The dual diaphragm pump

This paper reports a major advancement in gas pumping at micro- and meso-scale, made possible by the newly developed, electrostatically actuated, dual-diaphragm pump (DDP). The DDP uses a conformal pumping chamber and two electrostatically actuated, structured diaphragms, to achieve perfect rectification. The DDP demonstrates flow rates of about 30 ml/min and a power consumption of about 8 mW at an overall pump volume of about 1.5/spl times/1.5/spl times/0.1 cm/sup 3/. The DDP is fully symmetrical, having true bidirectional operation; has essentially zero dead space; and is fully scalable. For increased throughput the individual pumping channels can be built in 1D, 2D and 3D arrays. This feature allows the optimization of the individual pumping channel for best performance under electrostatic actuation, but allows scaling of the pumping rate to the desired level. Arrays of 2/spl times/3/spl times/5 pumps have been successfully demonstrated. A DDP array pumping 4 liters per minute will be about 4 times smaller in volume and will use about 4 times less power than the most advanced commercially available air pumps.

Introduction

Recent advancements in chemical and biological sensing have resulted in large increases in sensitivity together with significant reductions in the size, weight and cost of the detectors. Portable. systems capable of detecting traces of explosives at levels of fractions of parts per trillion have been demonstrated - and applied to the land-mine detection problem [1]. Conventional explosive detectors are floor-mounted instruments, many cubic feet in size. Also, biological sensors capable of detecting one microorganism per cubic meter of air are now being developed. When vapor-phase analytes or air-borne particles have to be detected, a sampling system is generally used for increasing the probability of detection and reducing the detection time. The pumps have not been keeping up with the developments in sensing, and a reliable, small, low power, low cost, high pumping rate, conveniently shaped pump is more often than not on the wish list of system developers.