There may finally be assistance available if you are the type of person who consistently forgets to charge your wireless headphones. The announcement coincides with the launch of the first commercially viable solar-powered headphones.
Both designs, produced by German sports titan Adidas and the Swedish outfit Urbanista, have solar panels built right into the headbands.
In each instance, the flexible panels are created by Exeger, a different Swedish business, which has spent the last ten years perfecting them to be as powerful, light, and flexible as possible.
Giovanni Fili, the CEO of Exeger, claims that it is both practical and, more importantly, environmentally responsible to do so.
Everyone despises charging, he claims. The new generation of young adults expects to be provided with means to do good [for the environment], and that is what we are delivering. But every time you don’t charge [using mains energy], it is a positive thing for the earth.
The Powerfoyle solar panels from Exeger are only 1.3mm thick. The method is based on titanium dioxide strips that have been dyed naturally. In the simplest terms possible, the dye absorbs light’s photons, which are later transformed into electrons.
In full sunlight, titanium dioxide solar panels are about half as effective as conventional silicon-based solar panels of the same size, but they are also substantially smaller and much simpler and less expensive to manufacture.
The solar-powered headphones continue to include an internal battery that has an 80-hour playback capacity. The Powerfoyle strip is used to charge this. According to Mr. Fili, the technology can presently produce an hour’s worth of energy “from just 20 minutes of English or Swedish summer sunshine.”
Even said, the panels can also generate some power from man-made light, such as indoor lights, therefore the headphones should always be charged unless it is quite late at night. Additionally, the headphones still feature a power connector in case backup power is needed after prolonged use.
Since so many of us keep our phones in our pockets and out of the light, Mr. Fili adds that solar panels on mobile phones are unlikely to be introduced very soon. Instead, he sees the panels attached to people’s bags and clothing so that phones can be charged from these.
Finnish company Planno is already making fabrics that have built-in solar panelling.
The firm is led by Elina Ilén, who is also a professor at the Polytechnic University of Catalonia’s Department of Textile and Paper Engineering, and a leading expert on wearable textile electronics.
Rather than producing clothing that can charge your mobile phone, the firm instead focuses on washable garments with built-in, solar-powered sensors. These can monitor various aspects of the wearer’s health, such as heart rate, temperature, posture, sleep quality and body fat levels.
“Although these solar cells do produce enough energy to power wearable devices, placing a solar cell behind a textile will never have the same efficiency of harvesting energy as a solar cell in direct sunlight,” says Ms Ilén.
“The textile’s thickness, density, structure, colour and finishing treatments will all have an impact on the amount of energy-harvesting potential.”
She adds: “Textile-based wearables are one of the best solutions for continuous health monitoring because product acceptability is easier to achieve. Patients are already wearing clothing, this technology can be hidden beneath the fabric to ensure comfort and discretion.”
At Loughborough University researchers are taking a different approach to power-generating fabrics. Instead of using solar cells, they are harvesting the static electricity created when a person moves and turning that into usable power.
The technology is based around tiny power converters called triboelectric nanogenerators (tengs). These are made from fibres such as cotton, polyester and nylon, which are covered in a polymer coating that attracts static. These flexible, stretchable, washable tengs can then be woven or knitted into the fabric of items of clothing.
“Our group is investigating how we can use regular textile materials and textile fabrication techniques to produce efficient tengs for wearable applications,” says project leader Ishara Dharmasena.
“The aim is to produce energy-generating textiles like T-shirts, base layers and trousers which are very similar to our regular clothing, but capable of generating electricity or acting as sensors to measure body movements.”
Dr Dharmasena, a Royal Academy of Engineering research fellow and lecturer at Loughborough, adds that in the future tengs could be used in conjunction with solar panels to create hybrid power-generating clothing.
Denise Wilson, the author of the book Wearable Solar Systems, hopes to see the market for solar-powered clothing expand greatly in the coming years.
“I think that we could benefit from more imagination when it comes to marketing wearable solar packs,” says Prof Wilson, from the University of Washington’s Department of Electrical and Computer Engineering.
“We have not yet taken advantage of what they can fully offer us in the global community.”
She adds that the biggest area for growth will likely be clothing that can charge mobile phones and other portable electronic devices. “For the average consumer, it may mean being able to charge on the go.”
But she adds that for such clothing to find widespread popularity, the solar panel systems will need to last at least one year without a significant loss of efficiency.
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