Datasheet

Bosch Sensortec | BME680 Datasheet
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Modifications reserved |Data subject not change without notice | Printed in Germany
Document number: BST-BME680-DS001-00 Revision_1.0_072017
4.2 Indoor-air-quality
BME680 is a metal oxide-based sensor that detects VOCs by adsorption (and subsequent oxidation/reduction) on its
sensitive layer. Thus, BME680 reacts to most volatile compounds polluting indoor air (one exception is for instance CO
2
). In
contrast to sensors selective for one specific component, BME680 is capable of measuring the sum of VOCs/contaminants
in the surrounding air. This enables BME680 to detect e.g. outgassing from paint, furniture and/or garbage, high VOC levels
due to cooking, food consumption, exhaled breath and/or sweating.
As a raw signal, BME680 will output resistance values and its changes due to varying VOC concentrations (the higher the
concentration of reducing VOCs, the lower the resistance and vice versa). Since this raw signal is influenced by parameters
other than VOC concentration (e.g. humidity level), the raw values are transformed to an indoor air quality (IAQ) index by
smart algorithms inside BSEC.
The IAQ scale ranges from 0 (clean air) to 500 (heavily polluted air). During operation, the algorithms automatically calibrate
and adapt themselves to the typical environments where the sensor is operated (e.g., home, workplace, inside a car, etc.).
This automatic background calibration ensures that users experience consistent IAQ performance. The calibration process
considers the recent measurement history (typ. up to four days) to ensure that IAQ ~ 25 corresponds to “typical good” air
and IAQ ~ 250 indicates “typical polluted” air.