A sensitive; simple and label-free method for DNA detection is presented. Irradiated polyethylene terephthalate foils were etched to present conical tracks at a density of approximately 5×10(7) tracks per cm(2). Probe DNA was immobilized at the narrow opening of the tracks (2-4nm diameter). The presence of target DNA resulted in changes in both conductance and rectification ratios in a concentration-dependent manner. DNA concentrations as low as 2nM could be detected using this simple two-step detection scheme.