Flowcell design and theory

[sgergo]

Hello to all,

please excuse me if I post at the wrong forum but I feel that my problem is somehow related with fluid mechanics. Also apologies for the poor technical language, my native language is Hungarian.

I'm in the designing phase of a flowcell whose primary role is to make surface contact between the sample and a glass surface covered with gold. The sample flowrate is 10-100 microliters/min. The flowcell has a milled channel on one side, which channel has an inlet and outlet on the other side to provide entry and exit for the sample.

In the assembly I would like to press the flowcell's channeled side against the golden surface thus making a closed 'pipe' for the sample. Because of the thin golden surface I can't use any gaskets. Without gaskets proper sealing depends on the contacting surfaces' smoothness and the pressure between the flowcell and the glass part.

I would be very grateful if somebody could share any experience, opinions on this kind of setup. All tips would be highly appreciated.

G.

 

[MikeHalloran]

If the gold won't withstand the pressure of a gasket, how will it withstand the pressure or stress of the electrical connection that I assume you'll need?

Are you assuming that gaskets will destroy the gold film, or has it already happened?






Mike Halloran
Pembroke Pines, FL, USA

 

[sgergo]

Hi Mike,

thank you for taking the time to reply. I uploaded a simple sketch of the system here:

http://tinyurl.com/2e2cf5

The problem with gasket is that every time I remove the flowcell, the soft plastic gasket rips off the gold layer (~50 nm thick).

There is no electricity here, only a laser which is coming from the glass side.

G.

 

[unclesyd]

The people in our electrochemical lab use a lot very thin films, like Mylar, Tedlar, etc on small electrolytic cells. I do know that Tedlar is very good release agent that might prevent the Gold from adhering to the plastic block.

If compatible with your fluids you might try one of the stretch films used by cooks, like Saran.

 

[MikeHalloran]

If the pressure is not great, you might try using silicone vacuum grease as a gasket, in a very thin film.

By very thin, I mean squeeze ~5 ul of grease between your thumb and forefinger, and leave a thumbprint on the plastic. With care and luck, that will squeeze out into a continuous film.



Mike Halloran
Pembroke Pines, FL, USA

 

[sgergo]

Thanks for all the input.

@unclesyd

Tedlar seems to be a good idea. However, I'm afraid it could be problematic to cut and fit a Tedlar layer between the gold and the cell. The dimensions of the milled channel: 12x1x0.5 (mm). Anyway, I'll check this idea.

@Mike

The pressure is not an issue as the flowrate is very low (10-100 uL/min) and it is produced by a tiny syringe pump. I wouldn't place any grease on the gold because it's a hassle to clean it properly by chemical means, and there is a chance that I cover the sensing region partially/entirely with grease.


G.