Measuring Phase Shift. A wave generator might be a good temperature sensor if you calibrate it over days

Andrey’s Electronics: Measuring Phase Shift with an Analog Multiplier at https://www.youtube.com/watch?v=Vh3FIJr666s

Stabilize your camera or get a flexible stable tripod. You have good stuff but you are jumping around. Nowhere have I seen anyone put the DC offset so well. But you need to hammer and refine, improve and re-do this until is is perfect enough for 5 Billion Internet users. Get some 24 bit 1 Msps ADCs and record the data for 24 hours. Your “temperature sensitive” and “sensitive to breathing on it” device is an uncalibrated sensor.. Maybe a good one – if you calibrate it. Package it and is can be useful for learning. Richard Collins, The Internet Foundation