# +-0.1°C Infrared Temp Sensor

Hi, I'm building a temperature gun right now (to measure fever) and am looking for an infrared temperature sensor with an accuracy of +-0.1°C. Does anybody know of any? I've only found some with +-0.5°C which obv. isn't enough.

Daniel

I've only found some with +-0.5°C which obv. isn't enough.

Why obvious ? If a difference in temperature of only 0.1°C makes the difference between possibly having the virus and not having it then I think that you are onto a loser.

What will the current temperature be compared with ?

Quote from: UKHeliBob Fri Oct 09 2020 12:30:23 GMT+0200 (Central European Summer Time) Why obvious ? If a difference in temperature of only 0.1°C makes the difference between possibly having the virus and not having it then I think that you are onto a loser.

Huh, that is true I guess, hadn't really thought about it that way. Thanks for pointing out that flaw. I guess i'll have to find a sweet spot in range that is safe but still wont show to many false positives.

What current temperature am I comparing it with? I'm kind of confused. My plan is to note if temperature is higher or lower than 38°C and trigger red/green led accordingly, also reading temp on lcd, if that is what you mean.

It would be better to use a higher accuracy sensor so that I could lower the error bounds in the code.

For example a 0.5°C accuracy thermometer: 38°C could show as up to 37.5°C, which would mean that a person with a fever would be considered well below fever temp. Therefore, in the code, i'd have to set the 'fever line' at 37.5°C to be safe. However, many people have this temperature as there normal body temperature, and would therefore falsy be recognized as having a fever.

Alternatively, a 0.2°C accuracy thermometer would mean that a fever line of 37.8 would be safe, affecting less people with that body temperature.

Am I missing something?
Thanks,
Daniel

My plan is to note if temperature is higher or lower than 38°C and trigger red/green led accordingly, also reading temp on lcd, if that is what you mean.

That should be easy, but my normal temperature may not be the same as yours and both may vary depending on the circumstances of the test such as whether we have recently come indoors from a hot or cold environment

All your test can show is whether the current skin temperature is above or below an arbitrary threshold unless you have a history for the individual being tested in the same circumstances so can detect a change in temperature

Yeah I researched some more and found that while difference in body temperature is less of an issue, circumstances play a heavy role in the accuracy of these thermometers. Also, thermometer guns are 'notoriously inaccurate' (Times) so it would be even less wise to use the result of this project in real life. However, I did learn a lot from this first creative project, and will be discontinuing it (I've already finished it but with a tmp36 sensor instead).
Thanks for you advice though u/UKHeliBob!

Daniel

I am glad that you got it working but didn't waste time on making it more accurate, but it is, of course, your time to waste when you do it as a hobby and the techniques learned doing this project may come in useful in future projects