A microfabricated device for the characterization of biological entities

A micro-fabricated pore is constructed and tested so that it can be used to characterize biological entities. The pore is prepared by bulk micro-machining of a silicon wafer. An oxide coated silicon diaphragm with the pore is placed between two chambers containing ionic buffer solutions to mimic a bilayer system. If a voltage is applied across the pore, electrophorelic passage of charged entities can be electrically detected through changes in the ionic current flow. When the entities traverse the pore, the ionic current is blocked and a decrease in the current can be observed. As an initial test case, negatively charged polystyrene beads which were 2.38nm in diameter, were electrophoretically driven across the pore. Then the bacterium Listeria innocua, suspended in Tris-glycine buffer, was also electrophoretically driven through the pore and its effective mobility was extracted. The device can also be used to study the interactions between organisms and the micro-fabricated surfaces. Work is continuing to scale the pore to the sub100A range to be used for characterization and possible sequencing of single molecules such as DNA.