flexiforce sensor - please help me

[nnn123]

Hi

I tried to calibrate the flexiforce sensor but i couldn't get a linear conductance graph although I followed all the steps provided in the user manual http://www.cytron.com.my/datasheet/sens ... Manual.pdf .
Furthermore, it does not gives stable reading when I conditioned/calibrated it. The resistance value kept on decreasing although if I waited for 3 minutes. Besides it also didn't give the same reading although the same amount of weight placed on it.

What should I do? Does this means the sensor has broken/damaged?

Thanks

[anhingus]

what you describe as resistance change over time is normal for this product - check the user manual, page 9, under drift.

if you look at the specs, implication is that you need to trap the pressure reading in a specific unit of time. flexiforce says 1 microsecond is good.

and then how did you calibrate? reasonable procedure is to do weighs at 10% intervals up to max, plot results, repeat 10 times and check for consistency.

specs look like you could get 12% variance in worst case measurement. and then there is the question of the goodness of conditioning circuit.

at any rate, tekscan seems to encourage user contact. they will be your best bet as to proper functioning.

good luck!

[anhingus]

thinking about it a bit more:

your sensor should to be hooked to a constant current source when taking
measurements. mfg suggests 1 ma.

with a constant current source in place, you can measure flexor values in
volts across the sensor to examine linearity.