abstract:In this study, thin film acoustic sensors were fabricated utilizing the r.f. planar magnetron sputtering method and micromachining techniques. Underwater testing results indicated that the maximum receiving sensitivity of −117.8 dBV μbar−1 occurred at 5.5 MHz. For the acoustic sensors tested, the highest transmitting intensities were 26.5 dBV/μbar at a fundamental resonant frequency of 7 MHz, 40.4 dBV μbar−1 at the third harmonic of 21 MHz, and 37.1 dBV μbar−1 at half the fundamental frequency or 3.5 MHz. Underwater measurements also indicated that the larger the sample area, the higher the transmitting intensity and receiving sensitivity.