CapHarvester: A Stick-on Capacitive Energy Harvester Using Stray Electric Field from AC Power Lines

Manoj Gulati, Farshid Salemi Parizi, Eric Whitmire, Sidhant Gupta, Shobha Ram, Amarjeet Singh, Shwetak Patel

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Abstract

Internet of Things (IoT) applications and platforms are becoming increasingly prevalent. Alongside this growth of smart devices comes added costs for deployment, maintenance, and the need to manage power consumption so as to reduce recurrent costs of replacing batteries. To alleviate recurrent battery replacement and maintenance, we propose a novel battery-free, stick-on capacitive energy harvester that harvests the stray electric field generated around AC power lines (110 V/230 V)without an ohmic connection to earth ground reference, thereby obviating the need for cumbersome scraping of paint on concrete walls or digging a earth ground plate. Furthermore, our harvester does not require any appliance or load to be operating on the power line and can continuously harvest power after deployment. In effect, end-users are expected to simply stick the proposed harvester onto any existing power-line cord in order to power a sensing platform. Our controlled lab measurements and real-world deployments demonstrate that our device can harvest 270.6 µJ of energy from a 14 cm long interface in 12 min. We also demonstrate several applications, such as distributed temperature monitoring, appliance state monitoring, and environmental parameter logging for indoor farming.