We want to attach a kind of antibody to a silicon substrate using an AFM (Atomic Force Microscopy) tip.
A major obstacle which we have tried to overcome is that we are supposed to put antibodies on particular nano-scale parts. Therefore first we have to find the exact place (by normal imaging) then we have to make a distance (not being in approach phase anymore) to be able to move to pick up the ink (the antibody in special solution) and go back to the nano-scale aim in order to deposit the ink . The DPN(Dip-Pen Nano lithography)method is used.
Now,Do yo have any idea how we can find the place again? we cannot have ink on the AFM tip and have a picture (to see where we are in each second) at the same time
It depends on how far away you need to move the tip to load the ink. If you can do this using the step motor controlled system of the AFM stage after making an image, then you can record the coordinates of the initial position and put them in again to come back after loading the ink. This is of course only possible provided that you have a system where in addition to the piezoelectric scanner there are also micromotors for the XYZ movement of either the sample or the tip. In my personal experience, the DI 3100 SPM from Veeco (now Bruker) and newer versions of that system can do it. The best chance you have is to use an AIST-NT Omega SPM that has micro-control of the position of both tip and sample.
In the end, it all comes down to how precise you expect to find the original region of interest. Keep in mind that there is the mechanical and thermal drift and also that the reproducibility of step motors is hardly better than 100 nm. In case that you have your AFM system coupled to a top or inverted microscope, then you could try using a sample that has micrometer-sized marks around the region of interest such that you can see it with the optical microscope. That would also help you to roughly locate the initial location once you are in DPL mode.
Good luck with these challenging experiments!
Thanks for your useful advice.
The problem is that the nano wires which we are trying to deposit antibodies on them have 60nm width. So i suppose it's not possible to re-find our exact place by using micro actuators.
I have seen some articles using tips with liquid reservoirs. It seems that if one could perform nano imaging and at the same time depositing the liquid this would be the solution to our problem. I would be grateful to have your view about these probe types. For instance the following links:
https://www.nanosurf.com/en/products/flex-fpm-flexafm-with-fluidfm-functionality
https://support.fluidfm.com/hc/en-us/articles/202091669-FluidFM-Basics
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