A sensing device comprises a substrate material layer and a plurality of sensors provided on the substrate material layer. The plurality of sensors is electrically connected to form a loop. The loop has two output ends. There is a loop output value between the two output ends. The loop output value varies when the sensors are subjected to an external force. Each sensor has one induction value. The induction value of each sensor is different from each other. A total induction value of any one or more sensors is different from a total induction value of the other one or more sensors.