It’s part kinetic art and part digital clock, all driven by marbles ... Color sensing (as well as detecting empty spaces) settled on IR-based sensors commonly used in line-following robots.

Here's everything you need to know about the IR Sensors that could appear in the Nintendo Switch 2's Joy-Con controllers ...

(InfraRed remote control) A handheld, wireless device used to operate audio, video and other electronic equipment within a room using light signals in the infrared (IR) range. Infrared light ...