Force sensitive sensors
A pressure force sensitive sensor measures physical pressure, weight of objects or the squeezing of the sensor. For textile pressure sensors are often piezo resistive materials are used. That means that the conductive material changes the electrical resistance when a force is applied on the sensor. Such materials are often carbon coated fabrics, non-woven or conductive silicon sheets. The resistances of the sensors start at about 100 Ohm under full load and rises up to 10-100 KOhm unloaded. The characteristic curve of behaviour of these materials are mostly not linear.
For the measurement, you need a voltage divider between the sensor and the µC. Another measurement principle for force Sensors are capacitive sensors. Therefore, an isolating material separates two conductive Materials and a plate capacitor is build. Due to the deformable isolating material the distance between the conductive layers changes, which results in a change of the electrical field between the electrodes and therefore in a change of the capacity of the sensor.
Applications: Occupancy detection, weight measurement, robotics, shoes, wearables, chairs