Boost Converter Sets New World Record for Energy Harvesting

Achievement date: 
2014
Outcome/accomplishment: 

The Nanosystems Engineering Research Center (NERC) for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST) has designed, fabricated, and tested a boost converter circuit that facilitates energy harvesting from body heat at lower DC input voltages than any previous design. The breakthrough boost converter harvests energy from less than 10 megavolts (mV) of input, which is a new world record by over two times the existing technology. The ASSIST NERC is headquartered at North Carolina State University (NC State) and sponsored by the National Science Foundation (NSF).

Impact/benefits: 

The boost converter will allow new battery-free, body-powered, and wearable health monitoring nanodevices and sensors – ASSIST systems – to continue to harvest energy whenever a thermoelectric generator (TEG) is outputting voltages below 10mV. Prior designs stopped working at just 30mV. This means that such systems can continue to be powered at much lower thermal gradients between the skin and the air. Additionally, the improved efficiency of the boost converter circuit means that more of the harvested energy will actually reach the chip as usable power. Taken together, these benefits will allow ASSIST systems a much better opportunity to operate reliably in self-powered mode.

Explanation/Background: 

The boost converter is a major accomplishment for ASSIST’s Integrated Sensor Node Design and Prototyping Thrust, a nanoscience reseach unit which focuses on integrating enabling nanotechnologies with intelligent chip power management strategies for computation, wireless communication and sensing.

In order to harvest energy from body heat, a special circuit, called a boost converter, is needed to convert the small voltage coming from the thermoelectric generator (TEG) into a higher useable voltage. If the boost converter can operate using lower input voltages, then it can provide better harvesting capabilities across a broader range of environmental conditions. ASSIST’s boost converter achieves a peak efficiency of 84% at high input voltage (VIN) values and it is best-in-class for efficiency at low VIN (52% at 20mV and 22% at 10mV).