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.
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.
Touch sensor in robotics, provide tactile force feedback for robotic arms to ensure safe, accurate, and independent handling of products and equipment
In sports, measure the actual grip forces on golf clubs, tennis racquets, baseball bats, etc. to better analyze the distinct forces involved, or diagnose a problem
Automotive Occupant detection