switchable thermal interfaces based on discrete liquid droplets可切换的基于离散液滴的热接口.pdfVIP

Micromachines 2012, 3, 10-20; doi:10.3390/mi3010010 OPEN ACCESS micromachines ISSN 2072-666X /journal/micromachines Article Switchable Thermal Interfaces Based on Discrete Liquid Droplets Yanbing Jia, Gilhwan Cha and Yongho Sungtaek Ju * Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095-1597, USA; E-Mails: icy@ (Y.J.); sharmony@ (G.C.) * Author to whom correspondence should be addressed; E-Mail: just@; Tel.: +1-310-825-0985. Received: 5 December 2011; in revised form: 22 December 2011 / Accepted: 22 December 2011 / Published: 6 January 2012 Abstract: We present a switchable thermal interface based on an array of discrete liquid droplets initially confined on hydrophilic islands on a substrate. The droplets undergo reversible morphological transition into a continuous liquid film when they are mechanically compressed by an opposing substrate to create low-thermal resistance heat conduction path. We investigate a criterion for reversible switching in terms of hydrophilic pattern size and liquid volume. The dependence of the liquid morphology and rupture distance on the diameter and areal fraction of hydrophilic islands, liquid volumes, as well as loading pressure is also characterized both theoretically and experimentally. The thermal resistance in the on-state is experimentally characterized for ionic liquids, which are promising for practical applications due to their n