MEAM Seminar Series Spring 2014
Seminars are held on Tuesday mornings, with coffee at 10:30 am in the Levine Hall Mezzanine and the seminar beginning at 10:45 am in Wu and Chen Auditorium (unless otherwise noted).
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January 28 Ph.D Defense, 9:00 a.m. Levine 307
Jonathon Yoder, Ph.D. Candidate, University of Pennsylvania
"HUMAN INTERVERTEBRAL DISC MECHANICAL FUNCTION UNDER PHYSIOLOGICAL COMPRESSION LOADING QUANTIFIED NON-INVASIVELY UTILIZING MRI AND IMAGE REGISTRATION"
The intervertebral disc (IVD) functions to permit motion, distribute load, and dissipate energy in the spine. It performs these functions through its heterogeneous structural organization and biochemical composition consisting of several tissue substructures: a central gelatinous nucleus pulposus (NP), surrounding fiber reinforced layered annulus fibrosus (AF), and cartilaginous endplates (CEP) positioned between the NP and vertebral endplates. Each tissue contributes individually to overall disc mechanics and by interacting with adjacent tissues. Disruptions of the disc’s tissues through aging, degeneration, or tear alter the affected tissue mechanical properties, adjacent tissue mechanical behavior, and ultimately overall disc segment function. Thus, there is a need to measure disc tissue and segment mechanics in the intact disc so that interactions between substructures are not disrupted. The objectives of this study were to develop, validate, and apply methods to visualize and quantify IVD substructure geometry and track internal deformations for intact human discs under axial compression. The CEP and AF were visualized through MRI parameter mapping and image sequence optimization for ideal contrast. High-resolution images enabled geometric measurements. No correlation was found between CEP thickness and disc level, however the periphery was significantly thicker compared to central locations. Clear distinction of adjacent AF lamellae enabled tear detection and detailed geometric quantification. Annular tears demonstrated “non-classic” geometry through interconnecting radial, circumferential, and perinuclear formations. Axial compression was performed using a custom-built loading device that permitted long relaxation times outside of the MRI, 300 mm isotropic resolution images were acquired, and image registration methods applied to measure 3D internal strain. Regional strain inhomogeneity was observed; strain was higher along the inner AF compared to outer AF, mid-axial disc-height compared to the bone-disc boundary, and within the posterior and lateral regions of the disc. Variation in strain magnitudes might be explained by geometry in axial and circumferential strain while peak radial strain in the posterior AF may have important implications for disc herniation. Overall this study established new methods to non-invasively in 3D visualize and quantify IVD substructure geometry and track internal deformations for intact human discs. These techniques will be valuable to study mechanisms of disc function and degeneration, develop and evaluate surgical procedures, and therapeutic implants.
Frances Ross, Research Staff Member, IBM T.J. Watson Research Center
"Visualising crystal growth in the transmission electron microscope"
In situ transmission electron microscopy is a unique and exciting technique for visualising and quantifying crystal growth. Physical and chemical vapour deposition and even electrochemical deposition can be carried out inside the microscope. By recording movies while growth takes place, we can measure kinetics, identify transient structures, and determine mechanisms. Here we describe two materials systems that illustrate the opportunities and challenges of in situ microscopy: the vapour-phase self-assembly of semiconductor nanowires from catalytic particles, and the liquid-phase electrochemical deposition of metals to form nuclei, thin films and dendrites. The range of materials and processes that can be examined suggests that in situ microscopy of crystal growth can play a key role in basic physics understanding and nanomaterials design.
Frances M. Ross received her B.A. and Ph.D. degrees from Cambridge University, UK, carried out postdoctoral research at A.T.&T. Bell Laboratories, and worked as a Staff Scientist at the National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, before joining IBM. She has been a visiting professor at Lund University, Sweden. Her research interests are based around the use of in situ microscopy techniques to study crystal growth and reactions in nanostructured materials. She has been awarded the UK Institute of Physics Charles Vernon Boys Medal, the MRS Outstanding Young Investigator Award and the MSA Burton Medal and is a Fellow of the APS, AAAS, MSA, AVS and MRS.D
Ladislav Kavan, Assistant Professor, Computer and Information Sciences Department, University of Pennsylvania
"Direct Methods for Skeletal Shape Deformation"
Skeletal shape deformation (shortly “skinning”) addresses the problem
of translating skeletal animation to deformations of a 3D shape, such
as the human body. There are two main classes of skinning methods:
direct and variational. Variational methods pose the task as an
optimization problem, minimizing an energy function. This talk focuses
on direct methods, which compute the resulting deformations in a
direct, closed-form way; this is typically much faster than numerical
optimization. First, I will explain how blending of dual quaternions
improves upon linear blending of matrices, leading to dual quaternion
skinning. Second, I will discuss how to address some of the
shortcomings of dual quaternion skinning using custom spatial mappings
(called “deformers”). The design of these deformers is inspired by
variational methods, allowing us to combine the quality of variational
methods with the speed of direct skinning algorithms.
Ladislav Kavan is an Assistant Professor at the CIS Department,
University of Pennsylvania. Prior to joining Penn, he was a Senior
Researcher at ETH Zurich and Research Scientist at Disney Interactive
Studios. Ladislav's research focuses on real-time graphics and
animation. His core area of expertise is deformation modeling, in
particular skin deformation for virtual characters, often known as
skinning. His other areas of interest include geometry processing and
physically-based simulation, e.g., how to combine data-driven and
physics-based techniques. Ladislav has also experience with
quaternions and related algebras (dual quaternions), subspace methods,
discrete differential geometry, collision detection, and real-time
rendering especially in the context of computer games. Most recently
he is studying applications of real-time graphics and geometry
processing in medicine, anatomically-based modeling and simulation of
the human body.
Ellad B. Tadmor, Professor, Department of Aerospace Engineering and Mechanics, University of Minnesota
"Mapping the Stochastic Response of Nanostructures"
Due to the extreme nonconvexity of the interatomic potential energy landscape the response of nanostructures to applied loading is inherently stochastic. This complexity is addressed head-on by the construction, using branch-following and bifurcation (BFB) methods, of an "Equilibrium Map" (EM) of the nanostructure. The EM describes all of the stable and unstable states of the structure at each value of applied loading and thereby enables a systematic procedure for identifying physically-meaningful response scenarios. These include the limiting cases of a quasistatic process (QP) and quenched dynamic (QD), as well as the rate-dependent case of driven dynamic (DD). The latter enables atomistic simulations at realistic loading rates. The method is applied to the uniaxial compression of a nanoslab of nickel modeled using a classical interatomic potential. The set of possible equilibrium solutions for this simple problem is surprisingly complex thereby demonstrating the need for such an approach.
Ellad B. Tadmor is a Professor of Aerospace Engineering and Mechanics at the University of Minnesota (USA). He received his B.Sc. and M.Sc. in Mechanical Engineering from the Technion -- Israel Institute of Technology in 1987 and 1991, and his Ph.D. from Brown University (USA) in 1996. His research focuses on the development of multiscale theories and computational methods for predicting the behavior of materials directly from the interactions of the atoms making up the material. He has published over 40 papers in this area and two textbooks (see http://modelingmaterials.org for information on the books). Prof. Tadmor is the Director of the Knowledgebase of Interatomic Models (openKIM.org) project which is tasked with developing standards for atomistic simulations and improving transferability of interatomic potentials. He was a Postdoctoral Research Fellow at Harvard University (USA), Associate Professor at the Technion (Israel), and Erasmus Mundus Scholar at the Ecole Normale Superieure in Lyon (France). He received the MRS Graduate Student Award in 1995 for his work on developing the quasicontinuum method, one of the leading multiscale methods, as well as numerous awards for excellence in teaching including the Salomon Simon Mani Award in 2001. Prof. Tadmor is on the Editorial Board of the Journal of Elasticity.
Wednesday, February 19: Joint MEAM/GRASP Seminar, 1:00 p.m. Levine 307
Matthew Turpin, University of Pennsylvania
"Scalable Trajectory Computation for Large Teams of Interchangeable Robots Applied to Quadrotor MAVs "
Large teams of robots have been implemented to great success in Kiva's
automated warehouses as well as UPenn's and KMel Robotics' swarms of
quadrotors. In settings such as these, robots must plan paths which
avoid collisions with other robots and obstacles in the environment.
Unfortunately, trajectory planning for large teams of robots generally
suffers from either the curse of dimensionality or lack of
completeness. I will demonstrate that relaxing the assumption of
labeling each robot and specifying a fixed assignment of robots to
destinations in the trajectory generation problem yields a number of
computational and performance benefits. My algorithm to solve this
Concurrent Assignment and Planning of Trajectories (CAPT) problem has
bounded computational complexity of O(N^3), preserves completeness
properties of a user specified single agent motion planner, and tends
to minimize effort exerted by any one robot. This algorithm generates
solutions to variants of the CAPT problem in settings ranging from
kinematic robots in an obstacle free environment to teams of robots
with 4th order dynamics in a cluttered environment. Finally, I will
show experimental results of the algorithm applied on teams of second
order aquatic vehicles as well as on quadrotor micro aerial vehicles.
I will also outline how time consuming aspects of this approach can be
parallelized and discuss possible decentralized implementations.
Matthew Turpin is a PhD candidate in the Department of Mechanical
Engineering and Applied Mechanics at the University of Pennsylvania
working with Vijay Kumar and Nathan Michael. He works on formation
control and trajectory planning for large teams of quadrotor
Thursday, February 20: Joint MEAM/MSE Seminar, 10:40 a.m. LRSM Auditorium
James Hone, Professor, Department of Mechanical Engineering, Columbia University
"Putting things on top of other things: Fabrication and applications of van der Waals heterostructures"
Ching-Long Lin, Professor, Department of Mechanical and Industrial Engineering and Applied Mathematical and Computational Sciences, University of Iowa
"A Multi-scale Imaging-based Statistics-guided Predictive Lung Model"
In this talk, I will present three stages of developing a multi-scale imaging-based human lung model that bridges macro and micro scales, macro and cellular/molecular scales, and individual and population scales. The ultimate goals of the research are to: (1) understand the lung structure and function relationship at both global and local levels, (2) develop sensitive techniques to assess lung function and enhance drug delivery, (3) improve our ability to detect the onset, progression, extent and location of pulmonary disorders in sub-populations. The first stage of the research is focused on development of a computational fluid dynamics (CFD) model of airflow in the subject-specific rigid 3D-1D coupled airway model that produces physiologically-consistent regional ventilation. The predictive nature of the model is demonstrated with the prediction of hot spots, where harmful and toxic particulate matter could accumulate. The second stage is focused on the interactions between airflow in the airway and airway wall/lung tissue and the mechanotransduction process. The lung model is further extended to include compliant airways in a dynamic lung setting via fluid-structure interaction or image-registration method. In order to integrate the mechanistic models (that predict fluid- and tissue-induced stresses) with a mathematical model of epithelial cells (lining the airway wall) for prediction of water homeostasis, a thermodynamics model for heat transfer and water vapor in the airway is implemented. Finally, I will present the statistics-guided computational framework that bridges individual and population scales.
Ph.D. Department of Mechanical Engineering, Stanford University, January 1994.
M.S. Department of Mechanical Engineering, Stanford University, June 1989.
B.S. Department of Mechanical Engineering, National Taiwan University, June 1986.
HONORS AND AWARDS
2013 Fellow, American Institute for Medical and Biological Engineering (AIMBE)
2011 Keynote Lecturer, European ECCOMAS Conference on Simulation and Modeling of Biological Flows (SIMBIO), Brussels, Belgium
2011 Invited Speaker, 18th Computational Fluid Dynamics Conference, Taiwan, R.O.C.
2011 Invited Chapter Author, Comprehensive Physiology, the landmark series Handbook of Physiology, Wiley-Blackwell
2008 Keynote Lecturer, Symposium on Natural and Artificial Respiration, Germany
2008 Featured Speaker, American Thoracic Society Conference, Canada
1999 The CAREER Award, National Science Foundation, U.S.A.
• Guest Editor, Journal of Computational Physics: Special Issue on Multi-scale Modeling and Simulation of Biological Systems, 2011-2013
• Lead, Cell-to-Macroscale Working Group, the Interagency Modeling and Analysis Group (IMAG) and the Multi-scale Modeling Consortium (MSM), 2010-present
Monday, March 17: MEAM Special Seminar, 1:30 p.m., Glandt Forum,
Hod Lipson, Associate Professor, Creative Machines Lab, Mechanical & Aerospace Engineering, Cornell University
"The future of 3D printing: From analog to digital materials "
3D Printers – machines that can automatically fabricate arbitrarily-shaped parts, layer by layer, from almost any material – have evolved over the last three decades from limited and expensive prototyping equipment in the hands of few, to small-scale commodity production tools available to almost anyone. It’s been broadly recognized that this burgeoning industrial revolution will transform almost every industry, and every aspect of our lives. But how? And where will this technology go next? This talk will describe the underlying principles common all areas that 3D printing technology is transforming. We will then look at the evolution of additive manufacturing to see where it will go next. From printing arbitrarily complex shapes to creating new kinds of materials, and ultimately, moving from fabricating passive parts to printing active, integrated systems, including electronics, actuators and sensors. Will we be able to print a robot that will walk out the printer, batteries included?
Hod Lipson is a professor of engineering at Cornell University in Ithaca, New York, and a co-author of the recent book “Fabricated: The New World of 3D printing”. His work on self-aware and self-replicating robots, food printing, and bio-printing has received widespread media coverage including The New York Times, The Wall Street Journal, Newsweek, Time, CNN, and the National Public Radio. Lipson has co-authored over 200 technical papers and speaks frequently at high-profile venues such as TED and the US National Academies. Hod directs the Creative Machines Lab, which pioneers new ways to make machines that create, and machines that are creative. For more information visit http://lipson.mae.cornell.edu
Fernando Muzzio, Professor and Chair, Department of Chemical and Biochemical Engineering, Rutgers University
"Continuous Pharmaceutical Manufacturing: The late revolution"
Continuous manufacturing methods have been adopted decades ago in most major industries. No so in pharma, where even today, batch manufacturing and acceptance sampling still rule the field. Among the many reasons given for this situation, “complexity of powders” and a “conservative regulatory mindset” are often cited.
However, in the last decade, as blockbuster patents expire and cost saving pressures mount, all while FDA increasingly demands higher quality execution, modernization of the manufacturing paradigm has become an urgent need. At the present time, the entire industry has focused on enabling continuous manufacturing options as soon as we can create them. The dam is about to crack, and a flood of innovation is safely anticipated.
In this presentation, I will discuss the role of material properties in the design and robust operation of continuous manufacturing systems. I will then describe the use of integrated system-wide models to design and optimize continuous manufacturing systems, including their required associated control architectures. I will conclude with a discussion of open issues and technical opportunities that remain unresolved.
Ph.D., Univ. of Mass. at Amherst, Chemical Engineering, 1991. Thesis: "Non-Linearity, Chaos, and Self-Similarity: Effects of Mixing, Aggregation, Reaction, and Breakup on Structure Formation." (Advisor: Prof. Julio M. Ottino)
B.S., University of Mar del Plata, Argentina, Chemical Engineering, 1985.
Professor II, Rutgers University, 2007-present
Director, NSF Engineering Research Center on Structured Organic Particulate Systems, 2006-present
Director, NSF-NIH Nanopharmaceutical Engineering IGERT training program, 2005-2011
President, Mixing Consultants Inc, 1996-present
Chief Scientific Officer, Acumen Biopharma LLC, 2012-present
Co-Chair, Technology subcommittee, National Institute for Pharmaceutical Technology and Education, 2005-2007
Chair, Education subcommittee, National Institute for Pharmaceutical Technology and Education, 2005-2007
Visiting Professor, Department of Chemical Engineering, University of Puerto Rico, 2004-2005.
Professor, Rutgers University, 2000-2007.
Associate Professor, Rutgers University, 1996-2000.
Director, Pharmaceutical Engineering Program, Rutgers University, 1995-2006
Director, Rutgers/NJIT Particle Processing Research Center, 1996-2002
Assistant Professor, Rutgers University, 1991-1996.
Voting Member, Committee on Pharmaceutical Sciences and Clinical Pharmacology, U.S. FDA. July 2010-present
Chair, Technical Board, Oncobiologics Inc.
Member, Scientific Advisory Board, Pharmaceutical Engineering Research Center, Graz University, Austria, 2008-present
Member, Scientific Advisory Board, Rutgers Energy Institute, July 2008 – present
Member, Scientific Advisory Board, Rutgers Institute for Advanced Materials, Devices, and Nanotechnology, January 2008-present
Member, Board of Directors, Rutgers Center for Innovative Ventures and Technology, January 2008-present
Editorial Board member, Integrated Pharmacy Research and Practice, 2011-present
Editorial Board member, Journal for Pharmaceutical Innovation, 2007-present
Editorial Board member, Pharmaceutical Technology, 2004-present
Committee of Visitors, NSF Program on Nanoscale Science and Technology, June 2004
American Institute of Chemical Engineers, North American Mixing Forum 2008 Award for Excellence and Sustained Contributions to Mixing Research and Practice
American Institute of Physics Prize (Gallery of Fluid Motion by Physics of Fluids) “Three-Dimensional Chaotic Mixing”, Physics of Fluids, Volume 16(9), S8, P.E. Arratia, MM. Alvarez, T. Shinbrot and F.M. Muzzio
Rutgers Board of Trustees Research Fellow (Gold Star) Award
Dupont Young Professor Award 1995-1997 ($75,000).
Dupont Education Award 1998-2001 ($45,000)
Hoechst-Celanese Young Professor Award, 1995 ($20,000).
Merck Fellowship for Young Faculty Development, 1993-1997 ($120,000).
3M Foundation Untenured Faculty Award, 1993, 1994, 1995 ($45,000).
Exxon Education Foundation Award, 1992, 1993 ($20,000).
Gold Medal for Academic Achievement (1985 highest GPA, University-wide), University of Mar del Plata, Argentina.
Buenos Aires State Award for Highest GPA, 1985.
Thursday, March 27: MEAM Special Seminar, 1:30 P.M., Towne Building, Room 337
Sarah Bergbreiter, Assistant Professor, Mechanical Engineering and Institute for Systems Research, University of Maryland
"Tiny leaps for robot kind: combining microfabrication and robotics"
Research on mobile microrobots has been ongoing for the last 20 years, but the few robots that have walked have done so at slow speeds on smooth silicon wafers. However, ants can move at speeds over 40 body lengths/second on surfaces from picnic tables to front lawns. What challenges do we still need to tackle for microrobots to achieve this incredible mobility? This talk will discuss some of the mechanisms and motors we have designed and fabricated to enable robot mobility at the insect size scale as well as the use of microfabrication to improve larger robots. Mechanisms and sensors utilize new microfabrication processes to incorporate materials with widely varying moduli and functionality for more complexity in smaller packages. Actuators are designed to provide significant improvements in force density, efficiency and robustness over previous microactuators. Results include a 4mm jumping mechanism that can be launched approximately 35 cm straight up as well as a 300mg robot that jumps 8 cm with on-board power, sensing, actuation and control.
Sarah Bergbreiter joined the University of Maryland, College Park in 2008 as an Assistant Professor of Mechanical Engineering, with a joint appointment in the Institute for Systems Research. She received her B.S.E. degree in Electrical Engineering from Princeton University in 1999, and the M.S. and Ph.D. degrees from the University of California, Berkeley in 2004 and 2007 with a focus on microrobotics. She received the DARPA Young Faculty Award in 2008, the NSF CAREER Award in 2011, and the Presidential Early Career Award for Scientists and Engineers (PECASE) in 2013 for her research on engineering robotic systems down to sub-millimeter size scales. She also received the Best Conference Paper Award at IEEE ICRA 2010 on her work incorporating new materials into microrobotics and the NTF Award at IEEE IROS 2011 for early demonstrations of jumping microrobots.
Mark Allen, Alfred Fitler Moore Professor, Department of Electrical and Systems Engineering. University of Pennsylvania
"An Electroplating-Based Approach to Volumetric Nanomanufacturing And Its Application to Energy Conversion and Storage "
The manufacture of materials with bulk volumes and precisely controlled nanostructure has led to the creation of materials with surprising and useful mechanical and electrical properties. Recently we have developed a ‘top-down’ technique based on sequential electroplating that allows the creation of highly-structured multilayer metallic materials, with precisely designed characteristic lengths in the hundreds of nanometers but volumes of manufactured material in the macro range. This electroplating-based approach also enables batch fabrication of nanostructures. The fabrication relies on automated and repeated multilayer electrodeposition of multiple metallic materials, followed by sacrificial etching of one metal. The remaining structure consists of individualized high-lateral-aspect-ratio sub-micron metallic films. Example applications of the use of these nanostructured materials in energy storage and conversion applications, including batteries and magnetic-material-based ultracompact DC/DC power converters, will be discussed.
Mark G. Allen received the B.A. degree in chemistry, the B.S.E. degree in chemical engineering, and the B.S.E. degree in electrical engineering from the University of Pennsylvania, Philadelphia, and the S.M. and Ph.D. (1989) degrees from Massachusetts Institute of Technology, Cambridge. In 1989 he joined the faculty of the School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, ultimately holding the rank of Regents’ Professor and the J.M. Pettit Professorship in Microelectronics, as well as a joint appointment in the School of Chemical and Biomolecular Engineering. In 2013 he left Georgia Tech to become the Alfred Fitler Moore Professor of Electrical and Systems Engineering and Scientific Director of the Singh Nanotechnology Center at the University of Pennsylvania. His research interests are in the development and the application of new micro- and nanofabrication technologies, as well as MEMS. He is a previous Editor-in-Chief of the Journal of Micromechanics and Microengineering, previous co-chair of the IEEE Microelectromechanical Systems Conference and of the Power MEMS conference, and will co-chair the 2016 Solid State Sensor, Actuator, and Microsystems Conference in Hilton Head, SC. He is a Fellow of the IEEE.
Pradeep Sharma, M.D. Anderson Chair Professor & Department Chair, Department of Mechanical Engineering, University of Houston
Classical mechanics is intrinsically size-independent and as such does not distinguish between structures that are self-similarly scaled from miles to nanometers. In this presentation, I discuss a specific physical phenomenon (flexoelectricity) that leads to size-effects in electromechanical coupling. I will argue, through computational examples, the tantalizing possibility of creating “apparently piezoelectric” materials without piezoelectric materials—e.g. graphene, emergence of “giant” piezoelectricity at the nanoscale, and a peculiar indentation size-effect in ferroelectrics. Finally, I will present evidence indicating the crucial role of flexoelectricity in a major bottleneck underpinning the use of ferroelectrics-based nanocapacitors used for energy storage. I will also briefly present ramifications of flexoelectricity for soft materials and biological membranes.
Pradeep Sharma is the M.D. Anderson Professor and Chair of Mechanical Engineering. He also has a joint appointment in the Department of Physics. He received his Ph.D. in micromechanics of materials (mechanical engineering) from the University of Maryland at College Park in the year 2000. Subsequent to his doctoral degree, he was employed at General Electric R & D for more than three years as a research scientist. There he worked in two simultaneous programs on Nanotechnology and Photonics apart from basic research in problems of theoretical and computational materials science. He joined the department of mechanical engineering at University of Houston in January 2004. His honors and awards include the Young Investigators Award from Office of Naval Research, Thomas J.R. Hughes Young Investigator Award from the ASME, Texas Space Grants Consortium New Investigators Program Award, the Fulbright fellowship and the University of Houston Research Excellence Award. He is a fellow of the ASME, was an associate editor of Journal of Computational and Theoretical Nanoscience and is currently associate editor of the Journal of Applied Mechanics and serves on the editorial board of several other journals.
Hod Lipson, Associate Professor of Mechanical & Aerospace Engineering and Computing & Information Science, Cornell University
"The Robotic Scientist: Distilling Natural Laws from Experimental Data, from cognitive robotics to computational biology"
Can machines discover scientific laws automatically? Despite the prevalence of computing power, the process of finding natural laws and their corresponding equations has resisted automation. This talk will outline a series of recent research projects, starting with self-reflecting robotic systems, and ending with machines that can formulate hypotheses, design experiments, and interpret the results, to discover new scientific laws. We will see examples from psychology to cosmology, from classical physics to modern physics, from big science to small science.
See Schmidt M., Lipson H. (2009) "Distilling Free-Form Natural Laws from Experimental Data," Science, Vol. 324, no. 5923, pp. 81 - 85. Try it on your own data
Hod Lipson is an Associate Professor of Mechanical & Aerospace Engineering and Computing & Information Science at Cornell University in Ithaca, NY. He directs the Creative Machines Lab, which focuses on novel ways for automatic design, fabrication and adaptation of virtual and physical machines. He has led work in areas such as evolutionary robotics, multi-material functional rapid prototyping, machine self-replication and programmable self-assembly. Lipson received his Ph.D. from the Technion - Israel Institute of Technology in 1998, and continued to a postdoc at Brandeis University and MIT. His research focuses primarily on biologically-inspired approaches, as they bring new ideas to engineering and new engineering insights into biology.
Friday, April 25: Masters Defense, Chia-Hsing Pi, 2:30 p.m., Towne 307
Chia-Hsing Pi, Masters Student, University of Pennsylvania
"Design, analysis, and applications of stress-engineered 3D microstructures"
Most microelectromechanical systems (MEMS) are fabricated using well-established surface and bulk micromachining processes. The overall objective of this thesis is to investigate the development of MEMS sensors made through an alternate approach, namely residual stress-engineering to obtain 3-D structures. Specifically, the research reported in this work includes the development of analytical models, simulations, and fabrication techniques for a new class of stress-engineered piezoresistive tactile sensors. The primary parts of this thesis are: (1) characterization of stresses in PECVD films for stress-engineering, (2) mechanical analysis of stress-engineered structures, and (3) design of piezoresistive tactile sensor.
Silicon nitride deposited via PECVD is a promising material for stress engineered structures. Measurements of residual stress as a function of processing parameters show that silicon nitride can have large tensile residual stress and the deposition parameters, such as flow rates and RF power, can be used to tune the stress magnitude. Stress engineered test structures were fabricated based on: (1) a combination of silicon, silicon nitride, and sacrificial silicon dioxide as well as (2) an alternate combination of silicon nitride, silicon dioxide, and sacrificial silicon. The ability to fabricate stress-engineered structures from both systems was investigated and successful structures were fabricated from the second system. The experimental results were compared to the analytical and finite element models and showed good agreement.
A novel piezoresistive tactile sensor based on stress-engineered structures has been designed. The overall system of the tactile sensing skin, signal acquisition, and user interface has been designed. The sensor is composed of a single crystal silicon piezoresistor and a stressed film for engineering the 3D shape. For piezoresistive sensing, the performance highly depends on the stress distribution. To maximize the sensitivity, only a single type of stress (tensile or compressive) can exist in the silicon layer. A detailed analysis of stress distribution and piezoresistive performance are described. A preliminary fabrication flow, photomask design are also presented.
Key words: stress-engineering, 3D microstructures, PECVD, piezoresistive tactile sensor
April 29: MEAM Seminar, Thomas Degnan, 3:15 p.m., Towne 337
Thomas Degnan, Manager, Breakthrough and Leads Generation for ExxonMobil Research and Engineering Co
"The Outlook for Energy: A View to 2040"
By 2040, global energy demand, driven primarily by population growth and improvements in living standards, will be about 30 percent greater than it is today, even with substantial gains in efficiency. Meeting this challenge will require a multiplicity of energy solutions. Emerging technologies such as renewables combined with a greater reliance on natural gas, will help meet the world's growing energy needs while also reducing the impact on our environment.
This presentation will provide an overview of the projected global demand for all types of energy and will highlight the needs in the power generation, transportation, residential / commercial and manufacturing sectors. The talk will highlight differences in the energy demand profiles of Organization for Economic Cooperation and Development (OECD) and non-OECD countries
Thomas F. Degnan Jr. is currently, manager of breakthrough and leads generation for Exxon Mobil Research and Engineering Company. He earned a B.S. degree in chemical engineering from the University of Notre Dame in 1973, a Ph.D. from the University of Delaware in 1977, and an MBA from the University of Minnesota in 1980. He has previously worked for 3M Corporate Research and the Mobil Technology Company. Degnan is a member of several advisory boards, including those of the College of Engineering, University of Notre Dame, Department of Chemical and Biomolecular Engineering, University of Delaware; Department of Chemical and Biochemical Engineering, John Hopkins University, and the Department of Chemical and Materials Engineering at Stevens Institute.