Batteries not Included: Circuits and Systems that Sense and Self-Power

Future wearable devices and other deployed sensor systems, including smart agriculture or environmental monitoring, will require new approaches for long-term powering and operation that avoid individual battery recharging. One approach is the use of thermoelectric energy harvesting, where energy is extracted from thermal gradients using a solid-state thermoelectric generator (TEG). Even centimeter-scale TEGs can provide microwatts of power from small temperature gradients, such as body heat, but they present a number of challenges in terms of low-voltage, highly-efficient energy conversion at the output. 

In this talk, I will present recent work in low-voltage energy harvesting applied to wearable devices, including some of our own low-level improvements in DC-DC converters and complete thermoelectric energy harvesting solutions - including true battery-less, wearable bioelectronic sensors powered by body heat. I will also present a number of ultra-low-power (ULP) sensor readout interface circuit approaches that enable ULP (<10µW) read-out for resistive-, voltage-, and current-domain sensors, such as temperature, pH, and electrochemical reactions. Together, thermoelectric energy harvesting combined with ULP sensors and read-out ICs are a promising avenue for powering wearable devices using body-heat energy harvesting.