MEMS-in-TEM for in-situ Nano Electromechanical Testing and High-Performance Energy Harvesters using Ionic Liquid

MEMS-in-TEM for in-situ Nano Electromechanical Testing and High-Performance Energy Harvesters using Ionic Liquid
Friday, March 6, 2015 - 3:00pm to 4:00pm
AllenX Auditorium
Hiroyuki Fujita
Abstract / Description: 

My research group has investigated MEMS fabrication and actuators since 1986. Recently, we inserted and operated MEMS devices in the specimen chamber of the transmission electron microscope (TEM). We conducted in situ TEM observation of the tensile and shear testing of nano junctions between two sharp tips. The tensile testing of a silicon junction of a few nm in diameter showed its extraordinary large plastic deformation. The shear deformation of a silver nano junction exhibited series of sub-nm steps correlated well with the crystalline spacing along an easy-to-slide plane; we may call those steps an atomic-scale stick-slip. Furthermore, we found the heat transfer through a short and thin, both in a few nm, silicon junction was much higher than the bulk value because of ballistic heat transfer. Also we have built a MEMS liquid cell in which the growth of a gold electrode by electroplating was observed in real time. We propose a high power-output vibrational energy harvesting based on ionic liquid. Ionic liquid enables very large capacitance (1.0-10 μF cm-2) on the electrode at bias voltage less than 1.9 V due to its extremely thin (~ 1 nm) electrical double layer. By mechanical squeezing and drawing the ionic liquid, that was solidified with a polymer additive, between a pair of electrodes at 15 Hz, we stably obtained the current output of 22 μAp-p cm-2 at 1.5 V.


Hiroyuki Fujita is Professor (1993-present) and served as the Deputy Director (2009-2012) of the Institute of Industrial Science (IIS), The University of Tokyo. He is also the Director of the Center for International Research on Micronano Mechatronics (2000-present). He received the B.S., M.S. and Ph.D. degrees from Department of Electrical Engineering of The University of Tokyo, Tokyo, Japan in 1975, 1977 and 1980, respectively. He joined IIS as an assistant professor just after earning his Ph.D. degree. Currently he stays in UC Berkeley as a Russell Severance Springer Professor. He received M. Hetenyi Award of Experimental Mechanics from the Society for Experimental Mechanics in 1986, Chevalier de l'Ordre des Palmes Academiques from Government of France in 2001, The Prize for Science and Technology in Research Category from Japanese Ministry of Education, Culture, Sports, Science and Technology in 2005, Outstanding Achievement Award from The Institute of Electrical Engineers of Japan in 2005, and The Yamazaki-Teiichi Prize from Foundation for Promotion of Material Science and Technology of Japan in 2013.