The principle of fine dust measurements using a smart-phone corresponds to that of simple optical sensors and it will help in drawing a pollution map.
“Instead of the conventional infrared LED in the sensor, the flashlight of the smart-phone emits light into the measurement area. This light is scattered by the possibly existing dust or smoke," said computer scientist Matthias Budde.
"The camera serves as a receptor and takes a picture representing the measurement result. The brightness of the pixels can then be converted into the dust concentration," said Budde, who developed the system as a member of the research group TECO of Karlsruhe Institute of Technology (KIT).
The smart-phone sensors are not yet as precise as specialised instruments. However, their costs are much lower and Budde plans to enhance accuracy by a high measurement density.
Measurements of many, closely adjacent sensors may be combined to results of reduced inaccuracy. Due to their close vicinity, the sensors might also be calibrated against each other.

Budde thinks that a potential application scenario is joint measurement or participatory sensing where interested citizens may measure data at various places in their city and share them by downloading the corresponding app.

These data may then be used to draw up a fine dust pollution map for the respective city in real time.

The sensor is planned to be attached to the smart-phone by means of a magnet, for instance. Adaptation of electronics will not be required.

Presently, the smart-phone sensor can measure concentrations of about one microgram per cubic metre. This is sufficient for detecting coarse dust and smoke, but not for typical fine dust concentrations in the microgram range.