Pulse Oximetry Sensor Judges Your Coffee Roast

Pulse Oximetry Sensor Judges Your Coffee Roast

Breakout board for the MAX30101, which [Zach] used as the basis of his roast gauge. The sensor is at the top edge of the board.
Parts designed and marketed for a specific application can nevertheless still be useful in other ways, and whenever that happens, it’s probably the start of a pretty good hack. Using a sensor for something other than its intended purpose is exactly what [Zach Halvorson] did to make the Roast Vision device, which uses the MAX30101, a sealed optical sensor intended mainly for pulse oximetry and heart-rate monitoring.

[Zach] is instead using that sensor to measure the roast level of coffee beans, and assign a consistent number from 0 to 35 to represent everything from Very Dark to Very Light. Measuring a bean’s roast level is important to any roaster seeking accuracy and consistency, but when [Zach] found that commercial roast gauges could easily cost over a thousand dollars, he was sure he could do better.


[Zach] settled on using a Sparkfun MAX30101 breakout board to develop his device, and Sparkfun shared an informative blog post that demonstrates how making hardware and tools more accessible can help innovative ideas flourish. The Roast Vision device has a 3D printed enclosure, and a simple top-loading design with an integrated sample cup makes it easy to use. One simply puts about a teaspoon of finely-ground coffee into the sample cup, and the unit provides a measurement in a couple of seconds. Fortunately the sensor works just ..

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