Sensor-equipped wearables like smartwatches, fitness bands, rings, and even some internet connected clothing have lurched their way into mainstream acceptance in recent years. Though many of the devices have become more compact over successive iterations, almost all still need some sort of battery to hold power. Batteries can add weight and need to be charged which can present issues with certain healthcare wearables where constant, uninterrupted monitoring of a user’s vitals are crucial.
Researchers from the Queensland University of Technology in Australia believe they may have come up with a solution: a thin, flexible, and cost-effective film that converts body heat into power. That energy source, the researchers argue in a study published today in Science, could then be used in lieu of batteries to power next generation wearable tech. The study builds off other recent research showing how small thermoelectric devices can essentially turn the human body into a mini geo-thermal reactor to power wearbels. It’s still early, but researchers are hopeful the film, if scaled properly, could help bring about more useful smart clothing and longer lasting wearable medical devices that could potentially function without batteries.
“Flexible thermoelectric devices can be worn comfortably on the skin where they effectively turn the temperature difference between the human body and surrounding air into electricity,” Queensland University Zhi-Gang Chen and paper lead author said in a statement.
Body heart power could lead to more sustainable electronics
To build out their flexible film, the researchers use tiny crystals called “nanobinders” to form a layer of printed bismuth telluride sheets. These nano binders formed a thermoelectric material that was useful for achieving impressive flexibility and efficiency. The team then used a complex chemical technique called “solvothermal synthesis” to create nanocrystals—tiny crystals with dimensions of just a few nanometers. They fabricated the film using a screen printing method which they argue could cut down on costs for large scale production.
The result of all that small-scale engineering is a thin film the researchers say can turn body heat into a power source. In addition to potentially helping create self-powered electronics, the researchers say the film could also be fit into tight spaces in order to cool computer chips. That cooling process could help increase the efficiency and performance of advanced computer chips increasingly found in smartphones and computers. That cooling process could also be helpful in large data centers, which currently use large amounts of evaporated water to keep servers from getting too hot. One day, the researchers said, films like this could even be applied to smart wearables that could power a heating or air conditioning system. In other words, that means future athletes might be able to throw on smart clothing that cools them using power derived from their own body heat.
The study comes just several months after researchers from the University of Washington demonstrated the creation of a similar stretchy thermoelectric wearable that also harnesses human body heat for power. In that study, published in the journal Advanced Materials, researchers created semiconductors that convert heat to electricity. Those are connected with printed liquid metal traces. The wearable was then able to power on an LED light using energy generated only from the user’s body and without a battery.
“This wasn’t possible before,” University of Washington Assistant professor Mohammad Malakooti said in a statement.
Researchers at Carnegie Mellon’s Department of Mechanical Engineering also recently created a first-of-its kind body heat powered wearable device equipped with a pulse oximetry sensor. Though still early, these advances hint towards a future where more self-sustaining electric equipment is possible. That would be useful for devices like glucose monitors or pacemakers where faulty or worn down power sources can lead to dangerous results. If properly scaled up, these self powered devices could also lessen, if even in a small way, our news to create ever more resource intensive and environmentally harmful batteries.
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