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Mohd Hafiz Ismail
Simulation and analysis of Piezoresistive microcantilever
Simulation of piezoelectric transducer microphone diaphragm based on different materials
2023-12
,
Shazlina Johari
,
Catherine Lim Ee Chen
,
Bibi Nadia Taib
,
Mohd Hafiz Ismail
,
Siti Noorjannah Ibrahim
Currently, most piezoresistive microcantilever sensors are configured with a dual-layer design that includes a piezoresistor integrated onto the upper surface of a microcantilever. The dual-layer design effectively enhances sensitivity and the piezoresistance effect. However, integrating the piezoresistor onto the microcantilever in the fabrication process necessitates additional steps, leading to extended manufacturing times and increased production costs. In this paper, the mechanical behavior of a single-layer piezoresistive microcantilever, namely displacement, stress, and strain, is investigated and analyzed using ANSYS Multiphysics. The contributing factors expected to affect the device's performance are its geometrical dimensions, and the materials used. Regarding the device dimensions, the length, thickness, and width of the cantilever were varied. It was found that the performance of the piezoresistive microcantilever can be improved by increasing the length and decreasing the thickness. The displacement of the microcantilevers increased by about 230%, from 75.76μm to 250.12μm, when the length was increased from 225μm to 350μm. The applied force ranged from 2uN to 12uN. Similarly, the stress and strain produced on the microcantilevers also increased by about 60.83% and 57.22%, respectively. From the material point of view, the microcantilever made with silicon always had the highest displacement value compared to silicon nitride, silicon dioxide, and polysilicon. This is due to the Young's modulus value, where materials with lower Young's modulus will have higher displacement and stress.
2024-06
,
Mohd Hafiz Ismail
,
Wen Jie Koh
,
Bibi Nadia Taib
,
Shazlina Johari
,
Siti Noorjannah Ibrahim
Piezoelectric microphone which utilizes MEMS technology is a type of transducer that converts an input acoustic signal into an output electrical signal. The characteristics of the microphone diaphragm such as the diaphragm design features and the type of piezoelectric materials used will affect the performance of the microphone in terms of sensitivity. It is hard to control the stress of the diaphragm used in the MEMS transducer microphone. A modification of the diaphragm is done in this project to reduce the residual stress of the piezoelectric transducer. In addition, finite element analysis namely structural, modal and harmonic were carried out using Ansys 15.0 to simulate the mechanical and dynamic behaviour of the microphone diaphragm. Two types of diaphragm structure were designed, namely square and circular, while three types of piezoelectric material which are AlN, PZT and ZnO were used as the diaphragm material. The structural analysis findings of the diaphragm subjected to 1 Pa pressure revealed that the circular diaphragm made of AlN material exhibited the highest stress, reaching 43.05 GPa, surpassing the stresses observed in the other two materials. On the contrary, the square diaphragm composed of PZT material demonstrated the lowest stress, with only 1.55 GPa. In terms of resonance frequency, the circular AlN diaphragm achieved the highest resonant frequency, reaching 449.84 kHz, whereas the square PZT diaphragm exhibited the lowest frequency at 200.25 kHz. In general, the circular diaphragm design consistently yielded higher first resonant frequencies compared to the square design.The results show that the circular diaphragm with AlN piezoelectric materials is the ideal diaphragm in the microphone because of the highest stress generated and the first resonant frequency. The stress is related to the sensitivity of a microphone while the high resonant frequency can lead to the better optimization of signal to noise ratio control.