Scanning Electrochemical Cell Microscopy Stable Imaging Method With a Backpressure at the Back of Its Nanopipet

Abstract

Scanning electrochemical cell microscopy (SECCM), is a local electrochemical measurement technique with a confined area of a surface, especially suited for the electrochemical mapping with topography imaging in a high-resolution way. Despite its wide application, the droplet evaporation/crystallization of its nanopipet tip impacts imaging stability for the large surface feature. Here we use single-barrel SECCM nanopipet with different backpressure to increase the meniscus droplet thickness and then improve the tip perceptive capability and imaging stability, avoiding the humidity effect. In this paper, finite element method and experiment are first employed to study the impact of the droplet height, contact radius, and half-cone angle of the nanopipet tip on the steady-state current when the meniscus droplet makes contact with the substrate surface. Further, the droplet positioning and SECCM scanning experiments are conducted to compare the imaging stability of the conventional and pressure-applied single-barrel nanopipet with the tip opening diameter 120 nm in different humidity environment. The experimental results demonstrate that the pressure-applied SECCM nanopipet can sense and image with hopping mode in lower ambient humidity and possess higher imaging stability (increase by more than 40% in number of successful images) than conventional nanopipet without pressure.