AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Trapping of Individual Airborne Absorbing Particles Using a Counterflow Nozzle and Photophoretic Trap for Continuous Sampling and Analysis
YONG-LE PAN, Chuji Wang, Steven Hill, Joshua Santarpia, US Army Research Lab
Abstract Number: 430 Working Group: Instrumentation and Methods
Abstract There is a need for improved on-line instruments for studying and monitoring aerosols. We describe an integrated opto-aerodynamic system and demonstrate that it enables us to trap absorbing airborne micron-size particles from air, hold them and then release them, and to repeat this sequence many times as would be appropriate for continuous sampling of particles from air. The key parts of the system are a conical photophoretic optical trap and a counter-flow coaxial-double-nozzle that focus, concentrates and then slows particles for trapping. This technology should be useful for on-line applications that require monitoring (by single particle analyses) of a series of successively arriving particles (e.g., from the atmosphere or pharmaceutical or other production facilities) where the total sampling time may last from minutes to days, but where each particle must be held for a short time for measurements (e.g., Raman scattering). This new system overcomes the trapping difficulty in air caused by the moving air current that focuses, concentrates and carries the aerosol particles into the small trapping region, greatly increases the trapping rate comparing to the passively launching methods generally used.