An acoustic vector sensor is a device that is capable of measuring the direction of wave propagation and the acoustic pressure. There are several types of vector sensors which can be used in water medium. These traditional vector sensors, however, still remain limitations such as poor response characteristic of low frequency signal, low signal to noise ratio (SNR) and limited minimization properties. Consequently, the development trend of vector sensor turns to predominant response characteristic at low frequency, minimization, high SNR for the demand of faraway detective.
Many research institutes have attempted to manufacture bionic sensor by use of MEMS technology to overcome the limitation of the traditional vector sensors. Biological sensory systems often show great performance which inspires engineers to design artificial counterparts. From under-standing the auditory function of hair cells in creatures’ ear, we proposed a piezoelectric micro-cantilever to be used for obtaining vector information of underwater sound field.
In this study, the design conditions of micro-cantilever sensor for the vector sensor are proposed by consideration of acoustic phenomenon in water. It has been shown that very thin and flexible micro-cantilever can be used to measure directly the particle velocity component in water. In addition, the response model for characteristic analysis of micro-cantilever sensor with consideration of piezoelectric effect is developed to convert the deformation of micro-cantilever by sound pressure to the electrical voltage. Designing process of piezoelectric micro-cantilever sensor have been established based on our lumped element model. Finally, the experiments have been conducted to verify the characteristic of sensor at low frequency acoustic sound in water. The experiment results shows that the receiving sensitivity of the piezoelectric micro-cantilever sensor is approximately -220dB (Ref. V/uPa, no pre-amplified). And the piezoelectric micro cantilever sensor possesses satisfactory directivity pattern at low frequency.