Date: Tuesday, Jan 6, 2015
Time: 1pm
Location: IPST Room 114

Committee:
Dr. Zhong Lin Wang, MSE (Advisor)
Dr. Meilin Liu, MSE 
Dr. Zhiqun Lin, MSE
Dr. Oliver Brand, ECE
Dr. Levent Degertekin, ME

Title: 

Scanning Probe Microscopic study of piezotronics and triboelectrification for their applications in mechanical sensing

Abstract:
As an important component in the modern industrial world, mechanical sensors have been receiving higher requirement when the “internet of things” and artificial intelligent era emerges. On one hand, applications in human machine interface, artificial skin and cell manipulation are chasing high sensitivity and/or high spatial resolution sensors. On the other hand, wide adoption of mobile computing, sensor networks and bio-implantable devices need the mechanical sensing technology to have ultra-low power consumptions. While optimized structural design and combined with advanced microcircuits within existing sensor frame can continue to enhance their performance, exploring and innovating new sensing mechanisms that have abrupt improvement will be of great scientific interest.

Piezotronic and triboelectric effects have recently been demonstrated with promising features on high sensitivity force sensing, and energy harvesting and self-powed devices, respectively. This thesis focuses on characterizing these two effects at nano scale and applying the triboelectric effect to a self-powered motion sensing technology. For piezotronic effect, both longitudinal and transverse sensing modes in CdSe, and GaN nanowires are investigated respectively. For triboelectrification, we quantified the tribo-charge intensity, multi-cycle friction effect, as well as its surface diffusion. Beyond that, effect of external electric field was investigated as an approach to manipulate the polarization and intensity. Finally, a concept of self-powered motion sensing technology is developed and demonstrated experimentally nanometer resolution, long working distance as well as high robustness.