Uploaded November 2025 | Updated September 2026, 2 weeks ago
This is a video about Polymer Dispersed Liquid Crystal (PDLC) film - a clear sheet that normally has a milky white appearance which diffuses any light passing through it. When you apply a voltage across the two sides however, the crystals in the sheet align and the sheet instantly becomes transparent!
It's trivial to use, and can be used for a whole range of interesting theatrical special effects, magic tricks, escape rooms, or other creative uses.
To demonstrate it, I created a window created from a 4x3 array of PDLC panels, which were individually switchable from relays, controlled by an ESP32. I then added a 4x3 matrix keypad (read using a PCF8574 GPIO port expander) so that pressing any of the keypad buttons would toggle the opacity of the corresponding panels.
You could use this to reveal a mechanism, a secret code, a set of symbols that needed to be matched in pairs (e.g. a memory "concentration" game), or many other ways... let me know what ideas you have for how it could be used!
Timings
00:00:00 - 00:03:00 Introduction and Demonstration
00:03:01 - 00:09:25 Hardware Overview
00:09:26 - 00:13:14 Wiring Diagram
00:13:15 - 00:21:31 Arduino/ESP32 Code Listing
00:21:32 - 00:22:34 Summary and Wrapup
You can find resources to accompany all the playful technology projects in this channel at patreon.com/c/playfultech
Join the discord server at discord.gg/afNsnqdv
This is a video about Polymer Dispersed Liquid Crystal (PDLC) film - a clear sheet that normally has a milky white appearance which diffuses any light passing through it. When you apply a voltage across the two sides however, the crystals in the sheet align and the sheet instantly becomes transparent!
It's trivial to use, and can be used for a whole range of interesting theatrical special effects, magic tricks, escape rooms, or other creative uses.
To demonstrate it, I created a window created from a 4x3 array of PDLC panels, which were individually switchable from relays, controlled by an ESP32. I then added a 4x3 matrix keypad (read using a PCF8574 GPIO port expander) so that pressing any of the keypad buttons would toggle the opacity of the corresponding panels.
You could use this to reveal a mechanism, a secret code, a set of symbols that needed to be matched in pairs (e.g. a memory "concentration" game), or many other ways... let me know what ideas you have for how it could be used!
Timings
00:00:00 - 00:03:00 Introduction and Demonstration
00:03:01 - 00:09:25 Hardware Overview
00:09:26 - 00:13:14 Wiring Diagram
00:13:15 - 00:21:31 Arduino/ESP32 Code Listing
00:21:32 - 00:22:34 Summary and Wrapup
You can find resources to accompany all the playful technology projects in this channel at patreon.com/c/playfultech
Join the discord server at discord.gg/afNsnqdv
