Browse Prior Art Database

Publication Date: 2014-Jun-06

Publishing Venue

The Prior Art Database


An apparatus and technique for particle delivery such as aerosolization. A filter media arranged for a flow therethrough is loaded with particles on the downstream side. The filter media can be housed in a capsule that is readily transported and used in field applications. After establishment of a steady therethrough, the particles remained captured by the media, but can be released by an impulse movement, for example vibrating or tapping the capsule, or by a disturbance in the steady state flow. The particles so released can be delivered to downstream instrumentation for various purposes, for example calibration of particle sizing instruments, or for powder characterization or biological analysis.

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       Various embodiments of the invention include an aerosolization technique for dry 5 supermicron (greater than approximately 1 µm) particles that requires no electronics, no aerosol conditioning, and has no vacuum or air requirements. Advantages include low cost, easy transport and ease of use.

        Particles used in aerosol research and instrument calibration can be generated using a wide range of dispersers and generation techniques. A nebulizer or electrospray can be used for 10 particle sizes less than 1 µm, and dry particle dispersers can be used for particle sizes larger than

1 µm diameter. While these devices provide controlled environments for particle generation, they require setup and often rely on other equipment to dry the aerosol and/or isolate the size of interest.

        Structurally, certain embodiments of the invention utilize one or more filters such as a 15 high efficiency particulate air (HEPA) grade filters to selectively disperse particles rather than capture them. Other grade filters can also be implemented. Dry particles of known size can be deposited into or onto the filter from the downstream side. Some of the particles are retained by the filter, even in the presence of a flow therethrough. When the filter is tapped or shaken in the presence of a steady flow, some of the particles are released into the air stream. Alternatively, 20 the flow can be pulsed to flex the filter and cause the release.

    In another embodiment, an array of filters are utilized, each filter being designated for particles of a certain size and/or material. Contamination can be an issue with particle generation


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if multiple particle sizes are run through or generated by the same generation system. By using an array of designated filters, cross-contamination is minimized since a separate filter can be used for each unique material or particle size.

       The technique can be used to generate calibration particles such as Polystyrene Latex 5 (PSL) spheres, Al Test Dust, hematite (Fe203), or any other powder. It is also contemplated that the technique can be utilized in liquid media systems.

        A degree of size separation occurs near the 1 µm regime using this technique. It has been observed that, if a supermicron powder is generated which also contains residue in the submicron regime, the smaller particles tend to be retained better in the media than the larger particles. It is 10 believed that a determining factor is the van der Waals force, so that particles with enough inertia tend to separate from the filter media than those with less inertia.

        The apparatus and technique has applicability besides calibration. One anticipated application is powder analysis and characterization. Pharmaceutical companies, for example, often use aerosolization to analyze materials. A small amount of material (e.g., 1 mg) can be 15 deposited in a filter capsule according to the present i...