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

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