Force and Position Sensing Resistors : An Emerging Technology

Force Sensing Resistor™ devices (FSR™) superficially resemble a membrane switch, but unlike the conventional switch, change resistance inversely with applied force. For example, with a typical FSR sensor, a human finger applying a force from 0,1 N to 10 N will cause the sensor to change resistance continuously from 400 kΩ to 40kΩ. These sensors are ideal for touch control, and may be applied where a semi-quantitative sensor is called for that is relatively inexpensive, thin (>0,15 mm), durable (10.000.000 actuations), and environmentally resistant. These sensors can be made into arrays or single elements up to 60 cm × 80 cm, and cover forces in the tens of grams to tens of kilograms range.Force and Position Sensing Resistor™ devices (FPSR™) can sense the position and normal force of a single actuator, such as a finger or a stylus, along either a straight line (a Linear Potentiometer) or on a planar surface (an XYZ Pad). Depending on the mechanical arrangement, positional resolution of 0,05 mm is possible.