Idea based off "The 555 FireFly by DJJules"
Essentally there are already LEDs that can blink or flicker without an external circuitry, via a small microchip embedded within the LED's epoxy case.
These LED blink circuitry are very efficient. If combined with the right resistor and and capacitor, it can blink for years.
This is often handy for things like blinking indicators on first aid kits. However what if the battery runs out, or you want the battery to last even longer?
Then try replacing the epoxy with glow in the dark paint! Also modify the embedded microchip to sense light level. If the glow pigment is below a certain amount of light, then trigger the next pulse. This means that the LED would not be blinking when there is enough light, only blinking if the room is dark, or the glow pigment is too low.
Thus making it a great way to power markers even longer! (especially if solar powered to a super capacitor)-- mofosyne, Feb 03 2014 Photoluminesence http://en.wikipedia...i/Photoluminescence [MechE, Feb 04 2014] Not a bad idea. I can't help feeling, though, that there's only so much light you can get out of a battery, and what you gain on the roundabouts you lose on the horses.-- MaxwellBuchanan, Feb 04 2014 And incidentally, isn't it just "luminescence"? Photoluminescence would be a bit like sonosound.-- MaxwellBuchanan, Feb 04 2014 It's light resulting from light, the same way electro- or chemo-luminescence are light resulting from electricity or chemical action respectively. See link for the wikipedia entry.-- MechE, Feb 04 2014 Ah - in that case, carry on.-- MaxwellBuchanan, Feb 04 2014 [ ] I sorta get it... the actual neat bit is the photocell usage. Of course by the same token it'd be even more efficient if the photocell simply didn't have any light reflect into it from the LED.-- FlyingToaster, Feb 04 2014 random, halfbakery