A Look inside a Flexible Open-Source Scanning Electrochemical Probe Microscope

Scanning electrochemical probe microscopy (SEPM) maps and investigates the chemical and physical properties of surfaces and interfaces using a micro- or nanoscale electrochemical probe, e.g., a microelectrode or a nanopipette, positioned close to an interface of interest. SEPM instruments share a common general architecture but are distinct from each other through the choice of probe and in the different physicochemical properties of the sample that can be investigated, including, among others, interfacial charge transfer rates, topography, permeability, or surface charge. Thus, a single instrument, with an appropriately flexible control system, can facilitate widespread access to the family of SEPM techniquesscanning electrochemical microscopy (SECM), scanning ion conductance microscopy (SICM), scanning electrochemical cell microscopy (SECCM), the scanning micropipette contact method (SMCM), and hybrid varieties of these techniques. Herein, we describe in detail a <i>flexible open-source SEPM instrument</i> that can perform <i>common and widely applicable SEPM techniques and experimenter-defined methodologies, with minimal programming from the user.</i> The instrument makes use of a field programmable gate array (FPGA)-based data acquisition card, and this contribution further illustrates the benefits of adopting FPGA architecture generally in electrochemical instrumentation. We describe the software and hardware for the instrument, using examples from the literature to illustrate how common SEPM operation modes and hyphenated techniques are readily implemented. Additionally, to demonstrate the application of custom-developed scanning protocols, we briefly present some further experimental examples. This Tutorial seeks to serve the needs of expert users of SEPMs and encourage new entrants alike. To this end, to encourage those who are interested in either setting up their own instruments or making optimal use of commercially available instruments, we also briefly include some more basic and general information on SEPM techniques and uses, to put the more advanced work and instrumental aspects in context.