Nanotube-on-graphene heterostructures for three-dimensional nano/bio-interface

Abstract

We report the synthesis, fabrication, and characterization of a nanotube-on-graphene (NT-on-Gr) field-effect sensor array for electrical detection of the biological activity of living cells. In order to form vertical nanotubes on a graphene surface, Ge/Si core-shell nanowires were vertically grown on graphene, followed by cap opening and Ge core-etching processes. Source-drain current versus water-gate potential measurements in electrolyte solutions with various pH values showed typical gate-dependent ambipolar characteristics with a decrease in pH sensitivity versus that of a flat graphene field-effect sensor. This is associated with limited solution gating of Si nanotubes that form nanoscale fluidic channels and thus interconnect the solution with the graphene field-effect sensor. The Si nanotubes also bridged interconnections between cells and the graphene field effect sensors, which were then able to record electrical spike peaks caused by cell networks. (C) 2017 Elsevier B.V. All rights reserved.