Coplanar electrode fluidic-based acoustic sensing method for underwater application
Loading...
Date
2016-06-01
Authors
Mohamad Faizal Abd Rahman
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The thesis proposed a novel fluidic-based acoustic sensing method for underwater applications. The capacitive principles based on coplanar electrodes configuration is selected as the sensing mechanism. The new structure device was proposed to overcome several issues faced by the conventional device based on Capacitive Micromachined Ultrasonic Transducer (CMUT) by adapting the microfluidic technology. Reliability issues caused by the over deflected membrane was overcame by introducing the liquid backing material underneath the membrane which increases the damping at high operating voltage and high external pressure. The use of softlitography technique for fabrication also gave an advantage due to its process simplicity. The sensing concept was proven through a development cycle which consists of modelling, fabricating and testing. The structural design had satisfied several design rules such as membrane deflection theory as well as penetration depth theory. The final testing showed the ability of the device to detect 200kHz acoustic signal transmitted from the underwater acoustic projector with capacitive pressure sensitivity of 0.4 fF/Pa. It was also found that the constant frequency vibration (10Hz to 100Hz) and change of temperature (-20 ̊C to 30 ̊C) has minimal effect on the sensing performance, thus showcased the stability of the sensor.