A new form of contact printing has been developed

23 September 2012
Posted by Dave Ansell.

Making a stamp and then printing from it is a very old technology dating back to half potatoes and before, but it has been being used for more and more high-tech processes recently. Many of these require a very high precision. This is a problem when you are dealing with normal printing because the surface tension of the ink you are adding tends to make the edges rounded and blurry.

Rubber stampThis is a problem that Wei-Ssu Liao and collegues at the University of California were trying to solve for the neuroscientist Anne Andrews, who wants to be able to stamp neurotransmitters with biomolecules.

The present approach is to subtract materials rather than add them. So they have covered a surface with gold, then covered it with a thin layer of a material, and then made a rubber stamp with a hydrophillic surface. When the stamp comes into contact with the material on top of the gold it reacts sticking it and the gold onto the stamp, the stamp can then be peeled off leaving a pattern, with a feature size down to 40nm - less than a 1000th of the width of a human hair. The stamps can be cleaned and then reused many times, making the process possibly very cheap.

It still isn't good enough for the stamping of neurotransmitters, but it is close to the feature size on modern computer chips. This means it could be useful for some of those processes, or the gaps could then be filled with useful material such as proteins for automated tests, or research processes.


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