Sweat-Powered Smartphones Tapped With Digital Tattoos
In a turn of events very similar to what we're experiencing with the VivaLnk Moto X digital tattoo collection, researchers in California have found themselves working with a temporary tattoo which allow human sweat to generate power. This device uses temporary tattoo sticky paper with a flexible lactate sensor imprinted upon it. From there, it's time to sweat.
The more you sweat, the more power you generate. The sensor works with an enzyme that strips electrons from lactate, while a cathode contains a molecule that accepts said electrons for power. This system allows you to contribute to a (notably weak) electrical current.
In its current iteration, this invention does not generate enough power to provide for even a digital watch, but in the future anything is possible – so says the group behind the experiments.
Dr Wenzhao Jia of the University of California, San Diego leads a group which also includes Dr. Gabriela Valdés-Ramírez, Amay J. Bandodkar, Dr. Joshua R. Windmiller, and Prof. Joseph Wang. Their research was first published in short on the 31st of May, 2013, and is well into trials now.
Above you're seeing a basic presentation video from the American Chemical Society on how the device works.
In recent research trials, they applied the tattoo to the arms of 15 volunteers, measuring electrical signals produced by these individuals as they rode exercise bikes for 30 minute intervals. The maximum amount of power produced was 70 microWatts per cm2 of skin.
A non-smart electrical watch requires "at least 10 microWatts" to be powered, while each of the electrodes the team has now generates about 4 microWatts across a 2 x 3-millimeter patch.
"So besides working to get higher power," suggested Jia, "we also need to leverage electronics to store the generated current and make it sufficient for these requirements."
Funding for this project comes from the Office of Naval Research as well as the National Science Foundation. Take a peek at our Wearables Hub for more information on the ever-growing world of wearable devices!