RAK12009 breathalyzer setup

Hi everyone, was considering a project, making a breathalyzer to measure the concentration of alcohol on the breath of the user. Seems like a reasonably simple setup with the RAK12009 WisBlock MQ3 Alcohol Gas Sensor.
My question is in relation to enclosure and how to keep it relatively sterile. I was going to locate it in the B4 outdoor enclosure. If I make a vent for the user to blow into (obviously with a vent out also), it would not be great for the pcb. How would others approach this?
I think best practice to get the most accurate is a “big” blow onto the sensor, as the last part of your breath has the most consistent reading (google reading)…

Hi @Andy ,

I have no experience on making breathalyzer. However whenever there is a new things to design, I always look on how other do it and see their approach. From there, we can see what might be the good practice and what can possibly be improved. Like on this teardown of a breathalyzer. It seems these breathalyzer has removable tip where the subject put his mouth.

As for the enclosure, I think B4 outdoor enclosure is big and not too handy.

My recommendation is to use the small Unify Enclosure - Unify Outdoor Enclosure IP65 100*75*38 | WisBlock Weatherproof Enclosure – RAKwireless Store

Then combo it with a belt clip mounting accessory - Unify Belt Clip Kit (Type E) – RAKwireless Store

You might need to do some 3D printed path way for the blowing air though.

thanks @carlrowan, I’ll check it out.