Patent Application
20090078657
The disclosure relates generally to devices and methods for analyzing samples containing particles, and in particular, to a device for separating cells and other particulates from blood and other body fluids.
Detecting and/or measuring the concentration of blood and other body fluid components is a common tool used in hospitals, doctors' offices, and in the home to identify diseases and physical conditions. Biological fluids such as blood, urine or cerebrospinal fluids, which may at times contain blood, are frequently employed biological samples for such tests. Components often measured include metabolites, proteins, enzymes, antigens, antibodies, lipids, and electrolytes. These components are often measured using a plasma, serum, or cell-free sample obtained by centrifuging or filtering whole blood or other body fluid to separate out the cells and particulates. Centrifuging the sample is often unsuited for urgent, on-site, and field applications, and existing filtration devices often tend to clog or allow some cells to pass through.
A device is provided for analyzing fluids involving separating cells and other particulates from a sample. The device includes a body and a separation region in the body. In one illustrative embodiment, the separation region contains a separation fiber that includes at least 99% non-crystalline silica. In some embodiments, the separation fiber has an average fiber diameter of from 0.75 μm to 1.59 μm, a density in the range of 0.048 g/cm3 to 0.096 g/cm3, and a boron content of less than 0.010%.
In another embodiment, a microfluidic cartridge is provided for analyzing particulate-containing body fluids. One illustrative cartridge may include a housing, a sample port in the housing, a separation region in fluid communication with the sample port, and an analysis chamber in fluid communication with the separation region. The separation region of the microfluidic cartridge may contain a separation fiber that includes at least 99% silica. In some embodiments, the separation fiber has an average fiber diameter of from 0.75 μm to 1.59 μm, a density in the range of 0.048 g/cm3 to 0.096 g/cm3, and a boron content of less than 0.010%.
A method of separating blood cells and particulates from whole blood is also provided. One illustrative method may involve the steps of providing a separation device including a separation fiber that includes at least 99% silica, and less than 0.010% boron content. In some embodiments, the separation fiber has an average fiber diameter of from 0.75 μm to 1.59 μm, and a density in the range of 0.048 g/cm3 to 0.096 g/cm3.
Separation of cells and other particulates from biological fluids such as plasma is often critical to the analysis of chemicals from both components. Lysing cells in the sample as a means of removing whole cells often introduces proteins and other interferents, and can complicate the subsequent analysis, especially analysis of plasma components.
Typically, bacteria range in size from about 1 μm to about 5 μm. Blood cells range in size from platelets, averaging about 1 μm to about 4 μm in diameter, to monocytes, ranging in size from about 10 μm to about 30 μm in diameter. In order to effectively filter out blood cells, bacterial and other particulates from a blood or body fluid sample, a material with improved particle retention properties over that achieved with glass wool is desired. In particular, a material having fibers with a diameter similar to or smaller than the diameter of the particles to be retained is desired.
Prior art devices commonly used glass wool as a means of filtering blood cells from whole blood.
Q-Fiber® was designed for applications requiring a fiber that does not degrade under extreme conditions. As a lightweight temperature-resistant insulation material that provides excellent sound absorption, Q-Fiber is used in a variety of aircraft and automotive uses.
Q-Fiber® has a low density, non-crystalline structure that provide superior insulation characteristics including a high degree of thermal resistance and stability, little or no degradation in extreme usage conditions, and is lightweight. Q-Fiber® forms the primary component for a diversity of insulating materials used in aerospace applications in which service temperatures range from −170° F. (−112° C.) to 2300° F. (1260° C.). Q-Fiber® is formed from high-silica-content sand which is melted, fiberized, acid-washed to remove impurities, rinsed, dried, and heat-treated for structural integrity. Q-Fiber® has a minimum silica content of about 99.7% after processing, and a boron content of less than 0.01%. Table 1 shows the typical chemical composition of Q-Fiber®.
Q-Fiber® has an upper temperature limit of 2300° F. (1260° C.), and a continuous service temperature limit of 1800° F. (982° C.). The average fiber diameter ranges from 0.75 μm to 1.59 μm and examples of the nominal density of felted Q-Fiber® include 0.048 g/cm3, 0.056 g/cm3 and 0.064 g/cm3, and 0.096 g/cm3.
To illustrate the effectiveness of Q-Fiber®, and as shown in
In another experiment showing the separation of 1 μm diameter beads from a low molecular weight compound by Q-Fiber®, the experiment as described with reference to
In the illustrative embodiment, the binder-free Q-fiber® 26 layer retains particles of 1 μm and larger, thus retaining bacterial cells, blood cells, and particulate components of blood, while permitting low molecular weight compounds to pass through.
Although the invention has been described with respect to at least one illustrative example, many variations and modifications will become apparent to those skilled in the art upon reading the present specification. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.
