So. I have a smartphone, and it is indeed smart.
I have bought a plug-on device called a Re, which is
basically an infrared LED and some driver hardware, that
plugs into the phone's connector. With this, and the
associated app, I can use my phone as a fully-
programmable remote control.
I have endless fun
changing channels on cafe TVs and other such childish
This is all well and etcetera, but it means I have to carry
the Re around with me. It's very small, but it still gets
forgotten, and I've already lost one.
The phone maker should, of course, build an IR LED into
the phone. But they haven't.
However, my phone does have a superbright LED for use as
a camera "flash" or as a torch.
What is called for is a small amount of a fluorescent
compound which absorbs at one of the wavelengths of the
"white" LED, and emits in the infrared. Such fluorophores
exist, both as dyes and as quantum dots (which are more-
A clearish paint, or adhesive tape, could therefore be
applied over the white LED. It probably doesn't need to
obscure all, or even most, of the LED - so there would still
be plenty of white light for normal use. But now the
"flash" LED would also emit in the infrared and, with
suitable apps, could act as a remote.
Would it be bright enough? Probably; Qdots (as an
example) are very efficient fluorophores. What I am not
sure of, though, is whether regular IR-LEDs are directional
and whether the fluorescence of this pseudo-IR-LED would
be directional enough.