For The Smallest Valve, The Secret Is Balance

A MIGHTY MICROVALVE THAT CONTROLS THE FLOW OF GASES could open a flood of new products, from a higher-tech version of pump sneakers to airline seats that adjust to the contours of your body.

Invented by BCAM International Inc. of Melville, N.Y., the patent-pending valve is part machine, part computer chip. It is about one centimeter wide and is made of silicon. Production versions will have sensing and control circuitry etched into the surface. Its mechanism is a minuscule, flexible silicon plank that bends up to close off air flow and bends down to open it. The trick is that the air pressures pushing on the two sides of the plank are balanced, so it takes very little power--about 15 milliwatts--to keep the valve either open or closed. The main valve is nudged in either direction by opening or closing a flap that controls the pressure of air against the bottom of the plank. That flap is just 100 microns across--about the width of a human hair.

BCAM says its microvalve is smaller, consumes less power, and is potentially cheaper to manufacture than its main competitor, the Fluistor valve from Redwood MicroSystems Inc. of Menlo Park, Calif. Redwood, though, says its microvalves permit greater accuracy and can handle a wider range of pressures.

BCAM says the valve will probably be used first in footwear, including cushioned shoes for diabetics, who are prone to pressure sores. For the medical-equipment industry, a smart microvalve could be embedded in a disposable drug-inhalation device to ensure that patients receive the proper dose.

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