A study of voice parameter measurements with PZT thin film acoustic sensor

With the development of Micro ElectroMechanical System(MEMS) technology in the sensor components have been shown on the achievements, with small size and can be a large number of production advantages. This study base the piezoelectric sensor components combined with the application of telemedicine, the original is made in the underwater acoustic sensor components of the MEMS process, improved into a general sound wave microphone, it will be applied to voice rehabilitation therapy. The thickness of the vibration film of the sensor is 2.5μm, which can reduce the sensing frequency of the acoustic element, and the actual occupied area of the element is within 9mm
²
. The total sensing film is connected with several sensing films. The area of a sensing film is 1.44mm
²
. The sensor is applied to the voice measurement system, with a high-pass filter amplifier circuit. This paper using MEMS process method to fabricate PZT thin film acoustic sensor, The sensor was set up in a water tank and measured, the distance between the B & K8104 and the sensors was 20cm. In addition, a same B & K8104 hydrophone was measured also for comparison. The receiving responsivity of fabricated acoustic sensor and hydrophone B & K8104 were shown in Figure 1. The responsivity of fabricated sensor at 4.5kHz to 5kHz were -50.85dBV to -51.82dBv. From figure1, it show that the fabricated PZT thin film acoustic sensor has flat response between 4kHz-20kHz. The response even better than hydrophone. So,the4.5kHz~5kHz range were used for voice measurement .In order to amplify the sensor's small signal, another design of a high-pass filter amplifier circuit was used in this measurement system.