AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Measuring Concentrations of Cigarette Smoke and Diesel Exhaust Using a MEMS-Based Microfluidic PM Sensor
IGOR PAPROTNY, Frederick Doering, Richard White, Paul A. Solomon, Lara Gundel, University of California, Berkeley
Abstract Number: 619 Working Group: Instrumentation and Methods
Abstract We have developed a miniature MEMS-based PM sensor that is able to detect mass concentrations of airborne particles in real-time. (MEMS stands for microelectromechanical systems.) The sensor consists of two main components: a rectangular jet virtual impactor that filters out coarse particles, and a thermophoretically-induced deposition-area, where a film bulk acoustic resonator (FBAR) measures the mass of the deposited particles directly. The use of microfabrication technologies allowed us to reduce the size of the sensor to 4 cm2 , enabling portable (perhaps wearable) real-time monitoring of airborne particles. In this talk we present the results of testing two prototypes of the MEMS sensors with cigarette smoke and diesel exhaust, and compare their performance to that of state-of-the-art real-time PM instruments. Our prototypes demonstrated a limit of detection in single μg/m3 using a flow rate of only 7 mL/min. The sensitivity coefficient of the rate of the frequency change (the output signal) ranged from 23 to 97 Hz/s per mg/m3. The sensitivity increased with increasing flow rate, as indicated by microscopic analysis of the PM deposition patterns. The sensor output was somewhat influenced by temperature and humidity, and effects of both factors were included in the analysis. Some loss of volatile mass was evident, and a correction factor was fitted to the data to improve reproducibility. We conclude by discussing future steps to further improve the sensitivity and reproducibility of our MEMS PM sensor.