Ultra-Low-Power System-on-Chip Eases Continuous Monitoring of Personal Health and Wellness

The “internet of things,” the constellation of stand-alone internet-connected devices that can be monitored and controlled remotely, is poised to transform the doctor-patient relationship. Wearable health and environmental systems can empower patients and doctors to transition from managing illness to managing wellness.

To make this leap, however, wearable devices need to be more comfortable and less dependent on batteries. UVA researchers led by Benton H. Calhoun, professor of electrical and computer engineering, have developed three generations of battery-less sensor nodes that harvest energy from their environment. Their solution combines sensing, computation, radio frequency communication, energy harvesting and power management into a single system-on-chip.

Their first system-on-chip design continuously monitored biosignals and powered itself exclusively from body heat energy; the thermoelectric generator used 0.019 milliwatts. The second-generation system-on-chip offered a platform for more widely applicable use, including the internet of things, consuming 0.006 milliwatts while processing and monitoring motion and activity data. The most recent system-on-chip accommodates multiple radio inputs and memory requirements while lowering power use to 0.0005 milliwatts. If your car were able to show a similar reduction of power, it could run for its entire lifetime on one tank of gas.

Their research advances the mission of the National Science Foundation’s multi-university Advanced Self-powered Systems of Integrated Sensors and Technologies center, more commonly known as the ASSIST center. The center develops technologies that maximize the power harvested from the body while simultaneously minimizing power consumption. The 10-year program envisions using nanotechnology to build miniature, self-powered, wearable and wireless sensing devices that can enable monitoring of personal health and personal environmental exposures.  

Looking beyond the mission of the center, Calhoun’s research group has set its sights on the next wave of devices that are out-of-the-box enabled for internet of things applications. Whereas advances in ultra-low-power circuits have led to demonstrations of self-powered nodes, the next generation of computing requires fundamental theory, engineering principles and design tools and frameworks to network self-powered systems. As new gains are made, these miniature devices and their ecosystem will enhance human sensing, allowing us to intuit what’s happening in our world beyond the information our five primary senses can provide.