Portable biofuel cells now produce electricity from lactic acid in sweat

Portable biofuel cells now produce electricity from lactic acid in sweat

A team of scientists led by associate professor Isao Shitanda of the Tokyo University of Sciences has just published a study describing a novel design for a biofuel cell matrix that uses a chemical in sweat, lactic acid. , to generate enough power to drive a biosensor and wireless communication devices for a short period of time.

More energy than previous designs

Your new biofuel cell matrix looks like a paper bandage that can be worn, for example, on the arm or forearm. It consists essentially of a hydrophobic paper substrate on which multiple biofuel cells are placed in series and in parallel; the number of cells depends on the output voltage and the power required .

In each cell, electrochemical reactions between lactic acid and an enzyme present in the electrodes produce an electrical current , which flows into a general current collector made of a conductive carbon paste.

This is not the first lactic acid-based biofuel cell , but a few key differences make this new design stand out. One is the fact that the entire device can be manufactured by screen printing, a technique generally suitable for cheap mass production. This was made possible by careful selection of materials and ingenious design. For example, whereas previous similar cells used silver wires as conductive paths, current biofuel cells employ porous carbon ink.

Another advantage is the way lactic acid is delivered to the cells. Layers of paper are used to collect sweat and transport it to all cells simultaneously through the capillary effect, the same effect by which water travels rapidly through a napkin when it comes into contact with a puddle of water .

They also transmit more power : they could generate a voltage of 3.66V and an output power of 4.3mW.