To improve the transmission performance and preparation of a transducer array, two planar array transducers based on connected 1–3 piezoelectric composites as a matrix were designed. Each transducer contained 25 array elements with a gap of 1 mm between them. The length, width and height of each array element were 1 mm, 26 mm and 5 mm, respectively. Two kinds of array transducers were tested through finite element simulation and experiments. The array transducer prototype was fabricated based on two kinds of composite materials, and the fabrication cycle was short. Our results show that the maximum transmission voltage response of the two-phase 1–3 full array driver is up to 179 dB at 200–400 kHz and the acoustic radiation intensity can be increased by up to 22% compared with the traditional splicing transducer array. It is suitable for short-range target positioning and measurement. Moreover, in the single element mode, the beam of the three-phase 1–3 transducer has no sidelobe and a single element −3 dB beam width of up to 91°. Furthermore, the beam width of the two-phase 1–3 type is 54°, and the acoustic radiation breadth is improved by 40.6%. The three-phase 1–3 type array transducer has the characteristics of concentrated acoustic transmission energy of the whole array, and its −3 dB beam width is 3.5°. The beam width decreased by 12.5%, indicating that the three-phase 1–3 type transducer is suitable for short-range target detection and perception. The two array transducers have their own advantages in transmitting the voltage response and beam width, which must be selected on the basis of the requirements of practical applications.

In this work, the bending vibration characteristics of the 2-2 piezoelectric composite trilaminar vibrator are studied by the finite element simulation and experiment. The simulation results show that the trilaminar vibrator has lower resonant frequency and larger vibration displacement under the fixed boundary condition compared with that of the free boundary condition, and its performance is relatively good. Then, the 2-2 piezoelectric composite and piezoelectric ceramic trilaminar vibrators are fabricated and their performances are tested under the fixed boundary condition. The experimental and simulation results show that the vibrator has pure bending vibration characteristics in the frequency band of 1.2–1.4 kHz, especially the 2-2 piezoelectric composite vibrator, which has lower frequency, higher electromechanical coupling coefficient and larger bending vibration displacement; thus, the 2-2 piezoelectric composite trilaminar vibrator is a better choice for the fabrication of a low-frequency transducer.

This paper proposes a spring-mass-damper model for a piezoelectric-capacitive hybrid micromechanical ultrasonic transducer (HMUT) in immersion. Based on this model, a dual-force actuation mode is identified, where piezoelectric micromachined ultrasonic transducer (PMUT) and capacitive micromachined ultrasonic transducer (CMUT) are strongly coupled to achieve enhanced sensitivity. In order to design HMUT efficiently, an electro-mechanical-acoustical equivalent circuit model (ECM) is constructed and then the round-trip gain is calculated to demonstrate its pulse-echo response. The ECM calculations results align with those of finite element model simulations, showing a relative deviation less than 4%. In the design cases, the transmit sensitivity of HMUT is twice that of PMUT and more than five times that of CMUT. The receive sensitivity of HMUT is 1% lower than that of CMUT, but an order of magnitude larger than that of PMUT. The round-trip gain of the HMUT is at least 24.9 dB higher than that of PMUT and 14.1 dB higher than that of CMUT. These results demonstrate the potential of HMUT in surpassing bulk piezoelectric ultrasonic transducers in pulse-echo imaging. Furthermore, the impact of cell pitch on the pulse-echo response of HMUT arrays is characterize.