Force Sensitive Resistor – Definition, Working, Symbol, Types, Uses & Characteristics

Define Force Sensitive Resistor?

What do you mean by Force Sensitive Resistor?

A force-Sensitive resistor is a material whose resistance changes when a force, pressure or mechanical stress is applied. They are also known as force-sensing resistor and are sometimes referred to by the initialism FSR.

Founder and History of Force Sensitive Resistor

The technology of force-Sensitive resistors was invented and patented in 1977 by Franklin Eventoff. In 1985 Eventoff founded Interlink Electronics, a company based on his force-sensitive-resistor (FSR). In 1987, Eventoff was the recipient of the prestigious international IR 100 award for the development of the FSR. In 2001 Eventoff founded a new company, Sensitronics, that he currently runs.

Working Principal of Force Sensitive Resistor

How do force sensing resistor (FSR) sensor work?

How force sensitive resistor can measure pressure/force?

Usually, force sensing resistors are very simple to be made and low cost, although they are not accurate. For this reason, basically when you use force sensing resistors you should only expect to get ranges of response instead of precise results. Therefore, while force sensing resistors can detect weight, they cannot detect exactly how many pounds of weight are on them. However, even not being extremely precise, for most touch-sensitive applications force sensitive resistors are a good cost vs. benefit deal.
Force Sensitive Resistor’s are usually composed by two substrate layers. Followed by the conductive film and the plastic spacer, which includes an opening aligned with the active area. After the spacer layer there’s the conductive print on substrate. When external force is applied to the sensor, the conductive film is deformed against the substrate. Air from the spacer opening is pushed through the air vent, and the conductive film comes into contact with the conductive print on the substrate. The more of the conductive ink area get in touch with the conductive film, the lower the resistance. Therefore, the more pressure applied on the sensor, the more the layers touch the conductive film and that makes the resistance go down.

Uses and Applications of Force Sensitive Resistor?

Musical instruments: In musical instruments, the force sensitive resistors are used to translate the emotions of a person into musical expressions through his touch.
Computer input devices: Force sensitive resistors are used to control the force and speed of the cursor movement.
Industrial applications: Force sensitive resistors are used in brakes, seat occupancy detection, motor speed control and mirror adjustor.
Robotics fingertips
Medical applications
Sports

What are the Main Advantages of Force Sensitive Resistor?

Advantages of force sensing resistors – FSR
Low cost
Small size
Highly sensitive to force

What are the Main Disadvantages of Force Sensitive Resistor?

Disadvantages of force sensing resistor – FSR
Low accuracy

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