*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.

The default I2C address is 0x59.

Power Pins

• VIN - this is the power pin. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V microcontroller like Arduino, use 5V. For a 3.3V microcontroller, use 3.3V.
• 3.3V - this is the 3.3V output from the voltage regulator, you can grab up to 100mA from this if you like.
• GND - common ground for power and logic.

I2C Logic Pins

• SCL - I2C clock pin, connect to your microcontroller I2C clock line. This pin is level shifted so you can use 3-5V logic, and there's a 10K pullup on this pin.
• SDA - I2C data pin, connect to your microcontroller I2C data line. This pin is level shifted so you can use 3-5V logic, and there's a 10K pullup on this pin.
• STEMMA QT - These connectors allow you to connect to dev boards with STEMMA QT connectors or to other things with various associated accessories.

Power LED

• Power LED - In the upper left corner, above the STEMMA connector, on the front of the board, is the power LED, labeled on. It is a green LED.

It's easy to use the SGP41 with Python or CircuitPython, and the Adafruit_CircuitPython_SGP41 module. This module allows you to easily write Python code that allows you to read the SGP41 gas sensor. You can use this gas sensor with any CircuitPython microcontroller board or with a computer that has GPIO and Python thanks to Adafruit_Blinka, our CircuitPython-for-Python compatibility library.

CircuitPython Microcontroller Wiring

First, wire up an SGP41 to your board exactly as shown below. Here's an example of wiring a Feather RP2040 to the SGP41 with I2C using one of the handy STEMMA QT connectors:

You can also use standard 0.100" pitch headers to wire it up on a breadboard:

Python Computer Wiring

Since there's dozens of Linux computers/boards you can use, below shows wiring for Raspberry Pi. For other platforms, please visit the guide for CircuitPython on Linux to see whether your platform is supported. 

Here's the Raspberry Pi wired to the gas sensor using I2C and a STEMMA QT connector:

Finally, here is an example of how to wire up a Raspberry Pi to the gas sensor using a solderless breadboard:

Python Installation of SGP41 Library

You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!

Once that's done, from your command line run the following command:

• pip3 install adafruit-circuitpython-sgp41

If your default Python is version 3, you may need to run pip instead. Make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!

CircuitPython Usage

To use with CircuitPython, you need to first install the SGP41 library and its dependencies into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.

Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

Your CIRCUITPY/lib folder should contain the following folders and file:

• adafruit_bus_device/
• adafruit_sgp41.mpy

Python Usage

Once you have the library pip3 installed on your computer, copy or download the following example to your computer, and run the following, replacing code.py with whatever you named the file:

python3 code.py

Example Code

If running CircuitPython: Once everything is saved to the CIRCUITPY drive, connect to the serial console to see the data printed out!

If running Python: The console output will appear wherever you are running Python.

# SPDX-FileCopyrightText: 2026 Liz Clark for Adafruit Industries
#
# SPDX-License-Identifier: MIT

"""Simple test for the SGP41 sensor"""

import time

import board

from adafruit_sgp41.sgp41 import SGP41

i2c = board.I2C()
sensor = SGP41(i2c)

# set ambient temperature and relative humidity
# for more accurate readings from the sensor
# can be used in conjunction with an external
# temp and humidity sensor
# sensor.temperature = 22.2 # Celsius
# sensor.relative_humidity = 30.9

for i in range(10):
    condition = sensor.conditioning()
    print(f"Conditioning the sensor, {(i + 1)} of 10 times: {condition}")
    time.sleep(1)

print("Sensor ready! Starting the loop..")
print()

while True:
    print(f"Raw VOC: {sensor.raw_voc}")
    print(f"Raw NOx: {sensor.raw_nox}")
    print()
    time.sleep(1)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

# SPDX-FileCopyrightText: 2026 Liz Clark for Adafruit Industries
#
# SPDX-License-Identifier: MIT

"""Simple test for the SGP41 sensor"""

import time

import board

from adafruit_sgp41.sgp41 import SGP41

i2c = board.I2C()
sensor = SGP41(i2c)

# set ambient temperature and relative humidity
# for more accurate readings from the sensor
# can be used in conjunction with an external
# temp and humidity sensor
# sensor.temperature = 22.2 # Celsius
# sensor.relative_humidity = 30.9

for i in range(10):
    condition = sensor.conditioning()
    print(f"Conditioning the sensor, {(i + 1)} of 10 times: {condition}")
    time.sleep(1)

print("Sensor ready! Starting the loop..")
print()

while True:
    print(f"Raw VOC: {sensor.raw_voc}")
    print(f"Raw NOx: {sensor.raw_nox}")
    print()
    time.sleep(1)

In the example, the gas sensor is instantiated on I2C and conditioned 10 times over 10 seconds. Then, in the loop, raw VOC and NOx readings are printed to the REPL every second.

Using the SGP41 gas sensor with Arduino involves wiring up the sensor to your Arduino-compatible microcontroller, installing the Adafruit_SGP41 library and running the provided example code.

Wiring

Wire as shown for a 5V board like an Uno. If you are using a 3V board, like an Adafruit Feather, wire the board's 3V pin to the SGP41 VIN.

Here is an Adafruit Metro wired up to the SGP41 using the STEMMA QT connector:

Here is an Adafruit Metro wired up using a solderless breadboard:

Library Installation

You can install the Adafruit SGP41 library for Arduino using the Library Manager in the Arduino IDE.

Click the Manage Libraries ... menu item, search for Adafruit SGP41, and select the Adafruit SGP41 library:

If asked about dependencies, click "Install all".

If the "Dependencies" window does not come up, then you already have the dependencies installed.

Example Code

/**
 * @file simpletest.ino
 *
 * Simple test for the Adafruit SGP41 sensor.
 *
 * Written by Limor 'ladyada' Fried with assistance from Claude Code for
 * Adafruit Industries. MIT license, all text above must be included in any
 * redistribution.
 */

#include <Adafruit_SGP41.h>

Adafruit_SGP41 sgp41;

void setup(void) {
  Serial.begin(115200);
  while (!Serial) {
    delay(10);
  }

  Serial.println(F("Adafruit SGP41 simple test"));

  if (!sgp41.begin()) {
    Serial.println(F("Could not find SGP41! Halting."));
    while (1) {
      delay(10);
    }
  }

  uint16_t serial_number[3];
  if (sgp41.getSerialNumber(serial_number)) {
    Serial.print(F("Serial Number: 0x"));
    for (uint8_t i = 0; i < 3; i++) {
      if (serial_number[i] < 0x1000) {
        Serial.print(F("0"));
      }
      if (serial_number[i] < 0x100) {
        Serial.print(F("0"));
      }
      if (serial_number[i] < 0x10) {
        Serial.print(F("0"));
      }
      Serial.print(serial_number[i], HEX);
    }
    Serial.println();
  } else {
    Serial.println(F("Failed to read serial number! Halting."));
    while (1) {
      delay(10);
    }
  }

  Serial.println(F("Conditioning (10 seconds)..."));
  for (uint8_t i = 0; i < 10; i++) {
    uint16_t sraw_voc = 0;
    if (sgp41.executeConditioning(&sraw_voc)) {
      Serial.print(F("SRAW_VOC: "));
      Serial.println(sraw_voc);
    } else {
      Serial.println(F("Conditioning failed!"));
    }
    delay(1000);
  }

  Serial.println(F("Starting measurements."));
}

void loop(void) {
  uint16_t sraw_voc = 0;
  uint16_t sraw_nox = 0;

  if (sgp41.measureRawSignals(&sraw_voc, &sraw_nox)) {
    Serial.print(F("Raw VOC: "));
    Serial.print(sraw_voc);
    Serial.print(F("\tRaw NOx: "));
    Serial.println(sraw_nox);
  } else {
    Serial.println(F("Measurement failed!"));
  }

  delay(1000);
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82

/**
 * @file simpletest.ino
 *
 * Simple test for the Adafruit SGP41 sensor.
 *
 * Written by Limor 'ladyada' Fried with assistance from Claude Code for
 * Adafruit Industries. MIT license, all text above must be included in any
 * redistribution.
 */

#include <Adafruit_SGP41.h>

Adafruit_SGP41 sgp41;

void setup(void) {
  Serial.begin(115200);
  while (!Serial) {
    delay(10);
  }

  Serial.println(F("Adafruit SGP41 simple test"));

  if (!sgp41.begin()) {
    Serial.println(F("Could not find SGP41! Halting."));
    while (1) {
      delay(10);
    }
  }

  uint16_t serial_number[3];
  if (sgp41.getSerialNumber(serial_number)) {
    Serial.print(F("Serial Number: 0x"));
    for (uint8_t i = 0; i < 3; i++) {
      if (serial_number[i] < 0x1000) {
        Serial.print(F("0"));
      }
      if (serial_number[i] < 0x100) {
        Serial.print(F("0"));
      }
      if (serial_number[i] < 0x10) {
        Serial.print(F("0"));
      }
      Serial.print(serial_number[i], HEX);
    }
    Serial.println();
  } else {
    Serial.println(F("Failed to read serial number! Halting."));
    while (1) {
      delay(10);
    }
  }

  Serial.println(F("Conditioning (10 seconds)..."));
  for (uint8_t i = 0; i < 10; i++) {
    uint16_t sraw_voc = 0;
    if (sgp41.executeConditioning(&sraw_voc)) {
      Serial.print(F("SRAW_VOC: "));
      Serial.println(sraw_voc);
    } else {
      Serial.println(F("Conditioning failed!"));
    }
    delay(1000);
  }

  Serial.println(F("Starting measurements."));
}

void loop(void) {
  uint16_t sraw_voc = 0;
  uint16_t sraw_nox = 0;

  if (sgp41.measureRawSignals(&sraw_voc, &sraw_nox)) {
    Serial.print(F("Raw VOC: "));
    Serial.print(sraw_voc);
    Serial.print(F("\tRaw NOx: "));
    Serial.println(sraw_nox);
  } else {
    Serial.println(F("Measurement failed!"));
  }

  delay(1000);
}

Upload the sketch to your board and open up the Serial Monitor (Tools -> Serial Monitor) at 115200 baud. You should see that the sketch has found your connected SGP41 sensor. Then, after conditioning the sensor, raw readings for VOC and NOx are printed to the Serial Monitor every second.

What is WipperSnapper

WipperSnapper is a firmware designed to turn any WiFi-capable board into an Internet-of-Things device without programming a single line of code. WipperSnapper connects to Adafruit IO, a web platform designed (by Adafruit!) to display, respond, and interact with your project's data.

Simply load the WipperSnapper firmware onto your board, add credentials, and plug it into power. Your board will automatically register itself with your Adafruit IO account.

From there, you can add components to your board such as buttons, switches, potentiometers, sensors, and more! Components are dynamically added to hardware, so you can immediately start interacting, logging, and streaming the data your projects produce without writing code.

If you've never used WipperSnapper, click below to read through the quick start guide before continuing.

Wiring

Wire up the SGP41 sensor as follows, using our convenient STEMMA QT cables, or via a breadboard.

Usage

Connect your board to Adafruit IO Wippersnapper and navigate to the WipperSnapper board list.

On this page, select the WipperSnapper board you're using to be brought to the board's interface page.

If you do not see your board listed here - you need to connect your board to Adafruit IO first.

Next, make sure the sensor is plugged into your board and click the I2C Scan button.

You should see the SGP41's default I2C address of 0x59 pop-up in the I2C scan list.

With the sensor detected in an I2C scan, you're ready to add the sensor to your board.

Click the New Component button or the + button to bring up the component picker.

Adafruit IO supports a large amount of components. To quickly find your sensor, type SGP41 into the search bar, then select the SGP41 component.

On the component configuration page, the SGP41's sensor address should be listed along with the sensor's settings.

The Send Every option is specific to each sensor's measurements. This option will tell the Feather how often it should read from the SGP41 sensor and send the data to Adafruit IO. Measurements can range from every second to every 24 hours.

For this example, set the Send Every interval to every 30 seconds.

Your device interface should now show the sensor components you created. After the interval you configured elapses, WipperSnapper will automatically read values from the sensor(s) and send them to Adafruit IO.

It can take a while for the SGP41 to start reporting usable data, even more so the first ever run, and the manufacturer's quick testing guide says to leave the sensor in ambient air for 1 hour before verifying NOx.

To view the data that has been logged from the sensor, click on the graph next to the sensor name.

Here you can see the feed history and edit things about the feed such as the name, privacy, webhooks associated with the feed and more. If you want to learn more about how feeds work, check out this page.

Files

• SGP41 Datasheet
• EagleCAD PCB files on GitHub
• Fritzing object in the Adafruit Fritzing Library

Schematic and Fab Print