Measuring body resistance with multimeter

Discussion in 'Off-Topic' started by TsAmE, Nov 21, 2010.

  1. TsAmE

    Thread Starter Member

    Apr 19, 2010
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    Using the 2 probes of my multimeter (placing the red probe on my left thumb and black probe on my right thumb) I measured about 1 mega ohm for my body resistance.

    Now what I want to know is would this be the resistance of my whole body, or would it be the shortest path the current would take between the 2 terminals (from left hand through chest to right hand)?
     
  2. debjit625

    Well-Known Member

    Apr 17, 2010
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    Its your skin's surface resistance.

    Good Luck
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    Given your sweat problem you probably have extra low resistance. Most people measure very high due to dry skin. Sweat, being basically salt water, is an excellent conductor.
     
  4. TsAmE

    Thread Starter Member

    Apr 19, 2010
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    True. If my hands are dry then I measure around 2 mega ohms.

    I also tried using the continuity feature of the multimeter when placing my thumb on each probe and there was no beep. Why is there no beep?
     
  5. debjit625

    Well-Known Member

    Apr 17, 2010
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    The continuity feature of the multimeter beeps only when you go down to a very low resistance approx below 100 or less(it depends on the meter check your meter's manual) ,and your skin resistance is very high for that value so it doesnt beeps.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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  7. TsAmE

    Thread Starter Member

    Apr 19, 2010
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    From what I read from that link this is what I think (correct me if I am wrong): if the red probe was on the left thumb and black probe on right thumb, the current would flow from the left hand, along the surface of the skin (past chest surface) to the right hand.
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    Possibly, but the path of least resistance may include the back or even down to the abdomen. Conduction follows sweat more than a line between points.
     
  9. tom66

    Senior Member

    May 9, 2009
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    There's a Darwin award for some idiot who stuck multimeter probes through their skin and into a vein, and caused fibrilation of their heart. Not sure if it's true, but a multimeter does put a few milliamps across a resistor.
     
  10. TsAmE

    Thread Starter Member

    Apr 19, 2010
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    Yeah I have came across this story before. What confuses me is that how is it possible that one can get current flowing in them (in blood through heart) if they just hold 2 terminals. Wouldnt current flow in someone only in case of sticking the probes into the skin?
     
  11. Paulo540

    Member

    Nov 23, 2009
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    Yes, and this is what was done. According to the story, some naval fella either pierced his skin with small needles (or just pushed the probes too hard, i forget) to see what his 'internal resistance' was.

    The gold standard for cardiac death is only about 100mA of current. Not too tall of an order for a 9v meter...
     
  12. t06afre

    AAC Fanatic!

    May 11, 2009
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    First you should know that skin impedance is very dependent of of parameters like frequency, and current density. The skin impedance will also be much higher then the underlying tissue. We are talking about around 1 K ohm from arm to foot, for the underlying tissue only. So the current would definitely NOT flow in the skin by putting one measurement pin on each thumb. Also The current flow in the human body is due to ion flow, not electrons. In order to do proper measurement on the skin. A transducer that senses ion distribution on the surface of tissue, and converts the ion current to electron current. Is needed for proper measurement. So your kind experimental measurement is not hazardous. As long as you use a battery operated multi-meter. But your approach is pure gobbledygook in any scientific relation.
     
  13. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Thank goodness our bodies don't come equipped with tail lights, government microchips (yet), or antipollution devices, or this type of thread would be locked. (sarcasm)

    I do think the forum leaders should consider relative risk, including delay in therapy, and legitimate value from such amateur approaches to serious health matters. Just watch the YouTube clip which began the related thread and the rather flippant comment about not plugging the device into a wall socket.

    John
     
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