Public Lab’s DIY spectrometry kit makes it possible for citizen scientists to do their own spectrometric analysis at home.
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Spectrometry. Listen to yourself say it out loud. Admit it. It sounds cool just to say “spectrometry.”(Whoa you just did it again!) As fans of Star Trek or Star Wars will attest to, spectrometers are must-have instruments in the scientific arsenal. I’m happy to let you know, however, that the use of a spectrometer (a.k.a ‘spec’) is not limited to fictional, futuristic worlds. In fact, from discovering new chemical elements to measuring DNA, spectrometry is a technique that’s dipped its toes in almost every field of research.
What’s all the fuss about a spectrometer?
Before I talk to you about a spectrometer, let me get into a little bit about the properties of light. You might know that objects appear a certain color because they absorb certain wavelengths of light while reflecting others. For example, leaves appear green because they absorb other colors except green. So if you took some leaf extract in a glass tube and passed light through it on one side, the light that comes out of the other side will have lots of green and little of the other colors (because they were absorbed by the leaf extract).
Put on your scientist hat (or a lab coat) and think about that for a moment. You’ll probably say, “Hey! If I can figure out what specific mix of colors a known substance is made of then I can use that to find out what an unknown substance is made of!” And put simply, that’s what a spec does. It’s an instrument that uses light to determine what a substance is made of.
A spec identifies the specific mix of colors that is absorbed by a sample producing what is known as an ‘absorption spectra‘ which is characteristic of that sample. Think of it like a fingerprint for every material. To do this accurately, the spec needs something that can effectively split light into its constituent colors. One option is to use a prism, which you’ve probably seen at some point. Another way is to use a ‘diffraction grating’ which is a surface with many small parallel lines that can also do the same job of splitting light.
One cool everyday object that acts as a diffraction grating is a CD or DVD. The tiny grooves on the disc act like a grating and split white light giving off the rainbow of colors that you see on its back side. The Public Lab DIY spec uses a DVD as a diffraction grating. The image below describes how a simple DIY spec works. And that’s the Cliffs Notes version. Public Lab’s spectrometer curriculum has lots more detail!
The Public Lab DIY Spectrometer
Our friends over at Public Lab have made it possible for you to do your own spectrometric analysis at home! When it started, the goal of the project was to create a cheap, do-it-yourself spectrometer that anybody could use to analyze materials and contaminants like oil spills and tar residues in urban waterways. In 2012, the team came up with an idea for a spec and crowd-funded it on Kickstarter. The Kickstarter project was a massive success and now Public Lab is selling the DIY desktop kit for $40 in its online store. However, if you prefer to build it from the materials you have at home, they have a great instruction manual for how to make it yourself.
They have also made a smartphone compatible Foldable Mini Spectrometer ($10 in the store) that you can carry around (and show off!). To be able to actually use the spec, the team at PublicLab built an open source software called Spectral Workbench that runs within your browser to help you record and analyze the data you collect. Whether you buy the kit or build it yourself, the Public Lab community has a wiki style page that is a great information resource.
To make it easier to get started, I’ve put together a plan to get you started with making and using your shiny new instrument:
1. What would you like to do with your spec? Check out this page of spectrometry activities. You can also look up this really cool (and really big!) Kickstarter backers-suggested list of ideas. For fun experiments you can test things like coffee, wine or beer! On a more serious note, you can read about detecting pesticides in fruits. At the end I would suggest you make a list of 2-3 experiments you want to try (if it’s your first time experimenting with a spec, start with an easy one!)
2. Buy the kit or make one yourself. Here’s the list of materials you will need (from the Public Lab website) and here are the instructions.
- stiff black card paper
- a clean DVD-R
- a USB webcam (preferably HD)
- a Type LB conduit body (basically a light-proof box with a couple holes)
- double-sided foam tape and a box cutter/x-acto knife
3. Ready with your spec? Now read up about how to use Spectral Workbench, the software that PublicLab has built to help you capture and analyze your data. You can also watch the introductory video. Spectral workbench also has an open source database of spectra for different materials that you can compare yours to.
4. Connect your spec and fire up Spectral Workbench. Make sure to calibrate your spec using a fluorescent light bulb. This will ensure that your readings are accurate and can be compared between samples.
5. Based on your project, find out how you can prepare your samples for testing.
6. Get some science done! Document your research and share it with the PublicLab community (you will need to sign up to post your research notes). Get input from your fellow citizen scientists to answer questions you might have or improve your experiment.
7. (Optional but definitely recommended!) If Scistarter helped you get started, tell us how it worked out. Give us a shout out on Twitter or Facebook! If you haven’t already, sign up to learn about cool projects in the future.
Images: PublicLab.org, Wikipedia
Arvind Sureh graduated with his MS in Cell Biology and Molecular Physiology from the University of Pittsburgh. He holds a Bachelor’s degree in Biotechnology from PSG College of Technology, India. He is also an information addict, gobbling up everything he can find on and off the internet. He enjoys reading, teaching, talking and writing science, and following that interest led him to SciStarter. Outside the lab and the classroom, he can be found behind the viewfinder of his camera. Connect with him on Twitter, LinkedIn or at his Website.