In summary, Force Sensing Resistors© (FSRs) are robust, polymer thick film (PTF) devices that exhibit a decrease in resistance when increased pressure is applied to the surface of the sensor. The basic construction of an FSR includes a printed resistor on flexible substrate; a spacer adhesive; and printed inter-digitating electrodes or flexible substrate. The FSR sensor is not a strain gauge, load cell, or pressure transducer. While it can be used for dynamic measurement, only qualitative results are generally obtainable. Standard FSR products have a common semiconductor make-up and only by varying actuation methods or electrical interfaces can different response characteristics be achieved. FSR response is very sensitive to the distribution of the applied force, the use of a thin elastomer between the applied force and the FSR can help absorb errors due to inconsistent force distributions. For applications requiring high force accuracy, part calibration using either the gain and offset trimming or curve fitting methods will be necessary. Additional resources are available at www.interlinkelectronics.com.