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Circuit that produces a tingling sensation in the fingers.

Discussion in 'Electronic Basics' started by Denis Gleeson, Dec 4, 2004.

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  1. Hello all

    Without going into the application in too much detail we are looking
    into
    the possibility of allowing the identification of items through a
    persons sense of touch.

    So what I am researching at the moment is passing a waveform down a
    pair of wires which when held (the wires that is) will allow the
    person to identify that they have the correct item (correct pair of
    wires in this case).

    Is there any information out there on this sort of thing? Has anybody
    tried this before? What sort of safety regulations etc. apply?

    Any help or suggestions appreciated.

    Regards

    Denis
     
  2. Rick Merrill

    Rick Merrill Guest

    Limit to 5ma (c.f. GFI)

    Maybe you wanto have a finger worn device that delivers the
    "tingle code" based on RFID? That could enable a blind
    clerk to work at a store someday.

    I suggest you look into PWM (pulse width modulation).

    Prior electrocutaneous example: http://kaz.med.wisc.edu/research.htm
     
  3. Mac

    Mac Guest

    I don't know what regulations apply but it seems like this would be
    exceptionally dangerous for people with electronic life-suppor
    equipment implanted in their bodies. (I'm thinking of pacemakers here.)

    Just something to keep in mind. Sorry I don't have any real information.

    --Mac
     
  4. Bob Masta

    Bob Masta Guest

    To expand on what others have said, the main safety issue is
    going to be keeping the current from passing through the
    heart (for pacemakers of just those with sensitive hearts),
    which basically means somehow guaranteeing that the
    current path is all in one hand, never from one hand to
    the other, or to an external ground, etc.

    One practical problem you will quickly encounter is that
    the voltage needed to produce a given current varies
    quite widely, since the skin pads of the finger tips are
    not very conductive when dry.

    Best regards,


    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
     
  5. Rich Grise

    Rich Grise Guest

    I've seen articles on a device with a little X-Y matrix of tiny little
    transducers, which when they're energized, the person can feel the
    vibrating ones somewhat like Braille. The app has a little sensor array,
    and they were using it to read ordinary text by feel.

    Or, just Braille tags.

    But don't ever do anything that intentionally gives people an electrical
    shock, except under strictly controlled lab or medical conditions.

    Or gags, like those lighters and books, but even they're illegal to sell
    these days.

    Good Luck!
    Rich
     
  6. dmm

    dmm Guest

  7. steve

    steve Guest


    An easier solution would be to use vibration, a small vibration motor
    (the type used in pagers), for instance, attached to the item can give
    the same tactile feeling (tingling) without the danger or headaches of
    passing currents thru items (and people!). Whether its practical or
    not depends on your specific application.
     
  8. So what I am researching at the moment is passing a waveform down a
    Very silly and exceedingly dangerous idea. No lawyer or insurance
    company will touch you with a fifty-foot cattle prod.

    Modulate the speed of a pager motor held in the hand. You can find
    good examples of this kind of technology in the sex toy industry (and
    I am not being facetious). See for instance
    <http://www.babeland.com/page/TIB/PROD/vibrators-couples/DM215780>. If
    the intended users of this appliance can tell the difference between
    the various settings, then your intended users will be able to, also.
     
  9. YD

    YD Guest

    This may not be very practical. The sensitivity level (too little/too
    much) is in a rather narrow range and varies greatly between persons.
    What one may not feel another goes OUCH. As ohters have stated, use
    some kind of vibrating transducer, piezo or micromotor.

    - YD.
     
  10. Jim Douglas

    Jim Douglas Guest

    Check out the medical device called a "Tens" unit, it's send a small tingle.
     

  11. Since the late 1970s there were devices available called Optacons.
    http://www.nfbae.ca/publications/index.php?id=375

    Unfortunatly this technology has disappeared from the market. It essencially
    consists of a neadle array (20 x 5) where such trigger is stimmulated by
    vibrating certain sets of these pins at a time.
    This in fact allows detailed pattern recognition without the effect of
    distress on the finger.
    I am using such device for 25 years now myself and as an engineer I am
    constantly looking for techniques to replace / rebuilt it.

    Applying electricity directly to the finger is imho not a good idea. Apart
    from safety considerations and possible long-term electrolytic effects I
    would assume that you'll lose sensitivity for this after a while.
    Vibrating mechanics of some kind triggered by something like an AC current
    would work but in order to provide useful information this requires a
    complex mechanical setup - just like on the Optacon.

    The most promissing approach that I ever considered is to create haptical
    stimulation by electrostatic / magnetic fields similar to what you can
    experience if you switch your old model color TV off and touch the tube
    glass.
    If one would switch such fields on and off quickly, shield the whole thing
    by some polymer with a suitable electronegativity characteristic and then
    put the finger right on this plastic it may be possible to trigger a certain
    part of the finger for a short time and - as a result - produce a picture.
    This is what the optacon does but the approach could result in a much less
    gragil technology with higher resolution and lower costs.

    /Roland
     
  12. I read in sci.electronics.design that Roland Zitzke
    about 'Circuit that produces a tingling sensation in the fingers.', on
    Wed, 8 Dec 2004:
    That would be a very distinct advantage. (;-)
     
  13. Roland, is this a device to help you see? I've read about these, but
    never actually had any direct contact. Can you recognize different
    faces? Or the fact that a face is in front of you?

    --
    Regards,
    Robert Monsen

    "Your Highness, I have no need of this hypothesis."
    - Pierre Laplace (1749-1827), to Napoleon,
    on why his works on celestial mechanics make no mention of God.
     
  14. Wieslaw Bicz

    Wieslaw Bicz Guest

    After I have read this post, I have had the idea, that I would be able
    to propose a novel idea for this purpose, that may be very attractive,
    because this allows to makes devices with even large surfaces, that can
    produce even large pictures. This idea is based on may experience, and
    this is the reason, whyI think, that this will work, but it requires
    some money for the development. The device will not contain any moving
    elements.

    If somebody is interested in it, I would be able to do this development
    and create a product. This can be surely patented.


    Wieslaw Bicz

    ---------------========== OPTEL sp. z o.o. ===========---------------
    ------===== R&D: Ultrasonic Technology/Fingerprint Recognition ====------
    ul. Otwarta 10a PL 50-212 Wroclaw Tel.:+48 71 3296854 Fax.:+48 71 3296852
    --------==== mailto: -=- http://www.optel.pl ====-------
     
  15. Yes, I use it because I am blind and it lets me recognize images when moving
    a CCD camera over it.

    As mentioned the represented image is quite small (20 x 5) and this is not
    enough for recognizing complex structures like a face in the sence that I
    could tell two faces apart.
    Biometry is a science of it's own ;-)

    With a device I suggested it could be a much larger image and that would
    certainly enable "TV for the blind" to some degree.

    /Roland
     
  16. Yes, I guess it would be possible to apply a core technology similar to
    displaying TV pictures line by line.

    experience, and
    You are right, and this is probably the problem why such technology is not
    further developed or even sold.

    The device will not contain any moving
    Sure not, the three things I see as obstacles is
    a) To find a suitable surface material
    b) to find components which are able to switch a high voltage on and off
    with high frequency and deflect it.
    c) Do extensive testing to see if the approach as such works as we think it
    might word.
    But I simply don't see a big market for such product since even my old
    machine is no longer made.
    /Roland
     
  17. The first part of the problem is to find a set of nerves on/in the body
    which can be used to "see". The fingertips are sensitive, but very small.

    I would try the skin on one of my thighs, it is fairly easy to attach a
    thin elastic cloth around it and leave it on all day.

    Then I need a way to excite the nerves in the skin of my thigh.

    200*300 points, or more, on the inside of the cloth will excite the
    nerves and create a picture which wraps around my thigh, and I use the
    nerves in the skin to "see" it.

    The idea about electrostimulation fits well into this device.
    I would simply try different combinations of frequencies and currents
    until I found a setting which gave the best "image" without being painful
    in any way.
    Mechanical stimulation is also possible, but would be a little more
    difficult to manufacture.

    A small videocamera can be hidden below or above my own face, in a
    band around my head, like a tennis player's sweatband, for example.

    So I would feel with my thigh what the camera sees.

    With some training it could become really useful.
     
  18. I read in sci.electronics.design that Roger Johansson <>
    IIRC, you have picked the body area where nerves in the skin are most
    sparse.
     
  19. That may be so but the number of receptors is big enough.
    Touch the thigh anywhere very lightly and you
    will feel it and you can tell exactly where it is touching.

    I thought about the back of the body first, because it is big area, but
    it would need some kind of adhesive and very flexible surface to stay in
    contact with every piece of skin. An elastic cloth around the thigh stays
    in contact with every piece of skin under it.

    To make a prototype I would try to find a very thin and flexible wire,
    which I could fix in the cloth, by sewing into the fabric. At the end of
    the wire I would take off the isolation for a few millimeters and make a
    loop or knot which does not irritate the skin mechanically.
    (copper wire may irritate the skin, so I would get some other surface
    metal on the wire, or chemically add a layer of zink or whatever works
    better against the skin than copper)

    Then I need a microprocessor which can be programmed to take the average
    of the light level in one small area of the video picture and send a
    signal of that level to the skin. Maybe 4*4 pixels for each skin
    stimulation point. (Because the number of pixels in the camera will
    probably be much higher than the number of pixels in my thigh cloth.)

    We need controls for intensity and contrast for the skin. They will work
    just like the intensity and contrast control on a tv. I might want to
    adjust these controls during the day, and when I sleep I turn down to
    black screen, or take of the cloth.
     
  20. Rich Grise

    Rich Grise Guest

    I seem to remember seeing a thing on edjamacayshunal TV where somebody
    actually put electrodes against some volunteer's brain, at the back, at
    the visual cortex. The lobes all have names, but all I can remember of
    them is Steve Allen pointing at a skull, saying, "This is the frontal,
    this is the top-al, this is the back-al, and these are the two sides-al."

    Occipital?

    But I don't think you're ready to have electrodes poked into your brain,
    are you? =:-O

    On a less goofy note, I do wonder how hard it would be to build a bigger
    array of little piezo thingies. Probably not all that hard, just big bucks. )-;

    Good Luck!
    Rich
     
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