DrJ
Member
- Joined
- Jun 16, 2015
- Messages
- 723
Probably like many people here, I've looked into buying a capnometer to monitor CO2 levels in my exhaled breath. Of course, they are very expensive! Looks like at least $1000 USD or more. Since I had some free time with the Thanksgiving holiday, I thought I'd look into what it would take to make one...
And it seems quite possible! As far as I can tell, you can buy an integrated circuit CO2 sensor, solder some wires between it and something like an Arduino to read the sensor output; power can probably be supplied by the Arduino. It seems an adequate sensor runs about $155USD in qty 1, and then an Arduino is about $25USD. Some misc wiring and solder would be needed, as well as some sort of tubing scheme to direct your breath to the sensor, and I would assume people have a computer to talk to the Arduino, but seems possible to build a basic but functional capnometer for under $225USD and a little programming. Still not exactly cheap, but more approachable than buying one.
Anyone see any problems with this? Or has ever tried it or know of someone who has? I don't really have a feel for the accuracy required, nor exactly how to go about calibrating the thing. It seems human exhaled breath has about 300,000ppm CO2, and I would guess you would want 1-2% accuracy on that number. Background air CO2 levels seem to be about 350ppm. Do these numbers sound right?
And it seems quite possible! As far as I can tell, you can buy an integrated circuit CO2 sensor, solder some wires between it and something like an Arduino to read the sensor output; power can probably be supplied by the Arduino. It seems an adequate sensor runs about $155USD in qty 1, and then an Arduino is about $25USD. Some misc wiring and solder would be needed, as well as some sort of tubing scheme to direct your breath to the sensor, and I would assume people have a computer to talk to the Arduino, but seems possible to build a basic but functional capnometer for under $225USD and a little programming. Still not exactly cheap, but more approachable than buying one.
Anyone see any problems with this? Or has ever tried it or know of someone who has? I don't really have a feel for the accuracy required, nor exactly how to go about calibrating the thing. It seems human exhaled breath has about 300,000ppm CO2, and I would guess you would want 1-2% accuracy on that number. Background air CO2 levels seem to be about 350ppm. Do these numbers sound right?