Microbial Rectifiers and Uses Thereof




When grown in vitro under various conditions, Geobacteraceae bacteria produce conductive protein filaments known as microbial or pilus nanowires. These microbial nanowires show promise for applications in nanoelectronics and bio-electronics. Current methods for producing microbial nanowires are limited by an inability to produce microbial nanowires in pure form, and the ohmic behavior limits uses to applications that require symmetric conductance. This excludes many nano-electronic and nano-medicine applications that require asymmetric conductance (rectification) for nano-wire functionality.


Description of Technology


Michigan State University’s invention demonstrates asymmetric conductance (i.e., rectifying behavior) of purified microbial nanowires. Asymmetric conductance is an advance over the ohmic properties in other technologies. Ohmic resistance is a measure of the degree to which a substance impedes the flow of electric current induced by a voltage, with resistance measured in ohms. Good conductors, such as copper, have low resistance while good insulators, such as rubber, have high resistance. This technology has the future potential to expand the range of applications of native and genetically engineered microbial nanowires in nano-electronics and nanomedicine, where rectification is a requirement for nano-electronic junctions.

The invention demonstrates that the purified microbial nanowires have rectifying behavior. The rectifying behavior of these purified nanowires is solely due to the protein composition, structure, and any chemical modifications of the native nanowires. Because of this, genetically engineered modification of these nanowires is possible (i.e., the rectification properties, along with the binding properties, of the nanowires could be customized for specific applications).


Key Benefits

  • Asymmetric conductance: The invention provides an alternative source (to semiconductors, polymers, and carbon nanotubes) of rectification in nanowires. Asymmetric conductance increases the range of potential applications for nanowire technologies.
  • Customization: The potential to modify and customize microbial, proteinaceous nanowires (i.e., create nanowires from native or genetically engineered stock, with electronic properties suitable for a particular application).
  • Biodegradable: The biodegradable nature the microbial rectifiers and nanowires makes them desirable for applications in nanomedicine.
  • In vitro assembly: Offers potential to reduce cost of synthesis of microbial nanowires with customized electronic properties.
  • Novelty of microbial production of nanowires: The single-step production of nanowires by biological means at high yield is more attractive than currently available technologies.




This technology provides an alternative to carbon nanotubes, semiconductors, and polymers for nanowires as components in nano-electronics and nano-biosensors.


Patent Status


Patent pending




Gemma Reguera, Stuart Tessmer, Joshua Veazey, Sanela Lampa-Pastirk


Tech ID




Patent Information:


For Information, Contact:

Thomas Herlache
Assistant Director
Michigan State University