5.2 KiB
MicroEnv v2.x
The MicroEnv is a compact and simplistic environmental monitoring sensor, based on the ESP32-C3 and the Sensirion SGP41 VOC/NOx and SHT45 temperature/humidity sensors, using ESPHome for integration with HomeAssistant.
Use a MicroEnv near a source of emissions to monitor air quality, evaluate temperatures, or as a general room environmental tracking sensor. It is, in effect, a cut down version of the environmental sensor package of my SuperSensor project in a much smaller, standalone footprint.
Power is provided by USB-C, which is also used for initial flashing. Once running, the device connects to WiFi to provide data to Home Assistant or via the ESPHome WebUI/API.
The Sensirion sensors are directly soldered onto the board along with their power management circuitry, using SMD techniques, which is in contrast to the socketed GY-form-factor sensors from version 1.x. This provides more compactness and flexibility in terms of positioning to ensure the temperature sensor is properly isolated from the rest of the system.
Version 2.x features an extended 5mm-width, 40mm-length "neck", the end of which contains the SHT45 temperature sensor, for maximum isolation from the ESP32 and SGP41 sensor, both of which produce heat which can negatively affect the SHT45 temperature. This emulates the design of many temperature probe devices which use similar long boards for isolation purposes and work quite well in this regard.
Since this revision uses directly SMD-mounted components, it requires fine soldering using solder paste and either a hotplate or, with extreme care, hot air soldering techniques. It is strongly recommended that anyone attempting to build one read the datasheets for the SHT45 and SGP41 sensors thoroughly to ensure they are not subject to overheating which can result in potential damage or incorrect operation. We recommend using low-temperature GA-SN solder paste for this purpose, and suggest ordering the PCB with lead-free HASL to facilitate this.
Parts List
Note: All prices are $CAD, as of late November 2025, excluding shipping, sales, and bulk discounts beyond those indicated.
Note: For AliExpress item links marked *, ensure you select the correct device; multiple different models share the page.
| Qty | PCB ID(s) | Component | Cost | Links |
|---|---|---|---|---|
| 1 | N/A | PCB - "MicroEnv" | $0.64 ($3.20/5) | EasyEDA/JLCPCB |
| 1 | ESP32-C3 | ESP32-C3 development board (SMD) | $2.46 ($12.28/5) | AliExpress* |
| 1 | SHT4x | Sensirion SHT45-AD1F-R2 | $9.37 | DigiKey.ca |
| 1 | SGP4x | Sensirion SGP41-D-R4 | $13.00 | DigiKey.ca |
| 1 | R1 | CR1206-FX-10R0ELFCT-ND (10Ω 1% 1/4W 1206) | $0.16 | DigiKey.ca |
| 1 | C1 | 399-C0805C106K8PACTUCT-ND (10μF 10V X5R 0805) | $0.19 | DigiKey.ca |
| 1 | C2 | 399-C0805C104K5RACTUCT-ND (0.1μF 50V X7R 0805) | $0.12 | DigiKey.ca |
| 1 | C3 | 399-C0805C105K3RACTUCT-ND (1μF 50V X7R 0805) | $0.18 | DigiKey.ca |
| T | $26.85 | plus tools, solder, etc. |
Case
The MicroEnv also includes a case to enclose the sensor while still providing good airflow to cool the microcontroller and provide quality exposure for the sensors. This case can be printed in any material, though ABS is recommended for rigidity and strength.
Calibration
Due to its design explicitly considering temperature accuracy, the MicroEnv should not require any Temperature Offset corrections in normal use; the option is however still provided just in case this is required in your environment.
The heat component of the SHT45 is explicitly disabled, as this should only be required in extreme humidity conditions.
Like its parent SuperSensor, the MicroEnv provides several additional configurable options for a "Room Health" metric system. For more detail, see the main SuperSensor README section on the Room Health system.