Harvesting body heat to power synthetic skins

Dr Yuqing Liu in the lab wearing a thermoelectric generator.

Researchers at the ARC Centre of Excellence for Electromaterials Science lead the way in utilising thermoelectric generators as a potential power supply for synthetic skins

A team led by Professor Jun Chen from the ARC Centre of Excellence for Electromaterials (ACES) and the University of Wollongong’s Intelligent Polymer Research Institute (IPRI) has released a new protocol to print compatible power supply for electronic skins (E-skins).

E-skins are artificial skin-type electronic devices, which hold great promise for the establishment of wireless health monitoring systems, and in applications in limb prostheses, soft robotics, and artificial intelligence. These synthetic skins can mimic the sensory and self-healing functionalities of natural skin, monitor vital signs, and deliver diagnosis remotely.

To date, however, the lack of ultrathin, stretchable and reliable power sources has dramatically hindered the commercial application of E-skins.

In a paper published the June 2019 issue of Joule, the research team proposes that the continually released thermal energy from our body provides a plausible solution to power the miniaturised sensors and circuits in E-skins.

The ACES researchers in conjunction with researchers from the University of New South Wales, the Nagoya Industrial Science Research Institute (Japan), King Abdulaziz University (Saudi Arabia) and Kyung Hee University (Korea). The research team also included Dr Ruoming Tian (UNSW), Dr Yuqing Liu (ACES and IPRI) and Professor Kunihito Koumoto (NISRI).

While most traditional thermoelectric generators are rigid, the team has proposed a device design where formulated inks are printed directly on a soft biocompatible substrate with pre-patterned electrodes that provide an opportunity to capture body heat for energy purposes.

The protocol utilises inks that can be tailored and customised to allow the production of a flexible, ultrathin generator that can conform well to the skin to potentially enable seamless integration into existing E-skins. The device features an induced thermal barrier and heat absorber, which will enable the generation of temperature gradients and convert body heat into electricity.

Professor Chen said the team had discovered some exciting advancements in creating a flexible, effective thermoelectric generator to power E-skins.

“Our proposal to use ink-based materials allows the integration of power supply and energy storage in a cost-effective way, and is a step in the right direction towards the field of wireless health monitoring and diagnosis,” Jun said.

“In particular, we found that solution-processable semiconducting materials can be formulated into inks and adapted for scale-up production.

“Further, the solution processability of these materials allows for the ink parameters such as active material loading, shear viscosity and surface tension to be carefully controlled, and provides solutions to some of the current barriers in thermoelectric devices in terms of flexibility, material degradation and low-power generation.”

Read more: Scientists turn up the (body) heat on electronic skins