We are conducting our experiment with 20 um width channels. We are using a punch for making inlet/outlet holes in our PDMS channels. However, there are always some fiber/dusts like residuals blocking our channels. We think that they are PDMS residuals remained in the channels after punching. Is there any way to clean those residuals or avoid making them?
Dear Morteza,
What we usually do is the following: Put a piece of scotch tape on the PDMS side which has the channels. Then, from the other side, punch the acces holes with a sharp hollow needle all the way trhough. Retract the needle with PDMS residue and remove the scotch tape. This should ersult in a clean PDMS channel surface.Flushing with IPA and blowdry with N2 can be performed if necessary.
see, please, section : 3.2. Removal of PDMS residues[1] , it might help.
1. PDMS residues-free micro/macrostructures on flexible substrates http://www.sciencedirect.com/science/article/pii/S0167931715002488
Dear Morteza,
What we usually do is the following: Put a piece of scotch tape on the PDMS side which has the channels. Then, from the other side, punch the acces holes with a sharp hollow needle all the way trhough. Retract the needle with PDMS residue and remove the scotch tape. This should ersult in a clean PDMS channel surface.Flushing with IPA and blowdry with N2 can be performed if necessary.
I use another piece of PDMS for a backing while punching from the side opposite of the fluidic similarly to Daniel and then I use the Scotch Magic Tape (best brand IMO) to clean and dust that may have snuck onto the surface (I don't always do this in a cleanroom) just before bonding to other layers. Also, make sure that you use a very sharp punch to get the cleanest hole possible. If your punch hole is not very smooth you will get pieces or PDMS tearing off while you insert your tubing in the punch port and won't matter how clean the device was before you started. Good Luck!
Dear Morteza Amjadi,
Our method is to design a array of micropillars as filters at the inlet of microchannel, the gap of micropillar should be larger than the microparticles you are flowing (if it applies in your experiments) and smaller than the width of microchannel, so that debris larger than the microchannel will be prevented entering the microchannel, and microparticles can go through. After adopting this method, we have never encountered blocking problem any more. Hope it helps.
http://www.nature.com/articles/srep04527
Regards,
Jun
It can also be helpful to use a syringe for punching (not only the needle tip) and then sucking air in while you remove it.
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