WO2022125073A1

WO2022125073A1 - Fluidic devices

Info

Publication number: WO2022125073A1
Application number: PCT/US2020/063747
Authority: WO
Inventors: John Michael LAHMANN; Si-Lam J. Choy; Paul Mark Haines
Original assignee: Hp Health Solutions Inc.
Priority date: 2020-12-08
Filing date: 2020-12-08
Publication date: 2022-06-16

Abstract

A fluidic device is presented. The fluidic device can include interconnected volumes and a port. The interconnected volumes can include a bulk fluid volume fluidically connected in series with a capillary volume to receive a density gradient column including a wash buffer or containing the wash buffer. The fluidic device can also include a port positioned outside and fluidically connected to the capillary volume to inject a gas into the capillary volume, thereby forming a separation gas bubble between an upstream portion of the wash buffer from a downstream portion of the wash buffer.

Description

FLUIDIC DEVICES

BACKGROUND

[0001] In biomedical, chemical, and environmental testing, isolating a component of interest from a sample fluid can be useful. Such separations can permit analysis or amplification of the component of interest. As the quantity of available assays increases, so does the demand for the ability to isolate components of interest from sample fluids. Fluidic devices can be used for these applications, among others. In some examples, fluidic devices can be used to prepare and process samples with small volumes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] FIG. 1 A graphically illustrates a fluidic device in accordance with the present disclosure;

[0003] FIG. 1 B graphically illustrates an example fluid processing system in accordance with the present disclosure;

[0004] FIG. 2 is a flow diagram of an example method of processing fluids in a density gradient column in accordance with the present disclosure; and

[0005] FIGS. 3A-3D graphically illustrate example methods of processing fluids in density gradient columns in accordance with the present disclosure. DETAILED DESCRIPTION

[0006] The present disclosure describes fluidic devices, methods of processing fluids in a density gradient column, and a fluid processing system that can be used in a more specific process of preparing samples for a PCR (polymerase chain reaction) assay. PCR assays are processes that can rapidly copy millions to billions of copies of a very small DNA or RNA sample, for example. PCR can be used for many different application, included sequencing genes, diagnosing viruses, identifying cancers, and others. In the PCR process, a small sample of DNA or RNA is combined with reactants that can form copies of the DNA or RNA. Because the volumes of samples fluid and reactant involved in this process are very small, it can be beneficial to use small fluidic devices and systems such as those described herein.

[0007] In accordance with examples of the present disclosure, a fluidic device includes a fluidic device with interconnected volumes including a bulk fluid volume fluidically connected in series with a capillary volume to receive a wash buffer. The fluidic device also includes a port positioned outside and fluidically connected to the capillary volume. The port is to inject a gas into the capillary volume thereby forming a separation gas bubble between an upstream portion of the wash buffer from a downstream portion of the wash buffer. The wash buffer in this example can be part of a density gradient column, and \the density gradient column can further include a sample fluid in the bulk fluid volume positioned above the wash buffer. The wash buffer in this instance has a greater density than a density of the sample fluid. The wash buffer can be loaded in the interconnected volumes and a portion of the wash buffer resides in the capillary volume. The capillary volume can have an interior channel average diameter from 1 mm to 4 mm and further includes a fluidic output. The port can be fluidly associated with a gas reservoir, such as a gas reservoir held by a flexible blister pack that when engaged provides an opening to the port and forces gas into the capillary volume, and/or a gas reservoir that is injectable into the capillary volume as the gas is displaced by a liquid. The fluidic device can also include a plugging fluid reservoir of a non-newtonian plugging fluid positioned outside the interconnected volumes. A plugging fluid injection opening can be positioned at a location along a length of the interconnected volumes to inject the non-newtonian plugging fluid into the interconnected volumes from the plugging fluid reservoir. The non-newtonian plugging fluid can have a sufficient viscosity to partition fluid upstream from the non-newtonian plugging fluid from fluid downstream from the non-newtonian plugging fluid. In one example, the gas can be air.

[0008] In another example, a method of processing fluids in a density gradient column includes establishing a density gradient column including a sample fluid positioned on top of a wash buffer, with the wash buffer having a greater density than the sample fluid. The density gradient column in this example is positioned within interconnected volumes that includes a bulk fluid volume and a capillary volume. The sample fluid occupies the bulk fluid volume and the wash buffer occupies the capillary volume (as a note, either can partially occupy the other fluid volume, e.g., the fluid interface between the sample fluid and the wash buffer can reside in the capillary volume, the bulk fluid volume, or at the border between the capillary volume and the bulk fluid volume). The method in this example further includes magnetically moving magnetizing particles having a biological component bound thereto from the sample fluid and into the wash buffer at a location where the wash buffer resides in the capillary volume, and displacing a gas into the capillary volume to form a separation gas bubble in the capillary volume that separates a downstream portion of the wash buffer from a balance of fluids positioned thereabove that includes the sample fluid in the bulk fluid volume. In one example, displacing the gas into the capillary volume can occur prior to the magnetically moving of the magnetizing particles. The magnetizing particles in this instance can be moved through the separation gas bubble into the downstream portion of the wash buffer. Alternatively, displacing the gas into the capillary volume can occur after the magnetically moving of the magnetizing particles into the downstream portion of the wash buffer. In further detail, displacing the gas into the capillary volume can include releasing the gas from a flexible blister pack located exterior to the capillary volume. [0009] In another example, a fluid processing system includes interconnected volumes including a bulk fluid volume and a capillary volume to receive a density gradient column, a wash buffer reservoir including a wash buffer and positioned outside the interconnected volumes, and a wash buffer fluid injection opening in the interconnected volumes to inject the wash buffer into the interconnected volumes through the capillary volume and partially into the bulk fluid volume. The fluid processing system in this example also includes a port positioned outside of the interconnected volumes and fluidically connected to the capillary volume of the density gradient column. The port is provided to inject a gas into the capillary volume, thereby forming a separation gas bubble that separates a downstream portion of the wash buffer from a balance of fluids positioned thereabove. In one example, the port can be fluidly associated with a gas reservoir containing the gas, and the gas reservoir can include a flexible blister pack that when pushed, provides access to the port and forces the gas into the capillary volume. The fluid processing system can also include a sample fluid with magnetizing particles having a biological component bound thereto dispersed therein. The sample fluid in this instance has a lower density than the wash buffer and is loaded or loadable above the wash buffer.

[0010] It is noted that when discussing a fluidic device, a method of processing fluids in a density gradient, and/or a fluid processing system herein, such discussions can be considered applicable to one another whether or not they are explicitly discussed in the context of that example. Thus, for example, when discussing a density gradient column, such disclosure is relevant to and directly supported in the context of the fluidic device, the method of processing fluids in a density gradient, and the fluid processing system. Terms used herein will have the ordinary meaning in the relevant technical field unless specified otherwise. In some instances, there are terms defined more specifically throughout the specification or included at the end of the present specification, and thus, these terms can have a meaning as described herein.

[0011] Furthermore, the present disclosure includes several figures illustrating specific examples of the technologies described herein. These figures show fluidic devices and fluid processing systems that include a variety of components arranged is specific ways depending on the purpose and function of the particular examples depicted. Although the figures illustrate examples that implement the technologies described herein in some detail, these examples also include many features that are optional, which may be changed or removed depending on the particular example. Accordingly, it is understood that the technologies described herein are not limited by the examples shown in the figures.

Fluidic Devices

[0012] In density gradient columns, in general, the greater or higher the density of a fluid, relative to other fluids in the column, the closer to the bottom of the column that fluid will be located. For example, when arranged vertically a first fluid having a first density can form a first layer of the density gradient column. A second fluid having a second density greater than a density of the first fluid can form a second fluid layer of the density gradient column. A third fluid having a third density that can be greater than a density of the second fluid can form a third fluid layer of the density gradient column and the like. Typically, when fluids are not arranged based on density, the fluids will self-arrange based on their density as upward rapid displacement may occur until the fluids become arranged according to their density.

[0013] The present disclosure describes fluidic devices that include interconnected volumes with a bulk fluid volume and a capillary volume. The interconnected volumes can be shaped and/or configured within a vessel to receive a density gradient column. A density gradient column can be a vertically layered fluid column including fluids positioned in fluid layers. The fluids may be positioned along a density-differential interface, along a capillary force-supported interface, or the combination thereof. The fluidic device can further include a port to inject air into the interconnected volumes. The port may be at a capillary volume of the interconnected volumes. The air can form a separation gas bubble that can become trapped in the capillary volume due to a surface tension of the fluid relative to the size and material of the interconnected volumes. This can provide the ability to position a fluid having a density less than a density of a fluid above the separation gas bubble within the density gradient column. Thus the separation gas bubble can act as a fluid layer that can allow for the arrangement of fluids with different densities outside of how fluids self-arrange in vertically oriented density gradient columns. The separation gas bubble can prevent upward rapid displacement of a less dense fluid.

[0014] Accordingly, as illustrated in FIG. 1 , fluidic devices 100 as presented herein can include interconnected volumes 110 (typically shaped and/or configured within a vessel) including a bulk fluid volume 112 and a capillary volume 114 to receive a density gradient column. The interconnected volumes can include a wash buffer 150 or can be shaped (such as by a vessel) to contain a wash buffer therein. The fluidic device can further include a port 120 positioned outside of and fluidically connected to the capillary volume of the interconnected volumes. The port can be positioned to receive air for injection into the capillary volume thereby forming a separation gas bubble that can be to separate an upstream portion of the wash buffer from a downstream portion of the wash buffer.

[0015] In accordance with a more detailed example, a fluidic device 100 is shown in FIG. 1 B. In this example, like in FIG. 1A, the fluidic device can include interconnected volumes 110 with a bulk fluid volume 112 and a capillary volume 114, along with a port 120 for receiving a gas. However, in this example, also shown is wash buffer reservoir 155 containing a wash buffer 150, a wash buffer fluid injection opening 157, and a gas reservoir 165 for injecting the gas, e.g., air, into the capillary volume. In one example, the air can be held in part within a body cavity 160 of the interconnected volumes, for example. The wash buffer reservoir and the gas reservoir in this example are shown as blister packs, but could be any of a number of devices used for injecting fluids into or through the capillary volume. As shown, the interconnected volumes can include a bulk fluid volume 112 and a capillary volume 114, and collectively the bulk fluid volume and the capillary volume can receive a density gradient column of multiple fluids of different densities. The wash buffer fluid injection opening can be present in the interconnected volumes to inject the wash buffer into the interconnected volumes through the capillary volume and partially into the bulk fluid volume. The port again can be positioned outside of the interconnected volumes and can be fluidically connected to the capillary volume to inject gas, e.g., air, into the capillary volume, thereby forming a separation gas bubble that can separate an upstream portion of the wash buffer from a downstream portion of the wash buffer. Also shown in this example, a plugging fluid reservoir 215 is present, and can include a non-newtonian plugging fluid 210 along with a plugging fluid injection opening 217 to inject the non-newtonian plugging fluid into the capillary volume (or in some instances, the bulk fluid volume). The non-newtonian plugging fluid can provide, in one example, a fluid barrier between fluids beneath the plugging fluid and fluids above the plugging fluid, e.g., to prevent back pressure from releasing fluid when ejecting fluids there beneath from the fluidic device (upon removal of the cap 195, for example).

[0016] FIGS. 1 A-1 B and 3A-3D herein depict various portions of example systems, methods, and/or devices. However, it is noted that the drawings and associated description herein can be viewed collectively and interchangeably with respect to structural components shown. Furthermore, these systems, methods, and/or devices can include other structures not shown that may be present upstream and/or downstream from the illustrated structures. For example, as shown in FIGS. 1A and 1B, the system or device shown can be part of a sample preparation cartridge module that includes a biological sample input 175 and a biological sample output 185. For example, the sample preparation cartridge module may include interconnected volumes arranged in series between the input and output in a linear direction to receive a vertically layered density gradient column. The various volumes may include, for example, the bulk fluid volume 112 and the capillary volume 114. However, there may be other volumes present above or below these portions, or which are included as part of these portions, e.g., sub-volumes. For example, the bulk fluid volume may include a mixing chamber (not shown) connected to the biological sample input to contain and mix a composition comprising a biological sample and a particulate substrate. In this example, the mixing chamber may reside as part of the bulk fluid volume separated by a displaceable, e.g., pierceable, membrane or other barrier. In other examples, the mixing chamber may reside as part of the entire bulk fluid volume. The capillary volume, on the other hand, may include a fluidic isolation chamber downstream of the bulk fluid volume (which may include a mixing chamber or be a mixing chamber) to separate particulate substrate and a biological component from the biological sample. The separation may be by the introduction of a non-newtonian fluid along the fluid column, or in other examples, the introduction of a gas, e.g., air bubble in the capillary volume to separate the mixing chamber from the fluidic isolation chamber, as described in greater detail hereinafter.

[0017] The bulk fluid volume, in further detail, can be upstream of the capillary volume. The bulk fluid volume can be wider and can have a larger cross-section than a cross-section of the capillary volume. Fluids in the bulk fluid volume may arrange by their respective densities. The bulk fluid volume can include a conical chamber, a cylindrical chamber, or a combination thereof. A cross-section of the chamber can be round, square, triangle, rectangle, or other polygonal in shape. In some examples, the bulk fluid volume can have a diameter (or width if not circular) at the widest cross-section of from 3 mm to 20 mm, from 5 mm to 15 mm, from 3 mm to 12 mm, from 10 mm to 20 mm, or from 3 mm to 10 mm. The bulk fluid volume can be where a majority of the fluid in the density gradient column resides. The bulk fluid volume can connect to the capillary volume at a capillary junction.

[0018] The capillary volume can have a smaller cross-section than a cross-section of the bulk fluid volume. The capillary volume can be an elongated tubular region and can have a round, square, triangle, rectangle, or other polygonal cross-section. In some examples, the capillary volume at the widest cross-section can have an interior opening diameter of from 0.1 mm to 4 mm, from 0.1 mm to 2 mm, from 0.5 to 1.5 mm, from 1 mm to 3 mm, from 2 mm to 4 mm, or from 2 mm to 3 mm. The capillary volume may be tapered. For example, the capillary can be tapered and can have an interior channel diameter of 4 mm at one end to an interior channel diameter at the opposite end of 1 mm. For example, the capillary can be tapered from an interior channel diameter of 3 mm at one end to an interior channel diameter at the opposite end of 1 mm, or from 2 mm at one end to an interior channel diameter at the opposite end of 1.5 mm, or from 2 mm at one end to an interior channel diameter at the opposite end of 1 mm. Notably, within the capillary volume, the density gradient column may or may not have fluids along the column separated strictly by their density. The narrow passageway, the capillary forces provided by the interaction of the fluids, and the fluid interfaces can enable lower density fluids to be retained beneath higher density fluids. For example, a gas may be able to be retained within the capillary volume below higher density liquid fluids due to the capillary forces at work.

[0019] In some examples, the interconnected volumes can include multiple pairs of bulk fluid volumes and capillary volumes. Bulk fluid volumes situated below a capillary volume can be separated from a capillary volume directly above that bulk fluid volume by a displaceable seal or valve.

[0020] The interconnected volumes can be made of various polymers (e.g. Polypropylene, TYGON, PTFE, COG, others), glass (e.g. borosilicate), metal (e.g. stainless steel), or a combination of materials. Additionally, the capillary volume of the interconnected volumes could be formed from multiple materials used in various microfluidic devices, such as silicon, glass, SU-8, PDMS, a glass slide, a molded fluidic channel(s), 3-D printed material, and/or cut/etched or otherwise formed features. The interconnected volumes may be monolithic or may be a combination of components fitted together.

[0021] The interconnected volumes can receive fluids that can form a density gradient column, such as a sample fluid, a lysis buffer, a wash buffer, a gas, a fluid reagent, and the like. Fluids can be arranged in the density gradient column in layers and individual layers can be phase separated from one another at fluid interfaces. In some examples, the phase separation can be based on fluidic properties of the various fluids, including a density of the respective fluids along the column. Fluid layers can be in direct fluid communication with adjoining fluid layers.

[0022] Within the bulk fluid volume, the greater or higher the density of a fluid, relative to other fluids in the column, the closer to the bottom of the bulk fluid volume the fluid will be located. A density of a fluid can be altered using a densifier. Example densifiers can include sucrose, cesium based densifiers such as CsCI, polysaccharides such as FICOLL™ (commercially available from Millipore Sigma (USA)), C19H26I3N3O9 such as NYCODENZ® (commercially available from Progen Biotechnik GmbH (Germany)) or HISTODENZ™, iodixanols such as OPTIPREP™ (both commercially available from Millipore Sigma (USA)), or combinations thereof.

[0023] In one example, a density difference between adjacent fluid layers can range from 50 mg/mL to 3 g/mL In yet other examples, a density difference between adjacent fluid layers can range from 50 mg/mL to 500 mg/mL or from 250 mg/mL to 1 g/mL Fluid density can be measured conventionally by calibrating a scale to zero with the container thereon and then obtaining the mass of the liquid in grams. The volume of the measure mass can then be determined using a graduated cylinder. The density is then calculated by dividing the mass by the volume to get the fluid density (g/mL).

[0024] Within the capillary volume, fluids can be arranged based on fluid properties, separated by a separation gas bubble, or the combination thereof. Fluids arranged based on fluid properties will arrange with respect to fluid densities, as described above. Arrangements with a separation gas bubble can allow for fluids to be arranged regardless of their density without intermixing. Incorporating multiple separation gas bubbles in the capillary volume can allow for sequential processing of a biological sample without requiring mechanical valves therebetween, which may provide a cheaper and simpler alternative to the inclusion of mechanical valves. This can be particularly useful in disposable and consumable fluidic devices.

[0025] Individual fluid layers in the interconnected volumes can provide sequential processing of a biological sample. For example, individual fluid layers can carry out individual functions, and in many cases, the functions can be coordinated to achieve a specific result. For example, in isolating a biological component found in a cell of a biological sample, sequential fluid layers from top to bottom of a density gradient column can act on the biological sample to lyse cells in a fluid layer, bind a biological component from the lysed biological sample to surface-activated magnetizing particles, wash the magnetizing particles with the biological material bound thereto in a wash buffer, combine biological material with a reagent, and/or elute the biological material from the magnetizing particles.

[0026] In some examples the density gradient column can include fluids such as a sample fluid, a lysis buffer, a wash buffer, a separation gas, a fluid reagent, and the like. In one example, the density gradient column can include a sample fluid in the bulk fluid volume and a wash buffer that can have a greater density than a density of the sample fluid. The wash buffer can be positioned beneath the sample fluid. The wash buffer may be present in a portion of the bulk fluid volume, in a portion of the capillary volume, or a combination thereof. In another example, the density gradient column can include a sample fluid, a wash buffer, a separation gas bubble, and a fluid reagent. In yet another example, the density gradient column can include a sample fluid, a lysis buffer, a wash buffer, a separation gas bubble, and a fluid reagent.

[0027] A vertical height of individual fluid layers in the density gradient column can vary. Adjusting a vertical height of an individual fluid layer can affect a residence time of a biological sample in that fluid layer. The taller the fluid layer, the longer the residence time therein. In some examples, all of the fluid layers in the density gradient column can be the same vertical height. In other examples, a vertical height of individual fluid layers in a density gradient column can vary from one fluid layer to the next. In one example, a vertical height of the individual fluid layers can individually range from 10 μm to 50 mm. In another example, a vertical height of the individual fluid layers can individually range from 10 μm to 30 mm, from 25 μm to 1 mm, from 200 μm to 800 μm , or from 1 mm to 50 mm.

[0028] The interconnected volumes may further include one or more openings, inputs, outputs, and/or ports. For example, the interconnected volumes may include an opening, an input, and/or a port to permit loading of fluids and reagents into the bulk fluid volume or the capillary volume. For example, a fluid injection opening can permit loading of a sample fluid, a wash buffer, and the like into the bulk fluid volume or the capillary volume. In one example, the device can include a wash buffer fluid injection opening. The interconnected volumes may also include one or more outputs. For example, the capillary volume may include a fluidic output that can permit dispensing of a biological component, a biological sample, a fluid, magnetizing particles, or a combination thereof. In yet other examples, the interconnected volumes may include an output for venting gas to relieve pressure in the density gradient column.

[0029] In yet other examples, the bulk fluid volume, the capillary volume, or the combination thereof can include seals, valves, plugs, or a combination thereof. In one example, seals, valves, and/or plugs can be used to temporarily prevent mixing of fluids and allow for independent manipulation of fluids. For example, a mixing chamber can be positioned as part of the bulk fluid volume or can be positioned above the bulk fluid volume of the interconnected volumes. The bulk fluid volume can be separated from the mixing chamber by a displaceable seal. The displaceable seal, e.g., by piercing, cutting puncturing, removing, etc., can allow for independent manipulation of the sample fluid before the sample fluid may be positioned over the wash buffer

[0030] The fluidic device can further include a port to inject air into a capillary volume of the interconnected volumes. The port can include an opening or input. In an example the port can include a puncturable self-healing injection port. Puncturable self-healing injection ports can include a self-healing polymer that can permit injection of a gas and later swell to close the puncture. The port, in another example, can be a microfluidic channel having an input and an output. In one example, the input of the microfluidic channel can connect to a chamber or a gas reservoir. In another example, the input can be situated to prevent back flow of a fluid therethrough based on a design of the microfluidic channel. In a further example, the input can include a cap. The output can be connected to the capillary volume of the density gradient column. Air injected into the port can flow into the capillary volume and become trapped.

[0031] In some examples the port may be fluidically associated with a gas reservoir. A gas reservoir can be sized and shaped to contain air in an amount capable of forming a separation gas bubble in the capillary volume of the interconnected volumes. The gas reservoir may be located to allow dispensing of air through the port into the capillary volume of the interconnected volumes. The gas reservoir can be a chamber, a channel, a flexible blister pack, a syringe, a bag, a balloon, or a combination thereof. In one example, the gas reservoir can be a flexible blister pack that when pushed, can open and force air out of the reservoir and into the interconnected volumes. In some examples, a gas reservoir may include an injection opening or may be associated with a fluid reservoir positioned upstream of the gas reservoir and fluidically connected to the gas reservoir. Air from the gas reservoir can be injected into the capillary volume as air in the gas reservoir becomes displaced by a liquid which can enter the gas reservoir from an injection opening or the fluid reservoir positioned upstream of the gas reservoir.

[0032] In yet other examples, the device may further include a plugging fluid reservoir that can be positioned outside of the interconnected volumes and may fluidically connect to the capillary volume via a plugging fluid injection opening positioned at a location along a length of the capillary volume. The plugging fluid reservoir can be a chamber, a channel, a flexible blister pack, a syringe, a bag, a balloon, or a combination thereof. The plugging fluid reservoir may include a non-newtonian plugging fluid. The non-newtonian fluid plug can be formed in the capillary volume above the separation gas bubble. In some examples, the non-newtonian plugging fluid can include Bingham plastics, viscoplastics, shear thinning fluids, or curable fluids. In certain examples, the non-newtonian plugging fluid can be grease-based. In various examples, the non-newtonian plugging fluid can include a mineral oil-based grease, a vegetable oil-based grease, a petroleum oil-based grease, a synthetic oil-based grease, a semi-synthetic oil-based grease, a silicone oil-based grease, or a combination thereof. Curable fluids can also be used as the non-newtonian plugging fluid. Curable fluids can include fluids that can undergo a curing process, through which the viscosity of the fluid increases. Some curing fluids can include monomers that can polymerize during curing to form a material having a higher viscosity than the original viscosity of the fluid. Curing fluids can also include gels, cross-linkable polymers, and other materials. A variety of curing processes can be used, such as chemical curing, thermal curable, ultraviolet radiation curing, and so on. The non-newtonian plugging fluid may have a sufficient viscosity to partition fluid upstream from the non-newtonian plugging fluid from fluid downstream from the non-newtonian plugging fluid. The non-newtonian plugging fluid may also hold back pressure to allow for dispensing of fluids downstream of a fluid plug and may be capable of filling in any imperfections or gaps in fluid channels.

[0033] The device may further include other reservoirs. Reservoirs of any type can be sized and shaped to contain a fluid, a reagent, or a combination thereof and can be positioned outside of the interconnected volumes and fluidically connected to the interconnected volumes via an opening, a microchannel, an input, a port, and/or an inlet to permit dispensing of a content within the reservoir into the interconnected volumes. A reservoir can be a chamber, a channel, a flexible blister pack, a syringe, a bag, a balloon, or a combination thereof. In one example, a reservoir can be a flexible blister pack that when pushed, can open and force contents within the reservoir out of the reservoir and into the interconnected volumes. In some examples, the reservoir can include a sealing layer that can maintain separation of contents in the reservoir and interconnected volumes until the sealing layer is broken. Breaking the sealing layer may allow contents of the reservoir to be released therefrom. In some examples the fluidic device can include a sharp point located near the sealing layer so that the sharp point can puncture the sealing layer when pressure is applied to a flexible blister pack. The sharp point may be located interior or exterior of the flexible blister pack. In other examples, the flexible blister pack can be designed to release fluid in other ways. In one example, the sealing layer can be easy to rupture so that the sealing layer can rupture due to pressure without a sharp point to puncture the sealing layer.

[0034] Additional types of reservoirs can include a wash buffer reservoir, a lysis fluid reservoir, a fluid reagent reservoir, or a combination thereof. Reservoirs can be sized and shaped to contain their respective fluid or reagent and may be located to allow dispensing of the fluid or the reagent therein into the interconnected volumes. Reservoirs may be arranged to allow a fluid or a reagent therein to be individually dispensed into the interconnected volumes, or reservoirs may be arranged in series to allow a fluid, a reagent, or a combination thereof to be dispensed sequentially or at the same time into the interconnected volumes; or can be arranged to allow for a combination thereof. [0035] The device may also include a removable or puncturable cap or seal that can cover an outlet of the capillary volume of the interconnected volumes. The density gradient column interconnected volumes can be a standalone component or can be part of a system.

Methods of Processing Fluids in a Density Gradient Column

[0036] A flow diagram 200 of processing fluids in a density gradient column is shown in FIG. 2. The method can include establishing 210 a density gradient column including a sample fluid positioned on top of a wash buffer, with the wash buffer having a greater density than the sample fluid. The density gradient column in this example is positioned within interconnected volumes that includes a bulk fluid volume and a capillary volume. The sample fluid occupies the bulk fluid volume and the wash buffer occupies the capillary volume (as a note, either can partially occupy the other fluid volume, e.g., the fluid interface between the sample fluid and the wash buffer can reside in the capillary volume, the bulk fluid volume, or at the border between the capillary volume and the bulk fluid volume). The method in this example further includes magnetically moving 220 magnetizing particles having a biological component bound thereto from the sample fluid and into the wash buffer at a location where the wash buffer resides in the capillary volume, and displacing 230 a gas into the capillary volume to form a separation gas bubble in the capillary volume that separates a downstream portion of the wash buffer from a balance of fluids positioned thereabove that includes the sample fluid in the bulk fluid volume. In one example, displacing the gas into the capillary volume can occur prior to the magnetically moving of the magnetizing particles. The magnetizing particles in this instance can be moved through the separation gas bubble into the downstream portion of the wash buffer. Alternatively, displacing the gas into the capillary volume can occur after the magnetically moving of the magnetizing particles into the downstream portion of the wash buffer. In further detail, displacing the gas into the capillary volume can include releasing the gas from a flexible blister pack located exterior to the capillary volume. [0037] Biological components can be intermixed with other components in a biological sample that can interfere with subsequent analysis. As used herein, the term “biological component” can refer to materials of various types, including proteins, cells, cell nuclei, nucleic acids, bacteria, viruses, or the like, that can be present in a biological sample. A “biological sample” can refer to a fluid obtained for analysis from a living or deceased organism. Isolating a biological component from other components of the biological sample can permit subsequent analysis of the isolated biological component without interference from the other components in the biological sample and can increase an accuracy of the subsequent analysis of the isolated biological component. In addition, isolating the biological component from other components in the biological sample can permit analysis of the biological component that would not be possible if the biological component was not readily accessible within the biological sample. Many isolation techniques can include repeatedly dispersing and re-aggregating samples. The repeated dispersing and re-aggregating can result in a loss of a quantity of the biological component. Furthermore, isolating a biological component with some of these techniques can be complex, time consuming, and labor intensive and can result in less than maximum yields of the isolated biological component.

[0038] In some examples, the sample fluid can include nucleic acids such as DNA or RNA, proteins, viruses, antibodies, or a variety of other biological materials. In one particular example, the method can be used to detect a virus and the biological sample can include DNA or RNA extracted from the virus. The DNA or RNA can be extracted by lysing viruses, which can result in a solution containing the viral DNA or the viral RNA in addition to fragments of lysed viruses and other materials. In some examples, the sample fluid can include RNA. The wash buffer can be a liquid that can be used to wash a biological sample.

[0039] The wash buffer can be an aqueous solution. For example, a wash buffer can include water, alcohol (such as ethanol), a binding agent, a salt, a surfactant, a stabilizing agent, buffering agents to maintain pH, or a combination thereof. In some examples, the wash buffer can include a densifier. The wash buffer can have a greater density than the sample fluid. Fragments and other materials from the biological sample that may be adhere to the magnetizing particles at locations other than the interactive surface group or the ligand on the exterior surface thereof can be washed off by the wash buffer. Thus, the wash buffer can be a liquid that can wash off these materials while also being safe for the biological component.

[0040] The density gradient column can be situated in interconnected volumes that can include a bulk fluid volume and a capillary volume. The sample fluid can occupy the bulk fluid volume and the wash buffer can occupy both the capillary volume and the bulk fluid volume of the interconnected volumes. In yet another example, the sample fluid can occupy a portion of the bulk fluid volume and the capillary volume and the wash buffer can occupy only the capillary volume of the interconnected volumes.

[0041] FIGS. 3A-3D schematically illustrate various example methods of processing fluids in a density gradient column, and also further illustrates the fluidic devices and systems described herein. Though some detail is shown in these FIGS., not every step is necessarily relevant to all possible methods. Various combinations of steps, sequences, or other variables can be practiced in accordance with the example provided in these figures. Furthermore, in order to provide additional clarity, the numerical references in these figures should be viewed collectively, even if not specifically described or shown for every structure in every individual figure.

[0042] As illustrated in FIG. 3A, a wash buffer 150 can be loaded into the bulk fluid volume 112 of the interconnected volumes 110 through the capillary volume 112 by depressing a wash buffer reservoir 155 that includes the wash buffer therein. A cap 195 can prevent the wash buffer from flowing out of an output of the interconnected volumes. While not illustrated, in some examples, an air pocket may remain in the capillary volume below the wash buffer reservoir near the cap. As shown in FIG. 3B, a sample fluid 170 including magnetizing particles 180 can subsequently be dispensed through a fluid injection opening 130 into a bulk fluid volume. The magnetizing particles can be surface-activated to bind a biological component of interest in the sample fluid. The density of the wash buffer can be greater than that of the sample fluid and can remain below the sample fluid. A density gradient column is formed from the sample fluid and the wash buffer. While the wash buffer is illustrated as extending in the bulk fluid volume, in some examples, the wash buffer can reside completely within the capillary volume and the sample fluid may extend into the capillary volume. As shown in FIG. 3C the magnetizing particles with the biological component of interest bound thereto can be magnetically moved by a magnetic field generator such as a magnet 190 or multiple magnets from the sample fluid into the wash buffer, and then further down into the wash buffer where the wash buffer resides with the capillary volume of the density gradient column. As shown in FIG. 3D a portion of the wash buffer containing the magnetizing particles in the capillary volume can then be partitioned off from a balance of the wash buffer thereabove to form an upstream portion of the wash buffer 152 and a downstream portion of the wash buffer 154. As shown in this figure, the downstream portion of the wash buffer includes the magnetizing particles. However, the partitioning can occur prior to moving the magnetizing particles. The partitioning, in further detail, can occur by depressing a gas reservoir 165 including air therein. The air can enter the capillary volume of the density gradient column through the port 120 and can form a separation gas bubble 160 between the upstream portion of the wash buffer and the downstream portion of the wash buffer. Because of the capillary forces in the capillary volume, e.g., the small size of the capillary volume relative to the air, the separation gas bubble created does not escape thereabove into the other fluids, but rather remains as a separation gas bubble that partitions an upstream portion of the wash buffer from the downstream portion of the wash buffer. The capillary force at an interface between the separation gas bubble and the fluid thereabove can be greater than a buoyance force of the gas if located in the fluid thereabove. The method illustrated above exemplifies one sequential order for processing fluids in a density gradient column. However, the methods are not so limited. For example, the sample fluid could be loaded into the interconnected volumes before the wash buffer is added thereto. The separation gas bubble may be formed before moving the magnetizing particles. The magnetizing particles can be magnetically moved by a magnetic field generator from the sample fluid into the wash buffer, and then into the separation gas bubble before moving further down into the wash buffer below the separation gas bubble in the capillary volume of the density gradient column.

[0043] In further detail, establishing a density gradient column can include dispensing a sample fluid over a wash buffer. The dispensing can occur by any technique that disposes the sample fluid over the wash buffer or the wash buffer below the sample fluid. In one example, the dispensing can include placing, pouring, injecting, pumping, expelling from a flexible blister pack, or otherwise positioning a wash buffer in a bulk fluid volume of a density gradient column and subsequently placing, pouring, injecting, pumping, or otherwise positioning a sample fluid over the wash buffer. In yet another example, the dispensing can occur by placing, pouring, injecting, pumping, or otherwise positioning a sample fluid in a bulk fluid volume of a density gradient column and subsequently loading a wash buffer from below the sample fluid into the bulk fluid volume of the density gradient column. The wash buffer may be loaded from below the sample fluid by injecting or pumping the wash buffer into the density gradient column or by expelling the wash buffer from a flexible blister pack by applying a force to the flexible blister pack to squeeze the wash buffer therefrom and into the density gradient column. The force applied to the flexible blister pack can be from 10 m kg s² to 40 m kg s², or from 10 m kg s² to 20 m kg s², or from 20 m kg s² to 40 m kg s². In yet other examples, a mixing chamber can be positioned above the bulk fluid volume of the density gradient column and can be separated from the bulk fluid volume by a displaceable, e.g., removable, puncturable, pierceable, etc., seal, or a valve, or the like. Upon displacing of the seal or opening of the valve, the sample fluid can be dispensed from the mixing region into the bulk fluid volume where the wash buffer may already be present, or may be loaded into the bulk fluid volume from below.

[0044] In further detail, the sample fluid, e.g., biological sample fluid, can be prepared and/or loaded in any of a number manners. For example, the sample fluid may be prepared by combining multiple components within the bulk fluid volume, e.g., combining carrier fluid or buffer with magnetizing particles and the biological component within the bulk fluid volume (which may be or include a portion thereof that acts as a mixing chamber). Thus, the biological component may become associated with the magnetizing particles in the bulk fluid volume, or the biological component may already be associated with the magnetizing particles where they are combined with the fluid carrier or buffer within the bulk fluid volume. Alternatively, the sample fluid may first be prepared in a vial or other vessel outside of the bulk fluid volume, and then the sample fluid can be added into the bulk fluid volume over the wash buffer either before, after, or at the same time that the wash buffer is loaded, e.g., from the bottom up through the capillary volume or also loaded from the top prior to loading the sample fluid. To cite one specific example, a biological sample or specimen may be collected using a swab or other biological sample collection instrument. The biological sample may include the biological component of interest. The released or eluted biological component can then be placed in the carrier fluid or buffer where the biological component is eluted into the carrier fluid or buffer. The biological component can become associated with magnetizing particles in the vial or vessel (or even thereafter in the bulk fluid volume, in some examples). Then, the biological sample fluid that includes the eluted biological component can be loaded into the bulk fluid volume or a mixing chamber fl uidically connected to or integrated as part of the bulk fluid volume. Thus, elution may occur outside of the cartridge module before sample input, or within the cartridge module where the carrier fluid or buffer is also loaded.

[0045] The magnetizing particles may either be present in the sample fluid when adding the sample fluid to the mixing chamber or the bulk fluid volume, or the magnetizing particles may be added thereto after the sample fluid is contained therein. The magnetizing particles may be placed, poured, injected, pumped, expelled from a flexible blister pack, or otherwise dispensed into the mixing chamber or the bulk fluid volume. The magnetizing particles may be added at from 5 μg to 100 μg, from 8 μg to 12 μg, from 5 μg to 50 μg, from 50 μg to 100 μg, from 25 μg to 75 μg, from 20 μg to 40 μg, from 80 μg to 100 pg, or from 5 μg to 15 μg.

[0046] In some examples, the method can include preparing the magnetizing particles by selectively binding a biological component to surface-activated magnetizing particles. The surface-activated magnetizing particles, as described in further detail below, can include an interactive surface group or a ligand on an exterior surface thereof that can be complimentary to the biological component. Selective binding can occur when combining the sample fluid including the biological component with the surface-activated magnetizing particles. In some examples, the combining may include admixing the sample fluid and the surface-activated magnetizing particles to increase collisions between the biological component and interactive surface groups or ligands on the exterior of the magnetizing particles.

[0047] The magnetizing particles can then be magnetically moved from the sample fluid into the wash buffer. The wash buffer can trap contaminates from the sample fluid and/or can remove contaminates from an exterior surface of the magnetizing particles. The magnetizing particles can be magnetically moved from the wash buffer in the bulk fluid volume to the wash buffer in the capillary volume. Magnetically moving can include positioning a magnetic field generator to attract and draw the magnetizing particles. In some examples, the magnetic field generator can be a magnet, a ring magnet, a current carrying wire, or the like. In an example, the magnetic field generator can be a current carrying wire. In another example, the magnetic field generator can be a magnet. The magnet may be a ring magnet that can surround an exterior circumference of the interconnected volumes. In other examples, the magnet can be positioned on one side of the interconnected volumes. In yet other examples, the magnet can be positioned below the interconnected volumes. Applying the magnetic field can attract the magnetizing particles. In some examples, moving the magnetic field generator vertically along the interconnected volumes can attract and thereby move the magnetizing particles vertically. As the magnetic field generator continues to move vertically, the magnetizing particles will move vertically by a corresponding amount. In some examples moving the magnetizing particles can include adjusting a magnetic field generated by a magnet. A strength of the magnetic field and the location of the magnetic field generator in relation to the magnetizing particles can affect a rate at which the magnetizing particles move through the density gradient column, e.g. as the distance from the magnetizing particles increases the force applied to the magnetizing particles decreases. The further away the magnetic field generator and the lower the strength of the magnetic field, the slower the magnetizing particles will move. As the magnetic field is strengthened, an attraction of the magnetizing particles towards the magnet will increase.

[0048] The wash buffer in the capillary volume may be partitioned off from a balance of the wash buffer in the bulk fluid volume of the density gradient column. The partitioning can include forming a separation gas bubble displacing air into the capillary volume to form a separation gas bubble between an upstream portion of the wash buffer and a downstream portion of the wash buffer. The separation gas bubble can remain in the capillary volume due to a surface tension of the fluid relative to the size and material of the capillary interconnected volumes. An amount of gas sufficient to form a separation gas bubble can be an amount that spans an interior channel diameter of the capillary volume. The amount will depend on capillary shape and interior channel diameter. In some examples, the amount of gas dispensed can range from 0.1 mL to 500 mL, from 250 mL to 500 mL, from 0.1 mL to 300 mL, from 5 mL to 100 mL, from 100 mL to 300 mL, or from 300 mL to 500 mL In some examples, the partitioning can occur after magnetically moving the magnetizing particles through the density gradient column. In yet other examples, the displacing of air into the capillary volume can occur prior to the magnetically moving of the magnetizing particles. The magnetizing particles can be moved through the separation gas bubble into the downstream portion of the wash buffer.

[0049] In some examples, the method can further include holding back pressure in the density gradient column. In one example, holding back pressure can include dispensing a non-newtonian plugging fluid into the capillary volume to form a fluid plug. An amount of non-newtonian plugging fluid can be an amount that spans an interior channel diameter of the capillary volume. The dispensing can include injecting, pumping, or expelling the non-newtonian plugging fluid from a reservoir or through an injection opening into the capillary volume of the interconnected volumes. Non-newtonian plugging fluids can include a Bingham plastic, a viscoplastic, or a shear thinning fluid. Bingham plastics can include materials that behave as rigid bodies at low stress but which flow as a viscous fluid at high stress. The transition between the rigid body behavior and the viscous fluid behavior can occur at various different stress levels, depending on the particular Bingham plastic material. Bingham plastics can include greases, slurries, suspensions of pigments, or others. Viscoplastics are a broader category of materials that can include Bingham plastics. Viscoplastic materials can experience irreversible plastic deformation when stress over a certain level is applied. When stress under this level is applied, the viscoplastic material can behave as a rigid body, as is the case with Bingham plastics, or the viscoplastic material can undergo reversible elastic deformation. Shear thinning fluids are materials that behave as a fluid with a high viscosity when low stress is applied, but the viscosity of the fluid decreases when the stress is increased. Examples of shear thinning fluids can include polymer solutions, molten polymers, suspensions, colloids, or others. In yet another example, holding back pressure can include capping an inlet opening of the interconnected volumes to prevent air flow into the interconnected volumes.

[0050] Once pressure is held back in the interconnected volumes, the method can further include dispensing the biological component and the downstream portion of the wash buffer from the capillary volume. Dispensing the biological component and the downstream portion of the wash buffer can include opening a valve, removing a cap, or piercing a seal that may be preventing fluid flow out of the interconnected volumes. In some examples, the biological component may be dispensed while bound to the magnetizing particles. In yet other examples, the biological component may be separated from the magnetizing particles in the capillary volume thereby releasing isolated biological component into the downstream portion of the wash buffer prior to dispensing. The separating can include heating the magnetizing particles and the fluid reagent. The heating can be at a temperature ranging from 40 °C to 95 °C, from 50 °C to 75 °C, or from 40 °C to 80 °C for a time period ranging from 1 second to 10 minutes, from 2 seconds to six minutes, from 5 minutes to 10 minutes, or from 2 minutes to 8 minutes. Releasing the biological component can allow for independent analysis of the biological component which may not be possible if the magnetizing particles would otherwise interfere with the subsequent analysis. To dispense the biological component without the magnetizing particles, a magnetic field may be applied to the capillary volume to trap the magnetizing particles in the capillary volume while dispensing the isolated biological component and the downstream portion of the wash buffer.

Fluid Processing Systems

[0051] In accordance with examples of the present disclosure, a fluid processing system can include features such as those shone in FIGS. 1 A and 1 B, and can include interconnected volumes 110, a wash buffer reservoir 155, a wash buffer fluid injection opening157, and a port 120 for injecting a gas, e.g., air, into the capillary volume. As illustrated, the interconnected volumes can include a bulk fluid volume 112 and a capillary volume 114 to receive a density gradient column of fluids, such as the wash buffer 150. In further detail, a sample fluid can be placed in the bulk fluid above the wash buffer, as shown in FIG. 3B by way of example. A wash buffer reservoir 155 can include the wash buffer therein and can be positioned outside the interconnected volumes to inject the wash buffer through fluid injection opening 157 and into the interconnected volumes through the capillary volume and partially into the bulk fluid volume. The port can also be positioned outside of the interconnected volumes and can be fluidically connected to the capillary volume to inject air into the capillary volume thereby forming a separation gas bubble that can separate an upstream portion of the wash buffer from a downstream portion of the wash buffer. The interconnected volumes, wash buffer reservoir, fluid injection opening, port, and gas reservoir can be as described above. Thus, the devices shown in FIGS. 1A-1 B and FIGS. 3A-3D can be implemented for use in accordance with example fluid processing systems of the present disclosure.

[0052] In another example, the system can further include a sample fluid. The sample fluid can include a biological component. The sample fluid can include DNA, RNA, proteins, viruses, antibodies, or a variety of other biological materials. In one particular example, the method can be used to detect a virus and the biological component can include DNA or RNA extracted from the virus. The DNA or RNA can be extracted by lysing viruses, which can result in a solution containing the viral DNA or the viral RNA in addition to fragments of lysed viruses and other materials. The sample fluid can have a lower density than the wash buffer and can be loaded or loadable above the wash buffer. Accordingly, the sample fluid may be positioned above a wash buffer when loaded in a bulk fluid volume of the interconnected volumes. The sample fluid can include magnetizing particles having a biological component bound thereto and dispersed therein. The magnetizing particles and/or biological component may be added to the sample fluid before or after loading of the sample fluid into the interconnected volumes.

[0053] The magnetizing particles, in further detail, can be in the form of paramagnetic microparticles, superparamagnetic microparticles, diamagnetic microparticles, or a combination thereof, for example. The term “magnetizing particles" is defined herein to include particles or microparticles, e.g., magnetizing microparticles, that may not be magnetic in nature unless and until a magnetic field is introduced at a strength and proximity to cause them to become magnetic. Their magnetic strength can be dependent on the magnetic field applied and may get stronger as the magnetic field is increased, or the magnetizing particles get closer to a magnet applying the magnetic field.

[0054] In more specific detail, “paramagnetic microparticles” have these properties, in that they have the ability to increase in magnetism when a magnetic field is present; however, paramagnetic microparticles are not magnetic when a magnetic field is not present. In some examples, the paramagnetic microparticles can exhibit no residual magnetism once the magnetic field is removed. A strength of magnetism of the paramagnetic microparticles can depend on the strength of the magnetic field, the distance between a source of the magnetic field and the paramagnetic microparticles, and a size of the paramagnetic microparticles. As a strength of the magnetic field increases and/or a size of the paramagnetic microparticles increases, the strength of the magnetism of the paramagnetic microparticles increases. As a distance between a source of the magnetic field and the paramagnetic microparticles increases, the strength of the magnetism of the paramagnetic microparticles decreases. “Superparamagnetic microparticles" can act similar to paramagnetic microparticles; however, they can exhibit magnetic susceptibility to a greater extent than paramagnetic microparticles in that the time it takes for them to become magnetized appears to be near zero seconds.

“Diamagnetic microparticles,” on the other hand, can display magnetism due to a change in the orbital motion of electrons in the presence of a magnetic field.

[0055] The magnetizing particles can be surface-activated to selectively bind with a biological component or can be bound to a biological component from a biological sample. An exterior of the magnetizing particles can be surface-activated with interactive surface groups that can interact with a biological component of a biological sample or may include a covalently attached ligand. In some examples, the ligand can include proteins, antibodies, antigens, nucleic acid primers, nucleic acid probes, amino groups, carboxyl groups, epoxy groups, tosyl groups, sulphydryl groups, or the like. In one example, the ligand can be a nucleic acid probe. The ligand can be selected to correspond with and to bind with the biological component. The ligand may vary based on the type of biological component targeted for isolation from the biological sample. For example, the ligand can include a nucleic acid probe when isolating a biological component that includes a nucleic acid sequence. In another example, the ligand can include an antibody when isolating a biological component that includes antigen. In one example, the magnetizing particles can be surface-activated to bind to nucleic acid such as DNA or RNA. Thus DNA or RNA molecules can be bound to the surface of the magnetizing particles. Commercially available examples of magnetizing particles that are surface-activated include those sold under the trade name DYNABEADS®, available from ThermoFischer Scientific (USA).

[0056] In some examples, the magnetizing particles can have an average particle size that can range from 10 nm to 50,000 nm. In yet other examples, the magnetizing particles can have an average particle size that can range from 500 nm to 25,000 nm, from 10 nm to 1 ,000 nm, from 25,000 nm to 50,000 nm, or from 10 nm to 5,000 nm. The term “average particle size" describes a diameter or average diameter, which may vary, depending upon the morphology of the individual particle. A shape of the magnetizing particles can be spherical, irregular spherical, rounded, semi-rounded, discoidal, angular, sub-angular, cubic, cylindrical, or any combination thereof. In one example, the particles can include spherical particles, irregular spherical particles, or rounded particles. The shape of the magnetizing particles can be spherical and uniform, which can be defined herein as spherical or near-spherical, e.g., having a sphericity of >0.84. Thus, any individual particles having a sphericity of <0.84 are considered non-spherical (irregularly shaped). The particle size of the substantially spherical particle may be provided by its diameter, and the particle size of a non-spherical particle may be provided by its average diameter (e.g., the average of multiple dimensions across the particle) or by an effective diameter, e.g., the diameter of a sphere with the same mass and density as the non-spherical particle.

[0057] In some example, the system may further include a magnetic field generator that can generate a magnetic field for magnetizing and/or moving the magnetizing particles. In some examples, the magnetic field generator can be a magnet, a ring magnet, or a current carrying wire. Applying the magnetic field, magnetic field motion, and/or differing magnetic field gradients can attract the magnetizing particles. The magnetic field may be turned on and off by introducing electrical current/voltage to the magnetic field generator. The magnetic field generator can be permanently placed, can be movable along the interconnected volumes, or can be movable in position and/or out of position to effect movement of the magnetizing particles in and through the density gradient column.

[0058] The magnetic field generator may create a force capable of pulling the magnetizing particles through the density gradient column, holding the magnetizing particles at a location in the density gradient column, or a combination thereof. When the magnetic field generator is turned off or not in appropriate proximity, the magnetizing particles can reside in a fluid layer until gravity pulls the magnetizing particles through fluid layers of the density gradient column, or they may remain suspended in the fluid layer in which they may reside until the magnetic field is applied thereto. The rate at which gravity pulls the magnetizing particles through fluid layers (or leaves the magnetizing particles within a fluid layer) can be based on a mass of the magnetizing particles, a quantity of the magnetizing particles, a size of the magnetizing particles, a density of the fluid in the fluid layer, a viscosity of the fluid in the fluid layer, and a surface tension at the fluid interface between fluid layers. The magnetic field generator can cause the magnetizing particles to move from one fluid layer to another, or can increase a rate at which the magnetizing particles pass from one fluid layer into another.

[0059] A strength of the magnetic field and the location of the magnetic generator in relation to the magnetizing particles can also affect a rate at which the magnetizing particles move through the density gradient column. The further away the magnet and the lower the strength of the magnetic field, the slower the magnetizing particles will move.

[0060] In an example, the magnetic field generator can be moveable in position, out of position, or at variable positions to effect downward movement, rate of movement, or to promote little to no movement of the magnetizing particles. In another example, the magnetic field generator can be positioned adjacent to a side of the density gradient column and can move vertically to cause the magnetizing particles to move therewith. In some examples, the magnetic field generator can be a ring magnet that can be placed around a circumference of the density gradient column. A movable magnet(s) can likewise be positioned adjacent to a side of the multi-fluid density gradient column that is not a ring shape, but can be any shape effective for moving magnetizing particles along the density gradient column. In some examples, the magnetic field generator can be moved along a side and/or along a bottom of the multi-fluid density gradient column to pull the magnetizing particles in one direction or another. In one example, the magnetic field generator can be used to pull the magnetizing particles downwardly through fluid layers of the density gradient column.

[0061] In yet other examples, a magnetic field generator can be used to concentrate and hold the magnetizing particles near a side wall of the density gradient column. For example, the magnetic field generator can concentrate the magnetizing particles near a side wall of the density gradient column and heat can be applied to decouple and separate an isolated biological component from the magnetizing particles. The magnetic field generator can continue to hold the magnetizing particles while an outlet of the density gradient column can be opened thereby allowing dispensing of the isolated biological component from the density gradient column separate of the magnetizing particles.

Definitions

[0062] It is noted that, as used in this specification and the appended claims, the singular forms "a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0063] As used herein, “Bingham plastid¹ refers to a class of materials that behave as rigid bodies at low stress but which flow as a viscous fluid at high stress. The transition between the rigid body behavior and the viscous fluid behavior can occur at various different stress levels, depending on the particular Bingham plastic material. Bingham plastics can include greases, slurries, suspensions of pigments, and others.

[0064] As used herein, the term “interact" as it relates to a surface of the magnetizing particles indicates that a chemical, physical, or electrical interaction occurs where the magnetizing particles surface properties that are different than may have been present prior to entering the fluid layer, but does not include modification of properties of the bulk of the magnetizing particles as they are influenced by the magnetic field introduce by the magnet. For example, a fluid layer can include a lysis buffer to lyse cells. In yet other examples, a fluid layer can be a surface binding fluid layer to bind the biological component to the magnetizing particles, a wash fluid layer to trap contaminates from a sample fluid and/or remove contaminates from an exterior surface of the magnetizing particles, a surfactant fluid layer to coat the magnetizing particles, a dye fluid layer, an elution fluid layer to remove the biological component from the magnetizing particles following extraction from the biological sample, a labeling fluid layer for binding labels to the biological component such as a fluorescent label (either attached to the magnetizing particles or unbound thereto), a reagent fluid layer to prep a biological component for further analysis such as a master mix fluid layer to prep a biological component for PCR, and so on. [0065] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though individual members of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on presentation in a common group without indications to the contrary.

[0066] Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. A range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include individual numerical values or sub-ranges encompassed within that range as if numerical values and sub-ranges are explicitly recited. As an illustration, a numerical range of “1 wt% to 5 wt%” should be interpreted to include not only the explicitly recited values of about 1 wt% to about 5 wt%, but also to include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3.5, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This same principle applies to ranges reciting one numerical value. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described.

EXAMPLE

[0067] The following illustrates an example of the present disclosure. However, the following is illustrative of the application of the principles of the present disclosure. Numerous modifications and alternative compositions, methods, and systems may be devised without departing from the spirit and scope of the present disclosure. The appended claims are intended to cover such modifications and arrangements. Example - Processing a Sample Fluid in a Fluidic Device

[0068] Interconnected volumes including a bulk fluid volume and a capillary volume was obtained. A biological sample from saliva was gathered on a collection swab. The collection swab was placed in a 3 mL buffer solution of Tris HCL, magnesium salts, and surfactant to prepare a sample fluid. Eight to twelve μg of magnetizing particles including silica, an iron core, and surface activation groups of nucleic acid probe complimentary to a selected stand of RNA were added to the sample fluid. The magnetizing particles had an average particle size of 1 micron. One hundred mLs of a wash buffer stored in a wash buffer reservoir including a foil blister was added to the capillary volume and the bulk fluid volume of the interconnected volumes by compressing the foil blister, thereby positioning the sample fluid over the wash buffer and establishing a density gradient column in the interconnected volumes. The magnetizing particles were then transported from the sample fluid, through the wash buffer in the bulk fluid volume, and into a portion of the wash buffer in the capillary volume by a magnet. As the magnetizing particles passed through the wash buffer the magnetizing particles were purified of contaminates. A gas reservoir including a foil blister was compressed to displace air into the capillary volume of the density gradient column thereby forming a separation gas bubble that separated an upstream portion of the wash buffer from a downstream portion of the wash buffer which included the magnetizing particles therein. An outlet at an opposing end of the capillary volume was unsealed by a needle and the downstream portion of the wash buffer including the magnetizing particles was dispensed from the interconnected volumes into a collection receptacle below.

[0069] While the present technology has been described with reference to certain examples, various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the disclosure. The disclosure may be limited only by the scope of the following claims.

Claims

CLAIMS What is Claimed Is:

1. A fluidic device comprising: interconnected volumes including a bulk fluid volume fluidically connected in series with a capillary volume, the interconnected volumes including the capillary volume to receive a wash buffer; and a port positioned outside and fluidically connected to the capillary volume, the port to inject a gas into the capillary volume thereby forming a separation gas bubble between an upstream portion of the wash buffer from a downstream portion of the wash buffer.

2. The fluidic device of claim 1 , wherein the wash buffer is part of a density gradient column, and wherein the density gradient column further includes a sample fluid in the bulk fluid volume positioned above the wash buffer, wherein the wash buffer has a greater density than a density of the sample fluid.

3. The fluidic device of claim 1 , wherein the wash buffer is loaded in the interconnected volumes and a portion of the wash buffer resides in the capillary volume.

4. The fluidic device of claim 1 , wherein the capillary volume has an interior channel average diameter from 1 mm to 4 mm and further includes a fluidic output.

5. The fluidic device of claim 1 , wherein the port is fluidly associated with a gas reservoir.

6. The fluidic device of claim 5, wherein the gas reservoir is held by a flexible blister pack that when engaged provides an opening to the port and forces gas into the capillary volume, or the gas reservoir is injectable into the capillary volume as the gas is displaced by a liquid, or both.

7. The fluidic device of claim 1 , further comprising a plugging fluid reservoir of a non-newtonian plugging fluid positioned outside the interconnected volumes with a plugging fluid injection opening positioned at a location along a length of the interconnected volumes to inject the non-newtonian plugging fluid into the interconnected volumes from the plugging fluid reservoir, wherein the non-newtonian plugging fluid has a sufficient viscosity to partition fluid upstream from the non-newtonian plugging fluid from fluid downstream from the non-newtonian plugging fluid.

8. The fluidic device of claim 1 , wherein the gas is air.

9. A method of processing fluids in a density gradient column, comprising: establishing a density gradient column including a sample fluid positioned on top of a wash buffer, wherein the wash buffer has a greater density than the sample fluid, wherein the density gradient column is positioned within interconnected volumes that includes a bulk fluid volume and a capillary volume, wherein the sample fluid occupies the bulk fluid volume and the wash buffer occupies the capillary volume; magnetically moving magnetizing particles having a biological component bound thereto from the sample fluid and into the wash buffer at a location where the wash buffer resides in the capillary volume; and displacing a gas into the capillary volume to form a separation gas bubble in the capillary volume that separates a downstream portion of the wash buffer from a balance of fluids positioned thereabove that includes the sample fluid in the bulk fluid volume.

10. The method of claim 9, wherein displacing the gas into the capillary volume occurs prior to the magnetically moving of the magnetizing particles, wherein the magnetizing particles are moved through the separation gas bubble into the downstream portion of the wash buffer.

11. The method of claim 9, wherein displacing the gas into the capillary volume occurs after the magnetically moving of the magnetizing particles into the downstream portion of the wash buffer.

12. The method of claim 9, wherein displacing the gas into the capillary volume includes releasing the gas from a flexible blister pack located exterior to the capillary volume.

13. A fluid processing system, comprising: interconnected volumes including a bulk fluid volume and a capillary volume to receive a density gradient column; a wash buffer reservoir including a wash buffer and positioned outside the interconnected volumes; a wash buffer fluid injection opening in the interconnected volumes to inject the wash buffer into the interconnected volumes through the capillary volume and partially into the bulk fluid volume; and a port positioned outside of the interconnected volumes and fluidically connected to the capillary volume of the density gradient column, the port to inject a gas into the capillary volume thereby forming a separation gas bubble that separates a downstream portion of the wash buffer from a balance of fluids positioned there above.

14. The fluid processing system of claim 13, wherein the port is fluidly associated with a gas reservoir containing the gas, wherein the gas reservoir includes a flexible blister pack that when pushed, provides access to the port and forces the gas into the capillary volume.

15. The fluid processing system of claim 13, further comprising a sample fluid, wherein the sample fluid includes magnetizing particles having a biological component bound thereto dispersed therein, and wherein the sample fluid has a lower density than the wash buffer and is loaded or loadable above the wash buffer.