Session 17: Power Technology
Flexible Thermoelectric Energy Harvesters with Liquid Metal Interconnects
Wednesday, June 21, 2017
4:20 PM - 4:40 PM
Flexible thermoelectric energy harvesters hold great promise for self-powered wearable electronics for long-term, continuous monitoring of health and environment. In this work, carried out within the ASSIST Engineering Research Center, we have developed a flexible/stretchable thermoelectric harvester relying on high performance bulk thermoelectric materials and low-resistivity, liquid metal (eutectic alloy of gallium and indium - EGaIn) stretchable interconnects. The device encapsulates the legs and the interconnects in a stretchable elastomer. Because the device employs bulk thermoelectric legs, it is compatible with any manufacturer's thermoetectric material offering a flexible technology with low cost-of-ownership to existing or future companies. The EGaIn technology enables stretchable, self-healing interconnects with high electrical conductivity and excellent mechanical properties. The interconnects can be printed thanks to the presence of the thin GaO skin oxide around the EGaIn and they can be quite thick. Consequently, the contribution of the interconnect resistance to the device total resistance is negligibly small. This is critical since the output power is inversely proportional to the total resistance and the existing flexible interconnect technologies (e.g Ag/AgCl) yield interconnects with resistance values that are simply too high for this application. To further enhance the device performance, the encapsulating elastomers are modified to tailor their properties to the requirements of the device in different sections (e.g high or low thermal conductivity). Our results suggest that it is possible to produce large area, flexible thermoelectric devices that perform as good as or better than their rigid counterparts.
Mehmet C. Ozturk is a professor in Electrical and Computer Engineering of North Carolina State University. His research interests include semiconductor devices, energy harvesting and flexible electronics. Dr. Ozturk is serving as the deputy director of the NSF sponsored ASSIST Engineering Research Center focusing on self-powered wearables for health and environment monitoring.
NC State University & ASSIST Engineering Research Center