Piezoelectric Transducer Trigger/sensor project

Discussion in 'The Projects Forum' started by nikoTesla, Aug 24, 2014.

  1. nikoTesla

    Thread Starter New Member

    Aug 24, 2014
    Hi, I'm a physics student from Nigeria and I'm interested in doing a project involving piezoelectric transducers.
    The project will deal with how a piezoelectric material can produce voltage from the mechanical stress of a human footstep,
    so my first question would be how and where can I find (buy) a piezoelectric transducer (plate) that can withstand the weight
    of a footstep and is not so sensitive to vibration that any little disturbance will produce voltage. Or how can I dampen the
    voltage response produced from ordinary vibrations/sounds/disturbances?

    Please suggest which of the following products on Aliexpress.com will be best suitable for this purpose (that's basically
    the only place I can easily get these piezoelectric materials shipped to Nigeria)






    If none of these piezoelectric products can do the job, can you please suggest where I can get the right materials.

    Secondly, I need the piezoelectric transducer to act as a sort of trigger/sensor such that the voltage is maintained for as long
    as the foot is on the device, as soon as the foot is removed, the voltage should be cut-off. Can the circuit described in this
    thread (using IC 555) be used for this specific purpose?


    Can you give me any TESTED circuit where a piezo trigger (or sensor) is made to produce constant voltage when pressed (or strained
    in one direction) and voltage is cut-off when pressure is released.

    Will be expecting your informative replies. Thanks.
  2. zyklag2005

    New Member

    Apr 6, 2012
    This seems to be the one piezoelectric material suitable for such a application. But i do not know if they will ship to Nigeria. But maybe you can get someone to buy and send it to you.
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    A piezeo disc will not maintain a voltage but when flexed in one direction will produce a + pulse, when reversed, produces a - pulse. Using a piezeo speaker element, 2 cm dia disc, maybe like second ref, /Genu/ , made a sandwich of 1/8 cork sheet; cork , disc, cork, 1/2 plywood top cover. On stepping on it, a 30 V neg. pulse, 40 ms fall tine 60 ms recovery; on release, 25 V + pulse produced with same rise & fall times. About 5 V P-P noise present.
    To detect, I think comparators would work by biasing one disc to about 9 V to det. _ pulses, other set to det. + pulses. Arrange outputs so that pressure produces a neg. pulse to trigger a 555; release of pressure to reset 555.
  4. Sensacell

    Senior Member

    Jun 19, 2012
    I made a simple 12" square "footstep sensing plate" by attaching the piezo disk from a large beeper to a piece of 1/2" acrylic with some double faced tape.
    The output went to a simple high impedance amp. it worked pretty well considering the simplicity.

    The key is mounting the disk with a semi flexible adhesive, to control the stress on the piezo disk. I mounted the sensor underneath in the center.
    Support the edges of the plastic, so it flexes from the load.
    Last edited: Sep 17, 2014