7Semi SGP41 VOC Sensor Breakout Board for Indoor Air Quality Monitoring

7Semi SGP41 VOC sensor breakout board for indoor air quality monitoring, built around the Sensirion SGP41 VOC and NOx gas sensor.

Overview

The breakout board is built around the Sensirion SGP41 VOC and NOx Sensor, a digital gas sensor designed for indoor air quality (IAQ) monitoring.

• It measures:

  • VOC (Volatile Organic Compounds)

  • NOx (Nitrogen Oxides)

• Provides processed air quality index values, not just raw gas resistance.

The sensor integrates two sensing elements on a single chip, enabling simultaneous VOC and NOx detection.

Working Principle

• Based on MOx (Metal Oxide) gas sensing technology.

• Uses a micro-hotplate to heat the sensing material.

• Gas molecules interact with the surface change in resistance.

• Internal electronics convert this into digital signa>

  The SGP41 does not directly output ppm like lab instruments.Instead, it uses an internal Gas Index Algorithm to generate:

  • VOC Index (0500)

  • NOx Index (0500)

  These indices represent relative air quality levels, not exact gas concentration.

  Output Data Types

  The sensor provides two types of outputs:

  1. Raw Signals

  • 16-bit digital raw values

  • Represent sensor resistance behavior

  2. Processed Signals

  • VOC Index (0500 scale)

  • NOx Index (0500 scale)

  These processed outputs are ready-to-use for control systems (like ventilation or purification).

  Key Technical Specifications

  Electrical

  • Supply voltage: 1.7 V to 3.6 V

  • Typical currenttrong>I2C (digital communication)

  Measurement

  • VOC range: up to ~1000 ppm (ethanol equivalent)

  • NOx detection: up to ~10 ppm NO equivalent

  • Response time:

    • VOC: < 10 seconds

    • NOx: < 250 seconds

  Physical

  • Package: DFN (2.44 2.44 0.85 mm)

  • Very compact suitable for embedded systems

  Environmental & Compensation Features

  • Built-in humidity compensation

  • Works with external temperature/humidity input for better accuracy

  • Operating range:

    • Temperature: approx. -10C to 50C

    • Humidity: 090% RH

  ts heavily on a software algorithm:

  Gas Index Algorithm

  • Converts raw signals into meaningful IAQ values

  • Automatically adapts to environment over time

  • Tracks baseline air quality

  This means:

  • Values are relative, not absolute

  • Sensor learns environment conditions over time

  Important Characteristics

  Advantages

  • Dual sensing (VOC + NOx in one chip)

  • Digital output (no analog calibration needed)

  • High long-term stability and low drift

  • Small size and easy integration

  • Resistant to contamination gases (robust design)

  Limitations

  • Cannot identify specific gases (only total VOC/NOx effect)

  • precise ppm for each gas

  • Sensitive to:

    • Humidity

    • Temperature changes

  • Requires initial warm-up and baseline stabilization

  Operating Behavior

  • Warm-up time: can take minutes to stabilize

  • Continuous measurement mode recommended

  • Sensor adapts to:

    • Daily air patterns

    • Environmental baseline

  Sudden spikes = change in air composition (not necessarily harmful)

  Breakout Board Role (7Semi)

  The breakout board mainly:

  • Exposes the SGP41 pins via I2C interface

  • Provides:

    • Power regulation (if included)

    • Pull-up resistors (for I2C)

  • Simplifies integration with microcontrollers

  reakout is a compact, intelligent air quality sensing solution that:

  • Measures VOC and NOx simultaneously

  • Outputs processed air quality indices

  • Uses advanced onboard algorithms instead of raw gas values

  • Is best suited for trend monitoring and air quality control systems