What Is a Capacitive Touch Sensor?
A capacitive touch sensor is a sensor that detects the small capacitance change created by a finger's touch. Compared to a mechanical button it doesn't wear out and is sleeker.
How Does It Work?
The sensor pad continuously holds a small capacitance. When a conductive finger approaches, this capacitance changes; the sensor interprets this change as a "touch". It works even through a glass/plastic surface.
Types
| Type | Property |
|---|---|
| Self-capacitance | Single pad, simple button |
| Mutual-capacitance | Grid, multi-touch (screen) |
Where Is It Used?
Phone and tablet screens, touch buttons, home-appliance panels and swipe/slider interfaces.
Sensitivity (Threshold) Adjustment
A threshold is set in touch sensors: when the capacitance change exceeds this threshold, it counts as a touch. If the threshold is too low there are false touches, if too high there's a failure to detect; so it's adjusted to the panel thickness and material.
Common Mistakes
- Thick surface: a too-thick panel lowers the sensitivity.
- Noise/moisture: water and electrical noise can cause false touches.
- Grounding: if the device is poorly grounded, touch detection weakens.
Frequently Asked Questions
Why doesn't it work with a glove?+
What's the difference from a mechanical button?+
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