Pressure pad sensor inquiry


#1

Hello,
I’m a year 12 student in NSW undertaking my HSC this year. As one of my subjects I am doing design and technology. For my project I need to have a pressure sensor around 1m x 1m that when stepped on it can send a signal lighting up required lights. Do you know of any products which can preform the required task?
Thank you,
Charlotte


#2

G’day,

One metre square is a bit of a challenge, but it could be made from one of these products with a bit of hacking;

https://littlebirdelectronics.com.au/products/eeontex-pressure-sensing-fabric
https://littlebirdelectronics.com.au/products/pressure-sensitive-conductive-sheet-velostat-linqstat
https://littlebirdelectronics.com.au/products/pressure-activated-mat-alarm-with-siren-and-strobe

A microcontroller would process the resistances and turn on the lights.

It may not be very reliable. It depends on the underlying surface, how long it has to last, and if it has to handle very sharp high heeled shoes.

In an industrial environment, an area of floor could be removed and a metal floor plate would rest on a load cell, or several load cells, e.g.

https://littlebirdelectronics.com.au/products/load-cell-200kg-disc-tas606

A microcontroller would take continuous measurements and turn on lights when mass exceeds a preset value.

For turning on lights, it is more common to use a passive infrared (PIR) motion sensor, but they have a field of view greater than one metre square, may not work in areas of high heat, may trigger spontaneously, and (if used for security) can be defeated with thermal cloaking.

Hope that helps!


#3

do you know if the Velostat is waterproof or will it need a protective covering?


#4

Velostat is conductive, so any water may form a new circuit, with a human or with itself. If you can’t have bare conductors then add an insulation layer through which the pressure can pass.


#5

If you use load cell the trick will be to balance the 1m x 1m plate in order give a sensible reading. Even if 200kg is enough for the weight you are sensing. I may be an idea to hinge the plate along one edge and placing the sensor under the opposite edge. if you then want to get an weight reading, opposed to simply sensing the presence or absence of an object on the plate, you will have to get your processor to do some arithmetic. Also think about calibrating the device for the weight of the plate.