The FSR is a variable resistor, constructed of several thin flexible layers, that varies in resistance as pressure is applied and released. As pressure is applied, the resistance lowers and then returns to its original value as the pressure is removed. An FSR’s main purpose is to measure the force applied to a specific area and then relay that information via selected output electronics. All FSRs use high-resistance, carbon-based inks which, along with other design factors, can be re-formulated to alter the functionality.
There are two basic FSR configurations: the ShuntModeTM and the ThruModeTM. Force Sensing Resistors can be designed as single-zone FSRs, Matrix Arrays, Discrete Arrays, Resistive XYZ (Digitizer) Pads, and Linear Potentiometers.
- Consist of printed silver interdigitated fingers that are shorted (“shunted”) by a printed FSR carbon layer.
- Can detect a wider range of forces with a more linear output.
- Are generally less costly due to fewer print steps and reduced ink usage.
- Are more receptive to lighter forces
- Not limited to the same print constraints as the ShuntMode’s interdigitated silver fingers, thus allowing for smaller form factors
- Require more silver and carbon ink, thus making them more costly than the ShuntMode FSR.
Among the many applications, some of the common FSR uses include:
- Up/Down and Force/Speed Controls
- Musical Instrument Controllers
- Infusion Pumps
- Podiatry Foot Gate Analysis
- Motor / Tool Speed Control
- Robotic Finger Tips
- Seat / Bed Occupancy Detection
- Inventory Control
Contact BTI to see how force sensors can be integrated into your applications.