Microfluidic-based capacitive sensor for underwater acoustic application

This work proposes a new concept of underwater acoustic capacitive sensor that operates based on the microfluidic mechanism. The main structures consist of a membrane, microchannel and coplanar detecting electrodes. The new sensor device is proposed to avoid the process complexity and facilities limitation during fabrication of the existing acoustic capacitive sensor meant for underwater application. The device is realised through a simple softlitography technique to produce the main detecting structure (membrane) and the detection region(microchannel). The final testing shows the ability of the device to detect an acoustic signal transmitted by an underwater projector at resonance frequency of 200 kHz. The linearity test of the coplanar electrodes configuration also yields the detection sensitivity of 0.021 pF/mm, operated at specific geometry. The result thus indicates that the proposed structure is able to become an alternative sensing device to the existing underwater acoustic sensor for low frequency underwater application.