Materials Science and Engineering Program
Jianhe Guo is a third year PhD student in the Materials Science and Engineering Program at The University of Texas at Austin (UT Austin). He received his bachelor's degree in materials chemistry from The University of Science and Technology of China (USTC) in 2012. He has been nominated for the “2015 HHMI International Student Research Fellowship”,received“2014 Harris L. Marcus Graduate Fellowship” in Materials Science &Engineering and “2014 Graduate Student Professional Development Award” by UT Austin. Working as a research assistant in Prof. Donglei (Emma) Fan’s group, he focuses his research on innovative design, manufacturing, and applications of micro/nanoelectromechanical (MEMS/NEMS) devices such as nanomotors, and also synthesis and applications of novel carbon materials including graphene and graphite foam
Recently, we reported an innovative type of nanomotors consisting of nanowires as rotors and patterned Au/Ni/Cr nanodisks as bearings. The dimensions of nanomotors were less than 1 µm, and could continuously rotate for 15 hours over 240,000 cycles. To understand the limitation of their lifetime, we systematically investigated the rotation dynamics by analytical modeling and determined the time-dependent torques and forces involved in the rotation. From the forces and torques, the extent of wear of nanomotors was successfully derived, which well agreed with the experimental characterizations. The results also proved that frictional force linearly increases with the loading in such rotary nanodevices operating in suspension, consistent with the predictionof the non-adhesive multi-asperityfriction theory. With these understandings, we enhanced the design of nanomotors and achievedan operation lifetime of 80 hours and over 1.1 million total rotation cycles. This research, shining new light on the frictional mechanism of recently reported nanowire nanomotor with demonstration of the most durable rotary nanomechanical devices of similar dimensions to the best of our knowledge, could be inspiring for innovative design of future nanomechanical devices with ultralong lifetime for practical applications.