Vampire batteries for implants eternal!

New Scientist pulls back the veil from a team of Canadian biotech researchers who have built a yeast-based fuel cell that can run on blood:

Such fuel cells would be especially useful for devices, such as intraspinal microelectrodes for treating paralysis, which need to be implanted in places where replacing a battery is tricky, says Mu Chiao, who co-authored the paper with Chin-Pang-Billy Siu, also at UBC.

The new fuel cell consists of a colony of Saccharomyces cerevisiae – the kind of yeast commonly used in brewing and baking – encapsulated in a fuel cell made of a form of silicone called polydimethylsiloxane (PDMS). The prototype is 15 millimetres square and 1.4 mm thick.

Methyl blue – a chemical often used to stain biological samples – is used as the electron mediator. This steals some of the electrons produced when the yeast metabolises glucose and delivers them to the anode side of the cell, creating a small current. On the cathode side, hydrogen ions that diffuse out of the yeast cells combine with oxygen to create water.