Makeblock Touch Sensor

The multi-touch module consists of multiple touch sensors, each of which can detect whether the corresponding touch point is being touched.

You can also extend the touch points through alligator clips or wires, so that the multi-touch module can be applied in more scenarios. For example, you can use a piece of wire to connect a touch point to a fruit.

The multi-touch module can adjust the threshold values intelligently. Each time the system starts up, all the threshold values are reset. In addition, the sensitivity of the multi-touch module is programmable. For example, you can set the sensitivity to high to implement air touch.

Working principle
The multi-touch module applies the principle of capacity detection. There is an initial capacity (Cp) between a touch point and the ground. When a touch point is touched by you or another conductor, another capacity is formed. When this happens, the capacity between the touch point and the ground changes, and the MCU determines that the touch point is touched.

To sum up, the determination of touching depends on the detection of capacity change, and therefore, the MCU may detect touching when no touch point is touched.

Real-life examples
Some robots are equipped with touch sensors on their backs to detect whether they are touched by users.
Your cell phone screen is large and complex touch sensor.
Specifications
Dimensions: 24 × 72 (mm)
Operating current: 18 mA