Batteries not Included: Circuits and Systems that Sense and Self-Power
Professor Matthew Johnston
Oregon State University
Corvallis, OR, USA

Abstract
A host of changes are in store for future electronic devices, enabled in part by broad advancements in power, packaging, and performance of integrated circuits and sensor systems. 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 a true battery-less, wearable bioelectronic sensor 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 wearable devices using body-heat energy harvesting.

Biography Matthew L. Johnston received the B.S. degree in electrical engineering from the California Institute of Technology, Pasadena, CA and the M.S. and Ph.D. degrees in electrical engineering from Columbia University, New York, NY. He is currently an Associate Professor in the School of Electrical Engineering and Computer Science at Oregon State University, where he joined in 2014.
Dr. Johnston was co-founder and manager of research at Helixis, a Caltech-based spinout developing instrumentation for real-time PCR, from 2007 until its acquisition by Illumina in 2010. From 2012 to 2013 he was a postdoctoral scholar in the Bioelectronic Systems Lab at Columbia University. He is also a co-founder of Chimera Instruments, which designs high-speed electrophysiology amplifiers used by biophysics researchers around the world. He currently runs the Sensors and Integrated Microelectronics Laboratory (SIM Lab) at Oregon State University, which leverages custom integrated circuit design and post-fabrication to build miniaturized sensor systems. His current research interests include integration of sensors and transducers with active CMOS substrates, lab-on-CMOS platforms for label-free chemical and biological sensing, bio-energy harvesting, stretchable circuits, and low-power distributed sensing applications.
Dr. Johnston was the recipient of the 2020 Semiconductor Research Corporation (SRC) Young Faculty Award, and he currently serves as an Associate Editor of the IEEE Transactions on Biomedical Circuits and Systems (TBioCAS), the IEEE Transactions on Circuits and Systems - II (TCAS-II), and the IEEE Open Journal of Circuits and Systems (OJCAS).