Dear ZWS,
I’m technical support from Seeeduino R&D.
Here 2 type of CO2 sensor that provide to you to choose.
figarosensor.com/products/4161pdf.pdf
figarosensor.com/products/4160pdf.pdf
And another PDF is from TAIWAN.Cheaper but accuracy is not high, because there are non-connect type sensor.
If you want can further connect us.
Yuri
OGS-202F2_R3-CO2.pdf (151 KB)
OGS-201F2_R1 CO2.pdf (192 KB)