I know Jellyfish and other bioluminescent creatures possess the ability to light using...[who knows?]...this thread title has a question mark.
But I think they use analog power control.
Something I'd rather do digitally if easy.
Ie...what's like glow-goo but has much shorter duration [ie like down to say <500 milliseconds to return 1/2 way to 'other' state] of charge/discharge ]light/dark[ characteristics ?
http://www.windycitynovelties.com/252c/glow-products.html?s_kwcid=TC-8923-4889869519-p-434225626
http://www.instructables.com/id/How-to-make-glow-stick-goo./
http://en.wikipedia.org/wiki/Phosphorescence
CRT phosphors are surely faster than 500ms.
If you need variable delay you can always go the photodetector—delay (sample and hold?)—emitter (LED?) route.
crt phosphors are definetly fast emitters... at least faster than refresh frequency of the crt... so in the units of milliseconds range.
the fact that something is phosphorescent on the other hand doesn't mean it is able to "use" light energy.
but what about analog and digital?! I don't see any connection...
(and glowsticks are actually not glowing because of phosphorescence)
Um... at the risk of being repetitive, I'd use a PIC and cheat.
I'd hook up a light sensor to the PIC - LDR is easy for the PIC to convert light to digital - and then make the PIC read light very infrequently, like maybe 10x/second, then light the LED according to some remember-and-fade-away algorithm by PWM.
Jellyfish and fireflies, etc. use "bioluminescence"
http://en.wikipedia.org/wiki/Bioluminescence
While squids and fish control bioluminescence with "photophores"
http://en.wikipedia.org/wiki/Photophore
I suppose a small electric current might be enough to induce oxidization of the Luciferin and therefore produce short bursts of soft blue or green light in the "goo", but according to the article, the enzyme Luciferase may be used to speed up the reaction.
There are lots of possible uses for the stuff, but it is apparently quite unstable when removed from the organism that produces it.
As far as I know, no viable substitute has been found.
no chance an enzyme will survive more than 10 seconds in a stompbox like environment... fluorescence is something easyer to handle, and the "fading" could be made with electronics...
by the way, what is this about??
Sometimes slow is cooler, such as like with LDR and then an LDR Voltage setting R with a cap on it...slows it right down !
Something to put on an LED to make it 'sluggish' ie some of the charge output would be sucked up by the charge storing 'unobtanium' then the LED and the UT substance would contribute to charge being released outside the smear of UT, as the LED faded instantly' to complete darkness, the unobtainium would then still be dissipating enough so that the LDR almost or barely/slowly gets to it's 'normal zero point'.
So then it'd be real easy to fiddle with LFO ramp rates Vs. Unobtainium smear thicknesses, even a blinking light would seem less 'blinky' and more fade-ish.