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Piezoelectric Flooring?

  1. Aug 21, 2011 #1
    Hi!

    I'm trying to find a way to use piezoelectric materials, and put them under floors or roads so that people's footsteps or a cars wheel will apply pressure on them, therefore creating an electric current.

    I need to find the materials to create a small square of piezoelectric flooring, so I could step on it and attach a voltmeter/ galvanometer to it to measure how much electricity a footstep could generate.

    I've heard of things like piezoelectric film, cables, and transducers..

    http://science.howstuffworks.com/environmental/green-science/house-music-energy-crisis1.htm

    So what are all of the materials I would need to create a setup like this?
    Does anyone have an idea where I could get those materials too?

    Thanks!
     
  2. jcsd
  3. Aug 21, 2011 #2
    Perhaps this can help:

    http://www.mide.com/products/qp/qp_catalog.php" [Broken]

    M.
     
    Last edited by a moderator: May 5, 2017
  4. Aug 21, 2011 #3
    Thanks, but I have no idea whatsoever of which thing I should need.
     
    Last edited by a moderator: May 5, 2017
  5. Aug 21, 2011 #4
    Not even my Physics teacher who has a phd knows what piezoelectricity is.. Can anybody help me?
     
  6. Aug 21, 2011 #5

    Pythagorean

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    My thinking is that any substantial amount of energy you can generate is going to drain a substantial amount of energy from a human being.

    So you'd have to have a lot of give in your floors to the point where it would be annoying and tiresome (like walking on a bed everywhere you go) to generate any kind of meaningful energy.

    Of course, this is assuming a personal home. If you have a mall, I could see how you might save some pennies per dollar from all the traffic with only a very small energy absorption per step (so that the people don't notice it) but of course, mall's have a higher electric bill too keep up with, too. Would it be worth the installation and maintenance?

    Also, could your customers potentially sue you for stealing their energy? :P
     
  7. Aug 21, 2011 #6
    Pythagorean, This is for a science fair, Im a 9th grader xd.
    And most likely going to be applied on roads/ airport..
    And yea, this is super expensive, but its still pretty cool..


    But now that I think of it, this is America, that could be perfectly valid case for a lawsuit..
     
  8. Aug 21, 2011 #7

    Pythagorean

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    Careful, that only raises my expectations nowadays.
     
  9. Aug 21, 2011 #8

    cjl

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    On roads would be problematic, as it would require the road to have significant give. That would increase rolling resistance substantially, increasing pollution and decreasing gas mileage for every vehicle that travels on the road, as well as likely increasing the required road maintenance.
     
  10. Aug 21, 2011 #9
    It would be under the road.. Also, i think piezoelectric materials only compress a maximum of 4% or so.

    And nobody's answered my questions yet :/
     
  11. Aug 23, 2011 #10
    Need help urgently :/
     
  12. Aug 23, 2011 #11
    As far as I know, piezo ceramics have been used as pressure or force transducers but the efficiency is very low. What I men is this: I you compute the work done while compressing the piezo and compare it to integral al the voltage times the current, the former is much larger. In the sensor area this is not a problem because we're not interested in efficiency.
    However I feel the project uses sound physical ideas, albeit the conversion from mechanical to electrical energy should be too low.
    There are meny piezo makers. I've found these:
    www.piezocryst.com/
    www.piezotechnologies.com/

    PS: I've never seen a piezo shaped like a tile.

    Good luck.
     
  13. Aug 24, 2011 #12
    Check my earlier post.

    Piezoelectricity comes from the deformation of the crystalline structure (of some materials). When the crystal is deformed, positive and negative charges forms on opposite faces of the crystal, which creates a voltage that can be alternating if the deformation is alternating (such as vibration). The inverse is also true: if an alternating voltage is applied, the piezo vibrates.

    Not sure this is the kind of project for a 9th grader. Considering the amount of energy that can be gathered from this kind of source, using it in tiles wouldn't be very effective and could probably only light a LED.

    M.
     
  14. Sep 7, 2011 #13
    Well, I realize its not that effective, but its for a science fair project..
    If you put this in the busiest areas of an airport, I'm sure it'd be very effective.

    Anyone else looking to help.. I need sources, or any places where i could obtain pre-made tiles of these, or even just helping me out in pointing out exactly what piezo component creates electricity when under pressure/ is designed specifically for it.
     
  15. Sep 14, 2011 #14
    I found a few senior theses/ projects on piezoelectricity..

    Something about piezo coax cable.. Anybody know what this is/ how it works?
     
  16. Sep 15, 2011 #15
    Sorry, but it does not work this way. You cannot be sure until you estimate it. Even a rough estimate will do.

    Consider the distance traveled by the top edge of the tile when a person steps on it. Keep in mind most piezo materials are crystalline and don't bend well. Assume reasonable value for a person's weight. Knowing the force and the distance, estimate the amount of work done to a tile when a person steps on it (ignore the dynamics, assume the force is constant. This is only a rough estimate).

    Consider the area of the area (pardon the pun), the average number of people there and how often they step. Compute average mechanical power output in watts per sq meter.

    Now pluck a tiny little fraction out of thin air, that would be a proportion of the energy actually converted to electricity (as opposed to energy converted into heat and also returned back to the person due to deformation being partly elastic).

    Then consider what sort of output your tiles are going to generate. Think of a way to convert short irregular pulses of unpredictable amplitude and duration into something useful. Conjure another small fraction, that would be the efficiency of your power converter.

    Finally, do the math, get the answer (in watts per sq. meter), see if you like it.
     
  17. Sep 15, 2011 #16
    Sorry, the piezoelectric response of materials is extremely weak. Just strong enough that they can be used as detectors by amplifying the signal, but way too weak as an energy source, no matter how many people there are at the airport. If you are thinking of harnessing footsteps as an energy source, a much more efficient system would be hydraulic (like a pump). Put a length of rubber tubing filled with water snaking under a tile, connect to valves and a turbine that drives a generator.
     
  18. Sep 15, 2011 #17
    Well, my point was, given very small displacement (some small fractions of a mm), even if you somehow manage to convert all availiable energy into electricity it will still not be enough to make it interesting.
     
  19. Sep 15, 2011 #18

    phinds

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    It seems to me that the unstated part of your OP is that your experiment should either directly produce a useful amount of electricity or should show in some way how it could be scaled up to do so.

    It is a good idea but suffers from the fact that it won't work, for the reasons others here have pointed out. I commend you for thinking of something clever to do. Now use that cleverness to recognize that you need to move on to another idea if you really want to show something meaningful.

    If it's too late for this project, that is unfortunate. Perhaps you should have started earlier.

    EDIT: by the way, if your prof has a PhD in one of the hard sciences (physics or engineering) and does not know what the piezoelectric effect is, I suggest you not give too much weight to anything he has to say. It is introduced in undergraduate physics.
     
  20. Sep 15, 2011 #19
    That hydraulics system sounds very interesting, and it probably is more viable (in a large area)
    I may ask if I could maybe switch my project to that, as it might not be too late..

    But also, I really dont care that right now, piezoelectric materials are very unefficient.
    Maybe placing them under landing/takeoff strips at an airport would work? They'd obviously have to be relatively deep underneath the stone they have, but it would be more efficient than in the airport itself.

    Although, it would be expensive to repair the system, it may be too fragile underneath that much pressure, and it would be expensive and hard to remove the landing strip and place this underneath it... But I would imagine that these landing/takeoff strips could be replaced regularly, i don't know.
     
  21. Sep 15, 2011 #20
    Anyways, if I would go with the hydraulic floor system, wouldn't the floor have to shift way too much? Either the floor would change positions enough for it not to be practical, or there would be too little pressure on the rubber tubes filled with water.
     
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