A Silicon Micromachined Valve Driven by a Bi-Stable Electromagnetic Actuator
Abstract In this contribution a micromachined open/closed valve is presented which is driven by a conventionally manufactured bistable electromagnetic actuator. Basically the micromachined valve part, 7 × 7 × 1 mm3 in dimension, is a sandwich construction of two KOH etched wafers with a specially formulated silicone rubber layer in between. This rubber sheet forms a flexible flow path, which can be open and closed to control a fluid flow. In order to provide a large stroke of about 200 μm, a precision-engineered bi-stable electromagnetic actuator was selected. This actuator consists of a spring-biased armature that can move up and down in a magnetically soft iron housing, incorporating a permanent magnet and a coil. It will be shown that this combination of micromachined and precision-engineered components provides the required low dead volume on the one hand and a large actuator stroke on the other. Another benefit of the application of a bi-stable actuator is the fact that only energy is needed in order to switch between the open and closed state. Moreover, the large stroke makes the valve particle tolerant thus allowing media like cell suspensions and whole blood.