Micro-scale energy harvester collecting energy from an idle sensorsenergy
Wireless sensor devices are heavily duty-cycled to minimize energy consumption. To further reduce the energy required for sensing, these devices often prefer passive sensors that produce output power proportional to physical quantity. Therefore, while a sensor output is not being sampled (i.e., idle time), the output power from the sensor is unused and, hence, wasted. Inspired by the observation, we propose a sub-threshold exponential charge pump architecture that works with an ultra-low capacity power source (e.g., passive sensor) that has an output voltage and current as low as 250 mV and 6 μA. Utilizing the charge pump as an energy harvester to a system, we eventually design and implement Senergy, a batteryless wireless sensing platform that uses a photodiode sensor as a sole power source. Specifically, the Senergy prototype reports light intensity through a 2.4 GHz radio whenever it has harvested sufficient enough energy from the photodiode sensor, thus achieving perpetual operation. We use the prototype to evaluate the proposed system based on two application scenarios, namely adaptive transmission of sensor data and providing an uninterrupted power supply to an on-board real-time clock.
- RESEARCH PUBLICATION
- Woo Suk Lee, Hrishikesh Jayakumar, and Vijay Raghunathan, “When they are not listening: harvesting power from idle sensors in embedded systems,” International Green Computing Conference (IGCC 2014), pp.1–10, Dallas, TX, USA, Nov 2014.
(This is the full paper version of the research that received the ISLPED 2014 Design Contest Award)
- Woo Suk Lee, Hrishikesh Jayakumar, Vijay Raghunathan, “When they are not listening: harvesting power from idle sensors in embedded systems,” ACM/IEEE International Symposium on Low Power Electronics and Design (ISLPED 2014), La Jolla, CA, USA, Aug 2014.
(ISLPED 2014 Design Contest Award)