Crash sensors need to detect a collision and convert it to usable signals within milliseconds. The accelerating forces acting on the sensors after a collision can be as high as 100g (100 times the earth's gravitational force). When a car is stopped abruptly by an impact, all bodies or objects that are not firmly fixed to the car will continue to move at the impact speed. The sensors measure this acceleration and relay it to the control unit as usable data.
Many of our cars are fitted with ultra-fast pressure sensors in the front doors. These sensors detect a side collision that pushes the outer door panel inwards, creating excess pressure. Acceleration sensors are also fitted near the C-pillars so that collisions from the side, which don't cause deformation of the front doors, can also be detected in time.