New temporary tattoo makes electricity from sweat (but only makes you cool temporarily)
Like marriage, tattoos often seem like a good idea at the time. But teens often fail to realize that the cool barbed wire tattoo is going to be little more than a picket fence when they get old. Now you can get a temporary tattoo that eventually wears off (hopefully by the time you have to go out and get a job) and serves a useful purpose while you wait for it to disappear.
Researchers at the University of California San Diego have designed a sensor which can be imprinted onto temporary tattoo paper and when affixed to a person’s arm, can not only monitor a person’s progress during exercise, but generates electricity from the person’s sweat. The sensors works by detecting lactate, which is naturally produced in sweat. The harder you work, the more lactate your body produces. The level of lactate produced by your body also increases to abnormally high levels when a person suffers from heart or lung disease and thus, the tattoo sensor is able to warn patients when something appears to be off.
In addition, the tattoo sensor contains an enzyme that strips electrons from the lactate. Since a battery works by passing electrons from an anode to a cathode, with a few tweaks, the researchers were able to turn the tattoo sensor into a sweat-powered biobattery that produced up to 70 microWatts per square centimeter, about enough electricity to power a watch for a medium-size bug. Oddly, people who are out of shape produce more lactate and thus, people who are in good shape generate less electricity.
Scientists are working on an improved model that will monitor more body functions and generate more electricity to power small devices like watches and other sensors.