Characterization of microfluidic-based acoustic sensor for immersion application

This paper reported the characterization study on a new type of acoustic microsensor meant for immersion or underwater application. The new proposed device is based on microfluidic technology that is found to be able to overcome the fabrication issues associated with conventional capacitive micromachined ultrasonic transducer device. The design parameters have been explained in detail as well as their design justification. In this paper, two experiments have been setup to characterize the device performance. First, the pulse catch technique was used to investigate the device's response toward acoustic pulse or burst signal. The result shows that different number of burst cycles affects the capacitive response of the device. Providing the acoustic projector with suitable burst cycle parameter had yielded capacitive response with resolution of 1.16 pF, which is useful to be deployed in any suitable application such as for control or communication purposes. Second, the vibration effect had been studied between the ranges of 10-100 Hz of vibration. For rapid transition of the vibration frequency, the fall transition has a comparable error compared with the rise transition with an error ratio of 37:1. In terms of fluctuation behavior of the response, operating the device at static or constant frequency vibration does not have significant differences on the response, indicating its stability at single-frequency operation.