Smart textiles use body heat to power devices as you exercise

Thermal energy and solar energy are not new, but as researchers have learnt more about how to harvest that energy and convert it into power, they turned their attention to turning body heat into electricity.

Professor Jun Chen of the University of Wollongong, spoke about his ongoing research into the area as previously Professor Chen was tasked with exploring how to harness the unused heat from the pipelines at oil-based industry to create renewable power.

His team at the ARC Centre of Excellence for Electromaterials Science (ACES), then started thinking about other ways to capture the heat for power, including using our body’s natural heat.

“Our body’s temperature is different to the temperature in the environment. Skin temperature is about 26 to 35 degrees … and inside we always keep our body at 36-38 degrees – it’s a very reliable temperature. Even when we are doing nothing, as adults we are losing 50 to 100 volts per day, through the heat exchange with our environment,”

Jun Chen demonstrates wearable tech at the Australian Institute for Innovative Materials Intelligent Polymer Research Institute.

We don’t need to convert all of the body’s heat, just a small portion” he adds. A wristband or shirt, for instance, could be powerful enough to charge a small medical device, a Nintendo Wii (14 watts), mobile phone (about 1 watt) or a laptop (45 watts).

It is the difference between our body’s temperature and the outside temperature that is the key and the technology works by using electrodes on either side of the fabric to convert this difference into an electric current that can charge small medical devices, fitness trackers or smart watch.While the more we move, the more energy we can generate, our mood can also make a difference.

“If we are happy, your body temperature goes up by about 4 degrees,” Chen says, suggesting we can “power” tech with happiness as well as fitness.

The challenge was that the heat-capturing technology was not user-friendly. “The device is rigid, it’s not flexible or comfortable or wearable,” Chen says.

So they began working with smart textile designers to create wearable technology that is flexible and can integrate into the clothes fibres to capture the heat and transform it into energy to power our electronic devices and the key to this and other advances in flexible and wearable electronics is selecting the right biomaterials that have passed all the medical tests already.

It’s still early days but flexible printed electronics and polymer research moves at an incredible pace so with this in mind Chen hopes to eventually bring on some industry partners to take the technology one step closer to market, which is perhaps at least five years away.


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