Chrome Dino
Chrome Dino with three different ways to make the dinosaur jump without touching the screen.
Chrome’s offline dinosaur jumps when you tap the screen. I built three ways to make that tap happen without a fingertip on the glass. Each one changes what the capacitive touchscreen senses in a different way.
Final Version: paper spring + copper tape + charging cable
See full demo video here.
This version adds a mechanical switch. One copper-tape contact sits on the screen, and a second contact connects to the charging cable. While the paper spring is up, the two contacts are apart and the screen-side tape floats. Pressing the spring brings them together, which connects the tape to the cable and so to the phone’s ground reference. The screen reads a touch and the dinosaur jumps. Releasing the spring separates the contacts and ends the touch.
Version 1: copper tape only
See full demo video here.
Copper tape on the screen already couples to the electrodes under the glass. On its own, though, it’s a small isolated conductor. Touching the tape connects it to a much larger conductor, the body, which is capacitively coupled to everything around it. That shifts the capacitance the screen measures. Once the shift crosses the controller’s threshold, the phone reads a touch and the dinosaur jumps.
Version 2: charging cable only
See full demo video here.
With the cable plugged in, its conductive parts are tied to the phone’s ground reference, or at least closely coupled to it. Holding the exposed metal end against the screen puts that reference one glass-thickness away from the electrodes. The metal end and the electrode form a capacitor. If the change is large enough, the phone registers a touch.
What I learned.
Versions 1 and 2 still needed someone to hold a hand or a cable against the glass. In Version 3 the paper spring decides when the touch happens, so the input becomes a press and release on a physical object instead of a touch on the screen.