A PZT–PVDF Stacked Transducer for Short-Pulse Ultrasound Therapy and Monitoring

Abstract

Therapeutic ultrasound technologies using microbubbles require a feedback control system to perform the treatment in a safe and effective manner. Current feedback control technologies utilize the microbubble's acoustic emissions to adjust the treatment acoustic parameters. Typical systems use two separated transducers: one for transmission and the other for reception. However, separating the transmitter and receiver leads to foci misalignment. This limitation could be resolved by arranging the transmitter and receiver in a stacked configuration. Taking advantage of an increasing number of short-pulse-based therapeutic methods, we have constructed a PZT-PVDF stacked transducer design that allows the transmission and reception of short-pulse ultrasound from the same location. Our design had a piston transmitter composed of a PZT disc (1 MHz, 12.7 mm in diameter), a backing layer, and two matching layers. A layer of Polyvinylidene fluoride (PVDF) (28 μm in thickness, 12.7 mm in diameter) was placed at the front surface of the transmitter for reception. Transmission and reception from the same location was demonstrated in pulse-echo experiments where PZT transmitted a pulse and both PZT and PVDF received the echo. The echo signal received by the PVDF was 0.43 μs shorter than the signal received by the PZT. Reception of broadband acoustic emissions using the PVDF was also demonstrated in experiments where microbubbles were exposed to ultrasound pulses. Thus, we have shown that our PZT-PVDF stack design has unique transmission and reception features that could be incorporated into a multi-element array design that improves focal superimposing, transmission efficiency, and reception sensitivity.

Passive Cavitation Detection With a Needle Hydrophone Array

“…A preamplifier was built with an OPA659 (Texas Instruments, Texas, USA) operational amplifier [Fig. 2(a)], similar to a design that we built previously [34]. Its frequency response was characterized using a sinusoidal input from a function generator (33500B series, Agilent Technologies Inc., Wood Dale, IL, USA) and recording the output with an oscilloscope (3 series, Tektronix, Oregon, USA).…”

“…It was aligned directly facing the sonicated region of the channel at a distance of 40 mm, and with its long axis parallel to the ultrasound wave propagation direction. The wall-less channel used in the experiments was within a soft polyacrylamide hydrogel (modulus of elasticity of 8.44 ± 0.82 kPa) [34,36], so that the reflection from the gel-water interface could be minimized. Lipid-shelled microbubbles with a heavy gas core were made in-house (average radius of 0.66 ± 0.38 μm) using a previously described method [37].…”

Microwave Properties of Ba-Substituted Pb(Zr0.52Ti0.48)O3 after Chemical Mechanical Polishing

“…5,6 Specifically, PZT has been considered e.g. for ultrasound transducers [7][8][9] or high-frequency bulk acoustic resonators. 10,11 Furthermore, PZT has been proposed as piezoelectric material in multiferroic composites [12][13][14] for microelectronic applications.…”