Beckman Institute Postdoctoral Fellows to present at Dec. 7 Director’s Seminar

Beckman Institute Postdoctoral Fellows Limei Tian and Yingjie Zhang will present at the final fall Director’s Seminar on Dec. 7 at noon in Room 1005. Tian will discuss “Soft, Skin-mounted Electronics for Health Care,” and Zhang will discuss “Materials by Design: Two-dimensional Electronic Metamaterials.” The lecture is open to the public, and lunch is provided.

“Soft, Skin-mounted Electronics for Health Care”

Limei Tian, Beckman Institute Postdoctoral Fellow

Abstract

Remarkable advances in the design and fabrication of soft, flexible electronics over the past decade form the basis of novel classes of skin-interfaced wearable medical devices capable of continuously measuring and wirelessly transmitting biophysical and biochemical parameters associated with physiological health and mental activity. These new systems are expected to revolutionize health care by improving outcomes and reducing costs, as they become integral parts of a more modern, connected medical infrastructure. In this talk, I will highlight recent advances in materials, mechanics, and manufacturing approaches for such systems designed for electrophysiology and thermophysiology. Specifically, we developed large-area, skin-like electrical interfaces that enable, through advanced pattern recognition algorithms, control of robotic prosthesis with sensory feedback provided by electrical stimulation. These platforms are also magnetic resonance imaging (MRI)-compatible, thereby allowing for the simultaneous measurements of electroencephalography (EEG) and functional MRI. The possible applications of such soft, stretchable electronics are quite extensive. I also will discuss the design and implementation of soft and stretchable thermal sensors for monitoring the interface between wearable and the residual limb.

Biography

Limei Tian is a Beckman Institute Postdoctoral Fellow. She earned her Ph.D. in mechanical engineering and materials science at Washington University in St. Louis. Her research interests are focused on the design, synthesis, and fabrication of unconventional materials and devices, which can expand the fundamental understanding of biotic-abiotic interactions at various length scales and foster technologies that enable advanced health care, renewable energy, environmental monitoring and sustainability, and homeland security. At the Beckman Institute, she primarily works with John Rogers, a professor of materials science and engineering and a member of Beckman's 3D Micro- and Nanosystems Group.

“Materials by Design: Two-dimensional Electronic Metamaterials”

Yingjie Zhang, Beckman Institute Postdoctoral Fellow

Abstract

Nanoscience offers a unique opportunity to design modern materials from bottom up, with controlled assembly of the nanoscale components. The last two decades have seen a plethora of such bottom-up fabricated materials and devices. While the structural control has been significantly improved and perfected, the electronic functionalities of these artificial systems are still far behind their single-crystal counterparts. This is mainly due to the imperfections at surfaces and interfaces of the nanomaterial building blocks. To overcome this bottleneck, I initiated a new strategy to design two-dimensional artificial solids: Assemble monolayers of closely-packed nanoparticles, and stack 2D semiconductor layers on top. In this way, the 2D layer experiences periodic modulation of charge doping, electronic coupling, and/or lattice distortions (strain). The designed 2D superlattices combine the advantages of the high electron mobility of 2D materials and the structural versatility of the nanoparticle assemblies, and exhibit novel electronic and optoelectronic properties. I will discuss particular examples of these hybrid systems showing emergent effects such as Dirac electron cloning and solar energy funneling.

Biography

Yingjie Zhang received his Ph.D. degree in applied science and technology from the University of California, Berkeley, in August 2015, with a major in applied physics, before becoming a Beckman Institute Postdoctoral Fellow. His Ph.D. research was conducted in the groups of Professor Miquel Salmeron and Professor Paul Alivisatos. He combined the expertise of the two groups, and he developed his unique approach of research: Use scanning probe microscopy to image the functioning mechanisms of solution-processed electronic and optoelectronic devices, and then design new, more efficient devices based on the discovered mechanisms. He received the Dorothy M. and Earl S. Hoffman Scholarship from American Vacuum Society in 2014, and the Graduate Student Silver Award from the Materials Research Society in 2015. At Beckman, he is collaborating with several faculty members (Nadya Mason, Joseph Lyding and Matthew Gilbert from the Nanoelectronics and Nanomaterials Group, and Narayana Aluru, from the Computational Multiscale Nanosystem Group) on a few projects involving two-dimensional materials and layered topological insulators. Zhang’s research covers a broad spectrum of materials and device physics, including molecular-level structural dynamics, quantum transport and electronic interference, and magnetoresistance and spintronic properties. He also is keen on exploring device applications, such as transistors, photovoltaics, memory, and quantum computing.