IO Rodeo Goes Ultraviolet with Its New UV Open Colorimeter Tool for Citizen Scientists

Capable of picking up on proteins and other molecules invisible to the original, the UV Open Colorimeter is now available.

IO Rodeo has launched a new variant of its open source Open Colorimeter analysis tool for educators and citizen scientists, shifting towards the far end of the spectrum with the new UV Open Colorimeter.

The original Open Colorimeter launched back in October 2022 as a tool to enable citizen science and educational experiments in the analysis of fluid samples. The open source gadget, driven by an Adafruit PyBadge running CircuitPython, shines a light of a specific wavelength through the fluid to be tested and measures how much of the light makes it through without being absorbed. By analysing the results, it's then possible to determine how much of the target analyte is in the sample.

The Open Colorimeter launched with a white LED as its light source, with optional 470nm, 520nm, 570nm, 595nm, and 630nm sources available. The UV Open Colorimeter, brought to our attention by Adafruit, takes things to a new dimension by swapping the LED for one which outputs one of six different wavelengths of ultraviolet light — 275nm, 278nm, 365nm, 385nm, 395nm, and 415nm — and the sensor for an Osram AS7331 with UV-A, UV-B, and UV-C measurement channels.

"These light wavelengths can be used to study both UV absorbance by proteins and other molecules, as well as used to excite fluorescence," Long explains. "In the tutorial […] we used the 275nm LED and the UV Open Colorimeter UV-C channel to measure absorbance of the standard protein, bovine serum albumin (BSA). We can see a linear relationship between light absorbance and BSA concentration. From our data we also calculated the molar extinction coefficient of BSA with the UV Open Colorimeter."

The UV Open Colorimeter is available to order on the IO Rodeo website starting at $220 with a 415nm light source; additional sources are available for between $8 and $26 each, depending on wavelength required. The firmware source, meanwhile, is available on GitHub under the permissive MIT license.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire:
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