System and Apparatus to Illuminate Individual Particles

An apparatus for illuminating individual particles comprising a device for moving and directing air containing particles into a system, the system comprising an electrodynamic linear quadrupole section, an ultra-violet electromagnetic radiation source located along the electrodynamic linear quadrupole section, and a collection device for collecting the particles. A method of illuminating individual particles comprising moving and directing air containing particles into a system, controlling the air flow by using an air pump that continuously pulls or pushes air through the system, directing the particles into an electrodynamic linear quadrupole section, confining the particles to the central axis of the electrodynamic linear quadrupole section, illuminating the particles with ultra-violet electromagnetic radiation, interrogating the particles, and collecting the particles.

DETAILED DESCRIPTION OF THE INVENTION

One purpose of the present invention is to supply a method, system and apparatus to illuminate small, micron (10−6meter) size particles with controlled amounts of ultra-violet electromagnetic radiation and then to collect the particles to interrogate for possible changes, such as the ability of live organisms to survive after the illumination.

Particles are moved through the system using a controlled air flow, such as can be achieved using a light to moderate air pump at the back end of the system that continually pulls air through the entire system.

FIG. 2shows the direction of the airflow from the top end to bottom end of the ELQ. With the use of common valves and meters, the airflow rate can be controlled, as known by those knowledgeable in the practice.

By way of the controlled airflow, particles are first taken into a charging section where they acquire a surface charge, as shown inFIG. 1. This section is located directly above the ELQ inFIG. 2, but is not shown. There are several methods by which the particle charging can be achieved as known by those familiar in the art, as described herein.

The charged particles then continue into the ELQ section where they are confined to the central axis of the ELQ, as shown inFIG. 2. Since each particle is charged with the same electrical polarity, the particles also repel one another, which naturally spaces them apart from the nearest neighboring particle while being held along the axis of the ELQ. The automatic distancing between the particles makes individual particle interrogation easier during the process of this invention.

The controlled airflow moves the particles from one end of the ELQ chamber to the other, where they are finally collected into a filter or collection surface. The filter or collection surface used in this case is such that the particles can be extracted at a later time for testing, such as for viability in the case of biological organisms, as understood by those skilled in the art of biological testing.

One to four cylindrically shaped light bulbs that emit UV radiation are used as a constant source of radiation along the path of the particles within the quadrupole, as shown inFIG. 3.

The length and intensity of the bulbs is a means to control how much UV radiation each particle will receive. The arrangement of the bulbs is such that the UV radiation will pass between the poles that comprise the ELQ and thus visible along the axis of the ELQ.

During the trip through the ELQ, each particle is illuminated by UV radiation produced by the UV bulbs. The speed at which the particles pass through the UV illuminated section also determines how much radiation each particle receives, and is controlled by the rate of airflow.

As the particles traverse the ELQ chamber, they are subjected to one or more interrogation lasers, as shown inFIG. 4. Interrogation lasers can be located above (upstream of airflow) or below (downstream to airflow) the UV radiation zone of the chamber. In cases when there is room, such as embodiments where there are only one or two UV bulbs or shorter length UV bulbs, these lasers can be placed along the path where the particles are receiving the UV radiation.

This method, system and apparatus allows for the illumination of airborne particles using UV on a single particle basis, without having to first collect them onto a substrate or into a liquid.

By illuminating the particles while in flight, the method offers a more realistic or free floating approach when quantifying the effects of UV illumination on natural aerosols, such as that which may be naturally occurring as particles suspended in the earth's atmosphere.

The particles are spatially confined by electrodynamic forces causing them to follow along the central axis of the ELQ while maintaining a distance between one another in an ambient air environment.

The present invention takes advantage of this situation to illuminate and interrogate individual particles on-the-fly, that is, before having to collect them onto a substrate or into a liquid as is commonly done by those in the field of aerosol investigations. Since more than many hundreds of particles can be passed through the system every second, the method is very rapid.

A further embodiment utilizes interrogation lasers along the path of the particle flow that are used as particle filters.

These lasers have enough power to push a particle far enough off the ELQ axis such that it is no longer held by the ELQ system and thus taken out of the collected sample. For instance particles may be filtered out of the flow stream based on particle parameters such as, but not limited to, morphology (size, shape, etc.) or physical properties (fluorescence, scattering, absorbance, etc).

The confinement of the particles to a well defined axis effectively cleans the sample for specific interrogations to build a statistical analysis based on single particle counts while selectively filtering the particle samples.

The main ELQ apparatus in the electronic sense, is an open circuit with a capacitance, and although voltages in the range of 1 kilovolts to 3 kilovolts are required, there is very little overall power consumption.

Particle Charging

An alternative to the in-flight charging of particles is to electrospray a liquid containing previously collected particles into the airflow of the ELQ. This method would be useful to analyze previously collected aerosol samples since the aerosol collectors that place the particles into a liquid solution are already commonly used in the field of aerosol sampling and collection.

UV Illumination

Instead of rod shaped UV lights, UV radiation is from a laser or set of lasers that emit light at UV wavelengths. Speed of the particles and spot size of UV laser illumination determine how long each particle is illuminated by the UV radiation.

Another possible embodiment is to employ various wavelengths other than UV to investigate particle reaction behavior over a broader range of EM frequency. The photons can be utilized as a reactant or catalysis to obtain photochemical reaction.

Particle In-Flight Filtering Using a Laser

It is also possible to collect a more specific subset of particles, such that a means to eliminate undesired particles from the sample is desired. An in-flight filtering method can be achieved by locating a second laser light source (L2) a known distance downstream from the first laser (L1), used as an interrogator, as shown inFIG. 5.

Depending on the outcome of the laser interrogation of L1, L2is used to deflect the particle off of the quadrupole axis by supplying a sudden pulse of light with enough energy to push the particle from the ELQ axis, and thus removing it from the collected set of particles.

Several pairs of such lasers can be directed along the path of the particles within the ELQ, and can vary in wavelength depending on the need of different wavelengths as dictated by the filtering requirements. In this embodiment the laser beam (L1) also serves as a trigger for the second laser source (L2) for the timing of the particle ejecting pulse.

It is also possible to use the same laser beam (L1) as the detection/interrogation and ejector if fast enough electronics are used and the laser is capable of quickly changing power output, such that a single particle is first interrogated by the laser in low power mode, followed by fast decision making electronics and then subsequently ejected by the same laser using a higher power pulse of short duration, all before the particle has a chance to flow out of the laser beam (L1) influence. This is achievable using existing technology for time scales on the order of milliseconds (0.001 sec) which is appropriate for typical particle flow rates within an ELQ.

Particle Collection

Instead of a filter to collect particles, a flat, conductive plate that is electrically grounded or electrostatically charged is used as shown inFIG. 5. The plate is charged such that it is at the opposite electrical potential as the particles. This causes the particles to be electrostatically attracted to the surface of the plate, where they stick and are later collected from. The plate may consist of only a small area that is conductive such that the collected particles collect onto a more specific collection location.

A flat, nonconductive plate with an array of conductive spots on the surface, with each of the conductors grounded or charged to a potential opposite of the charged particles, such that the particles are attracted to the conductive spots on the plate.

The area of collection is located on an X-Y translation that can be moved by automation or by hand to collect particles for certain amounts of time, then moved, creating an array of particle spots on a plate. This apparatus can translate the plate linearly or rotate the plate such that the particles will tend to impact on a different position on the charged plate when desired. This is particularly useful when using a plate with an array of conductive spots.

The above examples are merely illustrative of several possible embodiments of various aspects of the present disclosure, wherein equivalent alterations and/or modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. In addition, although a particular feature of the disclosure may have been illustrated and/or described with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Also, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in the detailed description and/or in the claims, such terms are intended to be inclusive in a manner similar to the term “comprising”.