Smart tattoo generates electricity from sweat, could power future wearable computers

Tattoo - Photo by kgberger

Smart tattoos are the hottest thing since mood rings. When they become commonplace, they will be a great way to eavesdrop on both vital signs and not-so-vital signs. The only thing that seems to be holding them back, is getting power to them. Joseph Wang, a researchers from UCSD, has now come up with a way to generate power for these devices without using any external equipment. The secret, is to harness electrons from lactate acid secreted in sweat.

The muscle “burn” we feel when exercising to exhaustion has been commonly associated with the buildup of lactic acid. For muscle, lactate is a waste product, a metabolic endpoint from which there is no escape. The brain, on the other hand, thrives on lactate. As far as the muscle is concerned, the brain is its metabolic trashman.

Exercise physiologists, quite naturally, have sought to measure lactate levels in the muscle or blood. When lactate was discovered to be released in sweat, a new sensor technology was born. Wang has taken the next logical step of adding provisions to accumulate charge when lactate is enzymatically sensed. By embedding enzymes that process lactate into the tattoo, he was able to extract 70 microwatts per cm² of skin.

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