Displacement improvement of piezoelectric membrane microactuator by controllable in-plane stress

• A simple method to generate controllable in-plane stress is presented.
• The displacement along with d31 is improved by an appropriate tensile stress.
• The stress generated by the bias voltage is calculated by an analytical model.
• The equivalent Young's modulus of the whole actuator change that causes resonance frequency shifts is investigated.

Aiming to improve the displacement of the piezoelectric membrane microactuators, controllable in-plane tensile stress was introduced by applying a bias voltage on the idle part of PZT. The stress generated by the bias voltage was calculated by an analytical model based on the theory of plates and shells. Analytical result shows that tensile stress with a magnitude of 10 MPa can be generated under 100 V bias voltage. The stress is large enough to cause the change of piezoelectric coefficient d31 as well as the displacement of the actuator. Then the experimental results on the PZT thick film actuators demonstrated that d31 was remarkable increased for both the disc actuator and the ring actuator under an appropriate bias voltage, improving the displacement by 6% and 42%, respectively. Furthermore, the resonance frequency shifts were observed as a result of Young's modulus change under the bias voltage.