A Glucose fuel cell for implantable brain–machine interfaces

Developers

B. I. Rapoport, J. T. Kedzierski, Rahul Sarpeshkar.

Description of the technology

Up to date, various solutions to the problem of providing power to biologically implanted devices have been proposed, prototyped, or implemented.

One of the newest projects in this area is an implantable glucose fuel cell developed by American scientists in 2015. Its main peculiarity is the use of use of cerebrospinal fluid as a physiologic niche for this fuel cell.

Implantable fuel cells have typically been designed for use in blood or interstitial fluid; to the best of our knowledge, the operation of a biofuel cell in the cerebrospinal fluid has not previously been describe

The researchers developed an implantable fuel cell that generates power through glucose oxidation, producing 3,4 µW/см2 steady-state power and up to 180 µW/см2 peak power. The fuel cell is manufactured using a novel approach, employing semiconductor fabrication techniques, and is therefore well suited for manufacture together with integrated circuits on a single silicon wafer. Thus, it can help enable implantable microelectronic systems with long-lifetime power sources that harvest energy from their surrounds. The fuel reactions are mediated by robust, solid state catalysts. Glucose is oxidized at the nanostructured surface of an activated platinum anode. Oxygen is reduced to water at the surface of a self-assembled network of single-walled carbon nanotubes, embedded in a Nafion film that forms the cathode and is exposed to the biological environment. The catalytic electrodes are separated by a Nafion membrane.

The availability of fuel cell reactants, oxygen and glucose, only as a mixture in the physiologic environment, has traditionally posed a design challenge: Net current production requires oxidation and reduction to occur separately and selectively at the anode and cathode, respectively, to prevent electrochemical short circuits. The fuel cell developed is configured in a half-open geometry that shields the anode while exposing the cathode, resulting in an oxygen gradient that strongly favors oxygen reduction at the cathode. Glucose reaches the shielded anode by diffusing through the nanotube mesh, which does not catalyze glucose oxidation, and the Nafion layers, which are permeable to small neutral and cationic species.

Practical application

It was demonstrated computationally that the natural recirculation of cerebrospinal fluid around the human brain theoretically permits glucose energy harvesting at a rate on the order of at least 1 mW with no adverse physiologic effects. Low-power brain-machine interfaces can thus potentially benefit from having their implanted units powered or recharged by glucose fuel cells.

Laboratories

• Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, (USA).
• Advanced Silicon Technology Group, Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts, (USA).
• Harvard Medical School, Boston, Massachusetts, (USA).

Links

Publications

• Rapoport, Benjamin I., Jakub T. Kedzierski, and Rahul Sarpeshkar. «A glucose fuel cell for implantable brain-machine interfaces." PloS one 7.6 (2012): e38436.
• Katz, Evgeny, and Kevin MacVittie. «Implanted biofuel cells operating in vivo-methods, applications and perspectives-feature article." Energy & Environmental Science 6.10 (2013): 2791–2803.
• Zebda, Abdelkader, et al. «Single glucose biofuel cells implanted in rats power electronic devices." Scientific reports 3 (2013): 1516.
• Wei, Xiaojuan, and Jing Liu. «Power sources and electrical recharging strategies for implantable medical devices." Frontiers of Energy and Power Engineering in China 2.1 (2008): 1–13.
• Ho, John S., et al. «Wireless power transfer to deep-tissue microimplants." Proceedings of the National Academy of Sciences 111.22 (2014): 7974–7979.