Simple, High Actuation Power, Thermally Activated Paraffin Microactuator

This paper presents a new yet simple family of microactuators that provide both large displacements ( m) and high forces ( N) hence suitable for microvalves. The actuators use the high volumetric expansion of a sealed, surface micromachined patch of paraffin heated near its melting point to deform a sealing diaphragm. Two types of actuators were fabricated using a simple 2-mask process. The first device consists of a m-thick circularly patterned paraffin layer covered with a m-thick metallized p-xylylene diaphragm. Devices m in radius produced a m peak deflection. The second device includes a constrained volume reservoir that magnifies the diaphragm deflection producing a m deflection with a paraffin thickness of only m. Actuators were constructed on both glass and silicon substrates. The glass devices using mW of power showed response times of ms. The response time for silicon devices was much faster ( ms) at the expense of a larger W actuation power.