I have a PDMS microfluidic device that I want to perfuse cells through (there are also adherent cells in the channels). Is there any difference if I use a syringe pump to push the cells through rather than pull them through (via vacuum)? I am thinking that pulling them through will prevent some of my tubing connections from accidentally falling out of their ports because the flow rate is relatively high. But does a negative pressure have any effect vs a positive pressure? Is there a preferred way to do this in microfluidics?
hi,
Depending upon one's end application and the conditions of the experiment, fluid is either pushed or pulled through the microchannels in the PDMS. Pulling will definitely help to prevent leakages in the PDMS devices as you are already aware of. Rest regarding the cells part is concern, am not experienced with it, but my best guess would be that their dynamics in the fluid should be same no matter which is the preferred fluid flow mechanism is employed. Cells or the particles in the flow will only see the drag force onto them. AS long as the reduce pressure is not going to boil off the fluid, there should not be any problem to perfuse the cells in to the channels via pulling in the fluid.
Regards
Amit
If you pull a thread of fluid, could it be that bubbles (of vacuum, steam) arise and the thread is torn into shorter filaments?
Regards,
Joachim
Joe Beil
As mentioned above by Amit Morarka , pulling or pushing in microfluidics is similar/same as long as all other variables are constant. Meaning there is a constant flow (our variable nL/min) without any leakage or blockage. In the streamlined flow, cells would not experience significant stress would be be due to the change in direction of fluid. This is however would also be dependent on your chip design.
Further regarding your concern of accidentally falling out the tubes, it could still happen. The pushing or pulling force itself do not cause stress on tubes. It is generally cause due to blockages. If there is some blockage in channels, the tubes might not be removed but a negative suction might develop which might harm your cells.
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