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I am trying to run some electrochemical tests(e.g.CV (Cyclic Voltammetry) & EIS (electrical impedance spectroscopy)) using half cell configuration on micro-organisms (e.g.bacteria). The bacteria are cultured in a medium (liquid). The half cell configuration is working, counter, and a reference (AgCl) electrodes.

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Usually, it is easy to clip a metal or any thin solid material. However, I don't know how to deal with a solution. Since the beaker will be filled with electrolyte, I am afraid it mixes with bacteria solution causing it to be removed from the electrode. I am avoiding add another material like tape or something as it might alter the measurement.

I am looking for a way to attach the Micro-organism to the working electrode.

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  • $\begingroup$ Try using a conductivity cell along with an AC source! $\endgroup$ – Raghavendra Singh Apr 5 at 19:19
  • $\begingroup$ Can you pre-grow the organisms on the eletrode as a biofilm? $\endgroup$ – Andrew Apr 5 at 19:22
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    $\begingroup$ It is generally good practice to define acronyms when first used. So, please define EIS! (I already know what CV means in your post.) $\endgroup$ – Ed V Apr 5 at 19:22
  • $\begingroup$ Yes, i was not aware of what they specifically were and couldn't even find it on google as all top posts were those related to resumes,etc. when i searched for CV....thus, i ended up giving the apparently wrong answer :// $\endgroup$ – Raghavendra Singh Apr 5 at 19:24
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    $\begingroup$ I defined them in the post. I apologize. $\endgroup$ – Anwar Elhadad Apr 5 at 19:33
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From what I understand, your main issue is connecting a solution in an electrical circuit without changing the composition of the solution due to electrochemical redox reactions.

So, there are two problems here. Firstly, passing direct current (DC) changes the composition of the solution. Secondly, a solution cannot be connected to the bridge like a metallic wire or any other solid conductor.

The first difficulty is resolved by using an alternating current (AC) source of power. The second problem is solved by using a specially designed vessel called conductivity cell.

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  • $\begingroup$ The solution to be connected in the circuit should be put in the conductivity cell, and an alternating current (AC) should be used. The theory behind this is that the two platinised electrodes will keep switching between acting as anode or cathode as the AC source reverses direction 50 times every second, so the ions remain free and move about in the solution and don't get deposited on the electrodes.You can read more about conductivity cells and alternating current if you want. The cell constant,G*,is calculated for the conductivity cell during the manufacture process and is printed on top $\endgroup$ – Raghavendra Singh Apr 5 at 19:13
  • $\begingroup$ The OP specifically mentioned cyclic voltammetry (CV) and the need to attach the micro-organisms to the working electrode. So your conductivity answer is not what was desired. $\endgroup$ – Ed V Apr 5 at 19:20
  • $\begingroup$ okay, sorry I wasn't aware of what CV and EIS meant, as it wasn't mentioned in the question....my bad $\endgroup$ – Raghavendra Singh Apr 5 at 19:26
  • $\begingroup$ Now that we have conformation that EIS is electrical impedance spectroscopy (I thought that was what it was, but knowing is better than probably knowing), maybe your answer could evolve to indicate how an EIS cell might be used or how it differs from a typical conductivity cell? $\endgroup$ – Ed V Apr 5 at 20:03
  • $\begingroup$ Yes, of course! I am reading up on that and researching right now, and will edit my answer as soon as i find a relevant solution... $\endgroup$ – Raghavendra Singh Apr 5 at 20:11
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Your reference electrode contains chlorine and silver, the ions from these elements can kill bacteria, you should avoid liberating gases too: oxygen is killing anaerobic bacteria. To avoid using metals for your electrodes (they react too much with bacteria: poison, catalyzer etc...) you can use graphite or conductive polymer (without silver). I don't know if bacteria would colonize carbon, but graphite is antiadhesive. You can put your bacteria on a substrate: paper and or gel placed in the liquid with electrodes fixed at 2 edges.

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