Wednesday, July 20, 2011

Well bugger, it's not working

I'm hard at work on my PhD at the moment, trying my best to graduate by next June. I had a committee meeting in February, and then with the committee's approval I spent the spring semester building a machine that I would use to accomplish the research. I finished the machine, and this summer I've been trying to - well, get some results. I had a schedule for this summer, that ended with me having some experimental results and a second committee meeting this August. (The results, of course, being popularly understood as a good thing to have for the meeting.)

But here's the thing - it's not working. I've tried a lot of combinations of parameters, materials, and processes, and I can't get the basic process of my research to work. Here is the basic process:

Step 1: Apply ink to stamp
Step 2: Stamp onto a glass slide

Not hard, right? Really, can't be that bad.

Well it took me a good three weeks to get the "apply ink to stamp" step to work. Turns out you have to have a stamp of the correct material, you have to do some pre-treatment to the surface of the stamp with the correct parameters, you have to apply the ink in the correct manner, and you have to use ink with the correct properties.

Ack. Not trivial.

But now it works, Step 1. Step 1 and me are good buddies. I can do Step 1 all day long.

But Step 2? Step 2 is not cooperating.

I tried using my machine to do the stamping, and it wasn't working. I thought, fine, I'll go back to doing stamping by hand. But that wasn't really working either. I could sort-of get it to work under some conditions, and one day I even got enough to transfer to take a picture of under the microscope. Finally! I thought, I have proof that I can transfer the ink from the stamp to the slide!

But it's not repeatable, and I have no idea why it worked that day and now I can't get any good results. A tease, I tell you, a tease...

Flat stamp? Patterned stamp? Different patterned stamp? Different temperatures? Different methods of stamping? Different ink? Different pressures? Click my heels three times and say "there's no place like home"? Tried all those, and nada.

And all the while, that schedule is glaring at me. I know that research does hit obstacles, but I always expected I would be able to figure a way around them - I always have so far. But if I don't get that committee meeting in August, one of my committee members goes away on sabbatical for a whole year. So this July has really been crunch time for me getting something worth showing.

Well, July is flying away, and I'm crunched alright. But I don't feel like I have anything to show for it, and I'm nearly out of ideas on what else to try.


  1. Room humidity? Depending on the type of glass you're using, the glass may behave differently depending on the humidity. Also, do you have any particular cleaning procedure in place for the glass slide?

    Just what comes to mind at the moment that you didn't mention already trying.

  2. How does the problem you are trying to solve differ from standard commercial pad printing (

    Are there standard solutions there that you could apply?

  3. In effect the result you have generated (cannot apply ink to glass) is in effect a result. There are two main options (aside from changing parameters)
    1. Search for a different but suitable slide material. Transparent plastic for example might be more corroperative.
    2. Use the surface treatment that you used previously on the stamp on the slide if possible.This may allow the ink to stick.
    At my work material scientists are often putting layers of various materials (polymers, TiO2 layers etc) on ceramics. A small few will have put layers on glass; I can see if they had any tricks.

  4. If the problem is a chemical one (ink doesn't stick to glass), try talking with a chemist who deals with glass a lot. There are a lot of surface treatments for glass (silane, poly-lysine, …) that change the chemical nature of the glass. Glass normally has a slight negative surface charge—if your ink is also negatively charged, that could cause problems. There is a lot of prior art in coating glass!

  5. All excellent suggestions - thank you! You are all correct in that I think the problem is the surface conditions of either my stamp, or the slide, or both.

    I am exploring plasma cleaning the slide (which is what I do to the stamp), adding a mold release to the stamp, and using different material for the substrate altogether. I'll also check with other groups on campus who may be printing various things.

    Will keep you posted - I appreciate it!