My microchannel consists of pillar structures separated by 25um gaps. During the experiments, these gaps are filled with dust particles which prevent the flow of fluid (water) through the channel. Anyone have suggestions on how to remove these particles?
Ultrasonic bath cannot be used as it leads to breakage of the pillar structures. I have tried flushing but it does not work. Does anyone know if piranha solution or sulfuric acid will dissolve dust?
Hello Endre,
Have you tried simply blasting with nitrogen/argon or filtered air?
Piranha solution will certainly remove any organic residues as well as leaving the surface hydrophillic. Take care with the preparation!
I would also suggest looking at the 'RCA' cleaning protocol (developed in 1965 by Werner Kern from Radio Corporation of America) that consists of organic and ionic cleaning steps (as well as an optional HF dip to remove the native oxide):
http://www.microtechprocess.com/pdf/MTS_RCA.pdf
Let us know how you get on.
Jules.
Hi Endre,
What type of particles are they? If they are organic particles, you may try to use acetone as a solvent to dissolve the dust. Just leave some solution in the channels instead of flush it, and probably you can make use of surface tension attraction to get the solution in the channels. Hope that can help.
Hi Andre
I would never use any acid solution to clean it if the channel surface getting rough it would make your work more difficult. Acetone is a good solution to try. watm it up a bit might help. Good luck!!
Hi, I worked on a chip that captures bacteria and I used all kinds of things and tried to wash with. All kind of detergents worked (for example 0,1% SDS). Also adding lysozyme worked to some extend. However, they leave rests of the detergents behind and then nothing adheres to the surface any more (that might be good in your case). Trying to clean with acid only made it (much) worse
Washing with 0.01% polylysine in water was reversible. It is in the paper below:
Separation of bacteria with imprinted polymeric films, Analyst, 2012, Schirhagl et al, DOI: 10.1039/c2an15927a
If the particles clogging the channel are organic, then use acetone to dissolve them. If this doesn't help use piranha solution to clean but make sure piranha solution doesn't damage your silicon channel with a spare piece. You can also use mild piranha with 7:1 ratio of acid and peroxide. Everything depends on what kinds of particles you are working with. You should have mentioned that in your question to get specific answers.
Thanks for your response. I tried flushing with acetone, then propanol and distilled water with surfactant Triton-X. This was surprisingly efficient. I also tried piranha, which was even more effective. I haven't tried to remove cells or other organic material yet, except polymer beads, which were dissolved bo both acetone and the piranha solution.
I tried the trick suggested in the second post by Hirak but it didn't work for me.
Hi Endre,
Though It is very old post, but now I am working with microchips for hydrogel infusion and want to clean it for reuse. I am facing the problem to clean it completely. Your above technique of using acetone, propanol and Triton-x help me to some extent but can not give the complete cleaning. would you please give me some more brief about your steps, please? Like what is the percentages and also did you put the solvent in the channel for sometimes for flash it away instantly. It will be helpful for my work.
Kind Regards
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