In this paper, a flexible piezo-composite transducer composed of the active piezoelectric material (PZT-5H) and passive polymer matrix (PDMS) was developed to achieve excellent flexibility, sensitivity and bandwidth for biomedical and industrial applications. The flexible electrodes (silver nanowires (AgNWs) mixed with PDMS) were deposited on the transducers using a spray coating method providing a sufficient conductivity of an electrode through the repeated bending tests. The flexible 1-3 composite transducer exhibited robust mechanical flexibility (curved radius < 5 mm) without failure due to the stretchable mechanical properties of PDMS and AgNWs network, which indicates that AgNW/PDMS electrode is a promising alternative to conventional metal-type electrodes such as Au film. The acoustic characterization suggests that the -6 dB fractional bandwidth (FBD, ~49 %) and transmitting sensitivity (~107 mV/V) of the prototyped transducer are promising for non-destructive testing (NDT), biomedical imaging and therapy.

This article provides a review of candle-soot nanoparticle (CSNP) composite laser ultrasound transmitters (LUTs) and compares and contrasts this technology with other carbon-composite designs. Among many carbon-based composite LUTs, a CSNP composite has demonstrated its advantages of maximum energy conversion and fabrication simplicity for developing highly efficient ultrasound transmitters. We focus on the advantages and challenges of the CSNP-composite transmitter in the areas of nanostructure design, fabrication procedure, and promising applications.

Reliable vibration sensing is essential to the immediate detection of unusual vibrations, ensuring the safety of nuclear power plant structures. For nuclear power plant applications, the sensor element must endure the harsh environment while retaining reliable performance. Aluminum nitride (AlN) single crystal is considered a promising candidate for the sensing unit due to its robustness to high temperature (HT) and irradiation conditions. However, there are few efforts in developing industrial accelerometers using AlN bulk-machined materials. This article aims to develop a shear-type accelerometer with AlN single crystal plates. The accelerometer's design is based on the numerical simulation results, followed by the fabrication of the sensor and the extensive validation under HT (~1000 °C). The sensitivity of the accelerometer was about 9.2 pC/g. The prototype sensor showed stable performance at varying temperatures from room temperature to 1000 °C. Furthermore, the sensitivity of the accelerometer was successfully sustained for 10 h under HT exposure of 1000 °C, and no obvious mechanical damage was detected after the test. After gamma irradiation for 1 month, the sensor performed stably, without any significant change in sensitivity. The developed AlN accelerometer can be a promising option to monitor the structural integrity of nuclear power plant structures.

Thrombo-occlusive disease is one of the leading causes of death worldwide. There has been active research on safe and effective thrombolysis in preclinical and clinical studies. Recently, the dual-frequency transcutaneous sonothrombolysis with contrast agents [microbubbles (MBs)] has been reported to be more efficient in trigging the acoustic cavitation, which leads to a higher lysis rate. Therefore, there is increasing interest in applying dual-frequency technique for more significant efficacy improvement in intravascular sonothrombolysis since a miniaturized intravascular ultrasound transducer typically has a limited power output to fully harness cavitation effects. In this work, we demonstrated this efficacy enhancement by developing a new broadband intravascular transducer and testing dual-frequency sonothromblysis in vitro . A broadband intravascular transducer with a center frequency of 750 kHz and a footprint size of 1.4 mm was designed, fabricated, and characterized. The measured −6-dB fractional bandwidth is 68.1%, and the peak negative pressure is 1.5 MPa under the driving voltage of 80 V _pp . By keeping one frequency component at 750 kHz, the second frequency component was selected from 450 to 650 kHz with an interval of 50 kHz. The in vitro sonothrombolysis tests were conducted with a flow model and the results indicated that the MB-mediated, dual-frequency (750+500 kHz) sonothrombolysis yields an 85% higher lysis rate compared with the single-frequency treatment, and the lysis rate of dual-frequency sonothrombolysis increases with the difference between the two frequency components. These findings suggest a dual-frequency excitation technique for more efficient intravascular sonothrombolysis than conventional single-frequency excitation