Electromechanical modeling and properties of the electret film EMFI

An electromechanical film can be manufactured with different thickness and elasticity. The thickness for sensor and actuator applications is typically between 30 and 70 /spl mu/m. The film is modeled using a simplified structure, which shows the reciprocity of the sensor and actuator operation models. The value of the transducer constant depends on the ambient temperature and increases at higher temperatures. During aging the transducer constant begins to decrease permanently at 323 K, but some sensitivity remains even at 333 K. Corona charging that gives a sensitivity value /spl sim/200 pCN/sup -1/ for HS01 type film is preferred over electron beam charging. The development of such films is aimed at sensor and actuator applications. An interesting field is the active control of sound where flat and efficient microphones and loudspeakers are needed.