I've been measuring changes in light values for a few months for a research project at school. I have a solution that is backlit by an LED on one side and an LDR on the other. The LDR has given me decent results, but I'm hoping to improve my precision by moving to a different type of sensor. I believe some of the issues I'm having is due to light refraction of the light through the glass beaker holding the solution, not sure. Because of the nature of the project, I can't use a traditional photo spectrometer, but Arduino sensors are pretty much fair game. I've been looking into different types of sensors and I've come across the AS7262 a couple times and was wondering if anyone has had any luck with them? If you have any recommendations for different photosensors, specifically if they were measuring liquid solutions, it would be greatly appreciated!
Photodiodes are much better than LDRs for measuring light intensity, but you generally need an amplifier to convert current into voltage. Here is a good tutorial on how to make one. Or use a commercial module like this one.
Light transmission changes in solution are often caused by light scattering, which can be measured using a similar sensor at right angles to the illumination.
If you are interested in changes in color, you would need filters in front of a photodiode, or a color sensitive detector like the AS7262.
Thank you so much, yes I'm specifically interested in light transmission over color. I will definitely look into it and watch the tutorial.
Another solution sends a variable color through the liquid, and measures the brightness. A variable color can be made using multiple monochrome LEDs of different frequencies/wave lengths. The receiver should be sensitive to a broad range of wave lengths, eventually a LDR is a good choice in this case. In either case the device must be calibrated for the brightness of the different LEDs, using clear water.
Mixing colors of RGB LEDs is not a good idea, because the resulting color consists of multiple monochrome colors only, not a single accumulated wave length.