Electrostrictive P(VDF-TrFE) copolymer based high performance micromachined unimorph actuators

Micromachined unimorph actuators based on the electrostrictive P(VDF-TrFE) copolymer have been fabricated. The performance of the devices has been modeled and characterized. The experimental results on the device responses are very close to the prediction of the model, indicating a high actuator displacement and voltage sensitivity. For a typical unimorph device with 1 mm length, the displacement at the center of the device can reach 30μm, and the ratio of the displacement/applied voltage is more than 30nm/V. Furthermore, over more than 3 frequency decades, the dispersion of the displacement is less than 20%, which indicates the high frequency capability of this polymer based MEMS. To demonstrate the high force capability of the device, the displacement response of the device was evaluated at 200 Hz in a fluid medium and there is no observable change in the displacement response in fluid medium when compared with that measured in air. Due to the large field induced electrostrictive strain and high frequency capability of the electrostrictive P(VDF-TrFE), the device is capable of operating at no-resonance model with high displacement and force output, and over a broad frequency range (DC to ≥10 kHz) . The observed performance of the device indicates that this type of electrostrictive P(VDF-TrFE) based MEMS is attractive for micro-pump, valves, and air coupled ultrasonic transducer array, etc.