Nanoprobe electrodes cut by physical stretch of Parylene-insulated carbon nanotube bridges

This paper reports the fabrication of nanoprobe electrodes based on carbon nanotubes (CNTs) for intracellular recording. The nanoprobe electrodes are cantilevers of single/bundle CNTs with insulating covers and exposed tips. Parylene-coated CNT bridges were cut into probes by physical stretch. CNTs were consequently exposed at the probe tips, because of low friction between CNTs. In this method, only wafer cutting by diamond pen is required to induce the physical stretch on the bridges. Parylene worked for stiffness enhancement of the probes as well as insulation. We achieved CNT probe electrodes of 1-10 μm in length and 80-300 nm in diameter. By electrochemical impedance measurement, we confirmed that the fabricated electrode had an electrical connection to electrolyte through the exposed tip.