I need your help..

Discussion in 'The Projects Forum' started by lidwina, Mar 16, 2010.

  1. lidwina

    Thread Starter New Member

    Mar 16, 2010
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    Hi, My name is Lidwina,
    I'm a product design student currently designing a product to bridge prenatal relationship between fetus and those around it.
    So my idea is to detect baby's kick and heartbeat and then convert it to light. I am thinking of using piezo sensors. oh, anyway, i have no electronic background at all. i totally need your help on the diagrams. cause im totally blind abt all of this.. will be very helpful if anyone can help me explain abit on what should i be doing, and how can i do it :)
    Anyone willing to help me ? :)
    thankyou much :D
     
  2. Bychon

    Member

    Mar 12, 2010
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    IMHO, you don't stand a chance with piezo transducers. They would require the fetus to kick them directly in order to produce any usable voltage. The usual method of monitoring human bio signs is a voltage detector and amplifier. I would start typing about differential amps, common mode rejection, and low pass filters, but with no background in electronics, it would sound like Charlie Brown to you, "wah wah wah".

    What you are proposing requires a full blown design engineer and weeks of development to adapt an available bio-monitor product to your purposes. This site doesn't do weeks of development.
     
  3. Wendy

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    Mar 24, 2008
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    I don't think it would be that complex. I'm thinking a simple microphone to listen for the sounds. The problem is making it unidirectional. The sounds could drive an LED bargraph.

    If the OP is willing to learn some electronics I don't see it being insurmountable, I've helped beginners several times (and it was a week of work or more each time). The onus is on the OP to do the work though, and it would be serious work and a bit of money for parts. Things like protoboards ($14), wire ($5), tools to strip and bend wire ($10), and miscellaneous parts ($30).

    It will also require about a month of reading. You can't become an expert, but you need some basics.

    So I think it can be done, but it depends on the OP (original posters) commitment.
     
    lidwina likes this.
  4. Bychon

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    Mar 12, 2010
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    Just one question..what is the sound of a fetus kicking an amniotic sack?
     
  5. retched

    AAC Fanatic!

    Dec 5, 2009
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    Squirrsshhhaafllooop I believe..
     
  6. Bychon

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    Mar 12, 2010
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    :D

    Good luck on that!
     
  7. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    It was exactly like that... well, at least in my case :D
     
  8. lidwina

    Thread Starter New Member

    Mar 16, 2010
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    bychon : i dont want to produce any usable voltage, i mean like, there will be a battery attached somewhere. i just want to detect the kick and show it everyone via lights.


    Bill_Marsden : please help me. I so want to make this happen :)
     
  9. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    My daughter is currently 7-1/2 months pregnant. The "kicks" tend to be very localized, all over the place. I'm not sure you are going to be able to detect this type of movement and still have a mother-to-be that won't try to share the discomfort with you. ;)

    Ken
     
  10. Wendy

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    Mar 24, 2008
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    You can experiment by recording the sounds over a duration. This might be a good practice run if you ever build anything. A simple tape recorder with a flat microphone would be how I'd do it. The microphone is probably the key.
     
  11. Wendy

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    One other thing, there is no guarantee this will work. I think it will, but I've been wrong before.

    Another thing, I don't think using magnets (inside the microphones) is a problem, but check with your doctor.
     
  12. Audioguru

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    Dec 20, 2007
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    A jet airplane above?
    A motorcycle or truck without a muffler within a few miles?
    A train nearby?
    Mom and Dad fooling around?
    Housework?
    An earthquake?
    A hurricane or tornado?

    Didn't you know that a microphone can hear everything?

    Edit:
    I forgot about thunder from lightning, guns and firecrackers.
     
  13. Wendy

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    Ever press a mic against flesh? It is a pretty good muffler. I suspect all the sounds will be low frequency.
     
  14. retched

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    If you used a unidirectional, built into an insulated case, you could isolate the noise in the body. But you would also pick up bowel sounds and other "unpleasantries" that could trigger the lights.

    Thats all I would need.. Be in a crowded elevator and have lights going off when I had gas.. And pregnant women do, unfortunately, have gas.
     
  15. Audioguru

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    The "head" on a stethoscope has an air cavity that picks up sounds that vibrate the air by the body but the head blocks outside sounds.
    Like my Stethoscope project that uses a jar lid for a "head":
     
  16. Bychon

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    Mar 12, 2010
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    "usable voltage" doesn't mean enough to start a car or run a light bulb, it means, "enough to be detected by the most sensitive electronics". If you can't produce enough voltage to be detected by the most sensitive electronics, you can't get any signal to process.
     
  17. jpanhalt

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    Jan 18, 2008
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    Modern stethoscopes have two heads, a diaphragm and a bell. The bell, which you describe, is often used in obstetrics for fetal heart rate monitoring. The diaphragm is used for higher pitched sounds, like some heart and breath sounds.

    While the bell might be better for fetal monitoring, I believe either will work sufficiently for the project. The diaphragm (i.e., contact method) might be easier to mount effectively to exclude extraneous noise and be less uncomfortable for long term wear.

    The bell needs to be pressed against the skin hard enough to seal around its rim. That is hard to accomplish for long periods with just tape, particularly on a surface that is flexing like a pregnant woman's abdomen.

    Just daydreaming here... wondering whether a thin flat speaker like one sees in many devices today (not sure of the actual mechanics) could also work as the pickup. It would be flat and comfortable to wear taped to the skin.

    John
     
    Last edited: Mar 18, 2010
  18. Wendy

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    That was kinda what I was thinking. The small plastic types about 1" in diameter. I'm still not sure about the magnet though. This is one project it is better to err on the side of caution.

    Since fidelity is not a real issue I think this can be pretty simple.

    I like AG's approach, but I'm also sure there are others.
     
  19. Audioguru

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    I recently volunteered for a Health study where doctors are making a database of how people's health is and if it changes.
    They had a device with a speaker and a probe. The probe was held against some gell put on my chest then on my ankle and we heard my blood flowing and my heart pumping.
    There was no acoustical feedback howling so the probe could not be a microphone.
    Maybe it sensed the temperature increasing when fresh blood goes by.
     
  20. jpanhalt

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    Jan 18, 2008
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    @AG,

    The probe was likely an ultrasonic, if you heard the blood flowing. I don't think such a thing would be practical or advised in the present case.

    John
     
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