Specifications

Key Specifications

Parameter	Value
Output Formats	JSON, CSV, Human-Readable
Host Compatibility	Linux, macOS, Windows, Android (drivers integrated in most OS)
Data Reporting Rate	Configurable from 3 seconds to 1 hour
Operating Range	-40 to +85 °C, 10-90 %r.H., 300-1100 hPa
Power Input	5V from USB port, ~25 mA
Dimensions	44.5 x 18.7 x 11.1 mm
Weight	5.6 g

Sensor Performance

Parameter	Value
IAQ Range	0 - 500
Sensor-to-Sensor IAQ Deviation	±15% (Typical)
Temperature Resolution	0.01 °C
Absolute Temperature Accuracy	±0.5 °C (@ 25 °C)
Humidity Accuracy Tolerance	±3 %r.H.
Humidity Resolution	0.008 %r.H

On Temperature and Host-Related Heat

The specified temperature accuracy of ±0.5 °C is for the BME680 sensor itself. When the uThing::VOC is plugged into a host device (like a PC or Raspberry Pi), heat from the host can be transferred to the board, causing the sensor to report a temperature slightly higher than the true ambient temperature. The device has been calibrated while connected to an external USB hub to minimize this effect. For best accuracy, consider using a short USB extension cable.

Output Data Points

The device provides the following data points in its output:

• Estimated Ambient Temperature [°C]
• Relative Humidity [% RH]
• Sensor Raw Resistance [Ω]
• Atmospheric Pressure [hPa]
• Air Quality Index (IAQ) [0-500]
• IAQ Accuracy Level [0-3]
• Equivalent CO₂ (eCO₂) [ppm]
• Equivalent Breath VOC (bVOC) [ppm]

Understanding the IAQ Score

The Indoor Air Quality (IAQ) score indicates the relative change in airborne Total Volatile Organic Compounds (TVOCs). The scale ranges from 0 (clean air) to 500 (heavily polluted air). The BSEC algorithm automatically calibrates itself to its environment over a period of up to four days, learning what constitutes "typical" good air (IAQ ≈ 25) and polluted air (IAQ ≈ 250) for that specific location.

Physical Dimensions

uThing::VOC rev.2 dimensions in millimeters [mm]