Sensitivity improvement of diaphragm type ultrasonic sensors by complementary piezoelectric polarization

A new and simple electrode configuration to improve the sensitivity has been proposed for piezoelectric ultrasonic sensors on silicon diaphragms. The new electrode configuration consists of two parts formed on both the areas of positive and negative piezoelectric polarizations and enables to improve the sensitivity compared to the conventional sensors by summing up both the outputs. Optimal electrode sizes have been decided by theoretical calculation of the total output voltage and the new sensor with the optimal configuration has been fabricated. The sensitivity of the new sensor has been improved 50% more than that of conventional sensors.