Force Sensitive Resistor Input for DC motor Output

What I'm Doing:

Clamping thin-films deposited on quartz substrates to the back of a prism.

What I'd like to do:

Quantify the amount of force used to obtain a "wetted spot" between the thin-film and the prism.

What I've looked into:

Force sensitive resistors seem like the way to go, the problem I'm having is the sensitivity of the resistors. I need it to be able to sense VERY small changes. I'm using a finely threaded screw to tighten the clamp, the magnitude of the changes I'm talking about are probably approximately proportional to the smallest perceptible change one can achieve by turning the screw with a screwdriver by hand. (hopefully that's clear).

What I Hope to get from this Forum:

Mainly just suggestions on components capable of meeting my needs without costing me hundreds of dollars

Future Dreams for the Project:

One day I'd like to be able to use a DC motor to drive the clamping process and use the output of the FSR as the input. So turn motor until FSR reads particular value then stops and holds position while I shine lasers and whatnot on it. Thoughts on the feasibility of this?

Thanks for your time


  1. Google "load cell". You appear to have a strain gauge load cell in mind.

  2. Quantify the force you need to apply and measure.

  3. If the screw doesn't provide a fine enough resolution, consider mediating the applied force by adding a strong spring in the mechanical circuit.