Cleber Borges

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  1. Hello @Andras ... Very cool your results ... This case study is very interesting! Have you considered putting all this information on a blog too? (It can be an inspiration and starting point for others).
  2. Hello @Andras ... I think bubble formation is critical ... 1- Is CO2 forming? 2 - Just some other gas coming out? 3 - Yes, temperature is a critical parameter in measurements that require a lot of accuracy ... But I don't know how much temperature variation can affect a preliminary study that doesn't need as much precision and accuracy. Cleaning the electrodes I think is a good idea ... It would be nice to check how much influence on the results ...
  3. Hello @Andras ... Actually, two parallel plates are enough as electrodes ... But always make sure that they are well fixed and constant as any change in geometry adjustment will cause a lot of variation in measurement. The arrangement would only need more sophistication if the electrode itself developed a chemical potential at its interface! Which is not the case here ... So I think your scheme is satisfactory. [ 1 ] I would like to know the results with your yeasts ... if you can post the results. Very good to see a case study. Thank you very much Cleber [ 1 ] - page 2 = *Two electrode setup* ( www.ecochemie.nl/download/Applicationnotes/Autolab_Application_Note_EC08.pdf ) ((( The two-electrode configuration can therefore be used whenever precise control of the interfacial potential across the WE electrochemical interface is not critical and the behavior of the whole cell is under investigation. )))
  4. Hello @Andras ... Could you show how your electrode scheme looks? I think it is also geometry / electrode setup is a very important parameter. Very cool the results of your experiments ... In electrochemical impedance spectroscopy (EIS), I see that the voltage amplitudes are much smaller than you are using ... In general, the articles show that they are 100mV amplitudes due to problems with linearities in Nerst's law ... Have you tested at lower amplitudes? Thank you very much. Best regards, Cleber
  5. hello @Andras ... My IA board (impedance analyzer) arrived a few days ago, but I did not even test it ... But now I have the AI board in my hands. Thanks for your attention. The IA board does not allow a reference electrode (RE) such as figure-item B. Such a scheme would be to not pass current between the working electrode (WE) and a reference electrode (RE). It would be to measure more accurately and discount several other effects in a more automated way. This scheme is not necessarily mandatory. You can use the scheme of just two electrodes as you mention. I am a chemist and I do not have much knowledge of the electrical / electronic part. I imagine that your measurements reflect well the salinity of the water tested. Actually, I think this device - AD2 - could provide a lot of chemical information of Impedance measurement, but I just started reading about it. It's great to know that more people are interested in AD2 and EIS ... so we can build a source of information. Regards, Cleber
  6. @Andras I ordered the IA card and it took six months to arrive in Brazil. (Digilent-USA did not want to sell me direct for having representatives in Brazil) ... So I left the project temporarily 😞 I'm sorry you can not contribute information Cleber
  7. Hello @attila, Good Morning, I imagined that using the reference resistors (such as the impedance analyzer extension board) could have been used the I-V method, since it would be easy to calculate the current value (I) ... But, given your explanation, I understand that the AI tool still uses the same method: Transfer Function Analysis (or the same as FRA - Frequency Response Analysis) ... [I needed this information to report] Thank you very much for your response and dedicated attention to this issue. Cleber Borges
  8. Hello @attila Thank you for your consideration and for your response. My question is more about the theory itself. Since I have the Magnitude and Phase experimental measure, the rest of the properties are reasonably easy to calculate by a CAD (algebra software) My concern is to know what are the real limitations involved in measuring when I ask about fundamental differences.
  9. Hello everyone, Reading about the EIS area - Electrochemcical Impedance Spectroscopy - I found that currently commercial potentiostats implement Impedance analysis by the method: FRA - Frequency Response Analyzer, also referred to as Transfer Function Analysis. As far as I understand, this method would be the same as the one implemented by the Network Analyzer tool in AD2 (am I right? 🙂 ), since in its description it consists of: "The Network Analyzer is used to analyze transfer functions (the ratio between an output function and an input function)" If I can have the Impedance Analysis (measurement) implemented by the two tools: (i) Network Analyzer and (ii) Impedance Analyzer; with differences observed between the two tools, for example, in the frequency range: Network Analyzer = 2 mHz up to 10 MHz - and no "open" and "short" compensation option Impedance Analyzer = 200 uHz up to 25 MHz - and with "open" and "short" compensation option Which made me have the following doubts: [1] - What is the fundamental difference between them? [2] - I saw that the Impedance Analyzer tool forces the current calculation while the Network Analyzer emphasizes the voltage attenuation. But what is the implication of this? In the literature, I saw the defense of the FRA method based on measurement accuracy. The source signal is multiplied by the attenuated signal and the result is given from this combination. [3] - Does the Network Analyzer tool algorithm follow this form? [4] - In the WaveForm examples, there is the use of reference resistors for use of the Network Analyzer tool. Is it mandatory to use them or can you close the circuit by connecting to Ground-GND? Many thanks for your attention and patience! These details may be basic to those trained in electronics, but it is difficult to find them in referrals from other areas. And it certainly makes all the difference trying to do the measurement correctly. Once again: thank you! Cleber Borges
  10. Hi @attila, Is there any future revision possibilities for the IA-adapter to be able to contemplate these three electrodes? Since minimizing the connectors, wires, welding ... And always using the same precision resistors greatly improve the accuracy of measurements. It would be an interesting platform for use in electrochemistry with the use of 3 electrodes. thanks Cleber Borges ps.: (here in Brazil I never found resistor 0.1% to buy) :-(
  11. Hi @attila, Good Morning! As far as I understand, this implementation: W1-C1P-DUT-C1N-C2-R-GND was tailor-made for the example I mentioned! Thank you very much because it will be much easier to do chemistry tests. In general, in Chemistry, the frequencies of ~ 1kHz - 100kHz are more usual and values of ~ nanofarad Thanks :-) Cleber Borges
  12. Many thanks @attila, But if you say you tested in the differential configuration, I will not try to do it because I do not have much experience or material for these tests. And logically for the use of 3 electrodes I would necessarily need to use differential mode. In any case, it would be very useful for electrochemistry if it worked.
  13. Dear all, Good afternoon! In electrochemistry, a system of 3 electrodes is used to: 1 - measure the Potential (V) between the Working Electrode (WE) and the Reference Electrode (RE) 2 - measure the current (i) between the Working Electrode (WE) and the Counter-Electrode (CE) The RE is constructed so that no electric current must flow between WE and RE. My question is: If I use the schematic of figure B, the tool: Impedance Analyzer, implemented in Waveform, will it use the potential difference of the channels of the Scope1 (+) port and the (-) port? My goal is to characterize the Impedance in WE (Working Electrode) as a Randle Cell (Figure C) without the interference of the other two electrodes - RE and CE. (Figure (A) illustrates the electrochemical cell in use in conventional potentiostats for voltammetric study) Thanks in advance for your attention and comments. Thank you very much Cleber Borges