Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
2002-06-20
2004-08-24
Drodge, Joseph (Department: 1723)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S511000, C422S069000, C422S129000, C417S048000, C417S050000, C435S004000, C435S287300, C436S180000
Reexamination Certificate
active
06780320
ABSTRACT:
BACKGROUND
1. Field of Endeavor
The present invention relates to fluidics and more particularly to a magnetohydrodynamic fluidic system.
2. State of Technology
Background information on microfluidics is contained in U.S. Pat. No. 5,876,187 for micropumps with fixed valves to Fred K. Forster et al., patented Mar. 2, 1999 including the following: “Miniature pumps, hereafter referred to as micropumps, can be constructed using fabrication techniques adapted from those applied to integrated circuits. Such fabrication techniques are often referred to as micromachining. Micropumps are in great demand for environmental, biomedical, medical, biotechnical, printing, analytical instrumentation, and miniature cooling applications.”
Background information on magnetohydrodynamics is contained in U.S. Pat. No. 6,146,103 for micromachined magnetohydrodynamic actuators and sensors to Abraham P. Lee and Asuncion V. Lemoff, patented Nov. 14, 2000 including the following: “Microfluidics is the field for manipulating fluid samples and reagents in minute quantities, such as in micromachined channels, to enable hand-held bioinstrumentation and diagnostic tools with quicker process speeds. The ultimate goal is to integrate pumping, valving, mixing, reaction, and detection on a chip for biotechnological, chemical, environmental, and health care applications. Most micropumps developed thus far have been complicated, both in fabrication and design, and often are difficult to reduce in size, negating many integrated fluidic applications. Most pumps have a moving component to indirectly pump the fluid, generating pulsatile flow instead of continuous flow. With moving parts involved, dead volume is often a serious problem, causing cross-contamination in biological sensitive processes. The present invention utilizes MHDs for microfluid propulsion and fluid sensing, the microfabrication methods for such a pump, and the integration of multiple pumps for a microfluidic system. MHDs is the application of Lorentz force law on fluids to propel or pump fluids. Under the Lorentz force law, charged particles moving in a uniform magnetic field feel a force perpendicular to both the motion and the magnetic field. It has thus been recognized that in the microscale, the MHD forces are substantial for propulsion of fluids through microchannels as actuators, such as a micropump, micromixer, or microvalve, or as sensors, such as a microflow meter, or viscosity meter. This advantageous scaling phenomenon also lends itself to micromachining by integrating microchannels with micro-electrodes.” The disclosure of U.S. Pat. No. 6,146,103 is incorporated herein by reference.
SUMMARY
Features and advantages of the present invention will become apparent from the following description. Applicants are providing this description, which includes drawings and examples of specific embodiments, to give a broad representation of the invention. Various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this description and by practice of the invention. The scope of the invention is not intended to be limited to the particular forms disclosed and the invention covers all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.
The present invention provides a magnetohydrodynamic fluidic system. A reagent source contains a supply of reagent fluid used in the system. A sample source contains a sample fluid that includes a constituent. The supply source and the sample source operatively merge into a reactor microchannel. MHD pumps move the reagent fluid and the sample fluid into the reactor. The MHD pumps move the fluid and the sample fluid in a manner such that an interface is formed between the fluid and the sample fluid. This causes the constituent to be separated from the sample fluid.
In one embodiment the magnetohydrodynamic fluidic system is an extractor of high diffusion coefficient molecules. The system includes a first sheath reservoir containing a first sheath fluid and a second sheath reservoir containing a second sheath fluid. A sample reservoir contains a sample fluid consisting of a mixture of large and small molecules. The system includes an extraction section that extracts faster diffusing small molecules to one of the sheath fluids. When pumped through the extraction section, the sample is sandwiched by sheath flow from the sheath reservoirs. As a result, the faster diffusing small molecules are extracted to the sheath flow in the extraction section and delivered to an extraction reservoir. The rest of the sample can be delivered to waste or to other sections for disposal or further processing.
In another embodiment of magnetohydrodynamic microfluidics a molecular loader system is provided. The system delivers small molecules to cells or proteins. The system loads cells or proteins with small molecules or nucleic acids. A first sheath delivery reservoir contains a first sheath fluid and second sheath delivery reservoir contains a second sheath fluid. A host reservoir contains a host fluid consisting of host cells or molecules. The first sheath delivery reservoir, the second sheath delivery reservoir, and the host reservoir all merge into a loading section through microchannels. This loading section then separates into a first waste reservoir, a second waste reservoir and a product reservoir. MHD pumps move the sheath fluids and the host fluids. A host fluid including the host cells or molecules is stored in the host reservoir. When pumped through the loading section the host fluid is sandwiched by sheath flow from the sheath delivery reservoirs. As a result, the fast diffusing small delivery molecules will diffuse to the product stream in the loading section and be delivered to the product reservoir. The rest of the sheath delivery fluid is delivered to the waste or to other sections for disposal or further processing. The diffusion lengths are adjusted by tuning the MHD pumps to modify the pressure ratios between the host flow and the sheath flows. This in turn sets the diffusion threshold of what size molecules to load into the host fluid.
In another embodiment of magnetohydrodynamic microfluidics a bioaccelerator reactor system is provided. The bioaccelerator reactor system includes a first loop and a second loop. MHD accelerators in the first loop and the second loop move a sample and a reagent through the first loop and the second loop. An interface is provided between the first loop and the second loop. The MHD accelerators in the first loop and the second loop move adjust the rate the sample and reagent flow at the interface. As the sample is delivered from the sample reservoir to the upper loop, it is accelerated by the sample MHD accelerator. Similarly, the reagent is delivered from the reagent reservoir to the lower loop and accelerated by the reagent MHD accelerator. The upper loop and lower loop are prevented from exiting to the collection chamber or the waste chamber by a counter pressures generated by restrictor MHD pumps. The sample and reagent merge only at the fluid interface with a predetermined reaction length. As soon as the desired reaction time is reached or a product is detected, the restrictor MHD pumps are reversed to collect the product into the collection chamber and the used reagents into the waste chamber.
The invention is susceptible to modifications and alternative forms. Specific embodiments are shown by way of example. It is to be understood that the invention is not limited to the particular forms disclosed. The invention covers all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.
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pat
Bachman Mark G.
Lee Abraham P.
Drodge Joseph
Scott Eddie E.
The Regents of the University of California
Thompson Alan H.
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