Wearable technology requires high-performance sensors with properties such as small size, flexibility, and wireless communication. Stretchability, sensitivity, and tunability are crucial sensor properties; stretchability and sensitivity ensure user comfort and accurate sensing performance, while tunability is essential for implementing sensors in diverse applications with different ranges of motion. In this study, we developed a high performance kirigami piezoelectric strain sensor. Using finite element analysis, the sensing performance was evaluated, and the kirigami patterns were optimized. The electromechanical properties of sensors with four different kirigami patterns were analyzed. A sensor voltage measurement circuit was also designed, amplifying the output voltage 86.5 times by improving measurement accuracy. A piezoelectric kirigami sensor was constructed with a sensitivity of 9.86 V/cm² and a stretchability of 320.8%, higher than those of previously reported kirigami piezoelectric strain sensors. Finally, the fabricated sensor was successfully applied in a haptic glove for playing musical instruments.

With the development of wearable devices and soft electronics, the demand for stretchable piezoelectric energy harvesters (SPEHs) has increased. Energy harvesting can provide energy when large batteries or power sources cannot be employed, and stretchability provides a user-friendly experience. However, the performance of SPEHs remains low, which limits their application. In this study, a wearable SPEH is developed by adopting a kirigami structure on a polyvinylidene fluoride film. The performance of the SPEH is improved by rearranging the stress distribution throughout the film. This is conducted using two approaches: topological depolarization, which eliminates the opposite charge generation by thermal treatment, and optimization of the neutral axis, which maximizes the stress applied at the surface of the piezoelectric film. The SPEH performance is experimentally measured and compared with that of existing SPEHs. Using these two approaches, the stress was rearranged in both the x–y plane and z-direction, and the output voltage increased by 21.57% compared with that of the original film with the same stretching motion. The generated energy harvester was successfully applied to smart transmittance-changing contact lenses.