2013 Progress Report: A compact, low-cost, network accessible, optical particle counter for the real time measurement of submicron aerosol particle size distributionsEPA Grant Number: R835139
Title: A compact, low-cost, network accessible, optical particle counter for the real time measurement of submicron aerosol particle size distributions
Investigators: Bertram, Timothy H
Institution: University of California - San Diego
EPA Project Officer: Hunt, Sherri
Project Period: February 1, 2012 through January 31, 2015
Project Period Covered by this Report: February 1, 2013 through January 31,2014
Project Amount: $250,000
RFA: Developing the Next Generation of Air Quality Measurement Technology (2011) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
The objective of this proposal is the development of a miniature, wireless optical particle counter (OPC) capable of measuring and transmitting submicron aerosol particle number and size distributions to a remote server in real-time. The proposal aims to provide the framework for significant improvements in the spatial and temporal resolution of continuous aerosol particle measurements on the city scale, while dramatically improving the availability of these data in real time.
Year 2 work has focused on the continued development and characterization of the blue diode optical particle counter. We are now working on Version 2 of the blue diode OPC. The redesign of the cavity was done to: 1) increase the solid angle of light scattered in the forward direction from particles in the beam path, and 2) replace the low sensitivity PIN diode with a high sensitivity PMT. This has resulted in a slightly larger optical cavity than V1 20cm in length. The new optical design is coupled with a new set of laser diode drivers that are more stable than V1, ultimately permitting detection of smaller peak heights that are associated with particles of diameter closer to 200 nm. We have broadened our efforts in this specific area to properly constrain the error associated with optical detection of ambient aerosol, with specific attention to: 1) particle size resolution, 2) impact of particle refractive index on retrieved size distributions, 3) impact of ambient RH, and 4) impact of coincidence counting on total number concentrations.