Sciencemadness Discussion Board

cleaning glass microfluidic channels

paimeiguel - 23-11-2012 at 08:03

Hi everyone!
I want to clean my glass microchannels after they get clogged with dust that looks fiber-like, so I am assuming it is either from paper or cloth. Any suggestions? I have tried the usuals: NaOH, HCl. But none of them has convining dissolving results... any ideas?
The channels are made in fused silica with an insulating layer of silicon
oxynitride. Thaks for the help!
Do you think plasma cleaning might work even if the channels are not directly in the surface?

White Yeti - 23-11-2012 at 09:08

Will piranha solution do the trick? I'm not sure what it would do to silicon oxynitride, but it seems like you're looking for a last resort. Piranha solution is a 3:1 mix of concentrated sulfuric acid to 30% hydrogen peroxide. If you don't have sulfuric acid, you can try base piranha, a similar mix, but with concentrated ammonia instead of sulfuric acid.

smaerd - 23-11-2012 at 11:05

concentrated sulfuric acid will eat away paper towels very easily probably also cloth.

Eddygp - 23-11-2012 at 13:09

yep. A good mixture I sometimes use is 40% sulfuric acid, 40% HCl and 20% H2O2

watson.fawkes - 23-11-2012 at 13:47

Whatever cleaning reagent you use, you'll have a secondary issue of getting fresh solution in and spent solution out. Since the channels are so tiny, you'll not be able to rely upon diffusion to get the cleaner in contact with the contaminant. Some combination of ultrasonic agitation, gravity, and suction may be required. I wouldn't recommend using pressure.

Eddygp - 23-11-2012 at 13:55

Yeah, careful, be sure it won't damage the object... Pressure would probably crack it.

White Yeti - 23-11-2012 at 14:42

Quote: Originally posted by watson.fawkes  
Some combination of ultrasonic agitation, gravity, and suction may be required. I wouldn't recommend using pressure.


Would centrifugation also be a viable option?

watson.fawkes - 23-11-2012 at 16:24

Quote: Originally posted by White Yeti  
Would centrifugation also be a viable option?
I would hesitate to try that. The forces involve could be rather higher than the unit would readily withstand.

GreenD - 23-11-2012 at 19:04

it may be an idea just to heat it slowly to high temperature... perhaps around 200-220C° followed by an above cleaning solution