The Light Fountain: a Bioluminescent Hourglass

Imagine having a lamp that requires no energy and turns off on its own. Also imagine having a pet that won't die without your constant supervision. These come together in the bioluminescent hourglass!

Bioluminescence is the ability of organisms to emit light, and has independently evolved in several different species. In the Bioluminescence Community Project at BioCurious, we've been working with a number of bioluminescent organisms, including tiny, single-celled creatures called dinoflagellates that live in the ocean are responsible for the phenomenon of glowing waves.

Dinoflagellates are a type of algae that will light up at night when they are being perturbed. Here, we give them a nice gentle stimulation to get them to glow, by running them through an hourglass

You can order dinoflagellates online at one of the links listed here.

Step 1: Prototype

Materials:

- 2 plastic bottles, with screw caps
- glue
- thin plastic tubing, such as the ink tube from a ballpoint pen, or tip of a narrow plastic syringe

Tools:

- drill (or hand-driven drill bits)
- knife

Rescue some plastic bottles with screw caps from the recycling bin and rinse them thoroughly.

Glue two screw caps back-to-back (we used hot glue, which is probably not the best choice, but has held up so far). Now you can poke a hole through both caps... which doesn't work terribly well. It turns out that if you only poke a single hole, you have to make it fairly large, because as the liquid wants to drip down, the air in the bottom bottle wants to go up, so if you poke a small-ish hole, surface tension will stop the whole thing from working!

We found out that it is much more effective to drill or poke two holes through the caps, and glue in place two little tubes, one pointing up, the other pointing down. That way there is a separate route for liquid to drop down, and one for air to bubble up.

You may need to slice the tubes at an angle to prevent surface tension from stopping the flow of drops. We used the ink tube from an empty Bic pen first, which worked but did not give a very reliable stream. Searching around for some other plastic tubes to use, we stumbled upon a box of very narrow plastic syringes in the lab. The tip of those syringes proved perfect for our purposes (see picture). Have a look around! You might stumble across something that works just as well - maybe the dispenser tip of a tube of superglue?

Fill up one of the bottles with your liquid of choice (for demonstration purposes, we used water with some green food coloring). Screw on the double cap, and screw the empty bottle on top of that. Invert and watch the show...

This prototype, with the syringe tips, took about 9 minutes to empty, and ran very reliably.

Step 2: The Big Kahuna

Materials:

- 2 1000mL Erlenmeyer flasks
- 2 matching (probably #9) rubber stoppers; the 2-hole variety, if you can find them
- 2 glass eye droppers
- 2 ~7 inch round wooden plaques
- 3 2 ft threaded rods (I believe we used 1/4 in.-20)
- 5 ft copper pipe (1/2 inch)
- 6 wing nuts of same size as the rod
- 6 acorn bolts of same size as the rod
- 6 washers
- 2 mouse pads or rubber matting

Total cost: ~$65

Erlenmeyer flasks and matching stoppers can be bought at laboratory supply stores, but many brewery supply stores carry them as well - much easier to find, and no questions asked! If you get second hand flasks on eBay or a second hand store, make sure you clean them very well (duh!), because "you don't know where that's been"...

Nice premade round wooden plaques can be found at arts and craft stores for just a few bucks. Ironically, you can often find almost exactly the same plaques under clockmaking supplies for double the price or more.

Tools:

- Pipe cutter
- Hack saw
- Scissors
- Freezer (optional)

Rubber stoppers with two holes seem to be hard to find. And forget about using the cork borer from your old chemistry set to poke a hole through a solid chunk of natural or synthetic rubber - it will merely bounce off. The best way to get a hole through a stopper (as recommended by the nice people at my local brewery supply store) is to freeze them as cold as you can, and then drill the hole.

Start with a small diameter drill and take it slow, clearing out rubber crumbs along the way. Gradually increase diameter of your drill bit until the hole is almost big enough to fit the glass eye dropper. If the rubber gets too hard to work on, pop it back in the freezer and work on the second stopper for a while. At the end, you can "polish" the hole with the drill on a higher speed, to get a smoother finish. Make sure the holes are nice and straight, and line up exactly with the holes on the second stopper!

Draw a circle on your wooden plaques with a diameter equal to that of the Erlenmeyer flasks. Mark three equidistant points along that circle (draw an equilateral triangle, or just eyeball it), and drill three holes just outside of the circle, with a drill bit larger than the threaded rod. The rods should slide easily through the drilled holes, and the flasks should sit easily between the rods without touching them.

The purpose of the copper pipe is to hide the unsightly threaded rod, and to prevent you from over-tightening the wing nuts on your contraption, which could wedge the stoppers in so tight they'll be hard to remove, or even crack the flasks! We put a layer of mouse pad material under each flask, to hold the flasks firmly in place against the wooden plaques, and also to give a bit more leeway to tighten the nuts. So you'll want to make sure to cut the copper pipe to length just a bit shorter than two flasks+stoppers, plus the thickness of two mouse mats. A pipe cutter as in the picture makes it a real joy to cut copper pipe effortlessly.

Insert all three rods through one of the round plaques, and add a washer and a wing nut on each. Cap the rod with an acorn nut - these will be the "feet" the hourglass rests on, so we don't want to scratch any surfaces by leaving the rod bare. Leave as little space between the wing nuts and acorn nuts as possible, so your hourglass doesn't wind up on stilts. Insert the two flasks, with some mouse pad padding on either end, add the second plaque on top, and three washers and wingnuts to hold the whole thing together. Mark on the threaded rods where would be a good place to cut them using the hacksaw. Now disassemble the whole thing, cut of the rods where you marked them, using a hacksaw, reassemble everything again, and cap with three more acorn nuts. Yes, disassembling and reassembling is a pain, but at least this way the length of the rods will be just perfect. Do make sure all three rods are exactly the same length, otherwise your light fountain will stand lopsided...

The last image above shows two of our junior scientists putting together the first version of the Light Fountain at BioCurious.

Step 3: The Light Fountain in Action

The first image above shows the Light Fountain on display at the East Bay Mini Maker Faire last October, filled with highlighter fluid (fluorescein). Next to a flask with steaming dry ice (cuz, well, we're scientists, right?)

The second image illustrates that fluorescein fluoresces very brightly under UV light - quite spectacular! You can just see a litle violet glow of the UV LEDs at top and bottom.

The final picture is of the Light Fountain filled with dinoflagellates. Hard to photograph, because they are not nearly as bright - but mesmerizing to watch in person!

We removed the flasks from the setup and filled them with a batch of dinoflagellates (in our example, Pyrocystis Lunula). In a room with minimal light, we reassembled the light fountain, turned it so the flask full of dinoflagellates was on top, and started a stopwatch. The light fountain took about 7 minutes to fully empty into the other flask.

One thing to note is that dinoflagellates need to maintain a circadian rhythm (day and night). They give off light at night in relative darkness. After about a month, they will require a monthly addition of growth media to survive. They were kept at room temperature away from windows or lamps or other sources of heat. This instructable provides instructions on how to care for your dinoflagellates.

Alternative: Other bioluminescent organisms can be used here, such as the Vibrio Fischeribacteria from this instructable. We have a big 1L culture of Vibrio growing up right now, and will post some more pics when it is ready to glow.