A foil type flexible pressure sensor using nitelide aluminum thin film

摘要

A foil type flexible pressure sensor based on piezoelectric of highly C-axis oriented nitelide aluminum (AlN) thin film deposited on an aluminum foil substrate was developed. The sensor is composed of two AlN thin films and three aluminum foils as electrodes which detect the electric charge generated by pressure acting on the AlN film. These components are alternately piled with each other. Therefore, the inner electrode is shielded from external unknown environment by the outer two electrodes. This laminated structure of electrodes contributes to avoid unexpected leakage of electric charge and induced electric charge by unknown external electric field. Furthermore, two AlN films generate double amount of electric charge in comparison with the case of single film. Experimental results using a prototype of the sensor shows excellent linearity of sensitivity. However, because of internal loss of the generated electric charge, the sensor cannot be directly applied to measurement of static pressure. We analyze the frequency response obtained experimentally, and construct transfer function of the sensor. We show that it is able to detect quasi-static pressure by using inversed transfer function with estimated parameters.