报告题目：Advanced Thermal Energy Harvesting Devices for Low-Power Electronic Applications
报告人：Prof. Dongyan Xu（Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong）
With the recent advance of wireless sensor network and wearable electronics, there is a strong motivation to develop low-cost energy harvesting devices that can scavenge energy from the ambient environment and convert it to electricity. In this talk, I will present our recent research efforts on developing two types of thermal energy harvesting devices: (1) thermoelectric generators; (2) thermogalvanic cells. High power density micro-thermoelectric generators were developed by integrating pulsed electroplating with microfabrication processes. Through systematic optimization of materials properties, a record high power density of 20.0 mW cm-2 is achieved at a temperature difference of 36?C for flexible thermoelectric generators. The high power density can be attributed to enhanced thermoelectric properties of electroplated materials, low parasitic contact electrical resistance, and high packing density of thermoelectric pillars. Compared to traditional thermoelectric materials, redox couples could achieve a much larger Seebeck coefficient typically on the order of mV/K. Recently, we demonstrated that I-/I3- redox couple could be tuned from “p-type” to “n-type” by adding thermoresponsive polymer into the electrolyte. The Seebeck coefficient and p-n conversion temperature were further tuned by adding potassium chloride solutions with different concentrations. At optimal conditions, we are able to achieve Seebeck coefficients of 6.0 mV/K (p-type) and -8.06 mV/K (n-type) for I-/I3- redox couple, in sharp contrast to 0.8 mV/K for pure I-/I3- electrolyte.
Prof. Dongyan Xu is currently an Associate Professor in the Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong (CUHK). Prof. Xu received her Bachelor, Master, and Ph.D. degrees from Tsinghua University and Vanderbilt University. After that, she worked as a Postdoc in the University of California, Berkeley and Lawrence Berkeley National Laboratory for two years. She joined CUHK in 2010 as an Assistant Professor and was promoted to Associate Professor in 2016. Her current research interests include nanoscale heat transfer, thermoelectric materials and devices, thermal management, and boiling heat transfer.