Abstract View
Laboratory and Modeling Evaluation of Particle-Dependent Inaccuracies in Low-Cost Optical Sensors
AMANDA GAO, David Hagan, Eben Cross, Jesse Kroll, MIT
Abstract Number: 483
Working Group: Instrumentation and Methods
Abstract
Light-scattering-based particulate matter (PM) sensors are beginning to achieve widespread usage in measuring air quality due to their low cost and ease-of-use, but their limitations are still poorly understood. More specifically, there are sensor inaccuracies that have yet to be characterized or explained—and this lack of knowledge can lead to sensor misuse and uninterpretable data. Here, we investigate the response characteristics of the commonly-used Plantower PMS nephelometer and Alphasense OPC-N2 optical particle counter to a series of laboratory experiments involving exposure to various distributions of monodisperse polystyrene latex (PSL) and ammonium sulfate aerosol, with the goal of characterizing low-cost inaccuracies in detecting particles with different size distributions and optical properties. We determine the size-dependent response of these PM sensors using measurements collected by reference instruments, and examine this data alongside the results of a physics-based open-sourced model (opcsim) that simulates sensor responses to experimental conditions using Mie theory. Taken together, these complementary approaches shed new light on the processes that lead to inaccuracies in low-cost measurements.