Spectrophotometry is an excellent teaching topic in science classrooms because it can bridge understanding of how different physical phenomena can be studied using one simple technique. But spectrophotometers can be expensive for high school budgets and third world clinical chemists, and the typical closed box design of these devices doesn’t help either. Alexander Scheeline, a chemistry professor at University of Illinois at Urbana-Champaign has developed a cheap and simple kit to convert almost any camera phone into a basic spectrophotometer at a cost of less than $3. And since just about every kid now has a camera phone, a class of 30 students can be outfitted for about $100.
For a light source, Scheeline used a single light-emitting diode (LED) powered by a 3-volt battery, the kind used in key fobs to remotely unlock a car. Diffraction gratings and cuvettes, the small, clear repositories to hold sample solutions, are readily available from scientific supply companies for a few cents each. The entire setup cost less than $3. The limiting factor seemed to be in the light sensor, or photodetector, to capture the spectrum for analysis.
“All of a sudden this light bulb went off in my head: a photodetector that everybody already has! Almost everybody has a cell phone, and almost all phones have a camera,“ Scheeline said. “I realized, if you can get the picture into the computer, it’s only software that keeps you from building a cheap spectrophotometer.”
To remove that obstacle, he wrote a software program to analyze spectra captured in JPEG photo files and made it freely accessible online, along with its source code and instructions to students and teachers for assembling and using the cell-phone spectrometer. It can be accessed through the Analytical Sciences Digital Library.
Scheeline’s study in Applied Spectroscopy: Teaching, Learning, and Using Spectroscopy with Commercial, Off-the-Shelf Technology
Full story: Can you analyze me now? Cell phones bring spectroscopy to the classroom…