Friday, November 11 • 2:30 PM – UTEB, Rm. 175

Reconfigurable Plasmonics and Metamaterials

Yongming Liu, Assistant Professor

Department of Mechanical and Industrial Engineering

Department of Electrical and Computer Engineering

Northeastern University, Boston, USA

Email: y.liu@neu.edu;

Group Website: http://www.northeastern.edu/liulab

Abstract: Plasmonics has become a very important branch in nano optics. It allows us to concentrate, guide, and manipulate light at the deep subwavelength scale, promising enhanced light-matter interaction, next-generation optical circuits, sub-diffraction-limited imaging, and ultrasensitive biomedical detection [1-3]. Furthermore, the assembly of judiciously designed metallic structures can be used to construct metamaterials and metasurfaces with exotic properties and functionalities, including anomalous refraction/reflection, strong chirality and invisibility cloak [4,5]. There is a pressing need of tunability and reconfigurability for plasmonics and metamaterials, in order to perform distinctive functionalities and miniaturize the device footprint. In this talk, I will present our recent work in reconfigurable plasmonics and metamateirals. First, I will discuss the first demonstration of reconfigurable plasmonic lenses operating in microfluidic environment, which can dynamically diverge, collimate and focus surface plasmons [6]. Second, I will present a novel graphene metasurface to fully control the phase and amplitude of infrared light with very high efficiency. It manifests broad applications in beam steering, biochemical sensing and adaptive optics in the crucial infrared wavelength range [7]. Finally, I will discuss origami-based, dual-band chiral metasurfaces at microwave frequencies. The flexibility in folding the metasurface provides another degree of freedom for geometry control in the third dimension, which induces strong chirality from the initial, 2D achiral structure [8]. These results open up a new avenue towards lightweight reconfigurable metadevices.

Biographical Sketch: Dr. Yongmin Liu obtained his Ph.D. from the University of California, Berkeley in 2009. He joined the faculty of Northeastern University at Boston in fall 2012 with a joint appointment in the Department of Mechanical & Industrial Engineering and the Department of Electrical & Computer Engineering. Dr. Liu’s research interests include nano optics, nanoscale materials and engineering, plasmonics, metamaterials, biophotonics, and nano optomechanics. He has authored and co-authored over 50 journal papers, including Science, Nature, Nature Nanotechnology, Nature Communications, Physical Review Letters and Nano Letters. Dr. Liu received Office of Naval Research Young Investigator Award (2016), 3M Non-Tenured Faculty Award (2016), Air Force Summer Faculty Fellowship (2015), and Chinese Government Award for Outstanding Students Abroad (2009). Currently he serves as an editorial board member for Scientific Reports, EPJ Applied Metamaterials and Nano Convergence.

References: [1] S. A. Maier, “Plasmonics: fundamentals and applications”, Springer Science+ Business Media (2007); [2] T. Zentgraf et al., Nature Nanotechnology 6, 151 (2011); [3] Y. M. Liu, et al., Nano Letters 12, 4853 (2012); [4] Y. M. Liu and X. Zhang, Chemical Society Reviews 40, 2494 (2011); [5] K. Yao and Y. M. Liu, Nanotechnology Review 3, 177 (2014); [6] C. L. Zhao et al., Nature Communications 4:2350 (2013); [7] Z. B. Li et al., Scientific Reports 5, 12423 (2015); [8] Z. Wang et al., manuscript in preparation.

For additional information, please contact Prof. Ying Li at (860) 486-7110, yingli@engr.uconn.edu or

Laurie Hockla at (860) 486-2189, hockla@engr.uconn.edu

Friday, September 9 • 2:30 PM – UTEB, Rm. 175

High-throughput 3D Printing of Functional Biomedical Devices 

 

Cheng Sun

Professor of Mechanical Engineering

Northwestern University, Evanston IL 60208

Abstract: Advancements in healthcare have opened up the promising opportunities for personalized medicine to improve patient outcomes while decreasing costs. However, widespread adoption remains a major challenge due to the additional time and expense required to individualize treatments to patient-specific conditions. Three-dimensional (3D) printing is an emerging technology with the potential to fabricate personalized biomedical devices at low cost with extremely short lead-time. Recent achievements in the field have utilized 3D printing to manufacture arterial stents, airway tubes, bones, and dental prosthetics with relative large dimensions. However, there remains a knowledge gap for the fabrication of biomedical device with fine feature size without compromising the fabrication speed. I will talk about a highly scalable 3D printing system – continuous liquid interface production microstereolithography (μCLIP) with sub-10 um fabrication precision. I will present our recent development of fast 3D printing of completely customizable stents using the μCLIP process. Stents achieved a lateral resolution of 7.1 x 7.1 mm, with a curing thickness of 20 mm. A 20 mm length stent was printed in approximately 70 minutes and had adequate strength. The mechanical properties of 3D-printed stents with struts of 150 µm and walls thickness of 500 μm were comparable to those of a control bare metal nitinol stent. Furthermore, 3D-printed stents are customizable, could be compressed and self-expanded within a clinically relevant time frame upon deployment, and significantly improve the mechanical properties of a pig artery after deployment. Furthermore, I will discuss the method to fabricate a customized contact lens using 3D printed mold. The biocompatibility and optical performance of the lens has been further characterized experimentally using rat model.

 

Biographical Sketch: Professor Cheng Sun is an Associate Professor at Mechanical Engineering Department at Northwestern University, where he has been since 2007. He received his PhD in Industrial Engineering from Pennsylvania State University in 2002. He received his MS and BS in Physics from Nanjing University in 1993 and 1996, respectively. Prior to coming to Northwestern, he was a Chief Operating Officer and Senior Scientist at the NSF Nanoscale Science and Engineering Center for Scalable and Integrated Nanomanufacturing at UC Berkeley. Dr. Sun received a CAREER Award from the National Science Foundation in 2009 and ASME Chao and Trigger Young Manufacturing Engineer Award, 2011. Dr. Sun’s primary research interests are in the fields of advanced manufacturing necessitate developments the emerging applications in the areas of photonics, energy, and biomedical engineering. His research group is engaged in developing novel micro-/nano-scale fabrication techniques and integrated nano-system. He has published more than 70 journal papers including publications in Science, Nature Nanotechnology, Nature Materials, and Nature Communication. http://sun.mech.northwestern.edu.

For additional information, please contact Prof. Ying Li at (860) 486-7110, yingli@engr.uconn.edu or Laurie Hockla at (860) 486-2189, hockla@engr.uconn.edu

February 21-27, 2016 marks Engineers Week. Take this time to step back and consider the amazing things engineers do for our society, and to watch the video below that highlights some of the impressive things going on at UConn Engineering.

Friday, November 6 • 2:30 PM – UTEB, Rm. 175

Analysis of Convection in the Presence of Apparent Slip

Marc Hodes

Associate Professor of Mechanical Engineering Tufts University, Medford, Massachusetts

Abstract: A liquid flowing over a structured surface in the form of, e.g., ridges parallel to the flow, may be suspended in the unwetted (Cassie) state. I will introduce the physical principles and micro/nanotechnology that are exploited to trap a liquid in this state, where the no-slip boundary condition does not apply. This complicates the solution of the Stokes (or Navier-Stokes) equations for the velocity profile as it imposes different types of boundary conditions along the solid-liquid interface and the liquid-gas interface (meniscus). The vast majority of previous research on such flows considered them adiabatic. We study them in the presence of heat transfer, where the thermal energy equation is too subjected to non-standard boundary conditions. We have solved a variety of diffusive “inner” problems in the vicinity of the structures, where a boundary condition that the flow or temperature field is 1-dimensional infinitely far away from the structures may be imposed. These yield expressions for the apparent hydrodynamic and thermal slip lengths that manifest themselves as Robin boundary conditions on the outer problems that span the whole domain, e.g., a parallel plate channel. Additionally, in the outer thermal problems, advection must be considered. I will present our conformal map and convolution theory-based analytical solution to an inner thermal problem that captures the effects of evaporation and condensation along menisci. Then, I will discuss our analytical results for the Nusselt number (Nu) governing an outer thermal problem where arbitrary and asymmetric hydrodynamic and thermal (apparent) slip are imposed on a thermally-developing Couette flow. Nu is in the form of Airy and exponential function-containing infinite series, where the first term corresponds to the thermally-developed flow limit. Lastly, I will discuss our present work on the effects of thermocapillary stress and meniscus curvature on both types of apparent slip lengths.

Biographical Sketch: Marc Hodes received his M.S. in Mechanical Engineering from the University of Minnesota, where he performed research on dielectric liquid cooling of microelectronics. In 1998, he received his Ph.D. in Mechanical Engineering from the Massachusetts Institute of Technology, where his research addressed salt deposition (fouling) in supercritical water oxidation reactors used for the destruction of hazardous organic wastes. After holding a succession of appointments from Postdoctoral Member of Technical Staff to Manager over a 10 year period at Bell Labs, he joined the Mechanical Engineering Department at Tufts University in the Fall of 2008 as an Associate Professor. Professor Hodes’ research interests are in heat and mass transfer and, over the course of his career, four thematic areas have been addressed, i.e., 1) the thermal management of electronics, 2) mass transfer in supercritical fluids, 3) analysis of thermoelectric modules and 4) analysis of convection in the presence of apparent slip. Current research is in two areas. First, analytical solutions for apparent hydrodynamic and thermal slip lengths for liquid flows over diabatic structured surfaces that capture the effects of curvature, thermocapillary stress or evaporation and condensation at menisci are being developed. Secondly, enhanced aircooled heat sinks are being developed by deriving semi-analytical optimization formula for longitudinal-fin geometry heat sinks that capture the effects of non-uniform heat transfer coefficients and by developing manufacturing methods for novel “three-dimensional” geometries. Students conducting research with Professor Hodes enroll in part of all of his 4 course sequence of undergraduate fluid mechanics, undergraduate heat transfer, thermal management of electronics and graduate heat transfer. Since joining Tufts University in the fall of 2008 Professor Hodes’ research has been supported by the Department of Energy, NSF, DARPA, Science Foundation Ireland, the Wittich Energy Sustainability Research Initiation Fund, Tufts University and domestic and foreign industrial partners.

For additional information, please contact Prof. Michael T. Pettes at (860) 486-2855, pettes@engr.uconn.edu or Laurie Hockla at (860) 486-2189, hockla@engr.uconn.edu

Friday, October 30 • 2:30 PM – UTEB, Rm. 175

The Science and Engineering of Developing Reliable Electronic Systems

Prof. Abhijit Dasgupta Jeong H. Kim

Professor of Mechanical Engineering Center for Advanced Life Cycle Engineering (CALCE)

University of Maryland, College Park, MD 20742

Abstract: This presentation will focus on some of the interesting lessons learned at the CALCE Center over the past 30 years in the science and technology of material aging mechanisms and system degradation modes in complex electronic systems. Modern engineering systems are becoming extremely electronics-rich where the electronics are intrinsically multi-functional systems with highly multi-physics aging and degradation mechanisms under complex life-cycle environmental and operational stress combinations. At the same time, ever-increasing demands for miniaturization have extended the degradation physics into the nano-to-micro length scales, requiring rigorous multi-scale approaches. A few interesting examples of such multi-physics multi-scale degradation mechanisms include creep-fatigue in high-temperature interconnect metal alloys, ‘cold-welding’ in gold-gold interconnects by solid-state diffusion, leakage currents due to the electro-chemistry of dendritic growth in metallization, and dielectric breakdown due to quantum tunneling effects. This pressure for miniaturization, combined with the need for increased functionality and increased affordability, have placed tremendous pressure on the science and technology of achieving and assuring reliability in complex electronic systems. Conducting this type of application-driven fundamental and applied research in a university setting, within the context of graduate thesis and dissertation research, poses unique challenges and imparts special training and skills to the student researchers, to equip them for a very diverse employment landscape. An overview and a few selected examples will be provided during this presentation, with particular emphasis on important lessons that graduate students can take away on how to prepare for the modern-day multi-disciplinary work-place and research environment.

Biographical Sketch: Dr. Abhijit Dasgupta, Jeong H. Kim Professor of Mechanical Engineering, has been teaching at University of Maryland since he obtained his Ph.D. in Theoretical & Applied Mechanics from the University of Illinois in Urbana-Champaign in 1988. His expertise is in the multi-physics, multi-scale constitutive behavior and damage mechanics of engineered materials, for applications in reliability assessment, for real-time health monitoring, and for accelerated stress testing of electronic/photonic systems, ‘smart’ structures, MEMS, and nanoscale structures. This research is funded by an international consortium of leading electronics manufacturers as well as by government funding agencies as NSF, ARL and ARO. He is an ASME Fellow and the current Chair of the Electronic and Photonics Packaging Division of ASME.
For additional information, please contact Prof. Xinyu Zhao at (860) 486-0241, xinyuz@engr.uconn.edu or Laurie Hockla at (860) 486-2189, hockla@engr.uconn.edu