AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Sensitive and Selective Gas Sensing Module for Isoprene
TIANNING ZHAO, Jianhuai Ye, Matthew Stewart, Scot T. Martin, Harvard University
Abstract Number: 676 Working Group: Air Quality Sensors: Low-cost != Low Complexity
Abstract Interactions between the emissions and atmospheric chemistry of biogenic volatile organic compound (BVOC) pose significant impacts on regional air quality and global climate change. Emission variations from plant species are often served as an indicator in biodiversity and ecosystem functioning as response to ecosystem change and stress. Accurate emission estimates of BVOCs have been the focus of constraining the model inputs to better simulate their atmospheric fate and evaluate corresponding impacts. Isoprene, the most abundant BVOC species, is highly reactive and of great atmospheric chemistry importance. Measurements using mass spectrometers and chemi-luminescence (Fast Isoprene Sensor) approach can provide accurate data but cannot be scaled up due to limits in size and cost.
In this study, a miniature isoprene-selective sensing module is designed to be compatible with any portable platform. Through optimization of temperature cycling profile and signal processing, non-selective metal oxide semiconductors (MOS) can reach detection limit of 1 ppb isoprene with a time resolution of 1 min. Selectivity towards isoprene is realized by adsorption removal of hydrophilic species and molecular sieving for larger isoprenoids. Major interferents, such as water vapor and monoterpenes, will be removed to a negligible level. The performance is further validated with collocated PTR-MS measurements.