[sdiy] flexible resistors?

[Josh Landau]

>Some trucks use strain gauges to measure axle load. Strain gauges are also
>used to measure the volume of nasty stuff in a vessel. How much pressure on
>the supports? Outputs are low. Use a differential amplifier.

FWIW... I spent this summer doing R&D on human weight measurement systems 
using strain gages... nasty stuff, when you really work with it.  Very low 
level signal, pretty noisy.

That said, some other gage manufacturers are Panasonic and CTS.

 >     Yep, sure is.  One name is "strain guage".  You can also get resistors
> > that vary with pressure.  Never played with them.  But, if you look hard
> > enough, you will find them.  I don't think they are cheap...

A strain gage is a resistor that varies with pressure.... the traditional 
method of using them is to put them in a half or full Wheatstone bridge, 
use a diff amp on the output, and then do massive signal conditioning on 
the diff amps output to recover a usable signal.  Dunno about pricing... my 
employer got good prices, but they were buying in large volume....

But relating the pressure change to flexion may be more difficult.

Josh Landau