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A comment on Replacing $100K diagnostic chip fab with Shrinky-Dinks and a laser-printer.

Re:Replacing $100K diagnostic chip fab with Shrinky-Dinks an... by regularfry on Monday November 09, 2009 @10:35AM (#931063)
Anyone know what scale factor shrinkage you get out of this stuff? I'd quite like to experiment with optical effects, but I don't know what feature size you can get and I haven't got any expanded polystyrene handy for testing.
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Re:Replacing $100K diagnostic chip fab with Shrinky-Dinks an... by aarongough on Monday November 09, 2009 @12:21PM (#931296)
"When heated in an oven or with a heat gun, the plastic shrinks by about 5/8ths and becomes thicker and more rigid, while retaining the colored design."

http://en.wikipedia.org/wiki/Shrinky_Dinks

Seems like you would be able to get pretty small feature sizes if you had a really high resolution printer to begin with...

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Re:Replacing $100K diagnostic chip fab with Shrinky-Dinks an... by regularfry on Monday November 09, 2009 @03:31PM (#931676)
It surprises me that 5/8ths is enough of a difference to be useful, but then I guess it's the way it bunches and forms a ridge that's important for the microfluidics, not the absolute feature size. Hm.
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Re:Replacing $100K diagnostic chip fab with Shrinky-Dinks an... by aarongough on Monday November 09, 2009 @05:15PM (#931864)
It didn't strike me that 5/8ths wasn't actually a huge amount until I thought about it.

If the ability to form troughs/ridges is the important thing then I think that the PCB etch/make mold technique would be just as useful. But I'm not sure what the smallest feature size is that you can make with this method:

PCB etch/make mold method:

Laser-print an inverse pattern mask on clear plastic film

Expose a UV sensitive photoresist PCB using the mask

Etch the PCB

Make a polymer mold (or mold the final part) using the troughs/ridges formed by the etched/unetched copper on the PCB

I know this method has been used for replicating fingerprint patterns in the past (Mythbusters!) and I remember hearing it being used for a few other things...

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