Perhaps someone had some experience with CO2 sensors?

I am looking for a decently accurate and good quality C02 sensor for my my environment sensor board based on ESP32 microcontroller. My sensor board is being powered be DC power supply by default but it also has a small battery (800mAh) so it can be unlplugged from DC and still be used for a while if need to take it outdoors.

My desired specifications:

1. 3.3V or 5V powered
2. Any communication protocol will be okay (i2c,serial,analog)
3. As little power consumption as possible ( from what I know some CO2 sensors use heating element which draws a lot of current hence not ideal for battery powered application)
4. Life expectancy - 5 years minimum
5. Budget < 50€
6. CO2 concentration range minimum (200-5000ppm)
7. CO2 concentration range ideal (0-10000ppm)

Some options I am considering:

https://www.dfrobot.com/product-1023.html

https://www.digikey.lt/en/products/detail/senseair/004-0-0010/10416531

 

You have omitted one important specification: CO2 concentration range.

 

You have omitted one important specification: CO2 concentration range.

You are right! I have added it to my initial post.

Funny note:
I remember you from all the way 2015 (When I joined this forum). What a good lad you are - probably helped thousands!

 

Some years ago I was helping my daughter's team at her university to monitor CO2 during respiration, to build a capnograph. Here's the letter I sent her a the time. Maybe the links are still helpful.

I've been researching a bit into what is required to make a capnometer. Looks like the consensus is to use IR, which you already know. The chemical sensors are cheaper but would require diluting breath with air to bring the CO2 level into range. I still contend this could be a way to go. BTW, if you had a capnometer, doe the team have what you'd need to make a capnograph? I mean, some sort of data acquisition and a computer? If not, getting an "average" value could be a challenge. You'd have to integrate one breath at a time. Maybe doable, but getting tricky.

So I looked up the absorbance spectrum of CO2, and happened to find the spectrum of water at the same place. Turns out there's a LOT of overlap, with water being more absorbent at most wavelengths (proving that CO2-as-greenhouse-gas is rubbish, but that's another story). The overlap with water is important since I imagine moisture in breath would otherwise throw off your readings. Fortunately, one peak for CO2 is at 4.26µ (4,260 nm) and is not shared by water. So you SHOULD be able to build a capnometer. They exist already, so we knew that.

I've managed to find a source for LEDs that emit in that area, see here. They seem willing to offer some applications help, but their website is bleak. The UK site may just be a collaboration with these Russians, who appear to be the "real" source of those same LEDs. They've published papers on the topic and should be happy to send you copies. I haven't found ANY other mid-IR LED source.

This is cool - I think this is a hat to detect CO2 or CO ! I couldn't find anything more on it, though.

Here's an industrial (not medical) CO2 sensor. It's $300, but looks pretty good otherwise. Looks like a good company, too. Maybe they'd sample you if you send them a U of I sweatshirt. Try it, you'd be surprised.

There are more suppliers here, in case you hadn't already seen these. Being Chinese, these guys might be cheap. Or these.

And finally, you really should see this.

 

Perhaps someone had some experience with CO2 sensors?

I am looking for a decently accurate and good quality C02 sensor for my my environment sensor board based on ESP32 microcontroller. My sensor board is being powered be DC power supply by default but it also has a small battery (800mAh) so it can be unlplugged from DC and still be used for a while if need to take it outdoors.

My desired specifications:

1. 3.3V or 5V powered
2. Any communication protocol will be okay (i2c,serial,analog)
3. As little power consumption as possible ( from what I know some CO2 sensors use heating element which draws a lot of current hence not ideal for battery powered application)
4. Life expectancy - 5 years minimum
5. Budget < 50€
6. CO2 concentration range minimum (200-5000ppm)
7. CO2 concentration range ideal (0-10000ppm)

Some options I am considering:

https://www.dfrobot.com/product-1023.html

https://www.digikey.lt/en/products/detail/senseair/004-0-0010/10416531

A while ago I looked at the Kemet USEQGSEAC82180 (Mouser £20.53) for a project and although this didn't proceed, the specs were favourable (22uA at 3.3V). Not as easy to implement as the ones you are considering as you would need your own PCB or a dev kit (Mouser £60)

 

Have you tried doing a google search for "DIY CO2 monitor" ? I get a lot of hits - for instance https://sensirion.com/media/documents/E0F04247/631EF271/CD_DS_SCD40_SCD41_Datasheet_D1.pdf.

 

Have you tried doing a google search for "DIY CO2 monitor" ? I get a lot of hits - for instance https://sensirion.com/media/documents/E0F04247/631EF271/CD_DS_SCD40_SCD41_Datasheet_D1.pdf.

Of course I did As you can see, there are many options available. The purpose of this thread was to hope that someone had some practical experience with any of CO2 sensors and could give me some practical suggestions.

I have been lately looking at:
https://www.digikey.lt/en/products/detail/senseair/006-1-0100/17125330

This sensor is mainly used for HVAC applications. What I am mostly concerned with is the handling of the sensor. How sensitive this sensor is to handling?

Since I am building a battery powered application where the user will be handling the enclosure and touching it with bare hands, there is a chance that the user will touch the diffusion area. I am not sure how sensitive this area is to bare hand touches. Maybe its gonna cause the sensor to work incorectly after a few touches. Can I clean this area if it gets dirty?





The sensor that you have suggested seems very simillar. It also has a diffusion area for sensing the CO2.