New energy source for future medical implants: brain glucose

The Matrix was right: humans will act as batteries
June 13, 2012

Brain power: harvesting power from the cerebrospinal fluid within the subarachnoid space. Inset at right: a micrograph of a prototype, showing the metal layers of the anode (central electrode) and cathode contact (outer ring) patterned on a silicon wafer. (Credit: Karolinska Institutet/Stanford University)

MIT engineers have developed a fuel cell that runs on glucose for powering highly efficient brain implants of the future that can help paralyzed patients move their arms and legs again — batteries included.

The fuel cell strips electrons from glucose molecules to create a small electric current.


In the 1970s, scientists showed they could power a pacemaker with a glucose fuel cell, but the idea was abandoned in favor of lithium-ion batteries, which could provide significantly more power per unit area than glucose fuel cells.

These glucose fuel cells also used enzymes that proved to be impractical for long-term implantation in the body, since they eventually ceased to function efficiently.

How to generate hundreds of microwatts from sugar


A silicon wafer with glucose fuel cells of varying sizes; the largest is 64 by 64 mm. (credit: Sarpeshkar Lab)

The new fuel cell is fabricated from silicon, using the same technology used to make semiconductor electronic chips, with no biological components.



Benjamin Rapoport, a former graduate student in the Sarpeshkar lab and the first author on the new MIT study, calculated that in theory, the glucose fuel cell could get all the sugar it needs from the cerebrospinal fluid (CSF) that bathes the brain and protects it from banging into the skull.

There are very few cells in the CSF, so it’s highly unlikely that an implant located there would provoke an immune response, the researchers say.


Structure of the glucose fuel cell and the oxygen and glucose concentration gradients crucially associated with its cathode and anode half-cell reactions (credit: Benjamin I. Rapoport, Jakub T. Kedzierski, Rahul Sarpeshkar/PLoS One)


Implantable medical devices 





Ultra-low-power bioelectronics







Ref.: Benjamin I. Rapoport, Jakub T. Kedzierski, Rahul Sarpeshkar, A Glucose Fuel Cell for Implantable Brain-Machine Interfaces, PLoS ONE, 2012, DOI: 10.1371/journal.pone.0038436 (open access)