How this waterproof solar cell generates power even after it gets soaked

By Warren Miller, contributing writer

Imagine a world in which everyone is wearing sensor technology in their clothing that monitors their heart rate, blood pressure, and other significant health factors. Will they all be wearing battery packs around their waists all day long to power all of these sensors? Of course not; they’ll be powered by solar energy collected by solar cells in our clothing. But what if you accidentally put your solar-powered clothing into the washer/dryer? Fear not; solar cells that can be laundered might not be far away.

Scientists at the University of Tokyo, in cooperation with the Japanese company RIKEN, have developed a thin, lightweight solar cell that could be woven into fabric and survive the rinse cycle. The cell’s surface area is covered in a waterproof coating that doesn’t adversely affect its ability to collect solar energy, an elastomer called PNTz4T. The cells can be bent, stretched, or even stepped on without significant decreases in their efficiency. Impressively, the cells can also produce a current of 7.86 milliwatts per square centimeter.

Although similar technologies have been developed in the past, none have had the combination of energy efficiency, long-term viability, and resistance to corrosive elements like air and water as these new solar cells.

The cell’s surface area is covered in a waterproof coating. Image source: University of Tokyo, RIKEN.

When the cells had been soaked in water for two hours, the researchers found that their efficiency decreased by only 5.4%. The researchers also subjected the cells to compression tests, compressing them by nearly half over 20 cycles while putting droplets of water on them. Even under such conditions, the cells still maintained approximately 80% of their original efficiency.

With such robust solar cell technology available, retailers could start weaving them into workout and exercise attire, which could, in turn, make health-monitoring technology sleeker and more lightweight. Your FitBit won’t look like a watch anymore because it will be woven into your shirtsleeve. Soon, hospital patients under long-term care won’t have to walk around hooked up to clunky machinery, and their gowns will contain all of the sensors and health monitors. Perhaps someday, you’ll be able to charge your cellphone by putting it in your pocket — your pants will become like a docking station, with solar cells in the legs gathering solar energy and converting it into electricity. 

But what if you spill a glass of red wine on your new, solar-cell-lined shirt? No problem; just throw it in the laundry basket.