Ultraviolet Torch

Have been trialing out this project with quite a few kids recently and have got a great response. It's super simple to build, cheap to make, and can help teach a broad range of topics.

There are all sorts of learning objectives you can teach with this one from early primary through to late secondary:

Light & shadow, color and vision
Electric circuits - basic series circuits, circuit symbols and diagrams, switches, LEDs and batteries
Microbes and diseases - transmission of diseases, hand washing and infection, bacteria
Atomic theory, the atomic model and electron shells, fluorescence and phosphorescence

I am publishing this simultaneously as both a "business card" version and an education version. They are pretty much the same build but this version leaves out the more complicated (printing) steps required to customize it, and gives much more detail on the educational side. I originally designed this for the Science Museum in London for an educational workshop but got lots of inquiries from teachers about how to use this in their teaching.

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Step 1: What you'll need

All you need is:

A couple of blank PVC ID cards
A 3mm ultraviolet LED
Some 5mm (or 1/4") thick foam of some sort that squishes and returns to shape again
1 x CR2032 lithium battery

You'll also need some way of gluing it together (hot melt glue is good) - I used some double-sided tape I had on hand as I find this much easier with groups of kids - we ran this in the Science Museum with 150 at a time, and didn't fancy all that glue!

I've put together a few links below of suggested suppliers and parts - with postage costs and minimum quantities you're probably looking at $2-$3 each if you order them in 100+. As I order thousands for the workshops I'm running, a couple of people have asked me if I can supply the bits, which I'm more than happy to with everything you need, including the foam already laser cut, white or UV LEDs, pre-printed cards, and batteries (works out around $1.50 each for 10+)

UPDATE: Due to the interest I have setup a little web store to sell these kits cheaply: www.flashlightcards.com

If you'd rather buy all the bits yourself, this is what you'll need:

ID Cards: http://www.smartcardsupply.com/Content/Cards/cards.htm - the cheapest blank ones here work out at about 15c each in packs of 100 and you'll need two for each card. These are pretty standard world-wide.
CR2032 Batteries: http://search.digikey.com/us/en/products/CR2032/P189-ND/31939 - these ones are 28c each
3mm UV LEDs: http://search.digikey.com/us/en/products/UV5TZ-395-30/492-1321-ND/2407229 - about $1 each if you get 25 or more. Something from 390nm to 405nm works OK but the lower the wavelength the better.
Foam: http://mdbuyinggroup.com/products/podiatrist-wholesale/plastazote%C2%AE-14-medium - about $11 which would be enough to make 100. I used 5mm, but 1/4" works as well. There may well be cheaper foams - type is not crucial as long as it is about this thickness - just needs to be able to be squished and return to its original shape.

jadekikyo says: Feb 1, 2012. 1:36 PM

Very cool! I had no idea that some flowers had a UV mark. I'm very curious now though. Now I want to get a uv light and go scoping out wild flowers, lol. I've seen emperor scorpians glow and man do they glow! They look super cool and I don't think you need a very strong light to see it on them.

tomward (author) in reply to jadekikyoFeb 2, 2012. 1:54 AM

Would love to see that - sadly no scorpions in the UK (where I live) that I know of!