Powering Wireless Sensor Nodes with Ambient Temperature Changes

Chen Zhao, Sam Yisrael, Joshua R. Smith, Shwetak Patel

Temperature-based power harvester and sensor node

Abstract

Power remains a challenge in the widespread deployment of long-lived wireless sensing systems, which has led researchers to consider power harvesting as a potential solution. In this paper, we present a thermal power harvester that utilizes naturally changing ambient temperature in the environment as the power source. In contrast to traditional thermoelectric power harvesters, our approach does not require a spatial temperature gradient; instead it relies on temperature fluctuations over time, enabling it to be used freestanding in any environment in which temperature changes throughout the day. By mechanically coupling linear motion harvesters with a temperature sensitive bellows, we show the capability of harvesting up to 21 mJ of energy per cycle of temperature variation within the range 5 °C to 25 °C. We also demonstrate the ability to power a sensor node, transmit sensor data wirelessly, and update a bistable E-ink display after as little as a 0.25 °C ambient temperature change.