Design of a light-scattering particle sensor for citizen science air quality monitoring with smartphones: Tradeoffs and experiences

Air quality is an aspect that gains more and more attention in the general public, as knowledge on the harmful effects on human health and the environment increase. Along with this, interest in low-cost instrumentation that enables end-users to measure particulate matter has grown, both for individuals, as well as for the use in distributed sensing scenarios. In this paper, we report on the design of an ultra-low-cost clip-on sensor for light-scattering particle measurements with camera smartphones. We present three design iterations and discuss the lessons learned during the design process and advantages and drawbacks of different design decisions. Aside from the specific hardware design, we discuss general errors that are likely to occur when non-experts carry out the measurement process and countermeasures to deal with them, independent from the sensor technology that is being used. This includessomehints for designing appropriate interaction in smartphone applications.

Keywords: Clip-on sensor;Camera smartphone; Participatory sensing; Air quality monitoring; Ubiquitous computing; PM; Citizen science; Environmental sensing; Mobile computing; Light-Scattering; Low-Cost; Pervasive sensing; Non-Expert users; Particulate matter