IO Rodeo Launches the Open Colorimeter, a CircuitPython Analysis Tool for Citizen Science

Designed to measure the concentration of a target substance in fluid, this clever gadget is driven by an Adafruit PyBadge.

Open source scientific instrument specialist IO Rodeo has announced availability of the Open Colorimeter, a 3D-printed CircuitPython-powered gadget designed to drive citizen science and education to new heights — arriving pre-programmed and ready-to-use.

"The Open Colorimeter is an open-hardware science instrument designed for researchers, educators, and hobbyists," IO Rodeo explains of the project. "3D-printed hardware designed using FreeCAD, [and the] electronics include [an] Adafruit PyBadge programmed with CircuitPython. We share in the goal of making science tools (like the Open Colorimeter) community-driven and supported. As always, all of our designs are freely available under open source licenses."

IO Rodeo's Open Colorimeter is now available to buy, offering substance analysis in the palm of your hand. (📹: IO Rodeo)

A colorimeter is typically used to figure out how much of a given substance is in a sample of fluid — the concentration of analyte, to use the official terminology. Light of a specific wavelength is shone through the sample and the amount absorbed subject to high-accuracy measurement, the readings from which can then be used to calculate the concentration.

Typical lab-grade colorimeters aren't cheap, but the Open Colorimeter aims to solve that. Based on IO Rodeo's earlier Educational Colorimeter, which launched in 2012 on the back of a successful crowdfunding campaign as an accessory for the Arduino Uno and compatibles, the Open Colorimeter aims at a broader use-case — thanks to a shift to a four-pin Qwiic and STEMMA QT compatible I2C bus.

The PyBadge-based gadget uses a 3D-printed housing and cuvette holder, and aims for out-of-the-box functionality. For those with specific needs, the bundled white LED board can be swapped for single-wavelength 470nm, 520nm, 570nm, 595nm, and 630nm versions — each tailored to specific analytes.

True to its mission, IO Rodeo is making both the firmware and the hardware available under open source licenses: the firmware has been published to GitHub under the permissive MIT license, while the design files for the enclosure and cuvette holder have their own repositories and are published under the Creative Commons Attribution 4.0 license.

Those who would like a plug-and-play experience, meanwhile, can pick up a fully-assembled Open Colorimeter from the IO Rodeo store at $160 with white LED board, three macro and three semi-macro cuvettes for samples, a light-blocking cap, and USB cable for battery charging; the optional single-wavelength LED boards are available as add-ons at $6 each.

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