Baseline measurement example for as7265x

Qwiic System
1

Heyo, I was reading a paper that used the as7265x spectral sensor to measure the concentration of compounds with nitrogen.

What should the baseline measurements of the sensor be with no light exposure and all LEDs on as well as for no LEDs on?

The absorption they measured was comparatively a lot higher than the absorption I measured. Specifically, UV channel A shows values around 3000 with an aluminum mirror 10mm away from the sensor and in complete darkness.

I’ve replicated the conditions for the sensor almost perfectly, but I don’t know why their values are so much higher than mine, even when I increased my gain to 64x. Please help.

Paper: https://pmc.ncbi.nlm.nih.gov/articles/PMC11078404/
Collected spectral data: S1_Table:SensorConsistencyTest

@Sparkynospark

2

Perhaps not perfectly enough?
You might need to experiment with multiple sensors. Did you use the exact same resin and uv light source?

3

In the experiment, there was no light exposure except for the light coming from the LEDs on the sensor itself.

I used the same type of resin (i.e. UV resin), but not the same brand of resin used in the paper. There aren’t a lot of bubbles, but either way, I doubt refraction can cause as much of a difference in readings from the paper as I’m getting.

The spread of data between dunking the sensor in 1x concentration of nutrient A and 1/4x concentration of nutrient A isn’t a lot. For prediction using the sensor to reliable, I need to have enough variation to create room for standard deviation.

I’m just trying to understand whether my sensor is broken or not or if there’s a setting I should be using that I’m not using.

4

There isn’t some pre-ordained figure; you’d need to test the sensor. Every single testing box have differing volumes, reflectivity, etc…but the first thing I’d focus on is disabling the LEDs so they are not a sneaky variable

1 Like
5

I see. I think you were right with your assumption regarding the status LED in my earlier inquiry. Now I don’t have oscillation. I will probably purchase one or two more sensors and take the average of results to validate readings.