A proportional microvalve using a bi-stable magnetic actuator

A simple electromagnetic miniature valve was fabricated using a combination of a micromachined coil and a permanent magnet. The dimension of the valve including the actuator is about 5/spl times/5/spl times/5 mm, and the valve has a 0.5 mm valve cap displacement which significantly alleviates the clogging problem by using a bi-stable actuation of the magnet. The smallest controllable amount of water was 0.7 /spl mu/1/min, and flow rates through the valve less than 900 /spl mu/1/min can be continuously adjusted by a duty ratio control of driving current to the micro coil.