Possible to make a basic electrodermal screening device?

Discussion in 'The Projects Forum' started by chaimpeck, Feb 12, 2013.

  1. chaimpeck

    Thread Starter New Member

    Feb 12, 2013
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    I am interested in trying to make my own electrodermal screening device. Essentially (and according to my currently naive understanding of it), this is a device that will read resistance across a person's body, specifically from certain acupuncture points.

    I have noticed that there are devices on the market that sell for thousands of dollars. I am interested in experimenting with such devices but cannot afford them. Those devices seem to geared towards medical practices and not for the causal experimenter such as myself.

    I am wondering if a basic multi-meter should do the trick. Will I get even slightly consistent results? And will an average 20-dollar multimeter effectively be able to read resistance across the human body?
     
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Yes. You need a multimeter and some pins.

    It hardly costs "thousands of dollars" unless of course you put it in a pretty box.
     
  3. justtrying

    Active Member

    Mar 9, 2011
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    check out this thread. Includes a cautionary tale, not to be taken lightly.

    A multimeter will not give you very accurate results. You pay a thousands of dollars for the box to spit out all sorts of numbers for you, the meaningless stuff that people pay money for... The value of the box vs. multimeter is how it measures impedance and the fact that it uses electrodes...
     
  4. t06afre

    AAC Fanatic!

    May 11, 2009
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    To me this sounds like a mixture of snake oil and Scientology. Can you tell us more about such an instrument. Like posting some links to sites describing that kind of instrument
     
  5. chaimpeck

    Thread Starter New Member

    Feb 12, 2013
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    @t06afre: I would have thought the same thing if I had read any of the descriptions of this found on google when you type "electrodermal screening".

    However, my family has been going to a doctor for the past 30 or so years and he has been helping us in so may amazing ways, just by accurately finding the particular ratio of certain food sensitivities and actually helping get over those sensitivities. There are so many discomforts and whatnot that people consider as "normal" or "part of life" - things like headaches or trouble sleeping or rashes, chronic fatigue, etc. etc. And he has helped us with these sort of things.

    For all of these years, I did not know what this device was that he would use to measure these things. I was always curious, but never really had the impetus to inquire. Just yesterday, I decided to ask. I was fascinated. He described the device that he uses as essentially a very accurate ohmmeter.

    The way that it works is that I would hold one end, which is a brass (or brass-looking) cylinder. He then touches the other end of this probe to a very specific point on the finger of my other hand. The machine then measures resistances across me and he uses this to establish a baseline. Then, he uses some software (the device has a USB port) to test against various pre-set food groups. He has a unique set of food groups that tend to be very accurate and what sets his work apart from many others out there who do similar work. So, he runs through these food groups and watches for added resistance. He then runs through some presets of different ratios of that particular group and also watches for resistance.

    An additional feature of this device (and it's most basic usage) is to test against actual foods. There is a metal plate on top of the device and you can put foods there that the patient might be sensitive too. It is amazingly accurate. I am not really sure of the science behind it, but I will attest that it works. By putting a food that I am sensitive to on the metal plate and then touching the probe, the conductivity goes down (or do we say "the resistance goes up"?)

    This was apparently invented by somebody by the name of Voll about 60 or so years ago. I was reading about his device (you can google) and his was not digital. It did not have a USB port or presets. Here's a picture:
    http://www.doctor.oost-west.com/images/Dermatron.jpg

    In my case, I would like to be able to try this at home. I do not care for the accuracy of these expensive devices (which at my doctor's office, he will use to actually make substances to help counter the allergen), but I would like basically take a ohmeter and attach a cylinder to one of the probes. For the other end, I'd like to find a probe that is not too sharp so I can try to find this particular point in my other finger. If there exists a probe with a ball-end (i.e. at radioshack or something) I would be interested in one of those. Finally, I want to try attaching a metal plate somewhere along the circuit (i.e. between one of the probes and the ohmeter) and measure what happens when somebody places certain foods that I know that I am sensitive to on the plate.

    My concern is that I will require something that is very sensitive to notice any difference. I am wondering here on this forum if I will need anything other than a standard ohmeter? Before I go to a local electronics store, I would like to have some idea of what I'm doing first. :)
     
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  6. chaimpeck

    Thread Starter New Member

    Feb 12, 2013
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    @justtrying Thanks for the link. I do not intend to pierce anything with the probes, but that is a good word of caution that even such a small voltage could have such repercussions.

    I specifically would want to find a probe that has a ball-tip. I'm not sure if such a thing is readily available at an electronics store, but that's what I'm looking for anyway.

    Could you elaborate on where you said "the fact that it uses electrodes"? Is there a difference between an "electrode" and a standard probe?

    Also, (and please excuse the electrical naivety) what is the difference between measuring impedance and measuring resistance?

    Thanks!
     
  7. chaimpeck

    Thread Starter New Member

    Feb 12, 2013
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  8. chaimpeck

    Thread Starter New Member

    Feb 12, 2013
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  9. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I would prefer an "analog multimeter" with a moving needle type meter.

    The whole thing does not inspire confidence that is it "science". It sounds exactly like a lie detector or galvanic stress response device, that shows your skin resistance going down when you are presented psycologically with "something bad".

    Maybe you should read up on the real science of galvanic skin response technology etc to get a better idea of what is actually happening? That will also give you better info on how to build something, and will help you decode the actual result from the meter reading. :)
     
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