Smartphone Sensors for Citizen Science Applications: Radioactivity and Magnetism

When proper measurement and calibration protocols are applied, smartphone sensors can generate relatively high-quality data among a variety of physical parameters that compare well with professional-grade, calibrated systems, but at far lower cost. This may open the door for a new generation of citizen science and crowdsourced applications involving the monitoring of these physical parameters for innovative research. Based on the calibrated results from a variety of apps and platforms, the direct use of smartphone sensor systems for conducting citizen science experiments is warranted, especially if modest adjustments to the recorded data are made using a small set of calibration curves. Radiation dosimetry variations near ±0.05 μSv/hr are dominated by noise, however at altitudes of 26,000 feet or higher, a clear cosmic ray signal can be easily detected above 0.5 μSv/hr. Magnetic fields can be detected with a random noise limit set by the digitization process at about ±200 nT, but a variety of instrument and unknown influences cause systematic errors as high as ±1,500 nT, which may be reduced somewhat by following appropriate measurement protocols. At this level, severe geomagnetic storms can be detected as an adjunct to auroral studies.