High-power MEMS switch enabled by carbon-nanotube contact and shape-memory-alloy actuator

Abstract

A forest of vertically aligned carbon nanotubes (CNTs) is integrated as an electrical contact material with a high-power, normally-open switch based on micro-electro-mechanical systems (MEMS) technology. A shape-memory-alloy (SMA) cantilever is thermally actuated to enable switching between the movable CNT forest and the copper electrode formed on the SMA. The out-of-plane SMA actuator provides high forces to enable distributed contacts with the CNT forest, achieving low contact resistances and high ON/OFF resistance ratios. The ON state of the switch shows contact resistances as low as 35 Ω with a dependence on the operating current. The device operation is performed with over 5-W input powers. Long-term operation with more than 1 × 106 switching cycles is demonstrated. The results indicate that a combination of the CNT-based contact and the SMA actuator may be a promising path to realizing reliable MEMS contact switches for high-power applications. A high-power micro-electro-mechanical switch is realized using a forest of vertically aligned carbon nanotubes (CNT) as contact material and a shape-memory-alloy (SMA) actuator. Large-force actuation of SMA enables vastly distributed contacts between the forest and the copper electrode, achieving low contact resistance and high current conduction. The contact material also shows varistor-like behavior. Long-term switching for over one-million cycles is demonstrated. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.