New VersaSCAN AC-SECM Technique for Mediator-Free SECM

New VersaSCAN AC-SECM technique for Scanning Electrochemical Microscopy (SECM) without an electrochemical mediator. The technique is available at no extra cost for SECM users (both new and existing systems).

Blue Scientific is the official distributor for Princeton Applied Research (Ametek) in Norway, Denmark, Finland, Sweden and Iceland. If you have any questions or if you’d like a quote, please get in touch:

PAR VersaScan

 Contact us on 01223 422 269 or


VersaScan AC-SEM

AC-SECM is a new technique for Princeton Applied Research’s VersaSCAN platform, for a mediator-free approach to SECM. This is complementary to LEIS (Local Electrochemical Impedance Spectroscopy).

Free for SECM Users

The new technique is available to all VersaSCAN SECM users at no additional cost. Simply update your software to the latest version of VersaSCAN (version 1.6.6465) – available as a download from the Ametek website. The latest version of the software is also compatible with VersaStudio (v2.52), PARSTAT 4000 potentiostats and the VeraSTAT LC.

What Information can you get from AC-SECM?

  • Infer sample topography on electrically homogeneous samples
  • Map local electrochemical activity
    • Image the formation of inhibitor films on metals
    • Detect blistering beneath organic coatings
    • Monitor the formation of corrosion pits
  • Probe local surface conductivity
    • Quality control
    • Surface defect analysis
    • Surface films formation
AC-SECM Example

Baranski, A. and Diakowski, P., / J Solid State Electrochem (2004) 8: 683–692

How Does AC-SECM Work?

AC-SECM is similar to traditional electrochemical impedance spectroscopy (EIS). A modulated potential or current is applied to the SECM probe and the modulated response is recorded (Z = VAC / IAC). The cell can be modelled with equivalent circuits
You approach the sample based on the impedance response measured at the probe. This response is affected by the equivalent circuit, which indicates the nature of the substrate. Line scans and area maps are recorded, which plot |Z| or Θ as a function of probe position.

Benefits of AC-SECM

  • Elucidate the topography of insulating samples – the sample is not polarised.
  • Simple localised corrosion studies, with no mediator.
  • Measure changes in surface reactivity, formation of defects in coatings, precursor sites for pitting and corrosion biproducts
  • Useful for biological systems where no suitable electrochemical mediator is available (AC-SECM is mediator-free)
  • Straightforward probe positioning

In addition to this, AC-SECM is available with Ametek SECM at no extra cost, for both new and existing systems. Contact us for details.

Complementary to LEIS

AC-SECM is a complementary technique to LEIS (Local Electrochemical Impedance Spectroscopy). Both techniques measure sample activity using impedance. While LEIS is a simpler technique, AC-SECM is higher resolution, with minimal distance between the probe and the sample. AC-SECM also gives you extra, complementary data, including information about electrochemical activity, kinetics, topography and conductivity.

PAR VersaScan

PAR VersaScan

PAR VersaScan System

AC-SECM is available on PAR’s VersaScan (VS-SECM model).The VersaScan is a platform for localised electrochemical and materials measurements.

  • Determine localised electrochemical events including:
    • Electrode kinetics
    • Metal dissolution
    • Biological studies
  • Approach curves experiments
  • Both Feedback and Generator-Collector imaging modes
  • Combine Constant-Distance with topographic measurement techniques (eg OSP), or Constant Distance SECM with EPFL Soft Stylus Probe technology

The applications of the VersaScan are extremely varied. The platform can equipped with ancillary equipment for different scanning probe experiments in a range of areas:

  • Corrosion – localised measurements, pitting, coatings, defects
  • High throughput electrochemical analysis – electrocatalyst evaluation, dielectric properties, corrosion inhibitors
  • Biological systems – flux of molecules entering/leaving a cell/tissue, biosensors, local electrochemical reactions
  • Electroplating/etching – microelectrode patterning, fabrication
  • Energy storage – porous electrodes, SEI formation, dissolution of metal ions

Further Information

Blue Scientific is the official distributor for PAR in the UK, Ireland and Nordic region. We are available to advise on the best configuration and techniques for your research – just get in touch!

PAR VersaScan

 Contact us on 01223 422 269 or

Local Electrochemical Activity

Local electrochemical activity of Mg after exposure to Na2SO4 for 24 hrs. Courtesy of Vincent Vivier et al. / ECS Abstracts.