AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
New Concept for a Low-Cost Particulate Matter Sensor Based on Rolling Filter Tape Light Attenuation
ELIZABETH CORSON, Jennifer Therkorn, Johns Hopkins University Applied Physics Laboratory
Abstract Number: 889 Working Group: Air Quality Sensors: Low-cost != Low Complexity
Abstract Many low-cost optical particle counters (OPCs) are commercially available that count/size particulate matter (PM) in the airstream. These low-cost sensors have limits to the range of particle sizes and concentrations that can be accurately measured, and can be very inaccurate in high humidity. Here, a new concept is proposed for PM measurement that may address these issues; this sampler will collect PM onto a rolling filter tape and read the PM mass loading with a low cost light sensor/LED combination. Integrating PM collection over a short time period (5-min, 1-hr), and then reading the filter, mitigates issues of high concentration and provides near real-time data. A pilot study was conducted to collect total suspended PM in an urban setting across various conditions using a Button Sampler with PTFE filters; this provided a range of loaded PM mass across the filters with four sample filters and one clean blank. A breadboard prototype costing less than $40 was assembled consisting of a light sensor (high dynamic range digital light sensor, Adafruit), an LED light source (NeoPixel Jewel LED, Adafruit), and an Arduino Uno. To control the distance from the filter and background level of light, the light sensor and LED were positioned across from one another in an assembly to take readings of the amount of light penetration through each filter (lux units). Plotting lux units versus time-weighted PM2.5 air quality index as reported from the nearby state air quality monitoring station resulted in a strong linear relationship (R2 = 0.89). Overall, this approach appears to be a very promising alternative method to the development of a low cost PM sampler. Future work will include prototype building and model training to calibrate PM mass loading (i.e., mass concentration) with lux unit measurements.