Influence of multicopter-induced vibrations on the measurement accuracy of optical particle counter

The use of uncrewed aerial systems (UAS) for high-resolution air quality monitoring is becoming increasingly important. However, the integration of low-weight and low-power sensors into these platforms poses challenges that can compromise data quality. This study investigates a significant measurement artifact observed when using Alphasense OPC-N3 optical particle counters on a DJI Matrice 300 multicopter. A reproducible decrease in the measured particle number concentration (PNC) values of up to 60% was observed immediately after take-off of the UAS. Through a series of systematic experiments, potential causes such as rotor downwash and platform-induced vibrations were investigated. The results clearly show that it is not the downwash, but the high-frequency vibrations of the propulsion system that are the main cause of the drastic underestimation of particle concentration. The implementation of measures to decouple the sensors from the UAS structure successfully eliminated this negative effect and restored measurement accuracy in flight. This study highlights the critical need for careful sensor integration and characterization to ensure reliable data in mobile air quality monitoring using UAS.