Aerosol Sensor Based on Air-gap Fabry-Perot Optical Microcavities

Chandra Raman, JACOB WILLIAMSON, Spencer Olson, Meagan Plummer, Robert Leonard, Matthew Marshall, Georgia Institute of Technology

     Abstract Number: 531
     Working Group: Instrumentation and Methods

Abstract
Optical technologies are enabling a variety of molecular and particle sensing applications. One emerging sensor type is the chip-scale planar whispering gallery mode (WGM) resonator [1], where the primary sensing mode involves changes in optical transmission when an aerosol particle adheres to or passes very close to the surface. However, a key limitation of WGMs is that as surface sensors, they do not directly probe particulate matter that is freely diffusing in air. Moreover, particle adhesion is often irreversible and causes sensor degradation. In this work, we present an alternative, non-perturbative sensor architecture based on high-finesse Fabry-Perot optical microcavities with a macroscopic air gap. The gap allows small particles to flow through the cavity volume without adhering to optical quality surfaces, thus allowing for long-lived and robust sensors that can enable long term field applications in aerosol detection. Beyond the PM10 and PM2.5 particulate matter standards, we are also exploring the potential use of this technology for sensing of ultrafine particles. Our results are promising for the realization of laboratory quality particle detection in portable devices for personal and environmental health monitoring.

[1] Xuefeng Jiang, et al, “Whispering-Gallery Sensors” (Review), Matter 3, 371–392, August 5, 2020.