One day, your morning gym workout or jog could not only be recharging you, but also recharging your smartphone or other small electronic device. Scientists have developed a biosensor mounted inside a temporary tattoo that can monitor the wearer’s progress as they exercise and harness their sweat to produce electrical power.

Share on Pinterest Biobatteries recharge more quickly than conventional batteries, they use renewable energy, and they do not explode or leak toxic chemicals.

The innovation is the work of a team led by Joseph Wang, Distinguished Professor and Chair of Nanoengineering at the University of California. They presented their novel biobattery approach at a recent meeting of the American Chemical Society in San Francisco.

Compared with conventional batteries, biobatteries have several advantages: they recharge more quickly, they use renewable energy (in this case body sweat), and they do not explode or leak toxic chemicals.

Prof. Wang says their work shows “the first examples of epidermal electrochemical biosensing and biofuel cells that could potentially be used for a wide range of future applications.”

As we sweat, we produce lactate, “a very important indicator of how you are doing during exercise,” says Dr. Wenzhao Jia, a postdoctoral student in Prof. Wang’s lab.

Generally, the more intensely we exercise the more lactate we produce, as aerobic respiration is not enough to produce the energy we need, and anaerobic respiration kicks in. Anaerobic respiration converts glucose or glycogen to lactic acid, generating energy in the process.

Professional athletes monitor their lactate levels to evaluate their fitness and training performance. Doctors also asses lactate levels during exercise to test patients for heart or lung disease, and other conditions marked by unusually high lactate.