JIAYU LI, Pratim Biswas, Washington University in St Louis
Abstract Number: 138 Working Group: Instrumentation and Methods
Abstract Compact low-cost sensors for measuring particulate matter (PM) concentrations are receiving significant attention as they can be used in larger numbers and in a distributed manner (Wang et al, 2015). A configuration for use of these networked sensors in a distributed manner is presented in this work wherein data collection is done using wireless technology. To ensure accurate and reliable representation of PM mass concentrations, the performance characteristics of such sensors need to be better understood. Computational and experimental approaches were used to establish the relationship of mass concentration to the optical signal obtained from the device. The dependence on material properties and size distribution of the particles was established. Theoretical calculations were based on the Mie regime scattering expressions. Experiments were based on aerosolized sodium chloride particles produced by a constant output atomizer and an ultrasonic nebulizer. The calculated light scattering intensity correlated well with the signal from the sensor (Sharp GP2Y1010AU0F) signal in both the small and large particle size ranges. The results illustrated that the calibration factor is different for these two regimes. A semi-empirical equation for the calibration factor as a function of the refractive index and size distribution parameters (total number concentration, the geometric standard deviation, and the geometric mean diameter) is presented. The well characterized wireless sensor system with fifteen calibrated sensors was used in several indoor and outdoor environments: such as a laser cutter workshop, woodshop, and high traffic outdoor area. These sensors were used to monitor the hotspots and generate 3D maps of particle concentrations. In field measurements, sensors showed instant and accurate responses, which demonstrates high-quality performance at both sampling and networking capability.
Wang, Yang, et al. Aerosol Sci. Technol. 49.11 (2015): 1063-1077.