What is a potentiostat and how does it work? 

Thank you for the kind words. I really appreciate it! Glad you enjoyed the video.

Thank you! Op amps can definitely be more complicated and I only mentioned enough about them to help with understanding a potentiostat. Glad the video was helpful!

Glad you like them! I'm hoping to get more videos turned out soon. Stay tuned!

Glad you enjoyed the video! Also, as a heads up we are doing a free webinar on how potentiostats work and iR compensation this Thursday March 7. pineresearch.com/webinar-registration/ if you want to know more check it out.

Glad you enjoyed the video and learned something. We've got more videos in the pipeline :)

Glad it was helpful!

Thank you! I'm glad you liked it :)

Will do!

Wow, that's a huge complement. Thank you! Veritasium is awesome, and great at making science really accessible. I'm just going to focus on the Echem related topics though :)

Glad it was helpful!

That is very kind, thank you! Appreciate you watching our video!

Glad you liked it!!!

Absolutely! I'm glad this was helpful. And yes, as a chemist or chemical engineer its hard to understand electronics books.

Thank you!!!

Not a problem. Glad you enjoyed the video!

Of course!!

You're welcome!

You are very welcome! Glad you liked it!

Glad you enjoyed it!! :)

Thanks a great suggestion Luiz. Honestly, I would need to talk to my electrical engineer to know how that works and what the pros and cons of such a configuration would be. I think my goal was just to get grad students using a potentiostat for the first time, a chance to understand how it works from a fundamental perspective. But this is definitely something worth looking into for future videos.

@@Pineresearch And for sure you achieved your goal! I believe that would be an interesting discussion for precision measurements. I'll keep an eye out for it!

You are very welcome! Glad you liked it!

Thank you! It takes a lot of work trying to make these videos. Some people, Some people, Some people call it insane, yeah they call it insane.

Thank you! Great question. A two-electrode configuration would be the case where the counter and reference electrodes are connected on one side, and the working sense + working drive electrodes are connected on the other side. But it would be the same operation by the potentiostat. The issue with two-electrode configurations is that as current flows from the counter electrode, the reference electrode potential starts to change. But the feedback mechanism is the same. I hope this was helpful.

@@Pineresearch Thank you, yes, your explanation helps.

You are very welcome!

You're Welcome! Thanks for watching.

Hahaha thank you!

Thank you very much, I am glad you enjoyed the video! We can certainly add a bipot operation to our ideas for possible content in the future, though to be honest the explanation of bipotentiostat operation is considerably more complicated than even the potentiostat is, and the schematic we use to describe a potentiostat here is already very simplified for educational purposes. To be blunt, I am not sure how easy or understandable it would be to simplify a bipotentiostat schematic and operation. But we appreciate the suggestion and we will keep it in mind for sure!

Thank you Brhane! You'll have to talk to our competitor Bio-Logic for a Cyclic Voltammetry video with EC-Lab software. But I do have plans for making a Cyclic Voltammetry video in the near future! 😀

Hello Soumya, great question. The idea behind the reference electrode is that you want to have a stable reference point in your electrochemical system. If you could have "ground" in your electrochemical cell I bet people would do it. But if you apply a voltage between the working and counter, both electrodes experience some kind of electrochemical process to maintain charge balance. That inherently means that potential at both electrodes changes. If you want to know the potential difference between the working and counter, that's easy, but it doesn't tell you anything because the counter electrode potential might be drifting a lot during the experiment. All that being said, 2-electrode experiments are common, and depending on the application you could get away without using a potentiostat, and just using a power supply to do experiments. I hope that was helpful!

You might need to speak with an electrical engineer to get the details, but the potential waveform itself (for CV/DPV techniques) is created at the potentiostatic set point. So the simplified potentiostat design makes sure that the potential you set is equal to the difference between the working and reference electrode, via the feedback mechanism, but you'll probably want a waveform generator connected to your potentiostatic set point to create the CV and DPV techniques. At this point you might want to purchase a potentiostat.

Great question. During a cyclic voltammetry experiment, we are controlling the potential and measuring the resulting current, so this would be a potentiostat.

Not a problem. I'd recommend checking out our introduction to cyclic voltammetry video. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-cz67DnyS9-w.html It doesn't cover all the details of a three electrode system, but I think it's a good starting point. We also have free webinars every couple of months (pending how busy we are) that go over some of the basics of electrochemistry.

Yes, I watched this video and I feel once again grateful for introducing me to the CV. It really helped it but actually I was looking for the whole phenomenon of three electrode system like why we need to use 3 electrode system instead of 2 electrodes system? Why it is necessary to keep the reference electrode? I mean the very basic questions like this. TIA

@@hamidqazi7021 I had this question too when I was learning Echem, it's not intuitive. If you had a two-electode system you could measure the potential difference between the two electrodes, and drive current between them to induce reactions, and let's say the current is kept constant and the potential is allowed to vary such that oxidation reactions and reduction reactions occur on the two electrodes. Because these reactions are occurring, it means the potential between them is changing (current is constant). So if I want to know more about the thermodynamics of the oxidation reaction I can measure the potential between the two electrodes and I get a potential associated with the oxidation reaction. But the problem is that potential is a relative quantity, the measured potential of the oxidation reaction is with respect to a changing electrode (the other electrode undergoing a reduction reaction). As such we employ a reference electrode in a 3 electrode configuration to maintain a stable reference potential that we can measure the working electrode (electrode of the oxidation reaction) potential against. If we measure the working electrode potential against an electrode where the potential is changing (electrode with reduction reactions), when we won't have an accurate measurement. As a side note, we are thinking about doing a Q&A livestream in the future. Would you mind if we used this question to kick off the livestream?

@@Pineresearch Thank you so much for a detailed response to my query. Indeed, it cleared some of my doubts. Referring to your Q&A session so yes off-course, I would like to request you to please inform me before arranging it, so that I may not miss it.

@@hamidqazi7021 Awesome! Yeah, stay tuned to our channel, we'll make an announcement and probably have a scheduled LiveStream you'll see on our channel.

Thank you! So just to clarify, are we talking about the voltage follower circuit, or the simplified potentiostat circuit? Voltage follower circuit from the video has the feedback going into the inverting input which creates negative feedback (although I didn't talk about negative and positive feedback in the video). For the potentiostat circuit, there was the electrochemical cell and electrometer inbetween the output voltage of the high gain op-amp, and the Vfeed back. At the end of the day, Vfeedback has to be equal to the potentiostatic set point otherwise the potentiostat wouldn't work properly. I hope this answers your question.

@@Pineresearch big thanks for your prompt follow-up! Yes, I meant the simplified potentiostat circuit. I can see somewhat differing simplified circuits for a potentiostat on different sites or in reference materials, so it seems to be okay to have variations in this simplified circuit. Also, the explanation in the video makes good sense to me. However, if the high gain opamp is functioning as a voltage follower, as it is defined in the literature, then any feedback should be connected to its inverting input by definition, otherwise we could not call that circuit a voltage follower, in my understanding. Finally, let me thank you for this video again. I teach a microbial electrochemistry-related subject to students, and your video was very useful in my class.

@@gabormehes1665 I'm glad you've found this video helpful and that you are sharing it with your students! There are a bunch of different simplified potentiostat circuits out in the literature, all should be valid to some extent, but sometimes difficult to conceptually understand. So in the strictest sense the voltage follower circuit doesn't have any other circuit elements in the feedback loop. The moment you add things like resistors and capacitors into the feedback loop, it is no longer a voltage follower. We have the electrochemical cell and electrometer in the feedback loop, which changes the Vfeed. We could flip the inverting and noninverting inputs on the electrometer and get positive feedback rather than negative feedback into the high gain op-amp. I would say that the voltage follower is conceptually needed to understand potentiostat operation. Please let me know if you have any questions. Where are you teaching microbial electrochemistry?

Great question! So if the difference between the working and ref is +0.5 V and you want to change it to +1 V. You set the potential at the potentiostatic setpoint to +1.0 V. At the high gain op-amp the equation is -Beta*(e_ - e+)= Vo. Vo is the output voltage at the counter electrode. In your case, you would have -Beta*(1-0.5) = -Beta*0.5. Because Beta is a very large number it amplifies the output of the counter electrode, but it's sign is negative (-Beta). So the output voltage of the counter electrode is a large negative number. The counter electrode will continue to apply this large negative potential until the difference between the working and reference electrode is = +1 V. At that point e_ and e+ at the high gain op-amp will be the same and the output at the counter electrode would be zero. I hope this was helpful and clarifies things. Please let me know if you have any further questions.

Hello Surajit Sinha. Great question. The main difference between a DC power supply and a potentiostat is the implementation of a reference electrode and a feedback loop to maintain a desired potential. A reference electrode is important because it represents a stable reference point when measuring the potential of one of your electrodes. As current flows across your electrochemical cell, both the counter and working electrode potentials will change, so you won't know which electrode is responsible for a chance in the potential. With regards to electrochemical polarization and EIS, it might be possible to use a DC power supply along with a linear sweep generator, but DC power supplies typically don't have the ability to different specific potential waveforms. I would also say that doing EIS is basically impossible to do with a DC power supply. EIS is an AC voltammetry technique, so a DC power supply won't work. I hope this was helpful.

@@Pineresearch Thank you very much for this valuable information. I want some guidance from your side. I have a Programmable 60 V DC Power Supply and I want to perform electrochemical corrosion studies of a certain material. So how do I perform in a two-electrode cell configuration and also how to measure corrosion voltage and corrosion current by developing a Tafel extrapolation plot from this DC Source. In your previous comment, you mentioned the linear sweep generator to be connected to the DC supply. So I want to know about digital storage oscilloscopes and can I use them to generate potential waveforms and perform EIS studies??

@@surajitsinha9055 Hello Surajit, I'm not sure exactly how to use the DC power supply for corrosion studies, and it will probably depend on what materials you are studying. I have limited experience with corrosion studies but in general, you need to keep the potential of your material very close to the open circuit potential, and only make slight adjustments to the potential (+ or - 10 mV), if you apply something as large as +1 V away from the open circuit potential you will most likely corrode the material like crazy and get limited corrosion data. The DC power supply will supply power to your system but I don't know how it will measure the potential and the current, you might need a digital multimeter. I do not know of any digital oscilloscopes that can be used to generate the waveforms to perform EIS, but I would recommend purchasing a potentiostat for doing all these studies. Doing EIS manually will be extremely time consuming and you need fitting data to analyze your EIS data. I would check out our website for a WaveDriver 100 potentiostat with EIS, that can do all your corrosion and EIS experiments. pineresearch.com/shop/potentiostats/wavedriver-series/wavedriver100-bundles/

Glad you enjoyed the video. I would need to know more about your electrochemical system (electrodes, electrolyte, etc) as well as your instruments to know how everything is connected. But for a multichannel potentiostat you can think of simply duplicating the single channel potentiostat process multiple times. I hope that helps

Hello Jonas. I think your understanding of the system is correct. It is like putting a big resistor between your WRKsense and REF lead in the potentiostat. There is a voltage drop that needs to be compensated for to get the user potential = the potential between the WRKsense and REF. This ultimately allows your chemistry to occur, but the potential values will be inaccurate. I have two thoughts with regard to potential control of the Au-NPs independent of ITO. First, you could try a series of experiments with the Au-NPs deposited on a glassy carbon electrode, or another conductive material, and see if you get a change in voltage. The other thing you could do is Electrochemical Impedance Spectroscopy (EIS), where you could attempt to model your system with a circuit equivalent, to know what the resistance of the Au-NPs, and perhaps other useful information about them. I guess I have 3rd idea. There is a technique called bipolar electrochemistry. You effectively have the Au-NPs on a non-conductive surface, but in-between the working and counter electrode. The electric field from the electrodes induces an electric field in the Au-NPs. It's kind of like a wireless electrochemistry technique. I don't know that much about it. Richard Crooks at UT Austin is an expert in the field and has a few articles on it. But that would be a way to control the potential of the Au-NPs without the ITO. I hope this was helpful.

I'm also working on NPs, can you give me your email

@@zemiecheabdelmalik2858 You can reach out to us at pinewire@pineresearch.com You can then let us know more about what you're interested in.

Perhaps there is a slight misunderstanding or interpretation to the output voltage from the counter electrode. I would say that there is a voltage difference between the counter and the working drive electrode, and this voltage is what drives current through the electrochemical cell. The only place for current to go is the working drive electrode because it has the lowest resistance. The reference and working sense leads are connected to the Op-amp inputs with high impedance. But the potential does not get amplified when it is measured at the electrometer.

That's a good question. It sounds like you are trying to set the potential of the reference lead through an external power supply that is disconnect with the electrochemical solution. This in principle would keep the potential stable and not run into the issues that "traditional" reference electrodes have. So there are a few issues with this setup. Remember that the electrometer output will be the voltage difference between the reference and working sense electrode. However, applying a set potential through an external power source into the reference lead will be the potential vs ground, but it won't necessarily be the potential vs the working. Potential and voltage are relative quantities, and the voltage measured from the power supply will be different that the potential measured inside the electrochemical cell. There needs to be a single reference point in the solution that everything is connected to. Breaking the electrical connections between the 3 electrodes will break the feedback circuit. I hope this was helpful. Its best to use a traditional reference electrode, rather than an external power supply.

@@Pineresearch Nice. Thank you so much.

I assume you liked the video. Thanks!

@@Pineresearch hahahaha, i would've make more intelegent comment if i know you would read my comment. Really good video man! very very clear explanation for something i've never heard about

WRKsense and WRKdrive are connected to each other in a typical electrochemistry experiment, but they are connected to different things in the potentiostat circuit. The WRKsense is connected to the electrometer for measuring the potential, and WRKdrive is connected to the sense resistor Rwrk. Does that make sense?

Hello Anil. You can purchase Pine Research Potentiostat's from our India Distributor Bat-Sol. www.bat-sol.com/ There sales email address is sales@bat-sol.com You should ask them for a WaveDriver 40 to do corrosion experiments.

Whenever your computer communicates with your potentiostat to change the working electrode potential, it does so through the counter electrode voltage. So counter electrode voltage is controlled indirectly through how you set the working electrode potential, via the potentiostatic set point. I hope this helps.

@@Pineresearch Thanks for reply.. Can you also tell me how to convert the current (converted to voltage using TIA) through WE to moles in solution?

@@PoeticBugBear We've got a video for that too ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-OuKvJVRPatk.html. You can convert charge into moles using Faradays constant

Actually there are a few decently Arduino build your own potentiostat papers out there. I don't know if they use the same circuit as this one, but they do exist.

There are a lot of different areas of electrochemistry you could go into. First, is this a PhD, MS, or Bachelors program? 2nd are you more into chemistry, engineering, or physics? Based on these the range of different degrees and focuses you can go into are quite large, but we can make some recommendations once we know what you like.

@@Pineresearch it is my 3rd year in bachelors of general chemistry. We will be asked to select our major in 4th year for research that was why I was asking. My physics is not good though.

@@Pineresearch thank you for replying. I just can't tell you how much it meant to me.

@@farhanaahmad408 Of course! We talk to a lot of undergrad and graduate students about careers in academia and industry. First and foremost you should do research that you are interested in. That will be regardless of it's applications and career opportunities, if you aren't interested in the research or work then you'll just be miserable. Electrochemistry does require some physics but honestly I believe that anybody can learn it, it takes time and practice. I would recommend you do whatever research you think is exciting and interesting.

çox sağ ol

I think you reached out to us earlier about another RU-vid video you want to post on Bilibili. I need to know more details about how the translation will work. Please email pinewire@pineresearch.com for us to continue the conversation.