I’ve been thinking of ways of creating interactivity with LEDs.
One of the issues you run into is controlling them. You can control a few with an Arduino easily but when you have a lot of them it starts getting messy pretty fast.
Something just dawned on me. I happen to have a piezoelectric disk so I put an LED against it and I was totally amazed that there was enough current to light the LED! So I soldered it and tried a few simple experiments.
So an LED can be activated mechanically. Further, this could prove to be a great way of harvesting small amounts of electricity from mechanical systems.