In this talk, I would like to introduce three approaches in small scale thermal science and engineering. The first part of the talk will focus on the utilization and characterization of nanosystems, i.e., carbon nanotubes and nanowires. Simultaneous measurements of thermal conductivity and Seebeck coefficient will be presented in the first part. To this end, a microfabricated device which is subsequently tailored by focused ion beam (FIB) is used to place a single nanowire across the designated metal electrodes. Nanomanufacturing by FIB was implemented to provide a platform for nanoscale measurement. In the second part, a novel method of measuring temperature and thermal conductivity of 2-D materials such as carbon nanotubes films and graphene at microscale level will be presented. This method involves with a cellular-level, high-resolution temperature sensing system using a micropipette thermocouple sensor. In addition, the 3-omega method was employed to measure thermal conductivity of 3-D cellular structures. To this end, we have developed a novel microheater technology, which allows temperature detection, at microscale levels. The microscale sensor measures the thermal response (periodic temperature variation subject to modulated heat input) of biological samples; the measured data combined with mathematical models was used to determine the thermal conductivity. The data output will be used for early disease detection, which is derived from differences in thermal properties in an in vitro human melanoma model of progression as well as thermal properties of ductal carcinoma breast cancer.
Dr. Tae Y. Choi joined University of North Texas in Fall 2006 as a founding junior faculty in the Department of Mechanical and Energy Engineering. After he earned his Ph.D. degree from University of California, Berkeley in 2002, he received his post-doctoral training at ETH Zurich, Switzerland. Soon after, he served as a lecturer for two and a half years at ETH before he came to UNT. He taught conventional and advanced mechanical engineering courses in the areas of thermal science and nanoscale energy transport. He conducted his research in small scale manufacturing and instrumentation such as characterization of micro and nanoscale thermal properties. He made significant contributions to scientific and engineering societies including American Society of Mechanical Engineers (ASME). He is an active member of ASME since 2007 while he has served in the ASME K-15 committee.