Can scanning probe microscopy be user-friendly?

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User-friendliness seems to be a key feature in operating any high end instrumentation these days, including electron or scanning probe microscopes.   Whenever you check out a product website, “user-friendly operation” or “user-friendly software” always seem to be appear on the list. I suppose the manufacturers are trying to encourage novice users to purchase and try the equipment and prevent potential customers from being scared off. 

Scanning probe microscopy certainly had a reputation in the 1990’s and beginning part of this century as being a sophisticated instrument that required a nontrivial background and expertise to run well.  It was certainly not a black-box or turnkey instrument and never promoted as such.  However, as the instrument penetrates far beyond the academic research market, and as the technology has matured, user-friendliness in both hardware and software have become a priority for vendors when manufacturing the microscopes.

So what have the manufacturers done to promote user-friendliness of SPM and how successful is it? 

Several steps in the experimental setup have certainly been simplified with great success.  Cantilever mounting process was a challenging step for many users in terms of having to manipulate these tiny chips into cumbersome holders. There are now cantilever chips with alignment guides so that no further manipulation of the chip is necessary, such as the one shown below and used in the Nanosurf NaioAFM.

 An alignment chip

Other setup steps have also been significantly improved such as laser alignment, tip approach, and cantilever tuning.  Many systems such as the Asylum Research Cypher and Bruker Dimension Icon now feature a “point and shoot” process to align the laser on a prescribed spot onto the cantilever. This saves on a sometimes frustrating process that would have previously involved find and “stepping” the laser beam (and not its reflection) along the cantilever substrate.

Cantilever from appnano.  New software allows the user to point and shoot onto the cantilever (such as the red circle above) to align the laser with one easy step.

With the laser aligned, tuning the cantilever in order to find its resonance frequency is an automated process on most systems.  A final improvement is the automation of tip approach to the sample where the instrument uses a sophisticated algorithm that monitors feedback parameters to bring the tip close enough to the sample to begin scanning without requiring user intervention.  Aside from saving the user time in this process, the automated approach also saves on the cantilever tip as it avoids “crashing” the probe into the surface. 

Recent efforts in user-friendliness have focused on technology to automate the actual imaging parameters such as scan rate, feedback gain parameters, and setpoint to remove this challenging optimization from the user’s hands.  Examples of this include GetStarted (Asylum Research) and ScanAsyst (Bruker Nano)

So how effective are all these moves towards user-friendliness?

I doubt SPM will ever really become a turnkey instrument.  Even with all the automation and software-run optimization, the user still needs to have a solid understanding of the instrument and how it works in order to run it effectively. What mode is appropriate for the sample? What cantilever should I use?  What is the correct image processing to get rid of the image artifacts?    Most users are not aware of the wide variety of modes and feedback schemes currently available in SPM; different imaging modes should be selected depending on the sample, features and type of information.  The cantilever dimensions (that govern its spring constant) are incredibly important for effective imaging, yet most users just pick cantilevers that are “lying around” without understanding what the differences in cantilevers are and which ones are appropriate for a given experiment.

The steps that vendors have taken to ease the operation for users are important and useful, but they don’t obviate the users from doing their homework.  There are many good textbooks out there such as Atomic Force Microscopy by Paul West and Peter Eaton (for beginners), Atomic Force Microscopy by Greg Haugstad (for beginner/intermediate users), and Scanning Probe Microscopy for Industrial Applications by yours truly (lots of industrial examples and focus on mechanical modes).  Also, hands-on training courses are given by AFMWorkshop and SurfaceChar.

Dalia Yablon, Ph.D



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