS (MNS/VIB-12)

2018;():V004T08A007. doi:10.1115/DETC2018-85181.

We present a concept and a theoretical feasibility study of a sub g threshold inertial micro sensor, which incorporates a curved bistable beam as a suspension element. For certain range of geometric parameters such a beam can exhibit lathing, namely remain in its switched configuration at zero actuating force. Since the device can be released from its latched state by an external acceleration force, it can therefore serve as a threshold inertial switch. While the snap-through force, associated with the switching from the initial to the buckled state, cannot be reduced without decreasing the frequency of the device, the release value of the acceleration can be tailored to be arbitrarily low. This allows design of a devices with sufficiently high stiffness in the initial and latched configurations, but with a very low release threshold. Our model show that for appropriately chosen parameters, it is possible to design a sub g threshold acceleration micro switch of realistic dimensions.

Commentary by Dr. Valentin Fuster
2018;():V004T08A008. doi:10.1115/DETC2018-85411.

This paper investigates the vibration of a coupled microcantilever beam structure, in which a rigid body at their free end connects the two beams. The coupled beams are under equal and out-of-phase forces applied by piezoelectric films, which result in overall torsional motion. The equations describing the motion of the structure as well as the boundary conditions are developed using the Hamilton principle under the assumption of the structure being an Euler-Bernoulli beam. Two equations for each beam are realized: bending and torsional equations, which are combined in one torsional equation. The equation is solved using Galerkin approximation. The effects of dimensional parameters and input parameters are investigated including height, width, thickness, beam arrangement, applied voltage, input frequency, and mass of the tip. Geometry and mass were found to have significant effects on the angle, while input voltage was found to have a small linear effect. The overall sweeping motion was found to have an angle well below one degree in general. This shows that while the piezoelectric actuators can generate torsional sweeping, the effect is at a small angle that depends more on design than actuation force.

Commentary by Dr. Valentin Fuster
2018;():V004T08A009. doi:10.1115/DETC2018-85534.

Curved bistable beams subjected to transverse loading may exhibit latching, namely remain in their buckled state under zero force. Under such circumstances, an opposite force is required for snapping-back (release) of the beam to its initial configuration. For an electrostatically actuated beam, two electrodes located at either side of the beam may therefore be required for bidirectional actuation. In this study, a new snapping and release procedures, are considered. The approach involves the preloading of the beam using an electrostatic force in the direction opposite to the beam desired movement, followed by a sudden release of the voltage. We show, by means of a reduced order (RO) model, resulting from the Galerkin decomposition, that such an actuation paradigm can not only be used to release a beam from its latched position, but can also create a snap-through response at a significantly low voltage.

Topics: Actuators , Electrodes
Commentary by Dr. Valentin Fuster
2018;():V004T08A010. doi:10.1115/DETC2018-85543.

In this paper a novel electrostatic MEMS combined shock sensor and normally-closed switch is presented. The switch uses combined attractive and repulsive forcing to toggle a cantilever beam to and from the pulled-in position. The attractive force is generated through a parallel plate electrode configuration and induces pull-in. The repulsive force is generated through electrostatic levitation from a third electrode and serves to pull the beam out of its pulled-in position. A triboelectric transducer converts impact energy to electrical energy to provide voltage for the third electrode, which temporarily opens the switch if enough impact energy is supplied. Triboelectricity addresses the high voltage requirement for electrostatic levitation. The multi-electrode sensor also addresses the low current output from the generator because it acts as an open circuit between the parallel plate and levitation electrodes. A theoretical model of the switch is derived to analyze stability and the dynamic response of the cantilever. Threshold voltages to pull-in and release the beam through repulsive forcing is calculated. Output voltage plots from a prototype generator under a single impact are applied to the sensor-switch model to demonstrate the working principle of the sensor-switch is feasible.

Commentary by Dr. Valentin Fuster
2018;():V004T08A011. doi:10.1115/DETC2018-85993.

We investigate the effects of squeeze air film and initial deflection on the resonance frequencies and modal damping of capacitive circular microplates. The equation of motion of a circular microplate, which are derived from the von kármán plate theory, coupled with the Reynolds equation are discretized using the Differential Quadrature Method (DQM). The eigenvalues and eigenvectors of the multiphysical problem are determined by perturbing the system of equations around a static solution. Therefore, the resonance frequencies, modal damping coefficients and mode shapes of the plate and the fluid can be determined. The advantage of using DQM is that the solution of the system can be obtained with only few grid points. The obtained numerical results are compared with the experimental data for the case of a capacitive circular microplates with an initial deflection. The increase of the static pressure leads to a shift in the resonance frequencies due to the increase in the stiffness of the plate. Also the initial deflection change the resonance frequencies due to the change in the effective gap distance. The developed model is an effective tool to predict the dynamic behavior of a microsystem under the effect of air film and with initial deflection.

Commentary by Dr. Valentin Fuster
2018;():V004T08A012. doi:10.1115/DETC2018-86215.

The modal decomposition of tapping mode atomic force microscopy microcantilevers in air and liquid environment was experimentally investigated to identify their complex responses. In experiment, the flexible microcantilevers and a flat HOPG sample were used. The responses of the microcantilevers were obtained to extract the linearized modes and orthogonal values using the methods for the proper orthogonal decomposition and the smooth orthogonal decomposition. The influence of the tapping setpoints and the hydrodynamic damping forces were investigated with the multi-mode response of microcantilevers. The results show that the first mode is dominant under normal operating conditions in tapping mode. However, at lower setpoint, the flexible microcantilever behaved uncertain modal distortion near the tip on the sample. The dynamics tapping effect and the damping between microcantilever and liquid influenced their responses.

Commentary by Dr. Valentin Fuster
2018;():V004T08A013. doi:10.1115/DETC2018-86271.

This paper reports on the design, fabrication, and characterization of non-interdigitated comb drive actuators in Silicon-on-Insulator (SOI) wafers, using a single mask surface microma-chining process. The response of the actuator is analyzed numerically and experimentally. The results show at the fundamental frequency; it behaves as a longitudinal comb drive actuator. At a higher frequency, it exhibits a high-quality factor which is appropriate for sensor applications.

Commentary by Dr. Valentin Fuster
2018;():V004T08A014. doi:10.1115/DETC2018-86296.

Dynamic behavior of a cantilever type nano-switch actuated by pure Casimir force is investigated. Residual surface stress, surface elasticity and intermolecular forces are included in Euler–Bernoulli beam model. Knudsen number dependent squeeze-film air damping model and an asperity-based contact model are incorporated. The proposed model is inherently nonlinear due to interactions between the different nonlinear physics. An approximate analytical approach based on Galerkin’s method has been employed for predicting transient dynamic responses, since no exact solutions are available. Predicted responses show that the beam tip hits the substrate and bounces before making a permanent contact. Actuation of the switch via pure Casimir force is demonstrated for certain length and gap combinations. Initial contact time which governs the switch performance, and the deflections under non-closure condition are also quantified. This study is envisaged to provide useful insights for the future design of Casimir actuated NEM switches.

Topics: Switches
Commentary by Dr. Valentin Fuster
2018;():V004T08A015. doi:10.1115/DETC2018-86428.

A scanning force microscope combining commercial AFM probes, printed circuit boards, and electrostatic actuation and detection is proposed and demonstrated. The electrostatic actuator is formed by the AFM probe and a fixed trace on a PCB. It is driven by a biased harmonic voltage with a frequency close to the probe’s resonant frequency. The separation distance between the probe tip and the specimen surface is managed to perform tapping mode scanning. A lock-in amplifier measures the second harmonic of the actuator current as the sense signal in an open-loop scheme. Preliminary results produced by the current’s magnitude and phase resemble the specimen’s topography.

Topics: Microscopes
Commentary by Dr. Valentin Fuster

12th International Conference on Micro- and Nanosystems: Functional Materials and Surface Engineering

2018;():V004T08A016. doi:10.1115/DETC2018-85158.

In the Letter, we reported the tension-induced Raman spectrum enhanced phenomena of graphene membrane. The standard micro-fabrication processes are utilized to fabricate micro-scale holes on Silicon-On-Insulator (SOI) wafers, and suspended graphene membranes are transferred onto target substrates with shallow holes and flat substrates using the dry and wet transfer techniques, respectively. The corrugated graphene near the hole is stretched smoothly due to the built-in strain during the transfer processes, and the intensity ratio between the 2D and G bands I2D/IG>5, which demonstrates the high quality of graphene sheet is obtained under the stretching stress. The intensity ratio between the 2D and G bands would diminish greatly when the graphene membrane is broken. Therefore, the Raman spectrum intensities of graphene membranes can be tuned by the built-in strain. The study can be helpful for further understanding the formation mechanism of corrugated graphene, the suppressing method of the small ripple in graphene, and the way to improve the quality of graphene.

Commentary by Dr. Valentin Fuster
2018;():V004T08A017. doi:10.1115/DETC2018-85504.

In this study, a microscale interface consisting of amorphous polyethylene (PE) chains with the united-atom (UA) model and face-centered cubic (FCC) crystal copper as the substrate was established. Moving the copper layer with a given rate, the damage evolution of the interface during the tensile deformation was examined by molecular dynamics (MD) simulations. The stress-strain relationship was obtained to capture the evolution of tensile deformation. The distribution of the temperature field was adopted to predict the damage initiation and the failure mode. The phase diagram of the failure mode with respect to the thickness of the PE layer and the loading rate was provided. The results show that the PE layer with smaller thickness brings higher load-bearing capacity with larger yield strength. As for the rate-dependence, a rate-hardening followed by a rate-softening of yield strength was observed. In addition, the failure modes evolves from cohesive failure to interfacial one as the loading rate of tension increases progressively. It can be assumed that the control parameter on the failure mode changes from pure material strength of PE to the bonding strength between PE and copper. Furthermore, a larger thickness of PE layer leads to the cohesive failure with higher probability under a narrow range of loading rate with small values. However, the thickness-dependence of failure mode attenuates gradually and diminishes ultimately under higher loading rate, which leads to the transformation from mixed mode to interfacial one.

Commentary by Dr. Valentin Fuster
2018;():V004T08A018. doi:10.1115/DETC2018-85581.

T gate structure is traditionally manufactured with a valley in its head, which requires the thickness of the head layer to thicker than the height of foot layer. As is presented in this paper, an innovative submicron fabrication process is investigated for T gate structures to construct a flat head in order to get rid of that constraint. In detail, the reason why conventional T gate fabrication cannot manufacture a flat head is analyzed, and then a general process for flat head T gate structure is proposed considering various resist and structure materials. After that, a typical submicron sample has been manufactured using aluminum and NiTi. Furthermore, the particular photo resists and recipes adopted in that sample are considered. To clearly illustrate the proposed technique as well as verify its feasibility, top views of the structure under optical microscope along with the measurement results of thickness after every step are recorded. According to those experimental results, the valley in T gate’s head is proved to be avoided during fabrication.

Commentary by Dr. Valentin Fuster
2018;():V004T08A019. doi:10.1115/DETC2018-85812.

In order to create shape memory alloy (SMA) bimorph microactuators with high-precision features, a novel fabrication process combined with electron beam (E-beam) evaporation, lift-off resist and isotropic XeF2 dry etching method was developed. To examine the effect of E-beam deposition and annealing process on nitinol (NiTi) characteristics, the NiTi thin film samples with different deposition rate and overflow conditions during annealing process were investigated. With the characterizations using scanning electron microscope and x-ray diffraction, the results indicated that low E-beam deposition rate and argon employed annealing process could benefit the formation of NiTi crystalline structure. Besides, SMA bimorph microactuators with high-precision features as small as 5 microns were successfully fabricated. Furthermore, the thermomechanical performance was experimentally verified and compared with finite element analysis simulation results.

Commentary by Dr. Valentin Fuster
2018;():V004T08A020. doi:10.1115/DETC2018-85868.

Different from traditional accelerometer, multi-threshold acceleration switch can be triggered to different working states by external accelerations without complex auxiliary circuits and controlling elements, which has great application potentials in aerospace, vehicle safety and consumer electronics. In this paper, a novel multi-threshold acceleration switch with anti-overloading function is designed and fabricated by incorporating both magnetic multi-stable structures and compliant cantilever contacts, which also can be used to distinguish specific acceleration pulse. To enhance the contact reliability, the magnetic compliant locking mechanism is introduced to prevent bouncing back phenomenon under overload acceleration. Considering the air-damping and multi-magnetic fields coupling effect, the dynamic design model is proposed for analyzing the nonlinear switch response. Then, threshold accelerations can be determined as ac1 = 3.78g, ac2 = 10.2g and ac3 = 6.95g in one direction while threshold accelerations in opposite direction are ac4 = 4.9g, ac5 = 8.47g and ac6 = 5.6g. The switch shows excellent threshold acceleration detection capability, and the inertial switch keeps open while the external acceleration is 0.2g less than the predefined threshold value. The experimental results show that the threshold acceleration with specific pulse width can be accurately identified, and the switch can bear strong overload acceleration comparing to traditional switches. Consequently, the proposed design method provides a new way for intelligent mechanical inertial sensors.

Commentary by Dr. Valentin Fuster
2018;():V004T08A021. doi:10.1115/DETC2018-86228.

Nanocomposites made of a hosting polymer matrix integrated with carbon nanotubes as nanofillers exhibit an inherent hysteretic behavior arising from the CNT/matrix frictional sliding. Such stick-slip mechanism is responsible for the high damping capacity of CNT nanocomposites. A full 3D nonlinear constitutive model, framed in the context of the Eshelby-Mori-Tanaka theory, reduced to a 1D phenomenological model is shown to describe accurately the CNT/polymer stick-slip hysteresis. The nonlinear hysteretic response of CNT nanocomposite beams is experimentally characterized via displacement-driven tests in bending mode. The force-displacement cycles are identified via the phenomenological model featuring five independent constitutive parameters. A preliminary parametric study highlights the importance of some key parameters in determining the shape of the hysteresis loops. The parameter identification is performed via one of the variants of a genetic-type differential evolution algorithm. The nanocomposites hysteresis loops are identified with reasonably low mean square errors. Such outcome confirms that the 1D phenomenological model may serve as an effective tool to describe and predict the nanocomposite nonlinear hysteretic behavior towards unprecedented material optimization and design.

Commentary by Dr. Valentin Fuster
2018;():V004T08A022. doi:10.1115/DETC2018-86252.

We introduce a novel microfabrication method using direct writing of photoresist with an ultrasonic microplotter equipped. First, the photoresist is driven into the pipette through capillary forces. The pipette is then used to directly write microfeatures on a polydimethylsiloxane (PDMS) substrate. The photoresist is cured on a hot-plate and used as a mold for replication. A second layer of PDMS is cast onto the mold. Once cured on a hot-plate, it is peeled off from the mold to obtain the desired microfeatures. We demonstrate that this method can be used for ultra-rapid and cost-effective fabrication of microchannels (39.65 μm wide) without need for clean room facilities.

Commentary by Dr. Valentin Fuster

12th International Conference on Micro- and Nanosystems: MEMS Sensors and Actuators

2018;():V004T08A023. doi:10.1115/DETC2018-85075.

Smart analysis of sensory data in real time is growing more important by the advent of the internet of things (IoT). Currently, this demand is being met by microprocessors utilizing classical computing algorithms or using simple machine learning schemes; which, aside from their high computing power requirements, are projected to reach an imminent plateau as transistor shrinking is reaching a physical limit. In this paper, we show the potential of transforming the dynamics of micro-electro-mechanical system MEMS by activating electrical resonance to perform simple neurological processes, such as detection and memory, similar to those existing in recurrent neurons.

Commentary by Dr. Valentin Fuster
2018;():V004T08A024. doi:10.1115/DETC2018-85439.

With enormous data being generated every day from countless applications and sensor networks, the need for efficient computing devices to process and make use of this data continues to grow and is projected to increase in the future. The idea of analog computing has been redeemed recently and is poised as the future computing paradigm in these applications due to its powerful computing power and lower energy consumption. This work presents a mechanism where MEMS devices are coupled together resulting in dynamic behaviors that qualitatively resemble that of the biologically-inspired Continuous-Time Recurrent Neural Networks (CTRNNs). Moreover, interesting oscillations behaviors and limit cycles attributed to various weight manipulations and excitation input levels have been observed.

Commentary by Dr. Valentin Fuster
2018;():V004T08A025. doi:10.1115/DETC2018-85743.

Complex logic functions based on micro electromechanical resonators has recently attracted significant attention. Realization of complex logic functions through cascading micro resonators has been deterred by challenges involved in their interconnections and the large required array of resonators. This paper presents a micro electromechanical system MEMS resonator with multiple input (actuation) and output (detection) that enables the realization of complex logic operations. The devices are based on a compound resonator consisting of an in-plane clamped-guided arch beam that is mechanically coupled from its guided side to two flexure beams and to another T-shaped resonant beam. As examples, we experimentally demonstrate using the device to realize a half adder and a 1:2 DEMUX, based on electrothermal and electrostatic tuning of the arch beam and side resonant beam. The logic operation is based on the linear frequency modulation. This paper demonstrates that with such compound MEMS resonators, it is possible to build more complex logic functionalities.

Commentary by Dr. Valentin Fuster
2018;():V004T08A026. doi:10.1115/DETC2018-85887.

Electrostatic micro-electro-mechanical-system (MEMS) devices show great potential in a variety of applications such as sensing and actuation; however, they are hindered by their high input voltage requirement. Double resonance excitation, which activates the system’s mechanical and electrical resonances simultaneously, was recently demonstrated experimentally to alleviate this problem. In this work, we present a mathematical model, based on the Euler Bernoulli beam model coupled with a circuit model, to simulate double resonance in MEMS devices and to shed light more onto the previously published experimental data. We show good agreement between the theoretical simulation and experimental data when the electrical resonance frequency band is sufficiently high.

Commentary by Dr. Valentin Fuster
2018;():V004T08A027. doi:10.1115/DETC2018-85898.

MEMS diaphragms utilizing an embedded cantilever array to sense pressure were investigated in an effort to detect blast-induced loads that potentially cause mild traumatic brain injury (mTBI). Overhanging cantilever beams of varying length sequentially contacted convexly deformed diaphragms during pressure loading to enable binned binary threshold pressure sensing. Diaphragms and overhanging cantilever beam arrays photolithographically defined using double-layer SOI-DRIE processes were designed to minimize footprint and maximize sensing resolution while avoiding diaphragm fracture. Analytic models based on classical plate theory were correlated with a FEA model to guide design decisions by predicting deflection behavior of circular diaphragms under uniformly distributed pressure loads. Fabricated sensors experimentally tested under static conditions revealed good agreement with modeling, and indicated such a sensor may be well-suited for integration into a future wearable device capable of sensing potentially mTBI-causing blasts using minimal power.

Commentary by Dr. Valentin Fuster
2018;():V004T08A028. doi:10.1115/DETC2018-86357.

A novel design for MEMS capacitive pressure sensors is presented that can effectively eliminate the temperature drift in sensor for high temperature applications. The design uses a bilayer membrane made of a thin metal film deposited on the top of membrane to balance the deformation the membrane experiences when the ambient temperature changes. The thermal expansion mismatch of the metal layer and the membrane results in out-of-plane bending if the temperature changes. This deformation can compensate the deformation in the membrane due to the temperature change. By optimizing the dimensions of the top metal layer (shape and thickness), it is possible to minimize the change in the device capacitance due to temperature rise. A coupled-field multiphysics solver in ANSYS® APDL is used for design, simulation and optimization of the sensor’s structure and to solve the governing equations of the coupled electrostatic and structural physics. The membrane material is silicon carbide (SiC), the top metal layer is nickel (Ni) and the substrate is a single-crystal silicon wafer. The thickness and dimensions of top metal layer is optimized using FEM simulations. The results display a very stable capacitance value for a large pressure range and over a wide range of ambient temperature (0–600°C), demonstrating the proposed design can effectively eliminate the temperature effect. Different pressure values ranging from 0.0 to 20 bars have been examined in the simulations and for most of the pressure range, a highly stable capacitance value is observed with less than 0.5% error over 600 °C temperature range.

Commentary by Dr. Valentin Fuster

12th International Conference on Micro- and Nanosystems: Micro/Nano Robotics and Manufacturing

2018;():V004T08A029. doi:10.1115/DETC2018-85007.

The smallest forming unit in two-photon photopolymerization (TPP) micro-manufacturing technology is the voxel, the appearance of which resembles a spheroid. Traditional TPP micro-manufacturing is planned using the minor-axis dimension of a spheroid, which is smaller than its major-axis, thus, the spatial resolution can achieve submicron level. TPP can be used to manufacture microstructures with complex shapes. However, such fine spatial resolution inevitably lowers the overall manufacturing speed. For a microstructure with a height of hundred micrometers, the prolonged manufacturing time substantially increases the risk of manufacturing failure. Whereas typical methods use the minor-axis dimension for manufacturing planning, this study developed a novel major-axis planning (MAP) method that uses the longest dimension of the voxel. In this study, the MAP was realized in a 4-axis micro-manufacturing system (i.e., a rotation axis was added to the 3-axis motion stage). Specifically, a specially designed L-type glass substrate was first placed on the rotation axis and was rotated 90°, rendering the working plane parallel to laser beams. Subsequently, horizontal laser scanning was performed, during which the laser focus moved from the working plane horizontally, to polymerize a high-aspect-ratio structure. The commercial polymer OrmoComp was used with the MAP; only 10 s was required to fabricate a microstructure that had a height of 100 μm and an aspect ratio of 17. This study verified that TPP micro-manufacturing on a voxel’s major axis can fabricate microstructures. Moreover, the L-type glass substrate can be controlled programmably to rotate an L-type glass substrate for 4-axis TPP micro-manufacturing in the future.

Commentary by Dr. Valentin Fuster
2018;():V004T08A030. doi:10.1115/DETC2018-85923.

A finite element dynamic model is developed to better understand impact events during large amplitude dynamics of a compliant, elastic-legged small-scale robot. The proposed motion of the robot would be achieved as a result of impulse forces generated from the forced collision of piezoelectrically-actuated, beam-like legs with the ground. The nominal robot leg is a prismatic continuous structure with uniform density, cross-sectional area and moment of inertia. Dynamic modeling in this work attempts to manage the non-negligible motion of the actuated beam tip in its axial direction at impact when large bending deformations are excited, which complicates prior analysis methods. For the micro-robot, this motion is proposed to be exploited as a means to produce locomotion in the horizontal direction, and hence must be accounted for. Finite element analysis approaches are adapted for the micro-robotic circumstances. Preliminary results are presented for the scenario of large deformation, unforced dynamics with impact, tested using centimeter-scale mock-ups for future thin-film based micro-robots. Needs and opportunities for further validation are briefly discussed.

Commentary by Dr. Valentin Fuster
2018;():V004T08A031. doi:10.1115/DETC2018-85951.

The miniaturization of an increasing number of complex hybrid micro-products is currently leading the development of several micro-components to manipulate and assemble, meeting various specifications related to the objects properties and the planned task. However, at the micro-scale, further challenges derive from the effects of surface forces between object and micro-gripper that have to be overcome for an effective and successful manipulation. When contact micro-grippers are used, specific solutions to support the release phase are needed. Further developments and novel tools should be developed for vacuum micro-grippers to actively release the components reliably and precisely. In this context, this paper presents a vacuum micro-gripper with an automatic releasing system able to overcome the adhesive forces simply and effectively. The paper reports the results of a preliminary computational fluid dynamics analysis and the development of a numerical model able to represent the main gripper characteristics and derive a first design procedure.

Commentary by Dr. Valentin Fuster
2018;():V004T08A032. doi:10.1115/DETC2018-86097.

The Fused Deposition Modeling (FDM) technology can be successfully used to manufacture biodegradable polymeric scaffolds for tissue reconstruction in case of critical size bone damages. Carbon nanotubes (CNTs) are able to mimic the extracellular matrix and their addition can improve the mechanical and electrical properties of polymers. In this way, the scaffolds are more likely to match the host bone properties and the cell adhesion, differentiation and proliferation can be enhanced. In this paper scaffold-like specimens, manufactured by FDM technology, are tested to evaluate the conductivity increase in PLA/CNT composite compared to pure PLA (polylactid acid).

Commentary by Dr. Valentin Fuster
2018;():V004T08A033. doi:10.1115/DETC2018-86130.

This paper presents, for the first time, the process of growing a pattern of carbon nanotubes (CNT(s)) on 316L stainless steel. The data presented is preliminary and requires further investigation to detail the growth behaviors of CNTs on stainless steel in regards to producing a pattern. However, this article presents the viability of producing a pattern on a stainless steel surface that can be used in bio-surfacing and electronic applications, among others. The results show that producing a CNT pattern on stainless steel can be achieved in a similar manner to that of producing a CNT pattern on a silicon wafer, with some vital differences in the photolithography and growth processes. The results also show that long CNT growth can lead to partial overgrowth of the pattern.

Commentary by Dr. Valentin Fuster
2018;():V004T08A034. doi:10.1115/DETC2018-86282.

A new fabrication process for stiffness-enhanced microstructures with high area-to-mass ratios is presented in this paper. In order to acquire an enhanced stiffness without ruining the structural parameter of area-to-mass ratio, multilayered metallic microstructures are proposed and fabricated by surface and bulk fabrication processes from Micro-Electro-Mechanical Systems (MEMS) technologies. Microstructures based on beams with symmetrically deposited metals are physically built and tested on wafers. A sacrificial silicon layer is used to form gaps between bimetal layers and the microstructures can be deployed vertically when heated due to the effect of thermal mismatch between different materials. The results show a dramatic thickness increase when actuated by Joule heating, and thus a great bending stiffness enhancement.

Commentary by Dr. Valentin Fuster

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