Scientists at the University of California, San Diego, have created a temporary tattoo that both monitors progress during exercise and harvests electricity from sweat.
The device responds to lactate levels in sweat, an important indicator of exercise intensity and fitness. Enzymes embedded in the sensor strip electrons from the lactate to generate a weak current, which can be measured to indicate lactate levels.
The researchers then went a step further by turning the tattoo into a small biobattery – an energy-storing device powered by organic compounds (in this case sweat). The current produced is very low at present, but the researchers are trying to boost this in a bid to power exercise watches or heart-rate sensors.
The tattoo may come as a relief for athletes, who are currently subjected to invasive and inconvenient blood sampling and testing during various stages of exercise in order to assess their fitness and response to training.
It could also prove to be useful for doctors measuring lactate levels during exercise testing of patients suffering from heart and lung disease – conditions that lead to abnormally high lactate levels.
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