EYE on NPI: Amphenol T6793 CO2 Sensor Module

This week's EYE ON NPI is a breath of fresh air - with the Amphenol Telaire T6793 CO2 Sensor Module (https://www.digikey.com/en/product-highlight/a/amphenol-advanced-sensors/t6793-co2-sensor-module), another great sensor we are happy to highlight from Amphenol Advanced Sensor group (https://blog.adafruit.com/2020/07/23/eye-on-npi-amphenol-ztp-148src1-thermal-sensor-eyeonnpi-digikey-adafruit-amphenolsensors/). This time it's a sensor to detect the concentration of CO2 in the air. Carbon dioxide, aka CO2, is a gas that is an essential part of the Earth's atmosphere and life in general. However, while essential, it can have negative effects when concentrations exceed certain level. It can impact the entire planet via global warming. But it can also have very local effects, for example on indoor air quality. Elevated levels of CO2 can lead to reduced cognitive ability and other health related concerns. Therefore, monitoring CO2 levels of inside air can be useful as a part of gauging general air quality. Folks have had CO2 air-quality sensors in buildings and homes for a long time but now they're extremely popular because CO2 levels are correlated with air freshness. Outdoor air is about 400 ppm CO2. Us humans love to breathe in air, extract the O2 and fill rooms with CO2. That means when there's poor ventilation to the outdoors, and lots of humans - the air is going to have higher and higher CO2 concentrations. (https://theconversation.com/how-to-use-ventilation-and-air-filtration-to-prevent-the-spread-of-coronavirus-indoors-143732) We consider under 1000 ppm to be 'good' but really we want to keep it under 600 ppm if we can since that has been shown to reduce transmission of airborne disease. (https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12639) There are two categories of CO2 sensors we see. One is the 'effective CO2' measurement, which is really a VOC sensor using doped MOX variable resistance sensors, and the other are 'true CO2' sensors which use NDIR. For example, the ENS160 breakout (https://www.adafruit.com/product/5606) we recently started stocking is a MOX sensor that will provide measurements of overall air quality based on volatile gases. It can also use this to approximate the CO2 concentration. But note it isn't actually measuring CO2! While this is fine for low cost or basic AQI measurements, it isn't a calibrated or reliable way to measure CO2. Instead, the right thing to do is use an NDIR sensor (https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor) like the T6793 CO2 Sensor Module (https://www.digikey.com/short/h4278vt7), which is a 'true' CO2 sensor that will tell you the CO2 PPM (parts-per-million) composition of ambient air. That means it's a lot bigger and more expensive than eCO2 sensors, but it is the real thing. Perfect for environmental sensing, scientific experiments, air quality and ventilation studies, and more. The Amphenol T6793 CO2 Sensor Module (https://www.digikey.com/short/h4278vt7) is a true NDIR CO2 sensor, with self-recalibration if used outside where it will be exposed to 400ppm CO2 signal at least once a week, and comes in two versions, one with 2Kppm and one with 5Kppm maximums. It's highly stable, and accurate with +-45ppm + 3% of reading accuracy and continuous 5 second readings. One thing we really liked about this sensor is that it has multiple output modes, no matter what your system integration requires. The T6793 comes with a wide selection: 100KHz I2C, UART, RS485 and even PWM output! The module comes with a 6-pin 0.1" / 2.54mm pitch header so it can be swapped out of a larger system after a few years or if the sensor gets contaminated. The PWM pulse rates and I2C registers are documented in the app note (https://www.amphenol-sensors.com/en/telaire/co2/525-co2-sensor-modules/3399-t6713) and there is some some Arduino code available on GitHub for reference. (https://github.com/AmphenolAdvancedSensors/Evaluation_Kits/tree/AAS_AQS_UNO_RH_CO2) If you want high-quality, reliable, and accurate CO2 sensing with a true NDIR sensor - you are in luck because the Amphenol T6793 CO2 Sensor Module (https://www.digikey.com/short/h4278vt7) is in stock right now at Digi-Key for immediate shipment! Order today and you can have this fancy golden sensor ready to use by tomorrow afternoon.