The Versatility of Piezoelectric Composites

Abstract

Piezoelectric materials possess the capability to interchangeably convert electrical energy into a mechanical response. While current piezoelectric materials exhibit strong properties, known limitations have inhibited further development. This review describes the ability to combine different piezoelectric materials into a composite to create well-rounded properties. The different types of connectivity classes are described as well as important design considerations and theoretical models. The contributions from the active and passive phases are outlined, focusing primarily on ferroelectric ceramics and polymer-based composites. The key advantage of piezoelectric composites is their ability to combine the flexibility of polymers with the high electromechanical coupling and piezoelectric coefficients of ferroelectric ceramics or single crystals appropriate for a variety of applications. Composites are prominent in medical ultrasound imaging and therapy, underwater acoustic sensing, industrial structural health monitoring, energy harvesting, and numerous other emerging applications. Expected final online publication date for the Annual Review of Materials Research, Volume 53 is July 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

A Review of Piezoelectric Energy Harvesting: Materials, Design, and Readout Circuits

“…Researchers continue to investigate novel composite materials and production processes in order to increase their performance and broaden their uses. Table 1 concludes this section by providing a qualitative comparison of the three groups of piezoelectric materials [47], showing some of the usual values for each group, predicted from a literature survey [3,47,58,[154][155][156][157]. However, treatments can change those properties.…”

Design and micromanufacturing technologies of focused piezoelectric ultrasound transducers for biomedical applications

“…Xu et al [63][64][65][66][67][68] used piezoelectric composites with a 1-3 connectivity pattern (onedimensional ceramic rods embedded in a three-dimensional polymer matrix) in wearable ultrasound devices, enhancing acoustic matching due to their lower impedance compared to traditional materials. Although the flexibility of piezoelectric composites is better than that of piezoelectric ceramics and single crystals, making them more suitable for integration into wearable devices that conform to the human body, achieving consistent material properties and performance across production batches remains a challenge due to variability in the embedding process [69].…”

“…According to the above principle, the acoustic impedance of the backing layer needs to be significantly different from that of the piezoelectric material to facilitate the desired attenuation and reflection characteristics. Ideally, the acoustic impedance of the backing material should be carefully chosen to be either significantly lower than the 35 MRayl typical of piezoelectric ceramics [69], aiming for an impedance mismatch that optimizes sound wave attenuation and minimizes backward propagation. Typically, a material with an acoustic impedance of 3 ∼ 5 MRayl is chosen to fabricate the backing layer.…”

An Emerging Era: Conformable Ultrasound Electronics

“…Especially 1–3 piezocomposites are the most widely used because they wisely utilize the geometry of the piezoelectrics to achieve high coupling factors, low acoustic impedance, good matching to water or human tissue, mechanical flexibility, and broad bandwidth combined with a low mechanical quality factor (Tables 4 and 5 ). [ 117 ] In recent studies, researchers mainly focused on the following three directions on piezocomposites. First, introducing new piezoelectric ceramics/crystal to fabricate new composites is still the main research direction to improve the acoustic performance of the transducers, such as 2.5Sm‐PMN‐30PT 1–3 composites (2.3 MHz, −6 dB bandwidth of 135.9%), [ 118 ] NBBT 1–3 composite ( k t > 71%), [ 119 ] PNN‐PZT composites, [ 120 ] textured PMN‐PZT composites, [ 101a ] etc.…”