Focused Electrostatic Collection of Aerosol Particles for Chemical Analysis by Spectroscopic Techniques

This CDC-developed technology is an aerosol preconcentration unit (APU) designed for use with spectroscopic detection techniques, including emission, Raman, or infrared spectroscopies. Most existing pulsed microplasma techniques, such as laser-induced breakdown, for aerosols rely mainly on filter-based collection and suffer from poor accuracy, precision, and detection limits and require long sample collection times. The APU is designed to address these drawbacks by pre-concentrating the aerosol particles on a tip of a microelectrode (a few hundreds of micrometers in diameter) to allow near-real time measurements with superior accuracy and precision. The APU is designed to be small, low-pressure drop unit for its use in a battery-operated, hand-portable instrumentation.

The design significantly improves accuracy and precision of measurements relative to existing methods. The APU can be integrated with a microplasma source (such as a laser-induced plasma) and the optical spectrometer to obtain elemental composition of aerosol particles. The unique features of this invention allow: i) semi-continuous or near-real-time measurement of elemental composition of aerosol particles, ii) measurement with high accuracy, precision, and repeatability, iii) collection of particles using electrostatic principles, iv) higher flow rates with smaller pumps because of a very low pressure drop, v) reliable calibration of the system, vi) easy miniaturization for portable instruments, and vii) lower detection limits, as needed, by increasing the particle collection time and/or sampling flow rate.