Mid Sweden University

Sustainable operation of microrobots mandatorily needs a continuous supply of energy, which is usually provided by a battery. However, with the miniaturization of the microrobot, the reduction of weight, and the limited lifetime of battery, self-powering of microrobot is a key challenge. Inspired by the crawling of cockroaches, we present an untethered insect-scale robot driven by moisture induced electric power. A moisture-based energy harvesting device has been exploited and embedded in the microrobot, which can capture and store atmospheric water under various environmental conditions through a hygroscopic gel and generate electricity based on redox reaction. The device produces an output voltage of ~1.4 V and an output current of ~43 mA. A combination of moisture-electricity powered vertical vibration and the asymmetric structural design of the microrobot enables its forward locomotion at an average speed of ~4.01 cm/s. Our work could facilitate multifunctionality in future self-powered microrobots and mesoscale devices. © 2021 Elsevier Ltd