If you've ever played with a black light, you've noticed that some substances glow brightly under these lights. In this case, we'll be using tonic water because it contains small amounts of quinine which glows a bright blue under ultraviolet.
Internet research shows that Quinine glows best under ultraviolet light at the wavelength of 350 nanometers (nm).
As far as I can tell, LEDs are not available at that wavelength, but quinine will still glow from nearby wavelengths. An ebay search turned up 355nm LEDs for $65 each (too expensive!) and 365nm LEDs for about $2 each, including shipping. The most time consuming part of this project for me was waiting the many weeks for ten 365nm LEDs to arrive from China. If you want to do this project, I suggest you go ahead and order a batch of these now.
- container with clear or lightly colored sides, and preferably a thin plastic lid
- Arduino to power your LEDs
- bottle of tonic water
- ultraviolet LEDs ( 365nm for choice of cost and quinine sensitivity)
- wires to connect LEDs to Arduino