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Perplexing switch application

Discussion in 'Electronic Design' started by Mike Chippendale, Apr 12, 2004.

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  1. I am working on a project that requires me to measure pressure and
    have it readout on an array of LEDs. It is intended to measure 4
    different zones in a mattress and display on the LED arrays, the
    amount of pressure being applied in the 4 corresponding areas. Three
    levels of intensity will be displayed in a 3-LED array for each of 4
    zones. The electronics end of it will use an algorith to calibrate
    the intensity to overcome the weight differences in the people who may
    be laying on the mattress. It needs to utilize "switches" of some
    nature that will be able to be fit into the lining of various
    mattresses (different support levels, padding etc.) , and function the
    same. The kicker to the whole project is that it will readout on a
    display that is connected to the sensors/switches with leads, and the
    whole system needs to be battery powered. Any
    advise/observations/comments would be appreciated.


  2. Tim Wescott

    Tim Wescott Guest

    Look for "pressure sensor" on the web. There's a number of MEMS
    pressure sensors with built-in amplifiers, etc., from a number of
    semiconductor manufacturers.
  3. Joerg

    Joerg Guest

    Mike, check out cabling in other high stress applications such as aircraft
    wiring. I believe that the wiring will be the neuralgic spot here for
    stress failure.

    LEDs in a battery application seem sub-optimal since they consume lots of
    power. How about a low power uC such as the MSP430 and an LCD display?

    Regards, Joerg.
  4. Luhan Monat

    Luhan Monat Guest


    You need a 'force sensing resistor' (FSR) - available from Interlink and
    others. Very proven technology. Relatively inexpensive.
  5. Hi Mike,
    this sounds like something I did about 10 years ago.
    I used custom made FSR (force sensing ressitor) sensors from Interlink.
    I was an array of 32*20 sensors. 20 of them in paralell stripes
    giving 32 lines along the mattress.
    These sensors do not really "measure" the pressure but give an approximate
    value for the pressure/force a person feels on the matress.
    It was used to select the best mattress for a person by calculating
    what deformation on different mattress types the person would generate.
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