Early in his career as a CBE faculty member, Dr. Michael Dickey and his research group made pioneering advances in the area of stretchable wires and electronics. Using a liquid metal of gallium and indium – a common, non-toxic alloy called EGaIn – the group’s breakthrough technology enabled them to fabricate antennas that can be stretched and flexed without diminishing their electrical properties. These “ultra-stretchable” wires are capable of being stretched up to eight times the original length and can self-heal after being completely severed.
Most recently, Professor Mehmet Ozturk and his research group in the NCSU Department of Electrical and Computer Engineering (ECE) incorporated the technology into a proof-of-concept device: a flexible thermoelectric energy harvester that might eventually rival the effectiveness of existing wearable electronic devices powered by body heat.
Wearable devices used to monitor a variety of health and environmental measures are becoming increasingly popular. However, at present the performance and efficiency of rigid devices are superior to flexible devices in their ability to convert body heat into usable energy.
While describing the prototype, Dr. Ozturk explained, “We wanted to design a flexible thermoelectric harvester that does not compromise on the material quality of rigid devices yet provides similar or better efficiency.” “Using rigid devices is not the best option when you consider a number of different factors.” Dr. Ozturk mentioned superior contact resistance – or skin contact – with flexible devices, as well as the ergonomic and comfort considerations to the device wearer.
“Using liquid metal also adds a self-healing function: If a connection is broken, the liquid metal will reconnect to make the device work efficiently again. Rigid devices are not able to heal themselves,” Ozturk added.
Dr. Francisco Suarez (ECE), Dishit P. Parekh (CBE), Collin Ladd (CBE), Dr. Daryoosh Vashaee (ECE) and Dr. Dickey co-authored the paper, Flexible thermoelectric generator using bulk legs and liquid metal interconnects for wearable electronics, that describes the work. Dr. Ozturk is the corresponding author. The group has a pending patent application on the technology.
Funding for the work comes from the NC State’s National Science Foundation-funded Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST) Center under grant (EEC1160483) and from other NSF support under grants ECCS1351533 and CMMI1363485.
The original version of this post was published in NC State News