Aerosol Fluorescence Sensor  

Biral have developed an Aerosol Fluorescence Sensor  for intrinsic fluorescence measurements on aerosols.

The sensor can be used as a stand-alone instrument or as an attachment to the Aspect aerosol size and shape analyser so providing enhanced measurement capability.

Biral's Aerosol Fluorescence Sensor (AFS) continuously measures the fluorescence from a volume of aerosol in two detection channels covering the UV and visual spectral bands.

Making the measurement on a volume of aerosol means that there is no limit to the particle size of the material that can be detected.

As well as being compatible with the Aspect aerosol size and shape analyser the AFS can be fitted with an aerosol concentrator for use when the target is dilute.

APPLICATIONS

Measuring intrinsic fluorescence from aerosol particles exposed to UV light has been developed, primarily, as a means of detecting biological weapons. A by-product of the work done in this area has revealed the potential for this technique to be used for other objectives. The most obvious of these is the detection of biological organisms for other purposes such as:

Research into transmission of diseases
Transmission of diseases such as SARS and new strains of flu are obvious examples where aerosols are known to be an important route of infection. Detection of these aerosols, particularly in venues where large numbers of people may be exposed, could be a valuable tool in controlling a potentially devastating pandemic.

Detection of atmospheric pollutants
A number of other components of the atmospheric aerosol, particularly pollutants such as fuel oils and other natural organic materials, also fluoresce. They may often be distinguishable from micro-organisms and other biological materials in terms of the parts of the spectrum in which they fluoresce and the specific intensity of that fluorescence.

Fluorescence of organic aerosols including ultrafines
One of the advantages of this Aerosol Fluorescence Sensor is that it can detect aerosols with particles much smaller than is possible with single particle fluorescence instruments.

HOW THE SENSOR WORKS

The AFS works on the principle of Ultra-Violet Light Induced Fluorescence (UV-LIF). The sensor uses an UV optical source to illuminate an airstream flowing through the sensor detection volume. The induced fluorescence is collected and imaged on to two wide band fluorescence detectors, enabling a generic discrimination between different aerosol populations. The sensor illuminates a volume aerosol sample and as a consequence the fluorescence measurements provide information about the average aerosol population, and enables changes to that population to be systematically mapped.

The sensor is controlled via a software suite that enables the sampling rate to be adjusted in order to increase the resolution of the data.  The data files can be saved for replay at a later date and can be used as evidence that a change in the aerosol population has occurred and to substantiate the nature of that event.