Forums
Bruker Media
Community Media
Bruker AFM Probes
SPM Digest
Application Notes
NanoTheater
Website
中文
Brochures & Datasheets
Publications
Probes Catalog
Events
Manuals & Documentation
Presentations
Guide to AFM Modes
News
Journal Club
Webinars & Video
Nanovations
Other
I have a question regarding cantilever spring constant calibration on Multimode IIa. I planned to use a „reference cantilever method“ but I'm not sure can I use it for cantilevers with very low spring constant (k= 0.01 N/m, as specified for example for Bruker tips MSNL) since I read in Veeco application note that k of cantilever should be in range of 0.3kref < k < 3kref and Veeco reference CLFC-NOBO has 3 cantilevers from 0.157 to 10.4N/m that is much higher then 0.01 N/m. I don't have any other reference cantilver. I'm also not sure can I use Thermal tune method with this equipment ( I dont have picoforce upgrade), and other methods I read seem quite time consuming. What method can you recommend me as most practical one and less time consuming? Can I also change contact time when doing force curves using this equipment? I would like to increase a contact time to increase the possibility of some binding events. Thanks in advance for any advice, Annie,
I have a question regarding cantilever spring constant calibration on Multimode IIa. I planned to use a „reference cantilever method“ but I'm not sure can I use it for cantilevers with very low spring constant (k= 0.01 N/m, as specified for example for Bruker tips MSNL) since I read in Veeco application note that k of cantilever should be in range of 0.3kref < k < 3kref and Veeco reference CLFC-NOBO has 3 cantilevers from 0.157 to 10.4N/m that is much higher then 0.01 N/m. I don't have any other reference cantilver. I'm also not sure can I use Thermal tune method with this equipment ( I dont have picoforce upgrade), and other methods I read seem quite time consuming.
What method can you recommend me as most practical one and less time consuming? Can I also change contact time when doing force curves using this equipment? I would like to increase a contact time to increase the possibility of some binding events.
Thanks in advance for any advice,
Annie,
Hi Annie,
The issue with having a much stiffer reference cantilever is that the softer cantilever will bend a lot more than the reference cantilever when the two are pressed together. So the resulting deflection sensitivities (Sref, Shard in the app note) will not be very different. Using the spring constants you give here and Eqn 5 in the app note you would predict that the deflection sensitivities would be just 6% different. That's getting a little too close to the experimental uncertainty in measuring the deflection sensitivity. If the reference cantilever were 0.03 N/m instead then the two deflection sensitivities would be ~33% different.
Unfortunately there is not a quick and easy alternative on a MM with the NS3a controller. It's possible to implement the thermal tune method yourself using either external hardware or even just sampling the deflection signal with the NS3a controller. But it does get rather complicated. The analysis part is explained to some degree in the app note, but actually implementing it is quite a project unless you routinely do programming of that sort of analysis. If you can find rectangular cantilevers with a suitable spring constant then the Sader method is somewhat simpler because there are not all of the worries about amplitude scaling. But I'm not sure that rectangular cantilevers exist with k~0.01 N/m.
Older MultiModes can be upgraded to the current MultiMode 8 version, which does include thermal tune spring constant calibration as a standard feature. It's somewhat costly of course, but there are many additional benefits besides just thermal tune.
You can pause on the surface during force curves by setting the "ramp delay" parameter to the desired time in seconds. This is called "Surface delay" in software version since v6.
Regards,
-Ben
Hello Annie,
I made a simple module and program for cantilever calibration in IIIa. If you are interested just drop me an email jbiofiz[at]gmail.com.
best
The program I mentioned in previous post and its description can be downloaded at https://nanohub.org/resources/12759