How to get rid of the drain tubing and peristaltic pump induced noise?

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engstar
engstar's picture
How to get rid of the drain tubing and peristaltic pump induced noise?

In patch clamp experiments, it is very annoying that the tubing and the peristaltic pump for draining the bath solution introduce great noise, which is irregular and not a 50 or 60 Hz line pickup . 
Shielding the tubing with alluminium  foil and grounding it only removes a part of the noise.
Inserting a drip-feed reservoir as is used in intravenous perfusion sets, in series with the tubing to break the electrical continuity of the perfusion fluid, does not take effect, though the  Axon Guide suggested this measure.
I am looking forward to your help.  

sharmakaushikp
sharmakaushikp's picture
I had the same problem in my

I had the same problem in my recordings too. I solved it completely by introducing 2 bubble-traps/ drip-feed reservoir in series, at that point where the outlet tubing (from the recording chamber) comes outside of the Faraday's cage. I have a similar setup in the inlet tubing also, at the point where the tubing just enters inside the Faraday's cage. However, I have to frequently replace these bubble-traps in 3-4 week time so as to keep noise levels to very minimum values. Also, I try avoiding the use of aluminium foils. Try looking for any ground loops, as they are a big problem again. I hope this helps you to solve your problems. Best of luck.

engstar
engstar's picture
Thanks a lot for your helpful

Thanks a lot for your helpful reply. Besides,

1) How did you make the bubble trapper?

2) 2 bubble-traps/ drip-feed reservoir in series: Do you mean either using 2 bubble-traps or using 2 drip-feed reservoirs?

Actually in our case the tubing is full of bubbles because the slow rate of flow can never fill the tubing.

3) There is no ground loop problem, because the noise is not a linepickup. The noise is irregular spikes.

sharmakaushikp
sharmakaushikp's picture
I mean the normal drip-feed

I mean the normal drip-feed reservoirs only, that comes along in the intravenous perfusion set (as shown in the attached picture). So I have connected 2 such things one after the other (only the bubble trap region and not the entire set) seperated from each other via a small tubing of around 5 cm length.

engstar
engstar's picture
Thanks a great deal. BTW,

Thanks a great deal. BTW, have you compared the difference between the effects of putting the drip-feed reservoirs inside and outside the Farady cage?

sharmakaushikp
sharmakaushikp's picture
Yes I have done that. In case

Yes I have done that. In case of the outlet system, it is the pump (kept outside) and the connected tubings (act like an antennae) that generate noise, and it is this noise that I need to minimize from reaching the chamber kept in the Faraday's cage. So attaching the drip-feed reservoir just at the exit point from the Faraday's cage works efficiently than placing it inside. But I guess you can try what suits best for your system. BTW, how is your noise problem now?

Moonshoon
Moonshoon's picture
you can also make your own

you can also make your own bublle trap with an eppendorf, it is very efficient.
Did you ground your tubbings ?

engstar
engstar's picture
Sorry for my belated reply.

Sorry for my belated reply.
I tried using reserviors of the infusion tubing to break the continuity of the liquid, but it turned out that the sucking force of the peristaltic pump was too weak to make a regular and even solution drainage. So, later we changed to use a vacuum pump outside the cage together with a bottle inside a cage. The noise is much smaller now.