This Interactive LED PCB Is Fun to Touch
Control 64 RGB LEDs under clear acrylic with a hand or other object.
Colorful LEDs form the basis for a large number of projects that we see here, and for a fairly large (and expandable) interactive light PCB, be sure to check out tuenhidiy's module. The device uses 64 RGB LEDs in an 8x8 matrix, arranged on a home-etched double-sided circuit board. This is an impressive feat in itself, and likely saved some money versus ordering it, since the panel is 20x30cm.
Interspersed between the LEDs are 12 IR LEDs, along with 16 phototransistors, which detect a person’s hand or other object via the reflected light. Notably, three columns of IR LEDs are used within the four columns of phototransistors, saving a few components when compared to matching an emitter for each sensor unit.
The device is driven by an Arduino Nano with multiplexer and shift register hardware, allowing it to scan input rows and columns as well as control 64 LEDs with the board’s limited I/O capacity. A clear piece of plexiglass is placed above the light/sensor board to protect the assembly. When a hand or other object is put on top of it, phototransistors light up based on the colorwheel rule defined in tuenhidiy's code. An etch-it-yourself PDF for the module is available in the project's write-up, and you can see it demonstrated in the video below.