Building a Capacitive Touch Sensor

Overview

Capacitive touch sensors replace mechanical buttons with copper shapes that detect when a finger changes their electric field. In this tutorial you will:

Draw a capacitive electrode using polygon surface-mount pads.
Connect the electrode to a capacitive touch controller.
Route the traces, ground reference, and LED indicator for feedback.
Simulate the PCB stackup with tscircuit before ordering the board.

The finished design exposes a responsive touch pad that lights an LED when it is activated.

export default () => (
  <board width="20mm" height="20mm">
    <chip name="U1" footprint={
        <footprint>
      <smtpad shape="polygon" layer="top" portHints={["pin1"]} points={[
        { x: -4.5, y: 2 },
        { x: -2.2, y: 2 },
        { x: -0.4, y: 0 },
        { x: -2.2, y: -2 },
        { x: -4.5, y: -2 },
      ]} />
      <smtpad shape="polygon" layer="top" portHints={["pin2"]} points={[
        { x: -1.8, y: 2 },
        { x: 1.8, y: 2 },
        { x: 3.6, y: 0 },
        { x: 1.8, y: -2 },
        { x: -1.8, y: -2 },
        { x: 0, y: 0 },
      ]} />
      <smtpad shape="polygon" layer="top" portHints={["pin3"]} points={[
        { x: 2.2, y: 2 },
        { x: 6, y: 2 },
        { x: 6, y: -2 },
        { x: 2.2, y: -2 },
        { x: 4, y: 0 },
      ]} />
    </footprint>
    } />
  </board>
)

Overview​

Overview