High-Performance Curved Piezoelectric Single-Crystal Composites via 3D-Printing-Assisted Dice and Insert Technology for Underwater Acoustic Transducer Applications

Exploring piezoelectric and piezophototronic properties of nanostructured LN-ZnSnS3 for photoresponsive vibrational energy harvesting

Piezoelectric energy harvesters have for some time been an advanced choice for self-powered electronics. While oxide-based piezoelectric nanomaterials are well studied for their quality mechanical energy harvesting potential, recent interest in developing multifunctional nanomaterials for harvesting simultaneous ferroelectric/piezoelectric and light energy for photodetectors, photovoltaics and piezophototronics has impelled the search for newer semiconducting dipolar materials. In this respect, LiNbO3 type-ZnSnS3 (LN-ZTS) is predicted to have low optical band gap energy and to possess a considerably expanded hexagonal R3c lattice with high ferroelectricity. Although it has been stabilised in thin-film form, the exclusive synthesis of LN-ZTS nanocrystals has not been reported. In this article, we report a one-step synthesis for R3c hexagonal LN-type ZnSnS3 (ZTS) nanoflakes and show that they could be highly desirable candidates for light-responsive mechanical energy harvesting via an impressive piezophototronic effect. A piezoelectric coefficient (d33) of ∼19 pm V-1 was measured using piezoresponse force microscopy and a considerable zero-bias photoconduction current was observed, which was utilized to harvest an output power of ∼0.13 μW cm-2 from an induced light intensity of 100 mW cm-2 under a mechanical impact of 17 N and 3 Hz. These findings establish a previously unreported ternary sulfide piezoelectric nanostructured material as potential candidate for designing piezophototronic devices by coupling optical functionalities and piezoelectric responses.

Structural Optimization and Performance of a Low-Frequency Double-Shell Type-IV Flexural Hydroacoustic Transducer

To amplify the displacement of the radiation shell, a double-shell type-IV curved hydroacoustic transducer was proposed. Through Ansys finite element simulation, the vibration modes of the transducer in different stages and the harmonic response characteristics in air and water were studied, and the bandwidth emission of the hydroacoustic transducer was achieved. By optimizing the size of each component, the resonant frequency of the transducer is 740 Hz, the maximum conductivity was 0.66 mS, and the maximum transmitting voltage response was 130 dB. According to the optimized parameters, a longitudinal acoustic transducer prototype was manufactured, and a physical test was conducted in an anechoic pool. The obtained resonant frequency was 750 Hz, the maximum conductivity was 0.44 mS, the maximum transmitting voltage response was 129.25 dB, and the maximum linear dimension was 250 mm, which match the simulated value of the virtual prototype and meet the expected requirements.

An Emerging Era: Conformable Ultrasound Electronics

Conformable electronics are regarded as the next generation of personal healthcare monitoring and remote diagnosis devices. In recent years, piezoelectric-based conformable ultrasound electronics (cUSE) have been intensively studied due to their unique capabilities, including nonradiative monitoring, soft tissue imaging, deep signal decoding, wireless power transfer, portability, and compatibility. This review provides a comprehensive understanding of cUSE for use in biomedical and healthcare monitoring systems and a summary of their recent advancements. Following an introduction to the fundamentals of piezoelectrics and ultrasound transducers, the critical parameters for transducer design are discussed. Next, five types of cUSE with their advantages and limitations are highlighted, and the fabrication of cUSE using advanced technologies is discussed. In addition, the working function, acoustic performance, and accomplishments in various applications are thoroughly summarized. It is noted that application considerations must be given to the tradeoffs between material selection, manufacturing processes, acoustic performance, mechanical integrity, and the entire integrated system. Finally, current challenges and directions for the development of cUSE are highlighted, and research flow is provided as the roadmap for future research. In conclusion, these advances in the fields of piezoelectric materials, ultrasound transducers, and conformable electronics spark an emerging era of biomedicine and personal healthcare.

Conformally Large-Area Single-Crystal Piezocomposites with High Performance for Acoustic Transducers

Large-area and conformal piezoelectric elements are highly desired for acoustic transducers to possess a large power source level and wide detecting range. To date, single-crystal piezocomposites attract much attention on enhancing the power source level and bandwidth for next-generation acoustic transducers, owing to their higher piezoelectric and electromechanical coupling properties compared to traditional piezocomposites. Unfortunately, it is still challenging to achieve large-area and conformal single-crystal piezocomposites because of the fragile nature, large anisotropy, and the limited grown size of piezoelectric single crystals. Here, we successfully fabricate the conformally large-area single-crystal piezocomposite with an area of 160 × 50 mm² and a bending angle of 162° by a modified 3D-printing-assisted inserting method. The single-crystal piezocomposite exhibits a high thickness electromechanical coupling factor k_t of 85% and a large piezoelectric coefficient d₃₃ of 1150 pC/N, surpassing those of the reported large-area piezocomposites. The influence of the volume fraction and curvature radius of single-crystal PCs and acoustic transducers was investigated. Furthermore, we designed an acoustic transducer based on the conformal single-crystal piezocomposite. Benefiting from the excellent piezoelectric and electromechanical properties of the single-crystal piezocomposite, the transducer indicates a high maximum transmitting voltage response of 171.8 dB. Especially, its bandwidth (-3 dB) achieves 60 kHz with a resonant frequency of 292 kHz, which is about 1.8 times superior to the conformal acoustic transducer based on the ceramic piezocomposite with a similar resonant frequency. This work may benefit the future design and fabrication of high-performance and complex-shape piezoelectric composites as key materials for next-generation transducers.

Application experience and research progress of different emerging technologies in plastic surgery

In the diagnosis and treatment of plastic surgery, there are structural processing problems, such as positioning, moving, and reconstructing complex three-dimensional structures. Doctors operate according to their own experience, and the inability to accurately locate these structures is an important problem in plastic surgery. Emerging digital technologies such as virtual reality, augmented reality, and three-dimensional printing are widely used in the medical field, particularly in plastic surgery. This article reviews the development of these three technical concepts, introduces the technical elements and specific applications required in plastic surgery, summarizes the application status of the three technologies in plastic surgery, and summarizes prospects for future development.