I'm a visual artist and currently working on a project for an exhibition. It includes a cube with LEDs installed inside and a peephole. When the audience look into the peephole to see inside the box, a sensor would sense their breathing, so it could change the brightness of the LEDs according to it—breathing out would equal brighter light, breathing in would decrease the light's intensity.
So my question is: is there any sensor that would enable me to do this? I'd prefer a cheap one - and I need it to be small.
Please don't post the same question in different parts of the forum.
(I deleted the other one)
You could use a BME280 to detect the increased humidity of being breathed-on, but you might want to include a small fan to clear the air once triggered.
The BME280 also measures temperature. Assuming the ambient temperature is significantly less than the breath temperature, you might be able to detect breathing in vs out. You could compare which reading is the most reliable or use both together.