Force Sensitive Resistor. Johnnie Chang. October 19th, 2009. Force Sensitive Resistor （ FSR ）. FSR is a type of resistor whose resistance changes when a force or pressure is applied. 1. Various Pressure/Force sensing principles. Piezoresistive. Capacitive. Electromagnetic.
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October 19th, 2009
FSR is a type of resistor whose resistance changes
when a force or pressure is applied.
The sensitivity of piezoresistive devices is characterized by the gauge factor (or strain factor):
ε = strain = ΔL / L
ΔR = change in resistance
R = unstrained resistance
α = temperature coefficient
θ = temperature change
A force sensing resistor is mainly made up of two parts.
A resistive material applied to a film
A set of contacts applied to another film
The resistive material serves to make an electrical path between the two sets of conductors on the other film.
Together they fit into a circuit that forms a simple voltage divider
When a force is applied to this sensor, a better connection is made between the contacts, hence the conductivity is increased.
The resistance of FCR is inversely proportional to the force applied.
Notice: The threshold, or "break force", that swings the resistance from greater than 1M to about 50-100 K.
The area enclosed by two doted curves represents a typical part-to-part repeatability envelope. This error band determines the maximum accuracy of any general force measurement.
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