This device, less than one half a square centimeter, produces displacement of a poppet of more than 100 microns with a force of one-half newtons. Flow through the valve is roughly proportional to current, so that with feedback it may be used to control flow. A feedback loop increases or decreases flow to bring the measured flow into equality with the set-point. This is incorporated in a low-cost, digitally operated flow controller. Pulse-width modulation is used to produce partial actuation.
Response time is a few milliseconds.
The layout of TiNi microactuators is such that several valves may be placed on a square centimeter of silicon substrate. This enables us to make multiple valve systems for microfluidic applications. Figure 1 Pneumatic valve with enclosure Figure 2 Detail of valve actuator mechanism Figure 3 shows a drawing of a liquid control valve which has been prototyped. The advantages of this valve are its very small dead volume, and that liquid is not subjected to heat or to materials which would contaminate it. This valve functions as a pneumatic pilot valve controlling pressure above a membrane.