did you try it with another pippette solution? You shoul check your pippette solution's ion concentration, especially the Cl

Also,  is your electrode chlorided well?  Is your bath electrode all fine (no corrosion etc?)

Also, it looks like the noise is electrical interference (it is oscillating at 50 Hz) is all your equipment grounded properly)

The RMS noise should always decrease when you touch the pipettes tip to the cell membrane because as you do so the resistance increases at the tip and the noise decreases. However, if you are pressing the pipette against a very flat cell, and you press too hard, you may see large amplitude low frequency noise that we call a dish-potential. Basically, the pipette is touching the bottom of the dish and if it does it break, it will flex and you generate

The patch circuitry is much more prone to current noise fluctuations when the resistance though the circuit is low - that's why it goes quiet when you make a gigaseal.  Thus, such oscillations are not a big worry in themselves with an open tip.  However, really big ones are enhanced by current passing through the electrode tip.  First thing to check is that you have set the current to '0' in the bath  - on your trace I note that the current (between oscillations) is negative to zero.  The fact that the oscillations do not cross the zero level supports this idea.

You may also need to recalibrate the current output and zero settings on the amplifier .  This can be done by going through the calibration routine with a dummy cell (you may want help with this from a technician or by calling the tech support).

Good luck!

Your noise is not coming from the 50Hz (or 60Hz). it's much slower. Your only option is to test your setup step by step. Start with Elise's suggestion: i.e., calibrate your system using the dummy cell. measure your RMS noise as Linda suggested. Use instructions on your amplifier manual (easy to follow); if you have an Axon amplifier, download the "The Axon Guide for Electrophysiology and Biophysics Laboratory Techniques" from Molecular Devices website. When satisfied with thsi part, test your pipette resistance and be sure that your electrodes are chlorided as David pointed out. Also, make sure, your bath is grounded as well as the rest of your equipment. Be sure to have some Chloride in your pipette solution. If you can't have Chloride, make sure you have some Fluoride that can carry your current. If all this don't work, call the manufacturers of your amplificator or the data Analogical to Digital converter. Sometimes, these sensitive equipment get a nasty discharge that can blow up some of the ships inside. All the best.

Thank you all for your suggestions! 

Murat: I have tried with different solution, to no avail. And this solution used to work fine for me till 15 days ago. 

David: I had chlorided my electrode as a troubleshooting step, but that didn't help. Bath electrode- I will have to check that again. As for electrical grounding- I have done some electrical grounding, but don't know if that's enough.

Linda: That could be a reason, but I think this happens every time I touch a cell. Even if I am not pressing hard against it. Any idea why that might be happening?

Elise: I haven't done that. Thanks! I will do that and check again.

Fouad: Thank you! I will follow through these steps.

Again, I really appreciate all the help and suggestions provided here. I will keep you updated.

Hi, Sarmishtha: although your signal looks overfiltered, I have seen something similar once in a while. Check that your anti vibration table is properly floated: when the platform is touching at least one of the legs, not only are you at risk of losing (destroying) your cells,but you get the strangest electrical noises, particularly if there are loops in the system. Dr. Nowak is right, this may be due in part to your electrode being very close to the dish bottom, so that with vibration, it literally touches bottom intermittently, thus the apparent cycles in your recording. Ah, if you depend on compressed gas, check the status of the tank; if you are using compressed air from the general building installation, it's likely the pressure is low.

I like Dr Ek-Vitorin's suggestion. If the table top is not floating is all 4 corners it may cause some this type of problem.

could you try to open your cell in this situation? If you succeed and it's over, you have problem with your capacitve compansetion settings (on amplificator as Fouad said). You should check those settings.

It looks like you have physical vibration. As suggested above try to check your table and the cable of your headstage, tubings,  etc.. to suppress all sources of vibration.

Dear Satpathy:

Firstly, as Elise said, make sure that you have no current passing through your pipette during G-seal formation. Passage of a constant current through the electrode may interfere with development of the seal and its stability, and can lead to current oscillations. Secondly, adjust the settings of Cm compensation (I presume you are using Axon amplifier). The trace you have attached to your post suggests that your system is over-compensated.

It is worth also checking the level of your solution in the bath. If it is too low, you may also have similar problems. Indeed, if Cm is over-compensated, with increase of Rs the amplifier will go in oscillating mode. Thus, make sure that during G-seal development the Cm compensation is kept low and set the output current to 0 pA. I hope this will solve your problem. 

Best luck!

Saak   

why are we talking about Cm compensation? Sarmishtha Satpathy wrote: "I get huge fluctuations in the membrane current as soon as my electrode touches the cell membrane". I understand from this that she gets this noise before even achieving a Giga seal. Am I correct Sarmishtha?

@Fouad Sorry for the late reply, but yes, i get noise even before achieving a Giga seal.

@All: Thank you everybody for your inputs. The issue is now resolved. I think the major issues were the electrical noise insulation and that the ground pellet needs to be rechlorided pretty frequently.

Regards,

Sarmishtha

Wow, that's noise.  It's most likely a software issue.  Ensure all the proper setting are being used.  Also, if your pipette opening is massive you could be consuming the cell and recording full blown capacitive release.  Thats unlikely however.  

How about checking your reference electrode.  If there's a faulty connection your headstage could be a lost child.  With no reference, the headstage is likely to be capable of giving you just about any false reading thats convenient for it at the time

Hi Philip! Turns out my reference electrode wasn't properly chlorided. So yes, you are right about the instrument running wild without it.