Wearable Biofuel Cell Produces Energy From Sweat
Scientists have developed a biofuel cell array that can power wearable electronics purely from the lactate in the wearer's sweat.
Researchers from the Tokyo University of Science have developed a wearable biofuel cell that runs on lactic acid found in the wearer’s sweat. The paper-based design can provide enough energy to power a low-energy Bluetooth transmitter and a commercial activity meter for a short time. Wearable electronic devices, such as health monitors and smartwatches, have been around for years, and the wearable market is expected to grow. That said, the options to power those devices have remained stagnant, with few updates to battery technology.
The researchers are looking to offset that problem with the wearable biofuel cell array, which looks like a paper bandage worn on the arm or forearm. The cell array was created using a water-repellent paper substrate with multiple biofuel cells arranged in series and parallel, with the number of cells dependent on the output voltage and power requirements. Each cell produces an electrochemical reaction between the sweat lactate and an enzyme doped onto the electrodes, which generates an electric current. That current flows into a collector designed using a conducting carbon paste, where it’s stored until needed.
The entire biofuel cell array is fabricated via screen printing and uses porous carbon ink for its conductive material. Lactate is collected through the cells’ paper layers, which is transported to the cells via a capillary effect, the same process that happens when you dip a paper napkin in water, where it then spreads to the entire surface. Tests carried out by the researchers showed that the paper-based biofuel cell could provide enough energy to power an activity meter for around 1.5-hours, which isn’t much. Still, it is an excellent step in refining the design for increased efficiency.