Device for Simultaneous Wind and Raindrop Energy Harvesting Operating on the Surface of Plant Leaves

Soft (bio)hybrid robotics aims at interfacing living beings with artificial technology. It was recently demonstrated that plant leaves coupled with artificial leaves of selected materials and tailored mechanics can convert wind-driven leaf fluttering into electricity. Here, we significantly advance this technology by establishing the additional opportunity to convert kinetic energy from raindrops hitting the upper surface of the artificial leaf into electricity. To achieve this, we integrated an extra electrification layer and exposed electrodes on the free upper surface of the wind energy harvesting leaf that allow to produce a significant current when droplets land and spread on the device. Single water drops create voltage and current peaks of over 40V and 15µA and can directly power 11 LEDs. The same structure has the additional capability to harvest wind energy using leaf oscillations. This shows that environment-responsive biohybrid technologies can be tailored to produce electricity in challenging settings, such as on plants under motion and exposed to rain. The devices have the potential for multisource energy harvesting and as self-powered sensors for environmental monitoring, pointing at applications in wireless sensor networks (WSNs), the Internet of Things (IoT), smart agriculture, and smart forestry.