Real-time electrical detection of the formation and destruction of lipid bilayers on silicon nanowire devices

Silicon nanowire (Si NW) two-terminal devices were fabricated to electrically probe the real-time formation and destruction of lipid bilayers. A liposome solution, containing the same ratio of zwitterionic/anionic lipids that are present in an Escherichia coli cell membrane, was applied to the NW devices. Lipid bilayer formation on the Si NWs was detected in-situ by observing electrical resistance changes complemented by confocal fluorescence microscopy imaging. The formation of lipid bilayers resulted in a 1% to 2% decrease in device current, consistent with the negative gating effect of the lipids on the NW surface. The devices demonstrated a ≈ 1 min electrical response time to lipid encapsulation. Removal of the lipid layer was achieved by exposing the devices to a detergent, which resulted in NW conductance returning to its original value with a ≈ 2 min recovery time. The lipid bilayer coated Si NWs demonstrate a novel platform to enable in-situ electrical probing of bacterial cell membrane mechanisms, interactions, and reactions.