Fig. 1

a Schematic diagram of the ONW array geometry on a gold electrode designed to minimize the unwanted, nonspecific binding or aggregation of biomaterials. b A well-oriented nanowell (ONW) array electrode composed of eight Au pads. The Au electrode on each pad was covered with a resist layer, i.e., a blocking layer. c An AFM image of an ONW array with a 200 × 200 probe grid on a gold electrode 800 μm in diameter. In fabricating the ONW array electrode, a 100 × 100 nm² well was generated on the resist surface at 500 nm intervals using nanofabrication technology. d An AFM image of probe ssDNA immobilized by streptavidin-biotin on an ONW array. Although there are also bright spots on the resist layer, these DNA/streptavidin complexes do not contribute to the electrochemical signals