MIT engineers have developed a fuel cell that is powered by the same fuel that runs the human body, glucose, thereby paving the way for developing implantable medical devices that don’t require an external power source.
The development proves the concept that implantable medical devices could 
generate enough power to help paralyzed patients move their arms and legs, according to a press release from MIT. Other institutions have demonstrated that paralyzed patients could use brain-machine interfaces to move a robotic arm, but those implants had to use a wall socket as a power source.
Benjamin Rapoport, a former graduate student that worked on the project and an author of the study, says:
It will be a few more years into the future before you see people with spinal-cord injuries receive such implantable systems in the context of standard medical care, but those are the sorts of devices you could envision powering from a glucose-based fuel cell.
The fuel cell strips electrons from glucose molecules to create a small electrical circuit. The cell, developed by a team led by Rahul Sarpeshkar, an associate professor of electrical engineering and computer science at MIT, is fabricated on a silicon chip, allowing it to be integrated with other circuits that would be needed for a brain implant. The development is described in the June 12 edition of the journal, PLoS ONE.
Using glucose as a fuel source is not new. Scientists showed in the 1970s that glucose could power a pacemaker, but the idea was abandoned in favor of lithium-ion batteries, which provided significantly more power per unit area than glucose fuel cells. Also, those fuel cells used enzymes that were impractical for the long-term implantation in the body because they eventually stopped working efficiently.
MIT’s fuel cell has no biological components, is fabricated from silicon, and uses the same technology used to make semiconductor electronic chips. A platinum catalyst strips electrons from glucose, mimicking the activity of cellular enzymes that break down glucose to generate ATP, a cell’s energy source. Platinum has a proven track-record of long-term biocompatibility within the body. The MIT researchers report that the fuel cell can generate up to hundreds of microwatts, which is enough power to run a clinically useful neural implant.
The research term theorized that the fuel cell could get all the sugar it needed from the cerebrospinal fluid (CSF), which bathes the brain and cushions it against the skull. Because the CSF has few cells, it is highly unlikely that an implant located there would provoke an immune response. Also, the CSF has significant glucose, which does not get catalyzed by the body. Because only a small fraction of the available power is used by the glucose fuel cell, researchers believe the impact on the brain function is likely to be small.
Source: “New Energy Source for Future Medical Implants: Sugar,” MIT News Office, 6/12/12
Image by Mohamad Sawan, used under its Creative Commons license.
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.
