Implantable, miniaturized microbial fuel cell

• US 20040241528A1
• Filed: 05/27/2003
• Published: 12/02/2004
• Est. Priority Date: 05/27/2003
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Lin, Liwei, Chiao, Mu, Lam, Kien-Bang
• Granted Patent: US 7,160,637 B2
• Time in Patent Office: Days
• US Class Current: 429/43
• CPC Class Codes: H01M 8/0206 Metals or alloys
• CPC Class Codes: H01M 8/0215 Glass; Ceramic materials
• CPC Class Codes: H01M 8/0228 in the form of layered or coated products
• CPC Class Codes: H01M 8/16 Biochemical fuel cells, i.e. cells in which microorganisms function as catalysts
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A miniaturized microbial fuel cell is described deriving electrical power from the biological activity of microbes, typically the metabolism of glucose by baker'"'"'s yeast. Microfabrication techniques are used to miniaturize the components as well as the overall fuel cell and are capable of integration with other biomedical and implantable devices. Substantial reductions in both the size and the cost of implantable systems are thereby achievable. Electrode structures are used that facilitate electron transfer and power production giving favorable power densities in a miniature fuel cell. In addition, the microbial fuel cell of the present invention extracts glucose or other metabolite(s) from the ambient body fluids as its fuel, thus achieving a renewable, long-term power source for implantable biomedical devices.

Claims

1. An anode for a microbial fuel cell comprising a substrate having a plurality of substantially parallel microchannels therein, wherein said microchannels have a current collecting coating thereon, and said coated microchannels have dimensions so as to provide no substantial impediment to the flow of said microbes therethrough.

2. An anode as in claim 1 wherein said microchannels have a width approximately ten times the mean diameter of said microbes and a depth approximately eight times the mean diameter of said microbes.

3. An anode as in claim 1 wherein said current collecting coating is Cr/Au

4. An anode is in claim 1 wherein said current collecting coating has a thickness for approximately 2000 Angstroms to approximately 2500 Angstroms.

5. A microbial fuel cell comprising:

a) an anode as in claim 1 in an anode compartment and in contact with an anolyte containing a plurality of electricity-producing microbes and nutrient substances therefore, further comprising means for nutrient ingress and waste egress from said anode compartment; and

,

b) a cathode in a cathode compartment in contact with a catholyte containing materials therein capable of accepting electrons from said cathode, further comprising means for oxygen ingress and waste egress from said cathode compartment; and

,

c) a proton exchange membrane configured so as to allow passage of protons from said anode compartment to said cathode compartment.

6. A microbial fuel cell as in claim 5 further comprising an electron mediator in said anolyte.

7. A microbial fuel cell as in claim 5 wherein said microbe is baker'"'"'s yeast.

8. A microbial fuel cell as in claim 5 wherein said nutrient is glucose.

9. A microbial fuel cell as in claim 5 wherein said electron mediator is methylene blue.

10. A microbial fuel cell as in claim 5 wherein said electron accepting material is iron ferricyanide ion.

14. A method of fabricating an electrode as in claim 9 wherein said current collector is Cr/Au.

11. A method of fabricating an electrode for a microbial fuel cell comprising:

a) coating a silicon substrate with low stress silicon nitride; and

,

b) etching a plurality of fluid ports in said substrate; and

,

c) etching microchannels in said substrate; and

,

d) coating said microchannels and said fluid ports with a substantially conformal coating of current collector.

12. A method of fabricating an electrode as in claim 11 wherein said etching of said fluid ports is anisotropic, producing thereby slanted sidewalls on said fluid ports.

13. A method of fabricating an electrode as in claim 11 wherein said microchannels have dimensions so as to provide no substantial impediment to the flow of said microbes therethrough.