Portable biofuel batteries now generate electricity from lactic acid in sweat

A team of scientists led by Associate Professor Isao Shitanda of Tokyo University of Science just published a study describing a new design for a biocell matrix that uses a chemical in sweat, lactic acid, to generate enough energy to drive a biosensor and wireless communication devices for a short time.

More energy than previous models

Your new biofuel battery matrix looks like a paper bandage that can be worn, for example, on the arm or forearm. It essentially consists of a hydrophobic paper substrate on which several 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, the electrochemical reactions between lactic acid and an enzyme present in the electrodes produce an electric current, which flows in a general current collector made of a conductive carbon paste.

This isn’t the first lactic acid-based biofuel battery, but a few key differences make this new design stand out. One is the fact that the entire device can be fabricated by screen printing, a technique generally suited to inexpensive mass production. This was made possible by careful selection of materials and ingenious design. For example, while similar earlier cells used silver wires as conductive paths, current biofuel batteries use porous carbon ink.

Another advantage is the way in which lactic acid is delivered to cells. Layers of paper are used to collect sweat and transport it to all cells simultaneously through the capillary effect, the same effect whereby water quickly moves through a towel when it comes in contact with a puddle of water. ‘water.

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

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