Force sensing resistor
A Force Sensing Resistor (FSR) is a brand name registered in the USA for a measuring element from Interlink Electronics , which changes its electrical resistance under the action of force or pressure .
An FSR consists of a sandwich of two plastic films . One is coated on the inside with FSR ink (a graphite-containing semiconducting paste ), the other with two electrically conductive contact grids nested in a comb shape. However, these are electrically isolated from one another and have external connections. The two foils are connected to one another by means of a double-sided adhesive layer. It also ensures that the coated “active” areas of the foils practically do not touch each other in the unloaded state. Only when pressure or force is applied to the sandwich are the contact grids electrically connected to one another via the FSR ink and the electrical resistance of the structure can be measured at the external connections. In the idle state this resistance is a few megohms (MΩ). As the force increases, the resistance drops because the active areas of the FSR sensor come into closer contact. This goes up to the saturation limit, which is approx. 1 kΩ and a pressure of 100 N / cm².
The moderate accuracy is sufficient for many applications. Today FSRs can be found in the automotive sector, in computer peripheral devices , in medical applications and in touchpads for capturing electronic signatures.
Web links
- Force sensing resistor . Interlink Electronics, consulted September 7, 2010 (technical description).
- RM Crowder: Tactile Sensors . January 1998.
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- ↑ United States Patent and Trademark Office, Registration Number 1725143 , registered October 20, 1992.
- ↑ Patent US5659334 : Force sensing pointing device. Published August 19, 1997 , Inventors: Stuart I. Yaniger, Mark C. Picket.
- ↑ Data sheet example