+ Post New Thread
Page 2 of 2 FirstFirst 1 2
Results 21 to 39 of 39
  1. #21
    Super Moderator
    Points: 60,116, Level: 59
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    12,277
    Helped
    2840 / 2840
    Points
    60,116
    Level
    59

    Re: Underwater electrode

    Hi,

    without specifications from your side?

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  2. #22
    Advanced Member level 5
    Points: 34,523, Level: 45
    Achievements:
    7 years registered Created Blog entry Created Album pictures
    SunnySkyguy's Avatar
    Join Date
    Sep 2007
    Location
    Richmond Hill, ON, Canada
    Posts
    6,673
    Helped
    1667 / 1667
    Points
    34,523
    Level
    45
    Blog Entries
    7

    Re: Underwater electrode

    This sounds like a flawed theoretical test without the theory and pointless without specifications. Water is an insulator not a conductor. Only the contamination conducts which is hard to control.
    A good design question lists your overall requirements™ The best question deserves a better answer. ™
    ... Tony Stewart EE since 1975



  3. #23
    Super Moderator
    Points: 26,821, Level: 39
    andre_teprom's Avatar
    Join Date
    Nov 2006
    Location
    Brazil
    Posts
    8,054
    Helped
    1008 / 1008
    Points
    26,821
    Level
    39
    Blog Entries
    5

    Re: Underwater electrode

    Quote Originally Posted by andre_teprom View Post
    Rather than describing what you expect from each sensor option, it would be better to specify exactly what you want to measure/detect; For example, it was not clear if you just want to detect the presence of water, or the depth of filling as well
    @Livio, even after reviewing all your replies it is not yet clear what is the purpose of that underwater electrode.
    --------------------------------------------------------------------------------------------------
    Part of the world that you live in, You are the part that you're giving ( Renaissance )



    •   Alt8th June 2018, 15:00

      advertising

        
       

  4. #24
    Advanced Member level 5
    Points: 13,753, Level: 28

    Join Date
    Nov 2012
    Posts
    2,564
    Helped
    596 / 596
    Points
    13,753
    Level
    28

    Re: Underwater electrode

    Quote Originally Posted by SunnySkyguy View Post
    ...Water is an insulator not a conductor..
    Pure water has some finite conductivity - approx 18 MOhm cm (resisitivity). Nothing great to write home but still...

    Finite ionization of pure water at room temp has great chemical and biochemical significance. Organic liquids like benzene or hexane or paraffin oil may be considered insulators for all practical purposes.



  5. #25
    Newbie level 6
    Points: 76, Level: 1

    Join Date
    Jun 2018
    Posts
    14
    Helped
    0 / 0
    Points
    76
    Level
    1

    Re: Underwater electrode

    Thanks SunnySkyguy for your comment. Just to be more precise: water is a solution containing ions and charged molecules. It is precisely for this reason that electrical signals can be transmitted through your neurons and it is for the same reason that some animals use electrical signals to navigate the environment, even underwater.
    While I admitted since the very beginning my ignorance on more technical matters (I would not actually ask to a forum to solve my doubts) I would say regarding the rest I am pretty sure about what I am doing.
    If not for your constructive advice, thanks for the interest in the topic.



    •   Alt9th June 2018, 12:17

      advertising

        
       

  6. #26
    Newbie level 6
    Points: 76, Level: 1

    Join Date
    Jun 2018
    Posts
    14
    Helped
    0 / 0
    Points
    76
    Level
    1

    Re: Underwater electrode

    Thanks Klaus for checking, I think In my first post and some few replies after I did.

    I just paste them here so that is easier to find what would be eventually missing in the explanation :)

    1)
    Hi all, first of all I am really no expert, so I apologize in case I make gross mistakes. I have some ideas in mind for a project and I would like to get some inputs in order to see what's feasible or not and what's the best way to do it.

    I would need to design an underwater electrode (no salty water, only fresh) that would produce voltage changes in the order of mV (1-20 mV). It does not really matter if the changes are positive or negative, however it could be nice to be able to control their sign. They definitely would need to be switched ON and OFF by some external trigger but they should also have the chance to stay "ON" for long times (hours or days). They should be shaped in a way that would allow an array arrangement (I was thinking about some sort of "tile"-like flat electrode). The tricky part (or maybe impossible) would be to have the circuit insulated but still able to produce detectable signals from the outside. The water pressure would not be super high... I plan to use them in very shallow water (20cm) on a 80x80cm surface.

    I though one way could be to use LEDs as when they light ON they cause a drop in the circuit voltage of some few mV (1-5 I guess). LEDs would have to advantage to be also visible and so if one has an array (as I plan to build) one could identify where the voltage change occurred. the array will be put in a square glass tank and the activity of the electrodes will be monitored through other recording electrodes.

    Ultimately the idea is to have an array of electrodes which activity can be patterned and programmed via software (or arduino-like solution).

    Any feedback on this or any idea on which materials/electrodes would be best to use in such a configuration ?
    As an alternative, would it make sense to use electromagnetic field through the glass tank ? I hope all this doesn't sound too stupid :)

    Thanks a lot !

    2)I do not need to record. I need the electrodes to produce a constant "detectable" potential that could be set or programmed via PC. The electrodes won´t record. They will just be emitters.

    I would record them just in trial sessions while testing (one important issue for example would be that each "tile" of the array, each electrode, would be detected as independent... or at least that there would be enough difference among electrodes so that they could create some sort of gradient). To see whether it would be possible to detect those signals (through amplifiers). The "electrical pattern" would be then used in experiments in which live animals will navigate the "electric field", field that can be changed via software depending on the need. The animal behavior would be videorecorded and that is why I thought perhaps using LEDs could be actually interesting so that one has a visual proof of what the pattern looks like (not only via software eventually).
    Hope this clears the doubts. If you have more specific questions of course please feel free to ask.



  7. #27
    Member level 2
    Points: 911, Level: 6
    DNA Robotics's Avatar
    Join Date
    Jun 2014
    Posts
    45
    Helped
    4 / 4
    Points
    911
    Level
    6

    Re: Underwater electrode

    In the marine environment they use silicon bronze or stainless steel for underwater hardware because they don't erode easily with electrolysis. The best stainless for propeller shafts is Aquamet 22. http://www.aquamet.com/aquamet22.nxg
    If you can find an old propeller shaft at a marina that is not eroded, it is probably Aquamet 22. It should conduct easily for your electrodes.


    1 members found this post helpful.

    •   Alt10th June 2018, 17:20

      advertising

        
       

  8. #28
    Super Moderator
    Points: 60,116, Level: 59
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    12,277
    Helped
    2840 / 2840
    Points
    60,116
    Level
    59

    Re: Underwater electrode

    Hi,

    I would need to design an underwater electrode (no salty water, only fresh) that would produce voltage changes in the order of mV (1-20 mV). It does not really matter if the changes are positive or negative, however it could be nice to be able to control their sign.
    What does this mean?
    Does it mean you want to control the magnitude of voltage of each segment from 1mV to 20mV? --> you need to give the resolution / granularity?
    Or has every segment a predefined voltage and you just want to switch it "ON"? --> then you need to say what the "OFF" state means: is it "high impedance" or is it tied to 0V?


    I though one way could be to use LEDs as when they light ON they cause a drop in the circuit voltage of some few mV (1-5 I guess).
    I still don't understand how you want to produce the 1..20mV with the use if a LED. Read a LED's datasheet. You will find no voltage value in this range.

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  9. #29
    Newbie level 6
    Points: 76, Level: 1

    Join Date
    Jun 2018
    Posts
    14
    Helped
    0 / 0
    Points
    76
    Level
    1

    Re: Underwater electrode

    Quote Originally Posted by DNA Robotics View Post
    In the marine environment they use silicon bronze or stainless steel for underwater hardware because they don't erode easily with electrolysis. The best stainless for propeller shafts is Aquamet 22. http://www.aquamet.com/aquamet22.nxg
    If you can find an old propeller shaft at a marina that is not eroded, it is probably Aquamet 22. It should conduct easily for your electrodes.
    Are you suggesting to buy the raw material (a steel sheet/plate), cut it, make electrodes out of it ? I don't know how easy is to find someone cutting a steel rod in thin "chips" but.... thanks, this is useful... I will consider it :)

    - - - Updated - - -

    Quote Originally Posted by KlausST View Post
    Hi,


    What does this mean?
    Does it mean you want to control the magnitude of voltage of each segment from 1mV to 20mV? --> you need to give the resolution / granularity?
    Klaus
    Yes, exactly

    Quote Originally Posted by KlausST View Post
    Or has every segment a predefined voltage and you just want to switch it "ON"? --> then you need to say what the "OFF" state means: is it "high impedance" or is it tied to 0V?
    both things would be fine, I think having them independent, with the possibility to set them at different levels, would be best. However an "all electrodes - same potential" solution would be also OK. One could impose some "granularity" by creating ON or OFF assemblies of different sizes.

    Quote Originally Posted by KlausST View Post
    I still don't understand how you want to produce the 1..20mV with the use if a LED. Read a LED's datasheet. You will find no voltage value in this range.

    Klaus
    I actually don't think using LED is a good idea... I thought about it at the beginning just because online there is a lot of material on how to set such arrays UP (both hardware and software). I could in theory apply similar reasonings to an array of electrodes, instead of one of LEDs... this is just an educated guess... but of course I might be wrong.



  10. #30
    Super Moderator
    Points: 47,636, Level: 53

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    11,848
    Helped
    2339 / 2339
    Points
    47,636
    Level
    53

    Re: Underwater electrode

    Quote Originally Posted by Livio View Post
    cutting a steel rod in thin "chips"
    Stainless steel is a common material in kitchenware. To cut it with a hacksaw is difficult. Power tools make it easier. For instance a metal cutting disk mounted in a circular saw. Or a grinding wheel a few inches diameter mounted in an electric drill. Or diamond-embedded wheels available for the popular Dremel mototool.



  11. #31
    Advanced Member level 5
    Points: 13,753, Level: 28

    Join Date
    Nov 2012
    Posts
    2,564
    Helped
    596 / 596
    Points
    13,753
    Level
    28

    Re: Underwater electrode

    I don't know how easy is to find someone cutting a steel rod in thin "chips" but...
    Stainless steel comes in several grades and you can find thin sheets that can be cut with scissors. BUT

    using stainless steel as an electrode material is a BAD idea. because:

    1. it has a protective oxide layer that interferes with charge transfer across the electrode;

    2. it does dissolve at higher potential (not 1-20mV as in your experiments);

    3. making a good electrical connection with SS is difficult (you can spot weld);

    4. The surface gets fouled very easily (even in distilled water: leave a freshly polished sheet in a test tube containing distilled water and see the surface gloss after 7 days).

    Just painting (electrode pattern on a glass surface) with aquadag is a better solution.



  12. #32
    Super Moderator
    Points: 244,634, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    42,495
    Helped
    12948 / 12948
    Points
    244,634
    Level
    100

    Re: Underwater electrode

    As far as I understand, this is a behavioral physiology experiment setup. Reviewing the thread, I get the impression that at least half of the contributions aren't understanding the context and respectively make misleading suggestions. Surely I don't apply to asses it in detail.

    I believe, a better idea is to get in contact with a scientist at your site who masters both physiology and electronics (also electrochemistry) and discuss the experiment details.


    1 members found this post helpful.

  13. #33
    Advanced Member level 5
    Points: 13,753, Level: 28

    Join Date
    Nov 2012
    Posts
    2,564
    Helped
    596 / 596
    Points
    13,753
    Level
    28

    Re: Underwater electrode

    As far as I understand, this is a behavioral physiology experiment setup...
    I am understanding slowly; usually such experiments are carried out with rats or mice; they learn the tricks faster.

    But the objective is still unclear to me and I fully concur with your suggestion.



  14. #34
    Newbie level 6
    Points: 76, Level: 1

    Join Date
    Jun 2018
    Posts
    14
    Helped
    0 / 0
    Points
    76
    Level
    1

    Re: Underwater electrode

    Quote Originally Posted by FvM View Post
    As far as I understand, this is a behavioral physiology experiment setup. Reviewing the thread, I get the impression that at least half of the contributions aren't understanding the context and respectively make misleading suggestions. Surely I don't apply to asses it in detail.

    I believe, a better idea is to get in contact with a scientist at your site who masters both physiology and electronics (also electrochemistry) and discuss the experiment details.
    Indeed it is, but I don´t see how this makes a difference. My plan was to definitely ask someone here locally. I personally think it is useful to get first my own ideas together (even asking around on a forum) and then further discuss with someone. I think it is helpful to put eventual suggestions or plans into context. I am not here to find a solution, I am here to find some ideas and suggestions. Thanks for your advice anyway :)



  15. #35
    Super Moderator
    Points: 26,821, Level: 39
    andre_teprom's Avatar
    Join Date
    Nov 2006
    Location
    Brazil
    Posts
    8,054
    Helped
    1008 / 1008
    Points
    26,821
    Level
    39
    Blog Entries
    5

    Re: Underwater electrode

    The "electrical pattern" would be then used in experiments in which live animals will navigate the "electric field", field that can be changed via software depending on the need. The animal behavior would be videorecorded and that is why I thought perhaps using LEDs could be actually interes
    One fact to be considered is that each animal, sensor setup, and each reservoir layout will give you a different set of information, and the work now goes into the field of data mining, which is a rather inferential 'science', ie you should try extract through different mathematical experiments how could group such patterns. In this case, there is no single solution, each raw data calls for a different approach; BTW, instead of measuring the electric field, I would recommend considering the magnetic field, and standardizing a salinity and temperature for water, in order to avoid discrepancies.
    --------------------------------------------------------------------------------------------------
    Part of the world that you live in, You are the part that you're giving ( Renaissance )



  16. #36
    Newbie level 6
    Points: 76, Level: 1

    Join Date
    Jun 2018
    Posts
    14
    Helped
    0 / 0
    Points
    76
    Level
    1

    Re: Underwater electrode

    Quote Originally Posted by FvM View Post
    As far as I understand, this is a behavioral physiology experiment setup. Reviewing the thread, I get the impression that at least half of the contributions aren't understanding the context and respectively make misleading suggestions. Surely I don't apply to asses it in detail.

    I believe, a better idea is to get in contact with a scientist at your site who masters both physiology and electronics (also electrochemistry) and discuss the experiment details.
    I am that scientist anyway (without the electronics and chemistry parts), I hope you don´t know of someone already on this... that would be a bit problematic :D



  17. #37
    Advanced Member level 5
    Points: 34,523, Level: 45
    Achievements:
    7 years registered Created Blog entry Created Album pictures
    SunnySkyguy's Avatar
    Join Date
    Sep 2007
    Location
    Richmond Hill, ON, Canada
    Posts
    6,673
    Helped
    1667 / 1667
    Points
    34,523
    Level
    45
    Blog Entries
    7

    Re: Underwater electrode

    For this to be a science project there needs to be some scientific input and output still missing from Livio.

    In Ireland...

    The electrical conductivity of Irish waters varies from place to place; the usual range in value is 45 micromhos per centimetre in acid waters and 300 micromhos per centimetre in the alkaline limestone waters.

    They use it for diverting trout and Eels away from dam turbines, or towards fish counters or for improved fishing.
    These types of experiments have been done for almost 90 years.

    When pulsed at 30 pps from a relay coil and 12V truck battery generates 350V with a pulse duration depending on above conductance and L/R ratio where 100 micromhos are now called 100 microsiemens (uS) which =1/R means 10kohms but the capacitance on the length wire is far more significant on pulses and can be as low as 100 ohms reactive impedance.

    They properties hold true also for detecting E fields.

    Livio said "water is a solution containing ions and charged molecules"

    Yes conductivity changes in typical lakes depending on pH level to support synapse propagation biology, but pure water is also a highly polar liquid which even when pure has a dielectric constant of 80 meaning is stores and conducts electrical charges 80 times better than air.. The pH offset just makes it more conductive (real resistance not stored charges)

    In biology, the dielectric stores a charge when triggered to discharge, propagates in a chain reaction of a stored charge as a pulsed rep rate in the dielectric.

    - - - Updated - - -

    The human CSF has a very strong negative temperature coefficient on conductivity with 1.79S/m and -2%/'C.
    Last edited by SunnySkyguy; 13th June 2018 at 12:33.
    A good design question lists your overall requirements™ The best question deserves a better answer. ™
    ... Tony Stewart EE since 1975



  18. #38
    Newbie level 6
    Points: 76, Level: 1

    Join Date
    Jun 2018
    Posts
    14
    Helped
    0 / 0
    Points
    76
    Level
    1

    Re: Underwater electrode

    Quote Originally Posted by SunnySkyguy View Post
    For this to be a science project there needs to be some scientific input and output still missing from Livio.

    In Ireland...

    The electrical conductivity of Irish waters varies from place to place; the usual range in value is 45 micromhos per centimetre in acid waters and 300 micromhos per centimetre in the alkaline limestone waters.

    They use it for diverting trout and Eels away from dam turbines, or towards fish counters or for improved fishing.
    These types of experiments have been done for almost 90 years.

    When pulsed at 30 pps from a relay coil and 12V truck battery generates 350V with a pulse duration depending on above conductance and L/R ratio where 100 micromhos are now called 100 microsiemens (uS) which =1/R means 10kohms but the capacitance on the length wire is far more significant on pulses and can be as low as 100 ohms reactive impedance.

    They properties hold true also for detecting E fields.

    Livio said "water is a solution containing ions and charged molecules"

    Yes conductivity changes in typical lakes depending on pH level to support synapse propagation biology, but pure water is also a highly polar liquid which even when pure has a dielectric constant of 80 meaning is stores and conducts electrical charges 80 times better than air.. The pH offset just makes it more conductive (real resistance not stored charges)

    In biology, the dielectric stores a charge when triggered to discharge, propagates in a chain reaction of a stored charge as a pulsed rep rate in the dielectric.

    - - - Updated - - -

    The human CSF has a very strong negative temperature coefficient on conductivity with 1.79S/m and -2%/'C.
    Thanks guys, I just wanted to have some input on the electronics part of my project. I am a biologist and I can take good care of the rest. I appreciate the input from everyone.
    Sadly, normally it is not a good idea to share project plans or other scientific details online before actually carrying out experiments. This is mainly do to competition or "intellectual property" issues.
    That is why I don´t feel to share any other information here as this thread is public.

    At the same time I appreciate your time and your inputs :)



    •   Alt13th June 2018, 13:43

      advertising

        
       

  19. #39
    Advanced Member level 5
    Points: 34,523, Level: 45
    Achievements:
    7 years registered Created Blog entry Created Album pictures
    SunnySkyguy's Avatar
    Join Date
    Sep 2007
    Location
    Richmond Hill, ON, Canada
    Posts
    6,673
    Helped
    1667 / 1667
    Points
    34,523
    Level
    45
    Blog Entries
    7

    Re: Underwater electrode

    Everytime I invented something, I learned later , it had already been done before somewhere else on the planet.

    For example on the subject of Partial Discharge ( usually in HV cables and transformers) this not unlike the synaptic pulse but scaled down in size and thus also for excitation potential. The higher the potential or ionic flow rate , the faster the pulse repetition rate.

    Stored Potential , V ( or U) can be modified by Q=CV or V=Q/C by changing the dielectric constant or capacitance or the accumulated ionic flow of charges. Wheras Activation Potential may have bio-chemical dependancies just like a tuneable hysteresis oscillator.

    But if you were to search Microsoft or Google (Scholar/Academic) you will find 10 thousand related thesis and published articles on PD.

    In my fields PDIV is the most simple sensitive test for detecting the threshold of insulation quality or dielectric strength or activation potential. More elaborate methods use Spectroscopy. ( swept f impedance)
    A good design question lists your overall requirements™ The best question deserves a better answer. ™
    ... Tony Stewart EE since 1975



--[[ ]]--