Abstract

This paper reports a new, deep reactive-ion-etching (DRIE) based microfabrication method to realize continuous electrowetting (CEW) for MEMS. CEW is a surface-tension driven actuation mechanism that drives a liquid-metal droplet along an electrolyte-filled microchannel by controlling the surface tension of the liquid metal with electric potential. DRIE process enables us to use silicon dioxide microchannel instead of the previously reported polymer which raised the question of long-term material compatibility between the electrolyte and channel material. The paper also discusses the design issues and scaling law to use CEW for microscale devices, revealing many advantages and justifying the CEW as a powerful microactuation principle for MEMS application. Experiment proved the effectiveness by demonstrating a low-voltage, low-power consumption, and high-speed operation in microscale. We obtained the speed of ∼10 cm/s for a mercury slug at an operating voltage less than 3 V and average current around 10 μA. A liquid micromotor with loop diameter of 2 mm demonstrates reliable operation (i.e., circling of the slug along the loop) at 420 rpm. Some of the possible applications include memory device, optical switch, microgyroscope, and angular inertial actuation device.

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