Investigation of membrane stress continuously adjustable fiber optic acoustic sensor based on inverse piezoelectric effect

Abstract

In this paper, a fiber optic acoustic sensor with continuously adjustable membrane stress technology is proposed, in which the stress exerted on the membrane can be flexibly adjusted by employing the inverse piezoelectric effect of lead zirconate titanate (PZT) tubular pedestal. First, the response mechanism of stress on the membrane is investigated theoretically. Based on this principle, the effect of adjustable stress on the flat response region and sensitivity of a single mode-multimode-single mode (SMS) fiber optic acoustic sensor are studied experimentally. The experimental results reveal that the flat response region of the sensor extends from 250 Hz to 450 Hz following the continuous increase in the membrane stress by changing the positive direct current voltage applied on PZT from 0 V to 100 V; meanwhile, the sensitivity decreases gradually from 336.5 mV Pa−1 to 162.7 mV Pa−1. The results also verify that the average minimum detectable pressure of the sensor is maintained at 0.54 mPa Hz−1/2 with a fluctuation of 0.08 mPa Hz−1/2 during the tuning process of membrane stress, which provides a flexible method for performance and applicability improvement of membrane-based fiber optic acoustic sensors.