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Published on : Oct 10, 2017

Thermoelectric generator (TEG), a type of solid state device, based on inorganic semiconductors has been found to be exciting for several large-scale energy harvesting applications. However, their use has been found to be infeasible for low-grade thermoelectric energy conversion that is less than 200o C. The use of TEG in low-grade applications notably include self-powered sensors or Internet-of-Things (IoT) devices that can be powered by universally available heat sources. For such applications, investigators have explored the potential of organic TEs based on conducting polymers and found them to offer several advantages. The prominent of them being their low thermal conductivities and low cost of fabrication, the scalability of these applications being a unique benefit.

Recently such TEs have been found to be promising for wearable devices that can harvest energy from the ubiquitous body heat characteristic of small temperature differentials. A study by three researchers at Georgia Institute of Technology, U.S., shows proof-of-concept wearable TEG using flexible conducting polymers and novel, scalable fabrication methods. The research was in part supported by PepsiCo, Inc. and the Air Force Office of Scientific Research, with special support from Qatar Science Leadership Program fellowship. The work is detailed in a paper published on September 28 in the Journal of Applied Physics.

Inkjet Fabric Printing and Fractal Interconnect Patterns Key to Wearable’s Functionality

The scientists demonstrated that using fractal geometries-inspired interconnect patterns and inexpensive continuous roll-to-roll (R2R) fabrication techniques, novel circuitry patterns can printed on paper to generate modular generators. The use of high resolution inkjet printing allows higher precision fabrication and fractal geometries enable a higher density power. In addition, the fractal design of the interconnect pattern allows researchers to effortlessly cut the modules along boundaries between different symmetric areas to provide the required voltage and power needed for various applications.

Though paper can be used for printing, they found fabrics to be promising for wearable applications since they can commercially weaved into textiles. One of the promising applications, opine scientists, can be to power simple and inexpensive biosensors that enable measuring heart rate. More sophisticated applications are being explored for fitness trackers or smartphones.