Acoustic energy harvesting: Innovations in harvesters, efficiency enhancement techniques, and future applications

Acoustic energy harvesting is a sustainable approach to capturing sound energy from noisy environments like airports and roads. Although promising, current systems produce limited power, making improved acoustic-to-electric conversion efficiency through advanced materials and designs a key objective. To address needs such as small device power, noise management, and environmental monitoring, harvesters increasingly integrate with next-generation sensors, providing low-power, renewable energy for sensor nodes and distributed monitoring. In these setups, harvested energy can drive miniaturised electronics, including self-powered sensors for data collection, environmental monitoring, and IoT applications. Furthermore, if noise reduction is required, the harvesters can pair with noise abatement technology, reducing unwanted sound while recovering energy, thus broadening sensor use. One potential route involves employing meta-materials and optimised transducer architectures to capture a broader range of acoustic frequencies, enabling better performance in acoustically rich environments such as urban centres. Meanwhile, advanced signal processing can help harvesters adapt to fluctuating sound sources and enhance power output. This paper consolidates notable research on boosting acoustic-to-electric efficiency, focusing on piezoelectric materials, resonant structures, and acoustic-electrical mechanisms. Given both sensor demands and technological hurdles, it explores design constraints and emerging opportunities, highlighting potential applications in distributed energy networks, smart city initiatives, and ecological protection, offering insights for future research to advance the field. This study fosters deeper integration of acoustic energy harvesting within sensor infrastructures. Effective synergy between acoustic energy harvesting and sensing technology may promote broader deployment of sustainable energy solutions and multi-scenario sensor networks. Researchers can navigate design trade-offs and new materials, paving the way for practical solutions that balance efficiency and sustainability. As development continues, interdisciplinary efforts involving materials science, acoustics, electronics, and systems engineering will be essential to fully realize acoustic energy harvesting's potential in real-world usage.