I have been involved in impedance analysis of porous silicon chips with and without lipid bilayer membrane. I am using EIS potentiostatic with frequency range from 100KHz to 0.01KHz with applied potential 10mV (rms). I setup current range to be auto but most of the time I got the error "Cell overloaded: 2A". How should I overcome this error. I am using Ag/AgCl as working and counter electrodes. Both electrodes are immersed in 1M NaCl electrolyte.
If you need any further information, please let me know.
Dear Prabpdh, Could you send it to me, too? I would very grateful
Thank you
To clarify more about terminals of electrodes used in experiment. Working electrode is a combination of working-sense electrode. Both working and reference electrodes are in the same chamber and counter electrode is in second chamber. Chambers are separated via nanopore Si chip.
Maintain the WE surface area always lesser than 10 times CE surface area may be one reason or u can use booster for current so that cell overload can avoid. And u said applied voltage is 10 mV try to decrease the applied voltage to minimum. I think this information is useful for u otherwise ignore.
Today i run the experiment with 100mV instead of 10mV but i got the same error. Electrodes got corroded as well. I am planning to use Platinum as WE and CE now. Can i ignore RE?
Hi Khan i told that decrease the applied voltage from 10mV to 1mV but you applied 100 mV. First u try with 1mV with the condition of Surface area and please use the reference electrode dont ignore if its not work then please use the current booster but in all the cases maintain the CE electrode surface area higher than WE surface area.
Today, I tried with 0.1mV but still I got the same overload current error. What do you mean by maintaining the surface area of CE higher as compared to WE. pl brief.
Can you explain how much surface area used for CE and WE (dipped area in electrolyte). or dimensions of CE and WE and how much height dipped in to the electrolyte.
My cell is working fine. there was problem regarding positioning of WE, RE and CE. BUT in nyquist plot (Zreal Vs Zimg), I have some -ve values for Zreal and semicircle is plotted 10% on negative side and 90% on positive. Why does it like this? My freq range is 1 to 100Khz with 50mV.
System is working fine with nyquist plot in first quadrant (positive). I got semicircle. Thanks guys for all your support. I am doing EIS measurements with confidence. Next step is to analyze the data and extract right information in term of Resistance and Capacitance.
Ag/AgCl are common reference electrodes due to the fact that their formal potential is both known and stable under normal conditions (not in highly acidic or basic pH). However, they are not usually employed either as a working or as a auxiliary electrode in EIS. This is propably the source of your problems. You should try using a GCE (Glassy Carbon Electrode) as working electrode (with and without the lipid layer membrane) and a platinum wire as an auxiliary electrode. Those electrodes allow a lot of current to pass through them, while the Ag/AgCl cannot. Moreover, if you want to be more precise in your experiment, you should also include Ag/AgCl but only as a third (reference) electrode.
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