Singular Characteristics of Nanonics AFM SECM Raman:
Origins, Capabilities and Importance in an Evolving Critical Measurement Tool
Electrochemistry is evolving into a crucial measurement tool with numerous applications in academia and industry.
The list of applications of electrochemistry extend from highly industrially relevant efforts to more academic investigations. The industrial realm encompasses areas from metallurgical refinement/corrosion of iron and steel to fuel cells and batteries (their development and disposal). Academic areas of interest include analytical chemistry embracing organic electrochemistry, pharmaceuticals, pollution etc and fundamental processes in biology such as bioelectrochemistry, nerve impulse propagation, chemical and mechanical energy conversion, clotting processes etc.
Electrochemical microscopy was pioneered originally by Professor Allan Bard of the University of Texas. It was recognized by Bard and others that the best probes for such electrochemical microscopy were based on glass. Such probes could be used on conductive and non-conductive substrates. Essentially, all work on electrochemical microscopy has used straight glass probes. This is seen in the picture below.
The problem with such probes is that the probe tip has to be brought close to the surface but there is no mechanism other than the electrochemical current for feedback of the probe surface distance. Since the current is very small it is difficult not to crash the probe and this has limited the dimension of the interrogation area of such probes to microns. Moreover, using the current as the feedback is very limiting since the current is the very thing that needs to be measured. Obviously, convoluting the current with the feedback is not desired.
Nanonics SECM AFM systems have evolved from Nanonics’ singular expertise in glass probes and an unfailing commitment to optical integration. This has led to a hybrid AFM SECM System with Raman Spectroscopy. This hybrid instrument allows for understanding not only the electrical currents that emanate from electrochemically active surfaces but also their chemical structure.
While such electrochemical currents are being measured the atomic force component correlates these currents with the 3D structure of the device and also controls the position of the electrochemical probe in X, Y and Z at the 0.1nm level. There is only one supplier Nanonics Imaging Ltd whose instruments have been used for such combined measurements and this is clear from the literature (i.e. Nanoscale, 2018, 10, 6962–6970).
To achieve such a fusion there is a series of mandatory specifications.
No manufacturer has found a way around the problem of using glass probes, the preferred probes in electrochemistry, while achieving a geometry and combination with AFM feedback that is effective. Thus, measurements have remained in the micrometric XY resolution regime rather than the nanometric spatial resolution that is required to achieve the full potential of this tool.
Nanonics is the only manufacturer in world that has concentrated on glass AFM probes and has developed, over the last 25 years, methods to cantilever such probes for atomic force applications. Nanonics has now introduced this expertise into the area of electrochemical microscopy with glass probes having the following structure:
This development has allowed combining AFM with electrochemical imaging. As a result, one can now use for electrochemical microscopy with the probe of choice, namely glass, and combine it with Atomic Force Microscopy for approaching within nanometers to a surface. This has allowed for 50nm resolutions as evidenced by publications with such glass probes using Nanonics Imaging systems. Thus, Nanonics is the only manufacturer with publications in the refereed literature demonstrating such capabilities.
