SECM is a powerful scanning probe technique that maps localized electrochemical activity. It works by positioning an ultramicroelectrode (UME) probe ↗ near a substrate surface in an electrolyte solution. The probe is polarized to drive a redox reaction of an electrochemical active species present in the solution. As the probe scans across the surface in the X-Y plane, the measured current reflects local variations in reactivity, conductivity, or topography.

One of the most common modes in SECM is the feedback mode. In this mode, the electrolyte contains a free-diffusing reversible redox mediator that undergoes electrochemical conversion at the SECM probe in a diffusion-controlled manner. As the probe approaches a conductive substrate, the mediator, oxidized or reduced at the polarized probe, is regenerated at the substrate and diffuses back to the probe, increasing the probe current (positive feedback). In contrast, when approaching an insulating substrate, the surface blocks the mediator diffusion to the probe, reducing the current (negative feedback).

Beyond amperometric feedback imaging, SECM systems support, among others, generation-collection mode, potentiometric imaging, and redox competition mode.

Spatial resolution in SECM is mainly governed by the size of the ultramicroelectrode probe and the probe-substrate distance. The active electrode diameter defines the lateral extent of the electrochemical measurement area, while the tip-substrate separation controls how much the diffusion layer spreads laterally before reaching the surface.

For high-resolution imaging, both a small probe diameter and close approach are required. Typical probe diameters range from tens of micrometers to a few hundred nanometers, enabling resolutions from micron down to nanometer scale. The RG value (the ratio of the overall glass insulator radius to the active electrode radius) also influences spatial resolution and probe behavior. Sensolytics probes provide the optimal balance for general SECM applications, ensuring a well-defined, predictable diffusion profile for the redox mediator while still allowing the probe to approach the surface closely without physical interference.

Sensolytics SECM systems are driven by integrated software ↗ that supports a comprehensive library of scan modes and measurement configurations without requiring time-consuming hardware reconfiguration:

Electrochemical & Measurement Modes:

• Amperometric Feedback Modes
• Generation-Collection Mode
• Redox Competition Mode
• Potentiometric & OCP Mapping
• AC-SECM

Positioning & Multi-Dimensional Mapping:

• Option Shearforce ↗: Non-contact distance control that decouples topographic and electrochemical activity signals, enabling measurements on rough, micro-structured, or mechanically sensitive surfaces.
• 2D / 3D Mapping: High-resolution X-Y scans and three-dimensional surface mapping.
• 4D Mapping: Spatially resolved kinetic analysis by recording a Z-approach curve (current vs. distance) at each X-Y position, generating a four-dimensional dataset.

Sensolytics SECM systems are modular platforms, designed for the investigation of localized electrochemical processes across a wide range of research and industrial applications. Key application areas include:

Corrosion and Surface Protection:

• Mapping localized pitting corrosion precursors and propagation.
• Evaluating the integrity, permeability, and defect distribution of anti-corrosive coatings.
• Monitoring galvanic corrosion and galvanic coupling processes in real-time.

Energy Storage and Electrocatalysis:

• High-throughput screening of novel electrocatalyst arrays (e.g., for ORR, OER, HER).
• Characterizing solid-electrolyte interphase (SEI) layers in battery research.
• Mapping spatially resolved ion conductivity and reactivity in fuel cell membranes.

Biological and Biophysical Chemistry:

• Non-invasive monitoring of single-cell metabolism and localized respiration.
• Spatially mapping enzymatic activity on bio-functionalized interfaces.
• Studying localized membrane transport and ion channel activity using potentiometric probes.

Materials Science and Semiconductor Research:

• Investigating heterogeneous charge transfer kinetics on multi-phase or micro-structured materials.
• Correlating surface topography with localized conductivity and electrochemical reactivity.
• Mapping photo-induced reactivity on light-harvesting semiconductor surfaces (using the Option SPECM ↗).