7Semi SGP40 VOC Air Quality Sensor Breakout with Qwiic I2C Interface
What this sensor is
The 7Semi SGP40 VOC Air Quality Sensor Breakout (Qwiic I2C) is a digital indoor air quality sensor that detects:
VOC (Volatile Organic Compounds)
Gases like alcohol, smoke, ammonia, etc.
It acts like a digital nose for air quality
Core Concept (VERY IMPORTANT)
This sensor does NOT give gas concentration directly
Instead:
Outputs raw signal + VOC Index (0500)
Uses internal algorithm to estimate air quality
VOC Index meaning:
~100 Normal air
100 Poor air quality
<100 Clean air
Key Specifications
Operating Voltage: 3.3V / 5V (breakout dependent)
VOC Index Range: 0500
Measurement Range: up to ~1000 ppm ethanol equivalent
Response Time: <10 seconds
Power Consumption: ~2.6 mA
I2C Address: 0x59
What it detects
The SGP40 detects a wide range of gases:
Alcohol
Ammonia
Benzene
Acetone
Hydrogen sulfide
Smoke
Basically: indoor pollution & human activity
Working Principle
Uses MOX (Metal Oxide) gas sensor
Gas exposure changes sensor resistance
Internal algorithm converts it into:
VOC Ity trends
No complex signal processing needed (library handles it)
Pinout (Qwiic / I2C)
VCC 3.3V / 5V
GND Ground
SDA I2C Data
SCL I2C Clock
Qwiic connector = plug & play (no soldering)
Key Features
Digital output (easy to use)
VOC Index (ready-to-use data)
Low power battery-friendly
Qwiic / STEMMA QT compatible
Long lifetime (>10 years)
Important Notes (VERY IMPORTANT)
1. Needs humidity com
Improves readings significantly
2. Not true gas measurement
No exact ppm for each gas
Only relative air quality (trend)
3. Needs algorithm/library
Raw data is NOT useful directlyYou must use:
Sensirion VOC algorithm
4. Warm-up time
Needs ~1 minute startup
Stabilizes over time
SGP40 vs ENS160
Feature | SGP40 | ENS160 |
Output | VOC Index | AQI + eCO + TVOC |
Accuracy | Good | Better (more processed) |
Complexity | Medium | Easy |
Use | VOC trends | Full air quality system |
Applications
Indoor air quality Smart ventilation systems
Environmental data logging
IoT air quality devices
When to use this
Use SGP40 if you want:
VOC detection
Simple air quality trends
Low-power IoT projects
When NOT to use
Avoid if you need:
Exact CO measurement use SCD40
Detailed gas analysis
Outdoor pollution monitoring
Final Understanding
This sensor = VOC trend detector (digital air quality index) Best for smart indoor air monitoring systems
Pro Tip (Very Useful )
Best combo:
SGP40 + SHT40/SHT41
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