Design and Modeling of a ZnO-Based MEMS Acoustic Sensor for Aeroacoustic and Audio Applications D. S. Arya 1,2,* Mahanth Prasad 1 1 CSIR-Central Electronics Engineering Research Institute, Pilani–333031 (Rajasthan), India, C. C. Tripathi 2 2 University Institute of Engineering and Technology (UIET), Kurukshetra University, Kurukshetra-136119 (Haryana), India tripathiuiet@gmail.com dhairya_arya@yahoo.in, mahanth.prasad@gmail.com Abstract— In previous research work related to the acoustic sensors, the researchers have focused on the individuality of the sensors for aeroacoustic application and sensors for audio range application. This paper describes a simple and novel model of acoustic sensor for aeroacoustic and audio applications (microphone). The model of the device presented in this paper shows interoperability. The sensor reported has the bandwidth of ~22 KHz, which covers the entire bandwidth of microphone and aeroacoustic sensors. A LEM (Lumped Element Model) is used to determine the characteristics of the device. The device has the square diaphragm of 1.5 × 1.5 mm 2 and a nominal thickness of 15 μm to sustain the high SPL (Sound Pressure Level). A piezoelectric ZnO layer 2.4 μm-thick is sandwiched between two Al-top and bottom electrodes. The top electrode is segmented to enhance the sensitivity of the device. Furthermore, a microtunnel of 100 μm wide and 21 μm deep is designed to achieve the lower cut-on frequency of ~5 Hz. The theoritical results show that the sensor has sensitivity (RMS) of 126.3 μV/Pa and 96.6 μV/Pa in case of central and outer electrodes respectively. The resonant frequency of ~ 85 KHz is obtained from lumped model, simulated using MULTISIM 13.0. The result is verified with MEMS-CAD TOOL COVENTORWARE ® . Keywords—Aeroacoustic, Lumped Element Model (LEM), Sound Pressure Level (SPL), Piezoelectric, Microtunnel. I. INTRODUCTION Most of the acoustic sensor have common structural traits. They have a mechanical element usually a diaphragm, or a cantilever beam, that is exposed to the incident sound pressure. The sound pressure cause the diaphragm to deflect, the deflection is detected by a transduction mechanism and typically an electrical output is generated. Prior acoustic sensors were focused on piezoresistive or capacitive based transduction which requires biasing [1] and adversely affects the cost parameter. It is evident that piezoelectric based transduction in acoustic sensors have less complexity and are easily deployed in any of the application like for hearing aid and in aircraft fuselage array [1]. The sensor described in [1] is solely for aeroacoustic applications with reported sensitivity of 39 μV/Pa but the acoustic sensor presented and described in further sections cover both the application areas with reasonably high sensitivity. The most important performance metric for the acoustic sensors are bandwidth and sensitivity. The region of the frequency response (Fig. 1) that is approximately flat is known as flat band and its corresponding magnitude value is termed as sensitivity, measured in V/Pa (Volts per Pascal) and relates the output voltage to the input pressure. Fig. 1 Ideal frequency response of acoustic sensor. *Corresponding author. Tel.: +91 7056339019