Resources:

SGP41 Datasheet
SHT45 Datasheet
Arduino Library for SHT45
Arduino Library for SGP41

7semi SGP41+SHT45 Environmental Sensor Probe for VOC, NOx, Temperature, and Humidity Monitoring
The 7Semi SGP41 + SHT45 Environmental Sensor Probe combines Sensirion’s SGP41 gas sensor with the high-accuracy SHT45 temperature and humidity sensor for indoor air-quality and environmental monitoring. The SGP41 provides separate sensing channels responsive to Volatile Organic Compounds (VOCs) and oxidising gases associated with NOx events, while the SHT45 supplies accurate temperature and relative-humidity measurements for environmental monitoring and gas-signal compensation.
The remote stainless-steel probe design allows the sensing elements to be positioned away from heat-generating controllers, displays, power electronics, and other components that could influence local temperature or humidity. Both sensors communicate digitally through I2C, with the SHT45 operating at address 0x44 and the SGP41 at 0x59. Sensirion’s Gas Index Algorithm can process the SGP41 raw signals into independent VOC Index and NOx Index values from 1 to 500, making the probe suitable for air purifiers, HVAC systems, smart buildings, indoor air-quality monitors, and IoT environmental nodes.
Key Features

4-in-1 Environmental Monitoring: Combines VOC, NOx, temperature, and relative-humidity sensing
Dual-Sensor Design: Integrates Sensirion SGP41 and SHT45 sensors
VOC Monitoring: Detects changes in indoor VOC conditions using the SGP41 VOC sensing element
NOx Monitoring: Provides a separate raw signal responsive to oxidising gases associated with NOx events
Gas Index Support: Compatible with Sensirion’s VOC and NOx Gas Index Algorithm
VOC Index Range: 1500
NOx Index Range: 1500
High-Accuracy Temperature: SHT45 typical accuracy of +-0.1C
High-Accuracy Humidity: SHT45 typical accuracy of +-1.0% RH
Humidity Range: 0100% RH
Temperature Range: -40C to +125C
Temperature/Humidity Compensation: SHT45 measurements can be supplied to the SGP41 for compensated gas sensing
Digital Interface: I2C communication for both sensors
Separate I2C Addresses: SHT45 at 0x44 and SGP41 at 0x59
Remote Probe Design: Helps separate the sensors from heat-generating electronics
Stainless-Steel Construction: Suitable for protected remote environmental sensing
Microcontroller Integration: Suitable for Arduino, ESP32, STM32, Raspberry Pi, RP2040, and other I2C hosts

Applications

Indoor air-quality monitoring
HVAC control systems
Air purifiers
Smart ventilation
Smart home environmental monitoring
Building automation
VOC event detection
NOx event monitoring
Kitchen and cooking-air monitoring
IoT environmental nodes
Laboratory environmental logging
Portable air-quality equipment
Demand-controlled ventilation
Industrial environmental monitoring

7Semi Enviroment SensorsSGP41+SHT45 Environmental Sensor Probe