Nanofluidic bipolar transistors

A semiconductor bipolar junction transistor (BJT) from a single double-conical shaped nanopores using controlled modification of the nanopore walls was fabricated. The nanopore was prepared in a 12 μm thick poly(ethylene terepthalate) (PET) foil by the track-etching technique. The chambers were filled with 0.1 m KCl solutions to various pH with a phosphate buffer and was adjusted with 0.1 m HCl and NaOH. Calculations of ion currents were performed using 2-D axial symmetry of a double-conical geometry. Pore entrances were connected to the 2μm square reservoirs. The modification was performed in two steps, each lasting 50 minutes, leading to the formation of positive charges near both openings of the pore and leaving the center of the pore intact. The calculated values of the ion current plateau increases with an increase of KCl concentration, and the saturation of ion currents occur at higher voltages.