Lam Bao Dang

Single mask, simple structure micro rotational motor driven by electrostatic comb-drive actuators

We report a design and fabrication of a new micro rotational motor (MRM) using silicon micromachining technology with the overall diameter of 2.4 mm. This motor utilizes four silicon electrostatic comb-drive actuators to drive the outer ring (or rotor) through ratchet teeth. The novel design of the anti-reverse structure helps us to overcome the gap problem after deep reactive ion etching of silicon. The MRM was fabricated by using silicon on insulator wafer with the thickness of the device layer being 30 µm and one mask only. The motor was successfully tested for performance. It was driven by periodic voltage with different frequencies ranging from 1 to 50 Hz. The angular velocity of the outer ratchet ring was proportional to the frequency. Moreover, when the driving frequency is lower than 30 Hz, the experiment results perfectly match the theoretical calculation.

Ionic JET flow in a circulatory miniaturized system

This paper reports a novel device for generating circulatory jet flow using bipolar discharge configuration. This arrangement, in which two electrodes serve as mutual emitters and reference defining the electric field, allows to generate simultaneously ionic wind with opposite charge, thus the ion flow is self-neutralized while keeping the momentum in desired direction. In order to prevent system from sparking over, between the two parallel electrodes is installed one millimetre thick polypropylene wall. Experiment and simulation has shown that the air flow is successfully circulated in the confined device with peak velocity of 2 m/s while consuming only 33 mW.