Electric field controlled nanoscale contactless deposition using a nanofluidic scanning probe

A technique for contactless liquid deposition on the nanoscale assisted by an electric field is presented. By the application of a voltage between the liquid inside a (FluidFM) nanofountain pen AFM probe and a substrate, accurate contactless deposition is achieved. This technique allows for the deposition of polar liquids on non-wetting substrates. Sodium sulfate dried deposits indicate that the spot size and height increases with t$^{0.33±0.04}$ and t$^{0.35±0.10}$ , respectively. The minimum observed diameter was 70 nm. By measuring the probe deflection and the electric deposition current, we confirm that deposition is truly non-contact. We propose a simple model based on a constant stream of liquid to the substrate, which explains our observations qualitatively.