7Semi SHT40 SGP40 VOC Environmental Monitoring Sensor Module Qwiic-Ready
🌿 7Semi SHT40 + SGP40 VOC Environmental Sensor (Qwiic)
📌 Overview
This module is a multi-sensor environmental board that combines:
- SHT40 → Temperature + Humidity sensor
- SGP40 → VOC (air quality) sensor
👉 Together, it provides complete indoor environment monitoring in a single compact module.
🧠 What It Measures
🌡️ Temperature
- Range: –40°C to 125°C
- Accuracy: ±0.2°C
💧 Humidity
- Range: 0–100% RH
- Accuracy: ±1.8% RH
🌫️ Air Quality (VOC)
- Detects gases like:
- Ethanol
- Acetone
- Formaldehyde
- Output:
- VOC Index (air quality level)
- Raw digital signal
⚙️ Working Principle
🔹 SHT40 (Temp + Humidity)
- Uses high-precision sensing elements
- Fast response and low power consumption
🔹 SGP40 (VOC Sensor)
- Uses MOx (metal-oxide) gas sensing technology
- Works like an “electronic nose” detecting overall air quality
- Outputs VOC index (not exact ppm gas values)
🔌 Key Features
✔ Dual-sensor module (3-in-1 monitoring)
✔ Qwiic / I2C interface → plug & play, no soldering
✔ 16-bit digital output → high precision
✔ Low power consumption (~2.6–3.5 mA)
✔ Fast response time (<10 seconds for VOC)
✔ Compact and IoT-friendly design
📊 Technical Specifications
| Parameter | Value |
|---|---|
| Interface | I2C (Qwiic compatible) |
| Supply Voltage | 3.3V / 5V |
| Current | 2.6–3.5 mA |
| VOC Range | 0–1000 ppm (ethanol equivalent) |
| VOC Response Time | < 10 sec |
| Humidity Response | ~6 sec |
| Switch-on Time | ~60 sec |
| Output | Digital (16-bit + VOC Index) |
🔌 Pin / Connection (I2C)
| Pin | Function |
|---|---|
| VCC | 3.3V / 5V |
| GND | Ground |
| SDA | I2C Data |
| SCL | I2C Clock |
👉 With Qwiic cable, you just plug directly (no wiring needed).
🤖 Applications
🏠 Smart Systems
- Indoor air quality monitoring
- Smart homes / HVAC systems
- Air purifiers
🏭 Industrial / IoT
- Workplace air safety
- Environmental logging systems
- Industrial monitoring
🧪 DIY Projects
- ESP32 / Arduino air monitor
- Weather station
- Portable air quality device
✅ Advantages
✔ Combines 3 sensors in one board
✔ Very accurate temperature & humidity
✔ Stable VOC detection (long-term reliability)
✔ Easy integration (I2C + Qwiic)
✔ Ideal for IoT and battery-powered projects
⚠️ Limitations (Important)
❌ VOC sensor does NOT give exact gas concentration
👉 It gives a relative air quality index (0–500)
❌ Sensitive to:
- Humidity changes
- Environmental conditions
❌ Needs:
- ~1 minute to stabilize after power-on
- Better accuracy after longer runtime
🆚 Compared to Other Sensors
| Feature | SHT40 + SGP40 | MQ Gas Sensors |
|---|---|---|
| Output | Digital | Analog |
| Accuracy | High | Moderate |
| Calibration | Easy | Hard |
| Warm-up | ~1 min | 5–20 min |
| Power Use | Low | High |
💡 When Should You Use It?
Use this module if you need:
✔ Accurate temperature + humidity + air quality
✔ Clean digital interface (I2C)
✔ Compact IoT solution
✔ Reliable indoor monitoring
🚀 Pro Tip
For best VOC results:
- Always use temperature & humidity compensation (from SHT40)
- Take readings every 1 second continuously
- Let sensor run for some time to stabilize baseline
