Andras

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  1. Thanks @attila for the tips! I would like to ask for your help: what would you do if you wanted to measure two (fluid) samples at the same time over and over? For my current experiments I would need to measure the capacitance of one sample and another sample as a control. I'm willing to build a small hardware if I need to, but I really would like to use AD2 and WaveForms to make it happen. Plan A is that I start up two WaveForm instances, one with AD2 and one with the Sound Card option, and I would create a small extension (with fixed resistance) to my soundcard following the diagram you showed me, and I would measure the impedance with both at the same time. Plan B would be that I build/buy a small digitally controlled switch (a small multiplexer basically) for the Impedance Analyzer, have the two probes on its inputs, and control the whole process with a WaveForms script (select the probe, make a measurement, select the other probe, make a measurement, repeat). What do you think?
  2. Thanks @attila, that's good to know! I might use my PC soundcard as a signal generator, it looks an easier workaround for now
  3. @attila That's pretty cool! Also, I'm not sure if this was there in the previous versions, but I really like the "Pick screen color" function, because I like to use RGB gradient tool (http://www.perbang.dk/rgbgradient/) to get my gradient colors. 👍 Anyway, I have a question relating to my next phase of my experiments: is it possible to use the BNC Adapter with the Impedance Analyzer? I would need to stimulate something with a signal generator while doing the capacitance tests over and over. As I quickly tested it, the Impedance Analyzer module seems to be not working if it's attached to the BNC module (which is attached to the AD2). Thank you!
  4. Hi guys, Today I created a mixture with tap water and glucose just as before. I made a short (3.3 minute-long) and a long (2.7 hour-long) experiment. I made a test with water + glucose mixture and then I did the test once again after I put the baker's yeast into the mix. I focused on both the impedance and capacitance values. Here are the results for the short test: The blue is the tap water for reference. The two reds are the water + glucose combination. I made the two measurements approximately 60 minutes apart, but I also made sure that they have the exactly same amount of glucose in them. I'm not 100% sure why the values are so different. The yellow/green are the baker's yeast mixtures having approximately the same amount of yeast put into the water+glucose mix I used in the previous tests. They showed a nice pattern, so I thought I repeat the experiment, and I let the yeast work for more time. So this is the result of the long test: Blue is tap water for reference. Orange is the baker's yeast. As you can see both the impedance and the capacitance show the activation of the yeast beautifully. I will probably use capacitance for my future tests, because that looks more persistent. @Cleber Borges, thanks, I will probably put together a summary of these when I'm finished with them on my blog (blog.biobalancedetector.com). I hope people will find this forum too @attila, thank you for the improvement! I noticed one more thing: if I use the Impedance Analyzer as you described (Start=Stop) and I generate a chart in the time-domain, the x-axis is not labeled. Could you add labels on it, so that we could see how much time elapsed during the measurements? The other thing is probably connected to this: the Vertical Quick Measurement tool seems to be not working in this mode, it doesn't move from the first column of the chart.
  5. Cool stuff @attila! Thanks, I will definitely try it tomorrow!
  6. Alright, I finished the tests for today, here are the results. I used "traditional" yeast now, and not the brewer's yeast as before. (A - blue - left) 27 Celsius water + 2.5g glucose + 2g yeast (B - red - middle) 27 Celsius 2.8% milk + 2.5g glucose + 2g yeast (C - green - right) 50 Celsius 2.8% milk + 2.5g glucose + 2g yeast [please note that all the temperatures converged to our room temperature in the end to 28 Celsius] The following two pictures were taken 5 minutes (light color) and 120 minutes (darker color) after mixing the ingredients together. And the impedance values in the 100 Hz - 2 kHz range: As a next step I will try to write a small script to make single impedance measurements every 30 seconds or so, and plot the changes over time, so that I could see the rate of the change over time.
  7. Hello @Cleber Borges Today I tested a few things: I made a measurement before and after cleaning the electrodes and I did the same before and after I whirled the mixture. Neither of them modified the values, which is good news. I have found one interesting thing though: if I make the impedance measurement while the temperature sensor is submerged in the mixture, it distorts the values in the 20-25 Mhz range. I use a multimeter to measure the temperature, so from now on I will not keep its probe in the mixture, and I will put it into the fluid only for a few seconds when I actually check its temperature. I can't tell at the moment if there is any gas formation, it looks like there isn't any. It can be because I set one parameter or ratio wrong. According to the literature my room temperature is higher than the ideal (it's 27-28 Celsius here) and the ideal would be somewhere below 20. Today I added salt to the mix, because the minerals are said to be critical for the yeast as well. Here are the results after 3 hours: (tap water + glucose + brewer's yeast + Himalayan salt) Since my goal would be to detect the phase of the yeast + sugar reaction with this impedance measurement, I will change the measured range to 100 Hz - 1 kHz, it looks like most of the changes are there. According to the data the reaction starts right away, but it stop after about 2 hours. This, again, can be because I use wrong ratios or at a wrong temperature, I need to make more tests. Andras
  8. Alright, so I made 9 consecutive measurements in 10 hours on both tap water and the yeast + sugar + water mix. The results for the water are the following: And results for the yeast: The values are changing for both over time, which is expected, but there are a few strange things: - The first tests for both are not in line with the changes happening later, they look off. - The amount of changes for both samples are similar, does this mean that it doesn't matter if it's something living like the yeast or non-living like tap water? - I'm not sure what the reason for the changes are: Could it be the little temperature fluctuation during the day? Could it be that the evaporation from both containers? - It's not proven yet, but I got the suspicion that small bubbles form on the electrodes during the time between the tests and they change the measured values. Would I get different results if I shook them or didn't shake the electrodes before the measurements? Also, I'm not convinced that the yeast started to work today. I can't really tell, I need to get more information about the brewer's yeast and its properties.
  9. Hi @Cleber Borges and @attila, Sure, my electrodes are simple wires fixed at a certain distance from each other, and they look like this: Do you know what kind of electrodes researcher normally use when they do EIS? It's interesting that you just mentioned the voltages, I tested them as well, because I feared that the high voltages would make changes in the target fluid especially if it's a living thing, like yeast. So here is the test I had, comparing the different amplitudes/voltages: Probably it isn't obvious on the screenshot, but the 5 mV - 50 mV charts are fuzzy, I think that amplitude would be not good for testing. 100 mV is the first value that looks ok to me, so I will start using that one from now on I repeated a few 100 mV tests a few hours apart on my current fluid sample which was tap water + glucose + brewer's yeast. The result were not consistent: I suspect that it is because there were some reactions going on with the sugar and yeast, so today I'm going to repeat the tests with a control sample of tap water, and the same glucose + yeast combination.
  10. Before I continued my tests with beer, I wanted to make sure of two things: a, the amount of the sample fluid does not influence the impedance values b, the measurement itself does not change the sample fluid so that its impedance is changed at every measurement For case A, I made 3 references with 1 cup, 2 cups and 3 cups of tap water. I used the same source and the same container for all the measurements. Then I made 3 other measurements of the same 3 cups of water. At this point I can conclude that the measurements are fairly harmless, there is only a small amount of change on the dataset after each consecutive measurement. I could probably use lower voltages, which could theoretically reduce the impact further. The amount of the test fluid does change the dataset somewhat, so I will keep that in mind when I go ahead with my further tests and I will try to keep the volume of the fluid fixed. As we could see from my previous post, the temperature is very important, so that's another parameter I will try to manage and keep constant between the tests.
  11. Hey guys, I've made some experiments that could be interesting for your as well. I put tap water into my ceramic container, I heated it to different temperatures and measured the impedance every 5 degrees. You can see the values between 60 ° Celsius (140 ° Fahrenheit) and 5 ° Celsius (41 ° Fahrenheit). Red is 60 Celsius, blue is 5 Celsius and there are 10 steps between them.
  12. @attila, could you also rename the "Close" button in the reference properties dialog to "Delete", please? It tricked me when I tried to rename a reference and I clicked on the close button afterwards (it removed the reference trance altogether). Also, could you make the column on the right hand side with the trace and references horizontally resizable? If I define longer reference names they are not visible. Thank you!
  13. Szia @attila, That's awesome, thank you, I really appreciate it! I'm looking forward to the changes!
  14. I did a quick experiment with different liquids. All of them are in a small ceramic container. The blues (Ref1, Ref2 and Ref5) are tap water. The red (Ref3) is salted water. The green (Ref4) is carbon-filtered tap water. I just put both the + and - wires of the Impedance Analyzer into the container and I made sure they are not directly connected. Here are the results: Cool stuff!
  15. @Cleber Borges, I'm sorry to hear that! I had to wait a few weeks as well here in Hungary, but it wasn't as bad as in your case. If you have no other option, let me know, I buy you one here and send it to you to Brazil. If you had the Impedance Analyzer, how would you make the measurements? I saw your other post: The Impedance Analyzer has only two wires: + and - So, would you put just those two wires into a liquid and run the Impedance Analyzer tool in WaveForms? Would you expect to get consistent result for the same type of liquids? Thanks! Andras