Humidity sensitive actuator

Abstract

Abstract A “Monomorph” is a new type of actuator, composed of a single ceramic plate which is driven in a bending mode similar to the “Bimorph.” It has been observed that humidity influences the bending displacement, electric resistance and electrostatic capacitance of a porous Nb-doped PZT “Monomorph.” A proton conductivity model is proposed to describe the humidity sensitive characteristics of this material. The model assumes a double layer capacitance is formed at the electrode-bulk interface under an applied electric field which plays an important role in the nonuniform distribution of the electric field. This “active layer” on and inside the surface brings about the bending displacement. This “Monomorph” has potential as a new piezoelectric humidity sensor.