I'm designing a PDMS fluidics device that has millimeter-wide channels (~1-2mm wide), and I'd like to put inlets on it. The PDMS layer is 5-6 mm thick and is plasma bonded to glass. So far, I've been 1) punching holes using a 1mm biopsy punch prior to plasma bonding, 2) performing plasma bonding, 3) then using 21 gauge needles that are inserted into the punched hole, and then 4) securing the needles with epoxy resin. Issue is often times they leak when I try to put in fluid. Any ideas on a better way to add in inlets?
It may also be possible that the tubing I use and the needle gauges aren't perfectly snug, so any recommendations are totally welcome!
The thing which is unclear in the question whether you are designing chip or trying to functionally use PDMS mould. I think these two are two different things.
Most of the times, leak is due to improper bonding which might be due to several reasons including improper/insufficient curing of the PDMS. Further, if you already speculate that your needles and tubing might be the cause, you could try to troubleshoot with it. In my experience, if the punch hole and needle are good fit, and the channels are clean before the bonding, there is no need of the resin.
Abhijeet Singh Okay sorry, I meant I am trying to functionally use the PDMS mold. There's no leak between the PDMS/glass interface, just the PDMS and needle interface. I think I'll look more into the holes and needles being a good fit. Thanks! Do you have any suggestions or recommendations for what hole size you punch and what needle size you use?
I have used specifics from certain vendor in Europe and I don't think it won't make any sense if I would recommend you the same products. Also, there can be some better products you can find according to your requirements. The only thin I would recommend is to check the integrity of all the components and optimize/standardize the configuration for a smooth and trouble less operation during the experiment phase.
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