High-Performance Piezoelectric Energy Harvesters and Their Applications

Energy harvesting holds great potential to achieve long-lifespan self-powered operations of wireless sensor networks, wearable devices, and medical implants, and thus has attracted substantial interest from both academia and industry. This paper presents a comprehensive review of piezoelectric energy-harvesting techniques developed in the last decade. The piezoelectric effect has been widely adopted to convert mechanical energy to electricity, due to its high energy conversion efficiency, ease of implementation, and miniaturization. From the viewpoint of applications, we are most concerned about whether an energy harvester can generate sufficient power under a variable excitation. Therefore, here we concentrate on methodologies leading to high power output and broad operational bandwidth. Different designs, nonlinear methods, optimization techniques, and harvesting materials are reviewed and discussed in depth. Furthermore, we identify four promising applications: shoes, pacemakers, tire pressure monitoring systems, and bridge and building monitoring. We review new high-performance energy harvesters proposed for each application.