Begining of the touch sensor

The touch sensor using QTC sheet is designed to respond human touch sensitively.
the contact electrodes are designed to place closed to each other where the QTC will conduct electricity when the pressure is applied.
The conductivity of QTC varies proportionally with the pressure.
The sensors are required to be as light as possible and need to be easily attached to the pressur-applying device of the jacket.
Thus, copper tapes, wire-wrapping wires and normal paper pieces are used to make the sensor. After that, the sensors are secured inside a thin transparent plastic bag.
At first, the sensitivity of the sensors are unstable. The problem was caused by unevenness of the soldiered joint with the copper and the thin wire.
The wires should also be long enough to be able to embed it below the jacket.
The circuit diagram of the sensor-pair is as follow (According to voltage-divider rule):

The resister values of R1 and R2 are 47k Ohm each. Sensor's sensitivity is directly proportional to the resistance of R1 and R2.
The measuring point of each sensor is at the joint with the sensor and resistor.
When pressure is applied at one sensor, the material will conduct electricity and the reading will be between 0 to 5 Volts. The more pressure applied, QTC material will be more conductive.