Color change methods, new tools and activities in broader GOSH



@lizbarry Talked today about color change methods. There’s more and more in the ag space, around both water quality, soil quality, and other stuff. Here’s a few things I’m aware of / things we’re working actively on:

  1. heard from a friend in the ag space (especially regenerative ag) they are quite excited about this --> . This is a soil test that differentiates, in the field, the types of microbiology present. They use a card-based color change method, and their app has software for quantifying the color change from an image. The typical method for this (which I think they use) is to normalize the camera to a black/white or colored object on the card which is standard.

  2. We’re going to try to run a few environmental tests, like these enzyme based tests for nitrates, total nitrogen, and phosphorous - , on the dropbot ( The color change can be quite subtle, so the tests we’ll run will be mostly to determine the accuracy we can get from the test - here’s more from Ryan - [hackathon project] Developing an automated workflow for colorimetric testing using digital microfluidics. We will likely try to differentiate color using a specially designed spectrometer from Alex at U of T, the Our Sci spec, and just images via openflexure to see what works and how well. The key here is once we have a repeatable method of known accuracy to color changes, we can then broaden that really to any color change method that can be done using the dropbot (meaning you need to move, mix, or wait with the liquid). There’s a lot of those! Also, other than using the dropbot, we can already do this all on the colorimeter / reflectometer we built, but of course that’s in larger quantities one shot at a time (and we sell it through BFA as a developer kit, but it’s just a colorimeter -

  3. Also… in terms of color determination using a cell phone, you may want to check out - . Their new version of the app (which is open source, but isn’t very public… so you’d need to contact the dev) uses color determination on the phone to try to differentiate soil types… so they definitely are addressing a similar technical challenge to what you’re interested in. Also, I believe their app is cross platform so it’s all written (I assume) in javascript and HTML5 so maybe usable. Anyway, can connect you if you run into trouble finding the right person.


thanks for the info @gbathree !
two questions…

  • do you know how method 1 works? does it really differenciate between microorganisms? or is just the bulk microbe biomass?
  • why and how are you going to use the openflexure? what extra info can you get with a microscope in a color change?


Hey @nanocastro no I do not know how it works… it’s not open source, but is interesting.

Well, I think of using open flexure similar to a well plate reader, but for one small well (like on the dropbot)… the questions is just can you get comparable and accurate enough results given that it’s a camera and camera’s are notoriously hard to calibrate and compare. However, it seems that richard and Julian are working on it --> Certainly camera’s are easier and cheaper and simpler (in theory) than a spectrometer, so feels like a good option to investigate.