Energy harvesting research pursues wearable tech powered by body heat

Scientists at the University of Southampton are developing an efficient nanostructured power source that can convert heat into electrical energy.

The new generation of flexible thermoelectric generators (TEGs) could harvest body heat to drive wearable technologies and produce electrical power from sources like hot water pipes.

Professor Steve Beeby, Head of the Smart Electronic Materials and Systems Research Group, is contributing to the three-year research programme that is combining inorganic materials with controlled 3D nanostructures and organic conducting polymers (OCPs) to enhance the technology’s power factor.

Wearable technologies such as smart watches, smart glasses and smart pacemakers have caused a paradigm shift in consumer electronics in recent years, however these devices are still powered by batteries that need frequent replacement or recharging.

TEGs would present an integrated, sustainable, battery-free alternative when realised in a high-performance solution.

Dr Iris Nandhakumar, project Principal Investigator, says: “Imagine a smart shirt that can generate its own power from body heat whilst automatically sensing and maintaining a person’s temperature. Flexible thermoelectric technology can be used to generate electrical energy, sense temperature and provide active cooling vital in applications where individuals are subject to extreme heat stress, such as firefighters.

“TEGs can generate up to several 100 microwatts power from heat radiated by the human body and are safe and long-lasting with zero emissions. Current versions however are plagued by low efficiencies, high manufacturing costs and are fabricated onto rigid substrates which makes them difficult to integrate into many applications.

“In this project we have taken a fresh approach to develop a new breed of TE hybrid materials for flexible TEGs based on low-cost and scalable fabrication methods using low cost and abundant materials.”

The Flexible Hybrid Thermoelectric Materials programme, which has been awarded over £600,000 from the Engineering and Physical Sciences Research Council, brings together a range of academic and industry partners with complementary expertise in the electrodeposition of inorganic TE nanostructures with OCP synthesis and printable energy harvesting.

Professor Steve Beeby says: “We are fabricating interconnected 3D nanowire networks of n and p-type inorganic TE with tunable diameters and lengths by template assisted electrodeposition.

“The nanowire assemblies are mechanically stable and have been predicted to exhibit high electrical conductivities with low thermal conductivities. These will be combined with novel flexible p-and n-type OCPs with high electron and hole mobilities to produce flexible and printable TE hybrid materials that will be tested inside a TEG prototype device.”

Thermal energy harvesting is predicted to become a $10 billion global market in 2020, helping exploit the huge potential in areas such as healthcare, fashion and entertainment that experts believe will make the market value for wearable technology reach $51.6 billion in 2022.