Single Electron Device As an Electrochemical Biosensor to Measure Biochemical Activity in a Cell

The conductance of nanoparticles modulates on charging by a single electron making them attractive for use in highly sensitive sensing devices. However, devices made from a single nanoparticle or arrays of nanoparticles have to be cooled to cryogenic temperatures to obtain the single-electron effect. Recently, we demonstrated the single-electron effect at room temperature in a monolayer network of one-dimensional “necklaces” of 10 nm Au particles. The necklace array network architecture is a metamaterial where the band gap can be tuned from 0 to up to ~6 V at room temperature by regulating the array’s overall shape. The high conductance band gap of over 1 V at room temperature allowed a highly sensitive electrochemical field-effect transistor (eFET) to be fabricated that operates in salt solutions. Biofunctional activities were monitored in real time by interfacing the eFET to living cells. In one application, the infection of a single virus on an algal cell immobilized on an eFET was measured in real time. In another application, the membrane potential modulation during photosynthesis was measured in real time as a function of the carbon source in the solution. The single-electron effect in a necklace array in air, the eFET performance, and the application as a cell-based biosensor will be presented.