*sniff* *sniff* ... do you smell that? No need to stick your nose into a carton of milk anymore, you can build a digital nose with the Adafruit SGP41 Multi-Pixel Gas Sensor, a fully integrated MOX gas sensor. This is a very fine air quality sensor from the sensor experts at Sensirion, with I2C interfacing so you don't have to manage the heater and analog reading of a MOX sensor. It combines multiple metal-oxide sensing and heating elements on one chip to provide more detailed air quality signals - and, unlike the SGP40, the SGP41 adds a dedicated NOx sensing pixel so you can measure both volatile organic compounds (VOC) and nitrogen oxides!

The SGP41 has two MOX hot-plate sensor elements (one for VOC, one for NOx), as well as a small microcontroller that controls power to the plates, reads the analog voltages, and provides an I2C interface to read from. Unlike the CCS811, this sensor does not require I2C clock stretching. We currently have an Arduino library for reading the raw VOC and NOx signals and a Python/CircuitPython library that can be used with Linux computers like the Raspberry Pi or our CircuitPython boards.

This is a gas sensor that can detect a wide range of Volatile Organic Compounds (VOCs) as well as oxidizing gases such as NOx, and is intended for indoor air quality monitoring. The SGP41 is the next generation after the SGP40, adding a second NOx sensing pixel. It does not give TVOC/eCO2 values out like the SGP30. Instead, the two raw signals from the sensor are processed using Sensirion's Gas Index Algorithm to give VOC and NOx Index values on a scale from 1 to 500 - where 100 indicates a typical indoor environment.

Please note, this sensor, like all VOC/gas sensors, has variability, and to get precise measurements you will want to calibrate it against known sources! That said, for general environmental sensors, it will give you a good idea of trends and comparison.

Another nice element to this sensor is the ability to set humidity and temperature compensation for better accuracy. An external humidity/temperature sensor is required and then the RH% and temperature are written over I2C to the sensor, so it can better calibrate the MOX sensor readings and reduce humidity/temperature-based variations.

Nice sensor right? So we made it easy for you to get right into your next project. The surface-mount sensor is soldered onto a custom made PCB in the STEMMA QT form factor, making them easy to interface with. The STEMMA QT connectors on either side are compatible with the SparkFun Qwiic I2C connectors. This allows you to make solderless connections between your development board and the SGP41 or to chain it with a wide range of other sensors and accessories using a compatible cable. QT Cable is not included, but we have a variety in the shop

We've, of course, broken out all the pins to standard headers and added a 3.3V voltage regulator and level shifting to allow you to use it with either 3.3V or 5V systems, such as the Arduino Uno, or Feather M4.