Carbon nanotube (CNT) composite surfaces for electrical contact interfaces

Abstract

MEMS relays boast numerous advantages over PIN diode and FET devices, for example: lower on-resistance, higher isolation and cut-off frequency. There are two common implementations of MEMS switches: capacitively coupled and metal-contacting. Whilst the use of capacitive switches at low frequencies is limited, they tend to be capable of surviving high numbers (>500,000,000) of switching cycles without showing any signs of mechanical failure. For metal-contacting switches, the electrical contacts are mechanically brought into contact without the presence of a dielectric layer on the contacts, consequently enabling the transmission of DC to high frequency signals. A combination of electrical and mechanical factors result in degradation of the contact surfaces over consecutive opening and closing processes which ultimately result in switch failure.

The use of gold-coated multi-walled carbon nanotube (Au/MWCNT) bilayer composites have been investigated as a method for improving the reliability of switch contacts. Using a gold-coated MEMS cantilever beam to test the composite contacts. With a load current of 50 mA (load voltage 4 V), the use of a composites contact resulted in a switching lifetime in excess of 44,000,000 hot switching cycles. With a load current of 10 mA, the lifetime is in excess of 500,000,000 cycles. The use of Au/MWCNT composites offer a promising solution to enhance the lifetime of MEMS switches.

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Identifiers

ORCID for Liudi Jiang: orcid.org/0000-0002-3400-825X

ORCID for S.M. Spearing: orcid.org/0000-0002-3059-2014

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