Microfluidic sample handling

Abstract

Structures, devices, and methods for handling fluids are provided. A valve includes a first channel having a first inlet connected to an upstream chamber. The first inlet of the first channel has a cross-section perpendicular to the flow direction that is the same as or smaller than that of the upstream chamber, thereby forming a hydrophobic junction with the upstream chamber at the first inlet. The valve also includes a compartment connected to a first outlet of the first channel. The compartment has a cross-section perpendicular to the flow direction that is larger than that of the first outlet of the first channel, thereby forming a hydrophilic junction at the first outlet of the first channel.

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 489,424, filed March 10, 2023, and U.S. Provisional Patent Application No. 63 / 489,681, filed March 10, 2023, the disclosures of each of which are incorporated herein by reference in their entirety.

[0002] Technical Field FIELD OF THE DISCLOSURE The present disclosure relates to devices and methods for handling fluids, and in particular to devices and methods for handling fluids in microfluidic devices. [Background technology]

[0003] Currently, 70% of all healthcare decisions depend on laboratory diagnostics, yet today's diagnostic process is disconnected from healthcare delivery. In primary healthcare systems, patients must travel to an outside blood collection facility to have their blood drawn, which is then shipped via courier to a laboratory for processing the next day. This means that test results are not received by healthcare workers until long after the patient has left. This disconnect in healthcare delivery and disease management leads to enormous waste in the healthcare system, including: a. Patients often delay getting tested or do not follow testing or follow subsequent medical recommendations. b. Gaps in the diagnostic process lead to missed tests, missed diagnoses, lack of intervention, and ultimately poor outcomes. c. Time is wasted by healthcare professionals reconciling test orders with patient records, and when intervention is required, even more time is wasted contacting the patient and facilitating subsequent steps in the patient's care pathway.

[0004] These issues are exacerbated when caring for patients from rural populations and populations adversely affected by social determinants of health, and there are many challenges to ensuring successful follow-up of patients from their initial consultation.

[0005] Several companies have developed point-of-care devices to bridge this gap. However, these devices are limited to a single type of test and cannot fully meet the primary care provider's workflow need for a single system that generates simple, comprehensive, and rapid test results. A product is currently under development to meet these needs. This product accomplishes this through a highly automated workflow enabled by the use of centrifugal microfluidic discs.

[0006] Centrifugal microfluidic devices are used in clinical chemistry, immunoassays, hematology, medicine, biomedical research, and other fields. These applications often require the metering, transfer, mixing, and / or other processes of fluids. Many of these applications also require the detection of concentrations and reactions. However, in microfluidic devices, it can be difficult to effectively control the metering, transfer, and mixing of fluids and accurately measure concentrations and reactions because the small scales involved can cause liquids to behave significantly differently from bulk liquids.

[0007] Therefore, there remains a need for improved devices and methods in centrifugal microfluidics to address these and other needs in the art. Summary of the Invention

[0008] In a first aspect, the present disclosure provides a simple and reliable valve that integrates both hydrophobic and hydrophilic principles in a single, simple structure, eliminating the need for surface treatment. The valve includes a first channel and a compartment. The first channel has a first inlet and a first outlet. The first inlet is connected to an upstream chamber and has a cross-section perpendicular to the flow direction that is the same as or smaller than that of the upstream chamber, thereby forming a hydrophobic junction with the upstream chamber at the first inlet. The compartment is connected to the first outlet of the first channel. The compartment has a cross-section perpendicular to the flow direction that is larger than that of the first outlet of the first channel, thereby forming a hydrophilic junction at the first outlet of the first channel.

[0009] In some embodiments, the compartment is deeper, wider, or both, than the first channel. In some embodiments, the compartment is cylindrical. In some such embodiments, the compartment has a circular, elliptical, oval, or polygonal cross-section.

[0010] In some embodiments, the valve further includes a second channel having a second inlet and a second outlet. The second inlet is connected to the compartment, and the second outlet is connected to a downstream chamber. In certain embodiments, the second channel has the same cross-section perpendicular to the flow direction as the first channel. In other embodiments, the second channel has a different cross-section perpendicular to the flow direction than the first channel. In some embodiments, the second channel is longer than the first channel.

[0011] In a second aspect, the present disclosure provides a device comprising a valve disclosed herein and an upstream chamber, in some embodiments, a portion of the upstream chamber adjacent to a first inlet of a first channel of the valve is tapered to smooth the transition between the upstream chamber and the first inlet of the first channel of the valve.

[0012] In some such embodiments, the tapered portion of the upstream chamber has a trapezoidal cross-section parallel to the flow direction. In some embodiments, the tapered portion of the upstream chamber is configured based at least in part on the fluid to be processed by the device. In some embodiments, the tapered portion of the upstream chamber has an angle of about -10 to -30 degrees, about -30 to -60 degrees, or about -60 to -80 degrees relative to the first channel.

[0013] In a third aspect, the present disclosure provides a device having a structure for capturing excess fluid. The device is rotatable about a rotation axis. The device includes a channel for transporting fluid by rotating the device about the rotation axis. The channel includes an inlet, an outlet radially outward of the inlet relative to the rotation axis, and a first portion between the inlet and the outlet. The device also includes a structure connected to a first side of the first portion of the channel. The structure is configured to (i) allow fluid transport when the device rotates at a first speed, (ii) collect fluid residue when the device rotates at a second speed greater than the first speed, and (iii) capture the collected fluid residue within the structure when the device is subjected to acceleration, deceleration, or both.

[0014] In some embodiments, the structure includes a pocket for receiving fluid residue and a chamber connecting the pocket to a first side of the first portion of the channel, the chamber having a depth greater than the first portion of the channel and the pocket, thereby acting as a valve between the first portion of the channel and the pocket.

[0015] In some embodiments, at least a portion of the structure is positioned radially outward of the first portion of the channel, and a radially innermost point at a junction formed by the chamber and the first side of the first portion of the channel defines a maximum allowable level of fluid residue. In some embodiments, a second side of the first portion of the channel is positioned radially inward of the maximum allowable level of fluid residue. In some embodiments, the first portion of the channel is curved.

[0016] In a fourth aspect, the present disclosure provides a device for inertial mixing of fluids comprising two or more distinct components, the device being rotatable about an axis of rotation, the device including a mixing chamber having curved sides that are not coaxial with the axis of rotation and configured to inertially mix fluids comprising two or more distinct components.

[0017] In a fifth aspect, the present disclosure provides a method for inertial mixing of a fluid comprising two or more distinct components. The method includes obtaining a device including: (A) a rotation axis and a mixing chamber having curved sides that are not coaxial with the rotation axis, wherein the mixing chamber contains a fluid comprising the two or more distinct components. In some embodiments, the volume of the fluid occupies at most 50%, at most 55%, at most 60%, at most 65%, or at most 70% of the mixing chamber.

[0018] The method also includes (B) accelerating the device in a direction toward the curved side of the mixing chamber to a first velocity, in some embodiments, the first velocity is based at least in part on the type of fluid, the amount of fluid, the shape of the mixing chamber, or any combination thereof.

[0019] The method further includes (C) suddenly decelerating the device so that the fluid moves toward the curved side of the mixing chamber due to inertia. The curved side of the mixing chamber converts the fluid's motion into a circular motion, creating a vortex, thereby promoting mixing of two or more different components in the fluid. In some embodiments, decelerating (C) is performed at a deceleration rate of at least 500 rpm / s, at least 1000 rpm / s, at least 1500 rpm / s, at least 2000 rpm / s, or at least 2500 rpm / s, at least 3000 rpm / s, at least 5000 rpm / s, 10000 rpm / s, at least 50000 rpm / s, or greater. In some embodiments, decelerating (C) brings the device to a complete stop.

[0020] In some embodiments, the method further comprises (D) repeating accelerating (B) and decelerating (C) one or more times.

[0021] In some embodiments, the mixing chamber includes a path opposite the curved side and not coaxial with the axis of rotation. In some such embodiments, the method further includes (E) slowly accelerating the device in a direction toward the path at a second velocity, and (F) suddenly decelerating the device such that the fluid moves toward the path of the mixing chamber by inertia. In some embodiments, the second velocity is based at least in part on the type of fluid, the amount of fluid, the shape of the mixing chamber, or any combination thereof.

[0022] In a sixth aspect, the present disclosure provides a method for inertially directing a flow of a fluid, the method including: (A) obtaining a device having an axis of rotation and a chamber having a path not coaxial with the axis of rotation, the chamber containing a fluid; (B) accelerating the device in a direction toward the path of the chamber; and (C) suddenly decelerating the device such that the fluid moves toward the path of the chamber by inertia.

[0023] In a seventh aspect, the present disclosure provides a capillary channel capable of bubble-free priming. The capillary channel includes an open end and a closed end positioned radially outward of the open end relative to the axis of rotation. The capillary channel also includes first, second, and third lanes. The first lane has an inlet at its open end for receiving a fluid. The third lane has an outlet at its open end for discharging air. The second lane is formed between and connected to the first and third lanes. The second lane has a flow resistance different from that of the first and third lanes, thereby facilitating bubble-free priming by allowing the fluid to first flow through the first lane from the open end to the closed end, and then flow through the second lane, the third lane, or both, from the closed end to the open end.

[0024] In some embodiments, the first, second, and third lanes collectively form a stepped cross-section perpendicular to the length of the capillary channel. In some embodiments, the first and third lanes are deeper than the second lane. In certain embodiments, the first and third lanes are substantially identical to one another. In other embodiments, the first and third lanes are different from one another. In some embodiments, at least two of the first, second, and third lanes have the same width. In some embodiments, at least two of the first, second, and third lanes have different widths.

[0025] In an eighth aspect, the present disclosure provides a device rotatable about an axis of rotation, the device comprising a vent port and a capillary channel as disclosed herein, the capillary being positioned radially outward of the vent port, and the outlet of a third lane of the capillary channel being connected to the vent port.

[0026] In a ninth aspect, the present disclosure provides a device having a constriction structure for directing fluid flow. The device includes a chamber and a channel connected to the chamber for delivering fluid to the chamber. The chamber and the channel collectively form a junction that minimizes or eliminates capillary flow as the fluid exits the outlet of the channel and enters the chamber. In some embodiments, the junction causes the fluid to flow from the outlet of the channel into the chamber in the direction of centrifugal force.

[0027] In some embodiments, the channel includes a protruding portion that forms at least a portion of the junction. In certain embodiments, the protruding portion includes a U-shaped wall on either side of the channel at the outlet of the channel. In other embodiments, the protruding portion includes a V-shaped wall on either side of the channel at the outlet of the channel. In some embodiments, the wall of the chamber adjacent the outlet of the channel curves radially inward relative to the outlet of the channel to form at least a portion of the junction.

[0028] In a ninth aspect, the present disclosure provides a method for measuring depth with a self-calibrating feature. The method includes (A) obtaining a device including a structure filled with an absorbing dye. The structure includes a first portion having a first depth and a second portion having a second depth. The first depth and the second depth are different from each other, but a nominal depth difference between the first depth and the second depth is known. In some embodiments, obtaining (A) includes obtaining a device with the structure and filling the structure with an absorbing dye.

[0029] The method also includes (B) measuring a first optical density of the absorbing dye in a first portion of the feature and a second optical density of the absorbing dye in a second portion of the feature, and (C) calculating an optical density difference between the first optical density and the second optical density. The method further includes (D) calculating a ratio of the optical density difference to a nominal depth difference, the ratio representing the product of the extinction coefficient and concentration of the absorbing dye. The method further includes (E) using the ratio to determine a first depth of the first portion of the feature, a second depth of the second portion of the feature, a depth of an additional feature of the device, or any combination thereof.

[0030] In a tenth aspect, the present disclosure provides a device for measuring depth with self-calibration capabilities. The device includes one or more structures, each of which includes a first portion having a first depth and a second portion having a second depth. The first depth and the second depth are different from each other, but a nominal depth difference between the first depth and the second depth is known, thereby enabling self-calibration of the depth of the structure of the device regardless of variations in device manufacturing.

[0031] In some embodiments, the one or more features include a first feature and a second feature at different locations on the device. In some embodiments, the first feature has the same nominal depth difference as the second feature. In other embodiments, the first feature has a different nominal depth difference than the second feature.

[0032] In an eleventh aspect, the present disclosure provides a method for measuring concentration regardless of manufacturing variations. The method includes (A) obtaining a device including a structure positioned in a path of a mixture having a first component. The structure includes a first portion having a first depth and a second portion having a second depth. The first depth and the second depth are different from each other, but a nominal depth difference between the first depth and the second depth is known. In some embodiments, the first component is hemoglobin.

[0033] The method also includes (B) measuring a first optical density of the first component in the first portion of the structure and a second optical density of the first component in the second portion of the structure. In some embodiments, the absorbance measurement is performed using a spectrophotometer or a microfluidic device.

[0034] The method further includes (C) calculating an optical density difference between the first optical density and the second optical density, and (D) determining a concentration of the first component in the mixture based at least in part on the optical density difference and the nominal depth difference. In some embodiments, the concentration of the first component in the mixture is determined by comparing the optical density difference to a calibration curve in the optical path corresponding to the nominal depth difference. In some embodiments, the attenuation coefficient of the first component is known, and the concentration of the first component in the mixture is calculated by dividing the optical density difference by the nominal depth difference and the attenuation coefficient of the first component.

[0035] In some embodiments, the method further includes (E) generating a calibration curve prior to determining (D). In some embodiments, generating (E) includes (i) preparing a series of standard solutions containing known concentrations of the first component, (ii) measuring the absorbance of each of the standard solutions at one or more particular wavelengths for the first component in one or more optical paths, thereby obtaining a plurality of absorbance values, and (iii) plotting the absorbance values ​​against the corresponding concentrations of the first component to generate a calibration curve for each of the one or more optical paths.

[0036] In a twelfth aspect, the present disclosure provides a device for measuring concentration independent of manufacturing variations. The device includes a structure positioned in a path of a mixture having a first component. The structure includes a first portion having a first depth and a second portion having a second depth. The first depth and the second depth are different from each other, but a nominal depth difference between the first depth and the second depth is known, thereby enabling measurement of the concentration of the first component independent of manufacturing variations of the device.

[0037] The devices, systems, and methods of the present disclosure have other features and advantages that will become apparent or be more fully set forth in the accompanying drawings incorporated herein and the following detailed description, which together serve to explain certain principles of exemplary embodiments of the present disclosure.

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more exemplary embodiments of the present disclosure and, together with the detailed description, serve to explain the principles and implementation of exemplary embodiments of the invention. The accompanying drawings are not necessarily to scale. For example, specific design features of the inventions disclosed herein, including specific dimensions, orientations, locations, and shapes, are determined in part by the particular intended application and environment of use. Furthermore, the components illustrated in the drawings can be combined in any useful number and combination. [Brief explanation of the drawings]

[0039] [Figure 1A] 1 is a schematic diagram illustrating a device including a valve, the valve being hydrophobic, according to certain exemplary embodiments of the present disclosure. [Figure 1B] FIG. 1B is a schematic diagram illustrating the device of FIG. 1A when the valve is hydrophilic, according to an exemplary embodiment of the present disclosure. [Figure 1C] FIG. 1B is a schematic diagram illustrating a cross-sectional view of the device along the dotted line in FIG. 1A. [Figure 1D] FIG. 10 is a schematic diagram illustrating a cross-sectional view of a device according to an alternative exemplary embodiment of the present disclosure. [Figure 1E] FIG. 1 is a schematic diagram illustrating an existing hydrophobic valve. [Figure 1F] FIG. 1 is a schematic diagram illustrating an existing hydrophilic valve. [Figure 2A] 1 is an image illustrating a device having structures for capturing excess fluid, according to some exemplary embodiments of the present disclosure. [Figure 2B]1 is a schematic diagram illustrating a structure for capturing excess fluid, according to certain exemplary embodiments of the present disclosure; [Figure 2C] FIG. 2C is a cross-sectional view taken along a vertical line in FIG. 2B. [Figure 2D] 10 is an image showing a device without structures for capturing excess fluid. [Figure 3] 1 is a flowchart illustrating a method for inertial mixing of a fluid comprising two or more different components, according to certain exemplary embodiments of the present disclosure. [Figure 4A] 1 is an image illustrating a device for inertial mixing of a fluid containing two or more different components according to an exemplary embodiment of the present disclosure. [Figure 4B] 1 is an image illustrating a device for inertial mixing of a fluid containing two or more different components according to an alternative exemplary embodiment of the present disclosure. [Figure 4C] 10 is an image illustrating a device for inertial mixing of a fluid containing two or more different components according to another alternative exemplary embodiment of the present disclosure. [Figure 4D] 10 is an image illustrating a device for inertial mixing of a fluid containing two or more different components according to yet another alternative exemplary embodiment of the present disclosure. [Figure 5] 1 is a flowchart illustrating a method for inertially directing fluid flow, according to some exemplary embodiments of the present disclosure. [Figure 6] 1 is an image illustrating a device for inertial fluid flow guidance, according to some exemplary embodiments of the present disclosure. [Figure 7A] 1 is an image illustrating a device having a capillary channel capable of bubble-free priming, according to some exemplary embodiments of the present disclosure. [Figure 7B] 7B is a cross-sectional view illustrating the capillary channel of FIG. 7A, according to certain exemplary embodiments of the present disclosure. [Figure 8A] 1 is an image illustrating a device having a constriction structure for directing fluid flow, according to some exemplary embodiments of the present disclosure. [Figure 8B]8B is a schematic diagram illustrating the constriction structure of FIG. 8A according to an exemplary embodiment of the present disclosure. [Figure 8C] 8B is a schematic diagram illustrating the constriction structure of FIG. 8A according to an alternative exemplary embodiment of the present disclosure. [Figure 8D] 10 is an image showing a device without a constriction structure to direct fluid flow. [Figure 8E] 10 is an image showing a device without a constriction structure to direct fluid flow. [Figure 9] 1 is a flowchart illustrating a method for measuring depth with self-calibration capabilities, according to some exemplary embodiments of the present disclosure. [Figure 10A] 1 is an image illustrating a device having features for measuring depth with self-calibration capabilities, according to some exemplary embodiments of the present disclosure. [Figure 10B] 10B is a cross-sectional view illustrating the structure of FIG. 10A, according to certain exemplary embodiments of the present disclosure. [Figure 11] 1 is a flowchart illustrating a method for measuring concentration independent of manufacturing variations, according to certain exemplary embodiments of the present disclosure. [Figure 12A] 1 is an image illustrating a device having features for measuring concentration independent of manufacturing variations, according to some exemplary embodiments of the present disclosure. [Figure 12B] 12B is a cross-sectional view illustrating the structure of FIG. 12A, according to certain exemplary embodiments of the present disclosure. [Figure 13] 1 is a schematic diagram illustrating a device (e.g., a disk) according to some exemplary embodiments of the present disclosure. [Figure 14] 1 is a schematic diagram illustrating a device (e.g., a disk) according to some exemplary embodiments of the present disclosure. [Figure 15] FIG. 1 is a block diagram illustrating a workflow according to some example embodiments of the present disclosure. [Figure 16A] A-1 is a schematic diagram illustrating a buffer loading process according to some exemplary embodiments of the present disclosure, and A-2 is a photograph thereof. [Figure 16B] B-1 is a schematic diagram and B-2 is a photograph illustrating the sample loading process according to some exemplary embodiments of the present disclosure. [Figure 16C] C-1 is a schematic diagram illustrating the buffer overflow process according to some exemplary embodiments of the present disclosure, and C-2 is a photograph thereof. [Figure 16D] D-1 is a schematic diagram illustrating the sample spillover process according to some exemplary embodiments of the present disclosure, and D-2 is a photograph thereof. [Figure 16E] E-1 is a schematic diagram and E-2 is a photograph illustrating the sample metering process according to some exemplary embodiments of the present disclosure. [Figure 16F] F-1 is a schematic diagram and F-2 is a photograph illustrating a buffer metering process according to some exemplary embodiments of the present disclosure. [Figure 16G] G-1 is a schematic diagram illustrating the spin acceleration process according to some exemplary embodiments of the present disclosure, and G-2 is a photograph thereof. [Figure 16H] H-1 is a schematic diagram and H-2 is a photograph illustrating the mixing process according to some exemplary embodiments of the present disclosure. [Figure 16I] I-1 is a schematic diagram illustrating a first measurement process according to some exemplary embodiments of the present disclosure, and I-2 is a photograph thereof. [Figure 16J] J-1 is a schematic diagram illustrating a second measurement process according to some exemplary embodiments of the present disclosure, and J-2 is a photograph thereof. [Figure 16K] K-1 is a schematic diagram illustrating a third measurement process according to some exemplary embodiments of the present disclosure, and K-2 is a photograph thereof. [Figure 16L] L-1 is a schematic diagram illustrating a sample separation process according to some exemplary embodiments of the present disclosure, and L-2 is a photograph thereof. [Figure 16M] M-1 is a schematic diagram, and M-2 and M-3 are photographs illustrating the self-calibration process according to some exemplary embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0040] Simplified and reliable valve design

[0041] Microfluidic systems often require the use of valves to regulate fluid flow, but existing solutions have limitations, such as requiring multiple components, complex fabrication processes, or surface treatments. For example, known solutions often require multiple components and complex fabrication processes, which can increase the cost and complexity of device manufacturing. Furthermore, known solutions often require surface treatments, such as coatings, to achieve the hydrophobic or hydrophilic properties necessary for proper valve performance. These treatments add additional steps to the fabrication process and can limit the range of usable materials. Furthermore, known solutions are often limited in their applicability to specific materials or environmental conditions; they may only work well with hydrophobic or hydrophilic materials or may be sensitive to changes in temperature or humidity. Furthermore, known solutions often lack a means to prevent sample drying (e.g., blood drying) and / or cell settling, which can cause blockages in microfluidic channels.

[0042] A hydrophobic material repels water and prevents it from spreading over its surface, whereas a hydrophilic material attracts water and causes it to spread over its surface, resulting in liquid 102 being trapped at the entrance to a narrow hydrophobic patch in the channel, as shown in Figure 1E, or at its widening if it is hydrophilic, as shown in Figure 1F.

[0043] Hydrophobic valves rely on the interaction between the liquid and the material of the valve disc to control the flow of liquid through a microfluidic channel. They are typically made of hydrophobic materials, such as certain plastics, to prevent the liquid from wetting the valve surface. Hydrophobic valves typically contain a constriction or hydrophobic patch within the channel, which creates a pressure drop and prevents the liquid from flowing through the valve. To open the valve, the liquid's pressure must rise above a certain threshold to overcome the pressure drop and allow the liquid to flow through the valve. One advantage of hydrophobic valves is that they do not require surface treatments, such as hydrophobic coatings, to maintain their hydrophobicity. Therefore, they are more cost-effective and easier to use than other types of valves, especially in mass production. Furthermore, hydrophobic materials are relatively inert and chemically resistant, making them suitable for use in a wide range of applications, including those involving aggressive or corrosive liquids.

[0044] For hydrophilic materials, the liquid spreads and wets the surface, increasing the total surface area in contact with the air, reducing pressure and forcing the liquid deeper into the channel. Hydrophilic valves control the flow of liquid through microfluidic channels by utilizing the pinning phenomenon of a liquid meniscus. When a liquid contacts a solid surface, it forms a meniscus, which can be held at the point of maximum curvature and prevent further flow. Careful design of the channel dimensions and geometry allows for control of the burst pressure, triggering the valve to open or close when the pressure exceeds a certain threshold. Burst pressure is determined by several factors, including the channel dimensions, surface tension, and contact angle of the liquid. The smaller the channel dimensions, the higher the surface tension required to maintain the liquid meniscus. Conversely, the larger the channel, the lower the surface tension required to maintain the meniscus. The contact angle of the liquid is also important because it determines how well the liquid wets the channel surface, thereby affecting the strength of the liquid-solid interaction. Hydrophilic valves have many important applications in microfluidic and lab-on-a-chip devices, where they are used to precisely control liquid flow and manipulate small volumes of fluid.

[0045] The stability of hydrophobic and hydrophilic valves can be affected by changes in the hydrophobicity or hydrophilicity of the material used to make the valve, which can reduce the effectiveness of the valve or even cause it to fail completely.

[0046] The present disclosure addresses these and / or other needs by providing a simple valve that is more effective and reliable in controlling the flow of fluids, particularly fluids containing blood. The simple valve of the present disclosure integrates both hydrophobic and hydrophilic principles into a single, simple structure, eliminating the need for surface treatments. This allows microfluidic devices to be manufactured more easily and cost-effectively, and improves reliability and performance. In some embodiments, the simple valve of the present disclosure includes sections designed to prevent fluid drying and cell settling, which helps ensure reliable valve performance even with thicker materials (e.g., thicker blood materials).

[0047] 1A-1C, a device 100 according to some embodiments of the present disclosure is shown. Device 100 includes an upstream chamber 110, a downstream chamber 120, and a valve 130 configured to connect the upstream and downstream chambers. Valve 130 generally includes a first channel 140 and a compartment 150. The first channel and compartment are configured such that the first channel forms a hydrophobic junction with the upstream chamber, e.g., functioning as a hydrophobic valve, and the compartment forms a hydrophilic junction with the first channel, e.g., functioning as a hydrophilic valve.

[0048] For example, in some embodiments, first channel 140 has first inlet 141 and first outlet 142. First inlet 141 is connected to upstream chamber 110 and has a cross-section perpendicular to the flow direction that is the same as or smaller than that of the upstream chamber. Therefore, if it is hydrophobic, it forms a hydrophobic junction with the upstream chamber, thereby stopping the fluid at the first inlet of the first channel. Compartment 150 is connected to the first outlet of the first channel and has a cross-section perpendicular to the flow direction that is larger than that of the first outlet of the first channel. Therefore, if it is hydrophilic, it forms a hydrophilic junction, thereby stopping the fluid at the first outlet of the first channel. In some embodiments, the compartment is deeper, wider, or both than the first channel. In some embodiments, the compartment is cylindrical. In some embodiments, the compartment has a circular, elliptical, oval, or polygonal cross-section.

[0049] Because the valve 130 integrates both hydrophobic and hydrophilic principles into a single structure, it is more stable, reliable, and has a wider operating range. For example, it can regulate liquid flow even if one of the features is compromised. This can help increase the valve's overall reliability and stability and extend its operating range. Combining both hydrophobic and hydrophilic features into a single valve improves performance and extends its operating range compared to conventional hydrophobic or hydrophilic valves. Furthermore, this allows one or more dimensions (e.g., length, width, height) of the first channel and / or compartment to be optimized without surface patterning to ensure reliable operation of the valve under both types of conditions. For example, in certain embodiments, the first channel can have a width of about 100 μm to about 200 μm, about 200 μm to about 300 μm, about 300 μm to about 400 μm, or about 400 μm to about 500 μm. The first channel may have a depth of about 100 μm to about 200 μm, about 200 μm to about 300 μm, about 300 μm to about 400 μm, or about 400 μm to about 500 μm. The first channel may have a length of about 200 μm to about 400 μm, about 400 μm to about 600 μm, about 600 μm to about 800 μm, or about 800 μm to about 1000 μm. However, the present disclosure is not limited thereto. For example, depending on the application, the first channel may be smaller, shorter, larger, or longer. Its width or depth may be at least 0.5 mm, at least 0.6 mm, at least 0.7 mm, at least 0.8 mm, at least 0.9 mm, or at least 1 mm. The length can be at least 1 mm, at least 5 mm, at least 1 cm, at least 2 cm, at least 3 cm, at least 4 cm, or at least 5 cm.

[0050] Valve 130 may include additional, optional, or alternative features. For example, in some embodiments, valve 130 includes a second channel 160 configured to prevent sample drying. In some embodiments, second channel 160 connects a compartment to a downstream chamber, e.g., having a second inlet 161 connected to the compartment and a second outlet 162 connected to the downstream chamber.

[0051] The addition of a second channel can help minimize sample (e.g., blood) evaporation, surface hydration, and / or water condensation in microfluidic systems. Sample evaporation, surface hydration, and / or water condensation can cause significant problems in microfluidic applications, including sample volume loss, channel clogging, the formation of surface contaminants, and degradation of sample quality. For example, blood drying is a major problem in blood analysis applications. Drying can lead to the formation of a barrier by red blood cells, causing valve malfunction and affecting the accuracy of the analysis. A second channel can help reduce these effects by providing a longer, more restricted path for the sample and reducing the sample's exposure to air and other environmental factors. This can help slow the rate of evaporation and surface hydration and prevent the occurrence of water condensation, thereby helping to maintain sample integrity and quality. Careful control of sample exposure to the environment is critical for the overall performance and reliability of the system.

[0052] The second channel may be configured the same as the first channel, or may be configured differently from the first channel. For example, in some embodiments, the second channel has the same cross-section (e.g., width and depth) perpendicular to the flow direction as the first channel. Alternatively, in some embodiments, the second channel has a cross-section perpendicular to the flow direction that is different from the first channel. In some exemplary embodiments, the second channel is longer than the first channel.

[0053] Optimizing the length, width, and / or depth of the second channel can depend on whether the channel clogs during evaporation. In some embodiments, the aspect ratio of the length to width and the length to depth of the second channel is greater than 2, greater than 3, greater than 4, or greater than 5. For example, in certain embodiments, the second channel has a length of about 1 mm to 5 mm and a width or depth of about 150 μm to about 400 μm. However, the present disclosure is not limited thereto. For example, depending on the application, the length of the second channel may reach several centimeters or more.

[0054] Referring to FIG. 1D , in some embodiments, the junction between the upstream chamber 110 and the valve inlet (e.g., first inlet 141 of the first channel) is configured to reduce blockage due to cell sedimentation. For example, in some such embodiments, a portion 112 of the upstream chamber 110 adjacent to the first inlet of the first channel of the valve is tapered to smooth the transition between the upstream chamber and the first inlet of the first channel of the valve. In some embodiments, the tapered portion of the upstream chamber has a trapezoidal cross-section parallel to the flow direction. In some embodiments, the tapered portion of the upstream chamber is configured based at least in part on the fluid 102 to be processed by the device. In some embodiments, the tapered portion of the upstream chamber has an angle of about −10 to −30 degrees, about −30 to −60 degrees, or about −60 to −80 degrees relative to the first channel. However, the present disclosure is not limited thereto. Depending on the application (e.g., the fluid to be processed), the portion 112 of the upstream chamber 110 can have different shapes, sizes, and / or angles.

[0055] The design of the junction between the upstream chamber (e.g., blood sample compartment) and the valve inlet can play an important role in preventing channel blockage due to cell sedimentation. For example, using a trapezoidal shape at the junction, as illustrated in Figure 1D, rather than a rectangle as illustrated in Figure 1C, can help reduce the likelihood of channel blockage by reducing the abruptness of the transition between the upstream chamber and the first channel. The trapezoidal shape allows for a smoother transition between the two sections, thus reducing the risk of cell entrapment or sedimentation at the junction that could cause blockage. This can improve the overall performance and reliability of the valve, maintaining sample flow through the channel and helping to ensure that the valve functions as intended, even with more concentrated blood materials.

[0056] The disclosed valves have many advantages over existing solutions. For example, in terms of complexity, existing solutions often require multiple components, complex fabrication processes, or surface treatments, which increase the complexity of microfluidic devices and make them more difficult to manufacture and maintain. The disclosed valves integrate both hydrophobic and hydrophilic principles into a single, simple structure, thereby reducing the number of required components and fabrication steps. In terms of reliability, existing solutions may not be reliable enough for certain applications because they can become inefficient when surface or sample properties change or when there is a delay between the time the sample reaches the valve and the time it passes through the valve. The disclosed valves combine simple sections into a single structure, and therefore, the valves can function more reliably with a wider range of materials, samples, and environmental conditions. In terms of cost, the cost of producing existing microfluidic devices can be prohibitive for some applications due to the high cost of surface treatments and complex fabrication processes. The disclosed valves eliminate the need for surface treatments, thereby reducing the manufacturing cost of microfluidic devices. Additionally, the passive nature of the valve, driven by centrifugal force generated by the rotational speed of the device (e.g., cartridge), eliminates the need for external manipulation, reducing the overall cost of manufacturing the fluidic device. Regarding evaporation and cell sedimentation, existing solutions may be ineffective in preventing sample drying (e.g., blood drying) or cell sedimentation, which can lead to valve malfunction. The disclosed valve or device includes features (e.g., tapered sections of the second channel and upstream chamber) that prevent evaporation and cell sedimentation, ensuring reliable valve performance even with more concentrated blood materials. Furthermore, the disclosed valve and device may offer flexibility in material selection. The availability of a wide range of materials, including both hydrophobic and hydrophilic materials, for cartridge fabrication opens up new possibilities for the design and fabrication of fluidic devices. The disclosed valve and device can be adapted to various environmental conditions, such as temperature and humidity, allowing for a wider range of applications.

[0057] In summary, the present disclosure provides a more effective solution for controlling fluid flow in microfluidic devices by simplifying device design, improving reliability, reducing cost, and preventing evaporation and cell sedimentation. The combination of these design features makes the disclosed valves and devices a major advancement in the field of microfluidic and fluidic devices, potentially providing advantages in a wide range of applications, including, but not limited to, biomedical and clinical applications.

[0058] Structure for capturing excess fluid

[0059] In many applications, excess fluid (e.g., blood) 204 temporarily accumulates at the bottom of a U-shaped channel, such as the one shown in FIG. 2D . However, the excess fluid is not completely trapped and, due to its high viscosity and / or other factors, is drawn into a downstream chamber (e.g., a metering chamber) during subsequent processing. Furthermore, the temporarily accumulated fluid can block access to the vent, increasing negative pressure and resulting in uncontrolled fluid movement. A common solution is to add a long, deep U-shaped structure. However, there is not enough room on the disk to accommodate such a structure, and a significantly larger volume of fluid (e.g., blood) would be required. Furthermore, with very concentrated samples, the blood may not be able to be pulled by drag forces without breaking down the blood. This can lead to channel blockage and increased negative pressure. The present disclosure addresses these and / or other needs by providing a structure that not only traps excess liquid but also allows for controlled fluid flow.

[0060] 2A-2C, a device 200 according to some embodiments of the present disclosure is shown. The device 200 is rotatable about a rotation axis 202. The device includes a channel 210 for transporting a fluid by rotating the device about the rotation axis. The channel 210 includes an inlet 211 and an outlet 212 positioned radially outward of the inlet relative to the rotation axis. The channel 210 also includes a first portion 220 between the inlet and the outlet. The first portion has a first side 221 (e.g., a side of the channel in the first portion) and a second side 222 (e.g., another side of the channel in the first portion). In some embodiments, the first portion of the channel may be curved. In some embodiments, the first side 221 may be positioned approximately radially outward of the corresponding second side 222. In some embodiments, the first side 221 has a generally concave shape and / or the second side 222 has a generally convex shape relative to the interior of the first portion of the channel.

[0061] Device 200 also includes a structure 230 connected to first side 221 of channel first portion 220. Structure 230 is configured to (i) allow fluid transfer when the device rotates at a first speed, (ii) collect fluid residue (e.g., excess fluid) when the device rotates at a second speed greater than the first speed, and (iii) capture the collected fluid residue within the structure when the device is subjected to acceleration, deceleration, or both.

[0062] For example, in some embodiments, structure 230 includes pocket 240 for containing fluid residue and chamber 250 for connecting the pocket to a first side of the first portion of the channel. Chamber 250 has a depth greater than the first portion of the channel and the pocket, thereby acting as a valve between the first portion of the channel and the pocket. In some embodiments, the pocket may be shallow, narrow, and / or relatively long so that excess fluid is retained within the pocket even when the disk is subjected to strong accelerations and decelerations. For example, in some embodiments, the channel or pocket may have a depth of up to 1 mm, up to 1.5 mm, or up to 2 mm, and the chamber may have a depth at least 0.1 mm, at least 0.2 mm, at least 0.3 mm, at least 0.4 mm, or at least 0.5 mm deeper than the channel or pocket. However, the present disclosure is not limited in this respect. The channels, chambers, and pockets may have other shapes or dimensions and may be positioned differently.

[0063] In some embodiments, at least a portion of the structure is positioned radially outward of the first portion of the channel. For example, in some embodiments, a portion of the pocket 240 or poker is positioned radially outward of the first portion of the channel. In some embodiments, the radially innermost point at the junction formed by the chamber and the first side of the first portion of the channel defines the maximum allowable level of fluid residue (e.g., the dashed line in FIG. 2B ). In some embodiments, the structure and / or operation is designed to ensure that the meniscus of excess fluid does not exceed the maximum allowable level. This provides an escape route for air trapped in the pocket and / or chamber.

[0064] In some embodiments, the second side 222 of the first portion of the channel is positioned radially inward of the maximum allowable level of fluid carryover. For example, in some embodiments, the bend in the second side of the first portion is positioned radially inward of the maximum allowable level. This prevents possible blockage of the channel and allows fluid to be transferred when needed or desired.

[0065] During centrifugation, most of the fluid (e.g., blood) is carried downstream. However, some residue adheres to the channel surface. This residue is pushed beyond the maximum allowable level and collected at the bottom of the first portion 220 of the channel by centrifugal action. As the rotation accelerates, the centrifugal force acting on the remaining blood increases and eventually overcomes a barrier (e.g., a valve formed by the chamber 250 and the channel and / or pocket) after reaching a threshold. The residue flows into the pocket 240 and, in some cases, reaches the very bottom of the pocket, depending on the rotation speed, the amount of residue, the configuration of the structure, and / or other factors. The residue then remains in the pocket, even when the device is subjected to acceleration, deceleration, or both.

[0066] Inertia-based mixing chamber and method

[0067] Mixing blood and buffer in centrifugal microfluidic devices can present many technical challenges. For example, blood cells can be damaged or destroyed when subjected to high centrifugal forces, resulting in hemolysis (rupture of red blood cells) and the release of hemoglobin into the buffer. This can interfere with downstream analysis and affect the accuracy of results. Blood can also clot upon contact with certain materials or surfaces, especially in microfluidic systems with high surface-to-volume ratios. This can lead to channel blockage or incomplete mixing of the blood and buffer. Furthermore, achieving complete and uniform mixing of blood and buffer can be difficult in centrifugal microfluidic devices due to the small volumes involved and the high rotational speeds. Incomplete mixing can lead to inaccurate or uncertain results.

[0068] Existing technologies related to blood and buffer include those disclosed in "Batch-mode mixing on centrifugal microfluidic platforms," ​​Lab Chip, 5, 560-565 (2005), "Reciprocating flow-based centrifugal microfluidics mixer disclosed in Review of Scientific Instruments," 80, 075102 (2009), and "Decanting and mixing of supernatant human blood plasma on centrifugal microfluidic platform," Microsyst Technol, 22, 861-869 (2016), the contents of each of which are incorporated herein by reference in their entirety and for all purposes. However, these existing technologies do not provide a satisfactory solution. The present disclosure addresses these and other needs in the art by providing a chamber with a curved section and using inertial motion to create a vortex to promote mixing.

[0069] 3, a flowchart illustrating an exemplary method 300 for mixing fluids according to some embodiments of the present disclosure is shown. In the flowchart, preferred portions of the method are shown in solid boxes, and additional, optional, or alternative portions of the method are shown in dashed boxes. It should be noted that the processes disclosed herein and illustrated in the flowcharts may, but need not, be performed completely or in the order in which they are presented.

[0070] Referring to block 302, in some embodiments, method 300 includes obtaining a device including: (A) a rotation axis and a mixing chamber having a curved side that is not coaxial with the rotation axis. The mixing chamber can be configured in any suitable shape and / or size and in any suitable location on the device (e.g., a disk or cartridge), so long as it has a curved side that is not coaxial with the rotation axis. The device can be used for any suitable application, including, but not limited to, mixing blood with a buffer.

[0071] For example, by way of non-limiting example, FIG. 4A illustrates device 400-1 rotatable about axis of rotation 402-1 and including chamber 410-1. Chamber 410-1 has curved side 420-1 that is not coaxial with axis of rotation 402-1. As another non-limiting example, FIG. 4B illustrates device 400-2 rotatable about axis of rotation 402-2 and including chamber 410-2. Chamber 410-2 has curved side 420-2 that is not coaxial with axis of rotation 402-2. As a further non-limiting example, FIG. 4C illustrates device 400-3 rotatable about axis of rotation 402-3 and including chamber 410-3. Chamber 410-3 has curved side 420-3 that is not coaxial with axis of rotation 402-3. As a still further non-limiting example, Figure 4D illustrates a device 400-4 that is rotatable about an axis of rotation 402-4 and includes a chamber 410-4. The chamber 410-4 has a curved side 420-4 that is not coaxial with the axis of rotation 402-4.

[0072] The mixing chamber contains a fluid 404 containing two or more different components. In some embodiments, the volume of the fluid is at most 50%, at most 55%, at most 60%, at most 65%, or at most 70% of the mixing chamber. However, the present disclosure is not limited in this respect. For example, in some embodiments, the volume of the fluid may be greater than 70% of the mixing chamber. In some embodiments, the fluid may have a volume of at least 200 μL, at least 400 μL, at least 600 μL, at least 800 μL, or at least 1000 μL. In some embodiments, the fluid may have a volume of at most 200 μL, at most 150 μL, at most 100 μL, at most 90 μL, at most 80 μL, at most 70 μL, at most 60 μL, or at most 50 μL.

[0073] In some embodiments, the mixing chamber has inflection points or sections where the sign of the curvature of the mixing chamber changes, such as inflection points / sections 430-1, 430-2, 430-3, and 430-4. In some embodiments, the inflection points / sections are configured to prevent fluid from flowing into the inlet of the mixing chamber. In some embodiments, the curved sides of the mixing chamber have a circular size of about 1 mm to about 10 mm, about 10 mm to about 20 mm, about 20 mm to about 30 mm, or larger.

[0074] Referring to block 304, in some embodiments, method 300 includes (B) accelerating the device in a direction toward the curved side of the mixing chamber to a first speed. The first speed may be based at least in part on the type of fluid, the amount of fluid in the mixing chamber, the shape of the mixing chamber, or any combination thereof. For example, in certain embodiments, the first speed may be about 300 rpm to about 500 rpm, about 500 rpm to 700 rpm, or about 700 rpm to about 1000 rpm. However, the present disclosure is not limited thereto. For example, in certain embodiments, the first speed may be less than 300 rpm or greater than 1000 rpm.

[0075] Referring to block 306, in some embodiments, method 300 includes (C) suddenly decelerating the device so that the fluid moves toward the curved side of the mixing chamber due to inertia. As the fluid approaches, the curved side of the mixing chamber converts the fluid's motion into a circular motion, creating a vortex, thereby promoting mixing of two or more distinct components in the fluid. In some embodiments, decelerating (C) brings the device to a complete stop. In some embodiments, decelerating (C) is performed at a deceleration rate of at least 500 rpm / s, at least 1000 rpm / s, at least 1500 rpm / s, at least 2000 rpm / s, or at least 2500 rpm / s, at least 3000 rpm / s, at least 5000 rpm / s, 10000 rpm / s, at least 50000 rpm / s, or greater. However, the present disclosure is not limited thereto. For example, in some embodiments, decelerating (C) may be performed at a deceleration rate of less than 500 rpm / s.

[0076] Referring to block 308, in some embodiments, the method 300 includes (D) repeating accelerating (B) and decelerating (C) one or more times. The method may repeat accelerating (B) and decelerating (C) any suitable number of times to produce sufficient mixing. In some embodiments, the method may repeat accelerating (B) and decelerating (C) at least 2 times, at least 5 times, at least 10 times, at least 15 times, at least 20 times, at least 30 times, at least 40 times, or at least 50 times.

[0077] The disclosed method uses the curvature and inertial motion of the mixing chamber to create a vortex. This vortex motion generates shear forces, which can induce fluid mixing. The method is based on the principle that components or particulates with different densities or viscosities in a fluid respond differently to the same inertial force, resulting in relative motion between them and ultimately mixing. The disclosed device and method can reduce hemolysis and coagulation and improve mixing efficiency. Its design is simple and does not require the design / addition of new features or the use of different disk materials / surface coatings.

[0078] Inertia-based device and method for directing fluids

[0079] Many factors contribute to moving or directing fluids in microfluidic devices. In microfluidic channels, capillary forces can dominate over centrifugal forces, leading to uneven flow patterns or flow stalls. This can result in incomplete delivery, uneven sample distribution, and channel blockage. At high rotational speeds, fluid viscosity can also affect flow behavior, leading to the formation of secondary flows and vortices, which can disrupt desired flow patterns. Furthermore, certain types of components, such as detergents dissolved in buffers, can alter surface tension or other parameters and therefore be prone to bubble formation. This may be incompatible with some centrifugal microfluidic systems and limit the types of tests that can be performed using this technology.

[0080] To address these challenges, various techniques have been developed, including optimizing channel design and surface coatings to control capillary forces and selecting appropriate fluids with favorable viscosities and surface tensions. Furthermore, sophisticated and expensive microfluidic systems with active feedback and control mechanisms may be used to regulate flow patterns and ensure accurate results. Examples of such techniques or studies include those disclosed in “Frequency-dependent transversal flow control in centrifugal microfluidics,” Lab Chip, 2005, 5, 146–150; “The Effect of Moment of Inertia on the Liquids in Centrifugal Microfluidics,” Micromachines, 2016, 7(12), 215; and “Demonstration of an efficient, compact, and precise pumping method by centrifugal inertia for lab on disk platforms,” 2019 J. Micromech. Microeng. 29 075001, the contents of each of which are incorporated herein by reference in their entirety and for all purposes. These require complex systems to move or direct the fluid.

[0081] The present disclosure addresses these and other needs in the art by developing a technique for directing liquid flow in centrifugal microfluidic devices using the inertial force of the liquid upon sudden deceleration and cessation of disk rotation. This technique uses a chamber and an adjacent chamber, with a wide channel connecting the two chambers to transfer liquid from one chamber to the other. When the disk's rotational speed suddenly decreases, the liquid responds by continuing to move in a direction tangent to the disk's rotational velocity vector. By carefully designing the size of the wide channel and considering factors such as air movement and surface tension, it is possible to direct the liquid to the desired chamber without the need for external forces or additional system complexity.

[0082] 5, a flowchart illustrating an exemplary method 500 for directing a fluid according to some embodiments of the present disclosure is shown. In the flowchart, preferred portions of the method are shown in solid boxes, and additional, optional, or alternative portions of the method are shown in dashed boxes. It should be noted that the processes disclosed herein and illustrated in the flowcharts may, but need not, be performed completely or in the order in which they are presented.

[0083] Referring to block 502, in some embodiments, method 500 includes (A) obtaining a device having an axis of rotation and a chamber having a pathway not coaxial with the axis of rotation, the chamber containing a fluid. For example, by way of non-limiting example, FIG. 6 illustrates device 600 rotatable about axis of rotation 602 and including chamber 610. Chamber 610 includes pathway 620, e.g., a channel, connecting chamber 610 to a downstream chamber. Chamber 610 contains fluid 604. In some embodiments, chamber 610 includes barrier 630 through which the fluid must pass to enter the downstream chamber.

[0084] Referring to blocks 504 and 506, in some embodiments, method 500 includes (B) accelerating the device in a direction toward the chamber path, and (C) suddenly decelerating the device so that the fluid moves toward the chamber path by inertia. In some embodiments, accelerating (B) can result in a speed of at least about 200 rpm, at least about 400 rpm, at least about 600 rpm, at least about 800 rpm, or at least about 1000 rpm. In some embodiments, decelerating (C) is performed at a deceleration rate of at least 500 rpm / s, at least 1000 rpm / s, at least 1500 rpm / s, at least 2000 rpm / s, or at least 2500 rpm / s, at least 3000 rpm / s, at least 5000 rpm / s, 10000 rpm / s, at least 50000 rpm / s, or greater. In some embodiments, decelerating (C) brings the device to a complete stop. FIG. 6 shows that a significant amount of fluid is transferred to the downstream chamber.

[0085] 6 illustrates chamber 610 as a mixing chamber, but this is by way of example and not limitation. Method 500 and the present technology can be applied to any other type of chamber. Furthermore, the shape, size, and location of chamber 610 and channel 620 can be easily modified to suit other applications. In some embodiments, the channel is configured to be wide enough to facilitate fluid movement.

[0086] In embodiments where chamber 610 is a mixing chamber, method 500 may be used to direct the fluids after they have mixed. Mixing of the fluids may be performed using method 300 or by other mixing techniques (e.g., the use of magnetic particles). For example, referring again to FIGS. 3 and 4C , in some embodiments, mixing chamber 410-3 includes a pathway 440 (e.g., a channel) opposite curved side 420-3 of the mixing chamber. Pathway 440 connects mixing chamber 410-3 to a downstream chamber. In some embodiments, mixing chamber 410-3 also includes a barrier 450 through which fluid must pass to enter the downstream chamber. In some such embodiments, method 300 may include (E) slowly accelerating the device at a second speed in a direction toward the pathway, and (F) suddenly decelerating the device such that the fluid moves toward the pathway of the mixing chamber by inertia.

[0087] Using inertia to direct flow can be utilized in a variety of microfluidic processes, such as sample preparation and analysis, drug delivery, and microscale synthesis. There is no need for special surface coatings to control capillary forces, no need for sophisticated and expensive microfluidic systems with active feedback and control mechanisms to adjust flow patterns and ensure accurate results, and no need to select appropriate fluids with suitable viscosities and surface tensions. Optimizing parameters such as chamber curvature, barrier height, and path length, width, and / or depth can ensure reliable and reproducible results.

[0088] Bubble-free priming channels

[0089] In microfluidic devices, it is difficult to remove all air bubbles from capillaries before filling them with a sample. The presence of air bubbles can alter the particle's settling velocity or interfere with optical detection of the settling process, leading to errors in sedimentation analysis. One approach to achieving bubble-free priming is to use a vacuum or pressure system to evacuate air from the capillary before filling it with a sample. However, this technique can be difficult to implement, especially for capillaries with small diameters or samples with low sedimentation velocities. Another approach is to use surfactants or wetting agents to displace air and promote wetting of the capillary's inner surface. However, the choice of surfactant and its concentration can affect the settling velocity, morphology, and integrity of delicate biological objects, such as blood cells, which can lead to additional errors. The use of stepped channels has been proposed in "Single-step centrifugal hematocrit determination on a 10-$ processing device," Biomed Microdevices (2007) 9:795-799, the contents of which are incorporated herein by reference in their entirety and for all purposes. However, this relies on the use of hydrophilic surface treatments and the capillary forces required to prime the channels. In summary, achieving bubble-free priming of closed-ended sedimentation capillaries requires careful attention to the selection of materials, methods, equipment, and sample preparation, as well as optimization of experimental conditions to ensure accurate and reproducible sedimentation analysis.

[0090] The present disclosure addresses these and other needs in the art by providing a capillary channel in which priming with a liquid is based on differential flow resistance along different lanes of the channel. Thus, the capillary channels of the present disclosure can be made of any untreated material, including hydrophilic and hydrophobic, and still achieve bubble-free priming.

[0091] 7A and 7B, a device 700 according to some embodiments of the present disclosure is shown. The device 700 is rotatable about an axis of rotation 702. The device 700 includes a vent port 710 and a capillary channel 720 positioned radially outward of the vent port relative to the axis of rotation 702.

[0092] The capillary channel 720 is configured with a stepped cross-section to facilitate bubble-free priming. It is designed to transport fluid (e.g., blood) from the inlet into the blind-ended capillary using centrifugally driven fluid resistance differentiation. The unique depth profile of the capillary ensures that air is not trapped during the filling process.

[0093] The capillary channel 720 includes an open end 721 and a closed end 722 positioned radially outward of the open end relative to the axis of rotation. The capillary channel may be oriented along a radius or at an angle relative to the radius. The angle may vary. In some embodiments, the angle may range from 0 to 60 degrees. The capillary channel 720 also includes a first lane 730, a second lane 740, and a third lane 750. The first lane has an inlet at its open end for receiving a fluid. The third lane has an outlet at its open end for evacuating air. For example, in some embodiments, the outlet of the third lane of the capillary channel is connected to a vent port. The second lane is formed between the first and third lanes and is connected to the first and third lanes. The first, second, and third lanes are configured such that the second lane has a different flow resistance than the first and third lanes, thereby allowing fluid to first flow from the open end 721 to the closed end 722 through the first lane 730, and then flow from the closed end 722 to the open end 721 through the second lane 740, the third lane 750, or both, to facilitate bubble-free priming.

[0094] In some embodiments, the first, second, and third lanes collectively form a stepped cross-section perpendicular to the length of the capillary channel, as illustrated in FIG. 7B. In some embodiments, the first and third lanes are deeper than the second lane, e.g., the shallower second lane separates the deeper first and third lanes. The bordering extensions act as a barrier, creating separation of two levels of fluid at adjacent edges. One level, where the fluid is exposed to lower resistance, facilitates filling of the closed-end channel, and as the fluid progresses downstream, air is removed through the higher-resistance level. When the fluid reaches the closed end of the capillary, it permeates the adjacent level, filling the capillary in the reverse direction without trapping air bubbles.

[0095] The third lane, accessible to the vent, is added to improve reliability and expand application range. This is especially true when the fluid (e.g., blood) crosses the edge separating the first and second lanes before reaching the closed end. This can occur if there is a defect in the wall or if the resistance difference is insufficient to clearly separate the flows. This process ensures that the capillary tube is filled without air bubbles. The number of lanes is not limited to three. For example, the number of lanes can be two or more, with the last one having access to the vent.

[0096] The first and third lanes may be configured substantially similarly to one another (e.g., to have the same width and depth) or differently from one another (e.g., to have different widths and / or depths). In some embodiments, at least two of the first, second, and third lanes have the same width. In some embodiments, at least two of the first, second, and third lanes have different widths. In certain embodiments, the first and third lanes may have a depth of about 500 μm to 1000 μm, about 1000 μm to 1500 μm, or about 1500 μm to 2000 μm. The second lane may be about 200 μm to about 500 μm, about 300 μm to about 700 μm, or about 600 μm to 1000 μm shallower than the first and / or third lanes. The radial length of the capillary channel can be at least 5 mm, at least 10 mm, at least 15 mm, at least 20 mm, at least 25 mm, or at least 30 mm. The width of each lane can be selected to provide different flow resistance between shallow and deep lanes. In some embodiments, the width of the first, second, and / or third lanes can range from about 100 μm to about 500 μm, from about 300 μm to about 700 μm, or from about 500 μm to 1000 μm. However, the present disclosure is not limited thereto. Depending on the application, the channels, including the first, second, and third lanes, can have any other suitable shape and size.

[0097] The capillary channels of the present disclosure do not require a vacuum or pressure system to evacuate air from the capillary before filling it with sample, nor do they require surfactants or wetting agents to displace the air and help wet the inner surface of the capillary. They are simple and can be used in a variety of applications.

[0098] A constricted structure for guiding fluid

[0099] Surface tension is an important factor in microfluidic devices, where the behavior of liquids can differ significantly from bulk liquids due to the small scales involved. The interaction between a liquid and a channel wall can lead to various phenomena, including capillary flow, in which the liquid follows the shape of the channel edges rather than the direction of the applied force. In some cases, this can be undesirable and must be eliminated. For example, surface tension can affect the direction a liquid follows after exiting a channel extension in a microfluidic device, resulting in a meniscus or curved surface at the liquid-air interface. The shape and strength of the meniscus depend on the fluid's properties, such as the fluid's surface tension, as well as the channel geometry and surface properties. If the liquid's surface tension is high and the channel extension geometry has angular edges that promote wetting, the liquid will tend to spread and follow the edge direction rather than the centrifugal force. This is known as capillary flow.

[0100] When fluid exits a small microfluidic channel and enters a larger chamber, surface interaction issues can arise. The surface properties of the larger chamber at the junction can affect the flow behavior and direct the flow in uncontrolled directions. For example, if the physical and chemical properties of the surface are non-uniform, the liquid may not leave the connection in the direction of centrifugal force but instead follow the angle of the connection, which can affect the operation of the system.

[0101] These technical problems can be alleviated by the use of surface treatments or the addition of surfactants. However, these increase manufacturing costs, can cause cell damage, and are complex. The present disclosure addresses these and / or other problems in the art by providing extensions such that centrifugal force acts in the opposite direction to, and thus offsets, the capillary force vector.

[0102] 8A-8C, a device 800 according to some embodiments of the present disclosure is shown. Device 800 is rotatable about axis of rotation 802. Device 800 includes a chamber 810 and a channel 820 connected to the chamber for delivering a fluid 804 to the chamber. The chamber and channel collectively form a junction 830 that minimizes or eliminates capillary flow as the fluid exits the channel (e.g., at the outlet of the channel) and enters the chamber. In some embodiments, this junction causes the fluid to flow from the outlet of the channel into the chamber in the direction of centrifugal force.

[0103] In some embodiments, the channel includes a protruding portion 840 that forms at least a portion of the junction. The protruding portion 840 is configured so that the fluid is constricted at the protruding portion for a short period of time until the centrifugal force overcomes the surface tension that holds the fluid in place. While held in this manner, the fluid does not move left or right, as would be the case with the straight edges shown in FIGS. 8D and 8E, where flat walls would cause the fluid (e.g., blood) 804 to flow unpredictably. As soon as the centrifugal force overcomes the surface tension, the fluid no longer interacts with the surface, and the fluid moves in the direction of the centrifugal force. In this manner, the direction of fluid flow can be predicted.

[0104] The protruding portion can be configured in any suitable shape and size. As a non-limiting example, FIG. 8B illustrates that the protruding portion includes U-shaped walls 841 on either side of the channel at the outlet. As another non-limiting example, FIG. 8C illustrates that the protruding portion includes V-shaped walls 842 on either side of the channel at the outlet. In some embodiments, the wall 811 of the chamber 810 adjacent the channel outlet curves radially inward relative to the outlet to form at least a portion of a junction. Fluids can be forced to move in a desired direction by applying centrifugal forces that exceed surface tension. This is accomplished by constricting the fluid in a channel extension, creating a moment of force equilibrium, and then releasing it when centrifugal forces become dominant.

[0105] In certain embodiments, the channel may have a width of about 100 μm to about 200 μm, about 200 μm to about 300 μm, about 300 μm to about 400 μm, or about 400 μm to about 500 μm, and / or a depth of about 100 μm to about 200 μm, about 200 μm to about 300 μm, about 300 μm to about 400 μm, or about 400 μm to about 500 μm. In some embodiments, the radius of curvature of the U-shaped wall may be about 100 μm to about 200 μm, about 200 μm to about 300 μm, about 300 μm to about 400 μm, or about 400 μm to about 500 μm. However, the present disclosure is not limited thereto. Depending on the application, the channel and protrusions may be configured in various shapes and sizes.

[0106] The constriction structures of the present disclosure eliminate the need for surface treatments that increase manufacturing costs and can cause cell damage, and also eliminate the need for added surfactants, which can be complex and can cause cell damage.

[0107] Device and method for measuring depth with self-calibration capabilities

[0108] Manufacturing variations in the depth of molded consumables can have a variety of causes. Among these are inconsistent molding conditions, where the depth of the molded consumables can be affected by improper control of temperature, pressure, cooling rate, humidity, etc. To account for these variations in the depth of molded consumables, appropriate measurement techniques must be used. Examples of such techniques include profilometers, depth gauges, laser scanners, optical interferometry, and ultrasonic sensors. However, measuring the depth of every consumable during assembly is a laborious and time-consuming task. Furthermore, consumables can change in depth over time.

[0109] Uneven depths in some consumable compartments can lead to unstable operation. For example, variations in the depth of molded metering chambers in microfluidic consumables can result in inconsistencies in the volume of dispensed liquid, which can lead to inaccurate test results. Microfluidic consumables are used for precise measurement and handling of small amounts of fluid in applications such as medical diagnostics, drug discovery, and genetic analysis. Inaccurate metering due to variations in the depth of molded metering chambers can result in erroneous measurements, leading to false positive or false negative results, which can have serious consequences in critical applications. Therefore, it is important to accurately measure the depth of molded compartments in microfluidic consumables to ensure accurate and reliable test results.

[0110] The present disclosure addresses these and / or other problems in the art by providing a self-calibration feature that a user can use to measure production errors in the depth of a device (e.g., a molded consumable) directly in situ and / or as part of an analytical method, with the measurement being quick (e.g., within seconds) and completely effortless.

[0111] 9, a flowchart illustrating an exemplary method 900 for measuring depth independent of manufacturing variations, according to some embodiments of the present disclosure, is shown. In the flowchart, preferred portions of the method are shown in solid boxes, and additional, optional, or alternative portions of the method are shown in dashed boxes. It should be noted that the processes disclosed herein and illustrated in the flowcharts may, but need not, be performed entirely or in the order in which they are presented.

[0112] Referring to block 902, in some embodiments, method 900 includes (A) obtaining a device including a structure filled with an absorbing dye, the structure including a first portion having a first depth and a second portion having a second depth, where the first depth and the second depth are different from each other, but a nominal depth difference between the first depth and the second depth is known. For example, by way of non-limiting example, FIGS. 10A and 10B illustrate a device 1000 including a structure 1010. The structure 1010 includes a first portion 1011 and a second portion 1012. The first portion 1011 has a first depth L1, and the second portion 1012 has a second depth L2. The first depth and the second depth are different from each other. These depths are subject to manufacturing variations and may not necessarily be equal to their nominal values. However, because production variations often have a similar effect on dispersion, the difference between these depths may correspond to a nominal depth difference. In other words, the nominal depth difference (ΔL) between the first and second depths is known, even if the first and second depths are not necessarily at their nominal values. In some embodiments, once the device is obtained, the absorbing dye is loaded into the structure.

[0113] Referring to block 904, in some embodiments, the method 900 includes (B) measuring a first optical density (OD1) of the absorbing dye in the first portion of the structure and a second optical density (OD2) of the absorbing dye in the second portion of the structure. In some embodiments, the first and second optical densities are measured using a spectrophotometer or a microfluidic device that measures absorbance.

[0114] Referring to block 906, in some embodiments, the method 900 includes (C) calculating an optical density difference (ΔOD) between the first optical density and the second optical density.

[0115] Referring to block 908, in some embodiments, the method 900 includes calculating (D) a ratio of the optical density difference to the nominal depth difference, which represents the product of the extinction coefficient and the concentration of the absorbing dye. For example, according to the Beer-Lambert law:

number

number

[0116] In some embodiments, this ratio is calculated as follows:

number

[0117] Referring to block 910, in some embodiments, method 900 includes (E) using the ratio to determine a first depth of a first portion of the structure, a second depth of a second portion of the structure, a depth of an additional structure of the device, or any combination thereof. For example, in some embodiments, the obtained ratio (ec) is then re-substituted into equation (1) to calculate the first depth L1 and / or re-substituted into equation (2) to calculate the second depth L2.

[0118] While FIG. 10A illustrates a device with one feature 1010 and FIG. 10B illustrates a feature 1010 with two different depths, it should be noted that a device can have more than one, two, three, four, five, or ten features, and a feature can have more than two, three, four, or five different portions with different depths. These features can be positioned anywhere suitable on the device to allow for multiple measurements to ensure depth consistency. These features can be configured similarly or differently from one another. They can also have various paired levels for calibrating deep and shallow channels, which can be two or more channels connected in series or standalone channels.

[0119] For example, in some embodiments, device 1000 includes one or more features. Each of the one or more features includes a first portion having a first depth and a second portion having a second depth. For each of the one or more features, the first depth and the second depth are different from one another, but a nominal depth difference between the first depth and the second depth is known. This allows for self-calibration of the depth of features (e.g., one or more features or other features) of the device regardless of variations in device manufacturing. In some embodiments, the one or more features include a first feature and a second feature at different locations on the device. In some such embodiments, the nominal depth difference of the first feature is the same as that of the second feature. Alternatively, in some embodiments, the nominal depth difference of the first feature is different from that of the second feature.

[0120] Device and method for measuring concentration independent of manufacturing variations - Patents.com

[0121] Measuring hemoglobin concentration is an important test for diagnosing anemia, monitoring blood loss, and assessing overall health. The use of microfluidic technology has made it possible to perform this test with small sample sizes and short times. However, microfluidic consumables can have manufacturing variations that can affect the accuracy of test results. Manufacturing variations in molded consumable depth can have a variety of causes, including inconsistent molding conditions, where the molded consumable depth can be affected by improper control of temperature, pressure, cooling rate, humidity, and / or other factors.

[0122] One way to address this issue is to calibrate the microfluidic device before use. Calibration involves determining the sensitivity and accuracy of the device by measuring the hemoglobin concentration of standard solutions. This information can then be used to adjust test results obtained from the device. However, this calibration relies on consistent manufacturing of consumables. For example, if concentration determination is based on the optical density index of hemoglobin, the optical path is a critical parameter. In this regard, the depth of the optical compartment of the microfluidic device must be accurately determined.

[0123] The present disclosure addresses these and / or other problems in the art by providing devices and methods for determining hemoglobin concentration by measuring the optical density of hemoglobin without the need to determine absolute depth. The methodology of this approach is similar to that for measuring manufacturing variations.

[0124] 11, a flowchart illustrating an exemplary method 1100 for measuring concentration independent of manufacturing variations, according to some embodiments of the present disclosure, is shown. In the flowchart, preferred portions of the method are shown in solid boxes, and additional, optional, or alternative portions of the method are shown in dashed boxes. It should be noted that the processes disclosed herein and illustrated in the flowcharts may, but need not, be performed completely or in the order in which they are presented.

[0125] Referring to block 1102, in some embodiments, method 1100 includes (A) obtaining a device including a structure positioned within a path of a mixture having a first component, the structure including a first portion having a first depth and a second portion having a second depth, where the first depth and the second depth are different from each other, but a nominal depth difference between the first depth and the second depth is known. For example, by way of non-limiting example, FIGS. 12A and 12B illustrate a device 1200 including a structure 1210 positioned within a path 1220 of a mixture having a first component (e.g., a mixture including hemoglobin). The structure 1210 includes a first portion 1211 and a second portion 1212. The first portion 1211 has a first depth L1, and the second portion 1212 has a second depth L2. The first depth and the second depth are different from each other. These depths are subject to manufacturing variations and are not necessarily equal to their nominal values. However, because production variations often have a similar effect on dispersion, the difference between these depths may correspond to a nominal depth difference. In other words, the nominal depth difference (ΔL) between the first depth and the second depth is known, even though the first and second depths are not necessarily at their nominal values.

[0126] Referring to block 1104, in some embodiments, the method 1100 includes (B) measuring a first optical density (OD1) of the first component in the first portion of the structure and a second optical density (OD2) of the first component in the second portion of the structure. In some embodiments, the first and second optical densities are measured using a spectrophotometer or a microfluidic device that measures absorbance.

[0127] Referring to block 1106, in some embodiments, the method 1100 includes (C) calculating an optical density difference (ΔOD) between the first optical density and the second optical density.

[0128] Referring to block 1108, in some embodiments, the method 1100 includes (D) determining a concentration of the first component in the mixture based at least in part on the optical density difference and the nominal depth difference. For example, according to equations (1) and (2), ΔOD is a function of ΔL as follows:

number

[0129] Therefore, the optical density difference (ΔOD) obtained from calculating (C) can be compared to a calibration curve constructed for the same optical path as ΔL. The calibration curve can be created using a quartz cuvette with a high precision depth. Therefore, the output signal can be used to determine the concentration of the first component (e.g., hemoglobin concentration) in the mixture. Because a calibration curve is used, the extinction coefficient of the first component (e.g., hemoglobin) does not need to be known.

[0130] In some embodiments, if the extinction coefficient of the first component is known (e.g., the extinction coefficient is determined for the wavelength used in the optical system of the device), a calibration curve is not necessary. The concentration of the first component can be calculated using equation (4), for example, by dividing the optical density difference by the nominal depth difference and the extinction coefficient of the first component, since ΔOD, ΔL, and e are known.

[0131] Referring to blocks 1110-1116, in some embodiments, method 1100 further includes (E) generating a calibration curve prior to determining (D). In some embodiments, generating (E) includes (i) preparing a series of standard solutions containing known concentrations of the first component, (ii) measuring the absorbance of each of the standard solutions at one or more specific wavelengths for the first component in one or more optical paths, thereby obtaining a plurality of absorbance values, and (iii) plotting the absorbance values ​​against corresponding concentrations of the first component to generate a calibration curve for each of the one or more optical paths.

[0132] For example, in some embodiments where the first component is hemoglobin, the method includes preparing a series of standard solutions containing known concentrations of hemoglobin, measuring the absorbance of each of the standard solutions at a specific wavelength(s) for hemoglobin using a spectrophotometer or microfluidic device, and plotting the absorbance values ​​against the corresponding hemoglobin concentrations to create a calibration curve. In some embodiments, the method also includes measuring the absorbance of unknown samples at the same wavelengths used to measure the standard solutions, and / or using the calibration curve to determine the hemoglobin concentrations of the unknown samples based on their absorbance values.

[0133] Like device 1000, device 1200 can have multiple structural portions 1210. Similarly, like structural portion 1010, structural portion 1210 can have more than two distinct portions. Furthermore, a device can have both structural portion(s) 1010 and structural portion(s) 1210 to perform both methods 1000 and 1200.

[0134] With the device and method of the present invention, the measurement of absorbance and therefore concentration is less dependent on depth, thus improving measurement accuracy.

[0135] 13, a device 1300 (e.g., a disk) according to some exemplary embodiments of the present disclosure is shown. The device 1300 is rotatable about an axis of rotation, such as a vertical axis of rotation 1303. In some embodiments, the device 1300 can be rotated at a speed of at least about 1000 rpm, at least about 1200 rpm, at least about 1400 rpm, at least about 1600 rpm, at least about 1800 rpm, at least about 2000 rpm, at least about 2200 rpm, at least about 2400 rpm, at least about 2600 rpm, at least about 2800 rpm, at least about 2900 rpm, at least about 3000 rpm, at least about 3500 rpm, at least about 4000 rpm, at least about 4500 rpm, at least about 5000 rpm, at least about 5500 rpm, at least about 6000 rpm, at least about 6500 rpm, or at least about 7000 rpm during one or more processes. In some embodiments, the device 1300 can be rotated at a speed of up to about 500 rpm, up to about 600 rpm, up to about 700 rpm, up to about 800 rpm, up to about 900 rpm, up to about 1000 rpm, up to about 1200 rpm, up to about 1400 rpm, up to about 1600 rpm, up to about 1800 rpm, up to about 2000 rpm, up to about 2200 rpm, up to about 2400 rpm, up to about 2600 rpm, up to about 2800 rpm, up to about 2900 rpm, up to about 3000 rpm, up to about 3500 rpm, up to about 4000 rpm, up to about 4500 rpm, or up to about 5000 rpm during one or more processes.

[0136] In some embodiments, device 1300 (e.g., a disk) includes multiple units, such as units 1310-1, 1310-2, and 1310-3, arranged circumferentially. In some embodiments, device 1300 includes 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 units. In some embodiments, units 1310 include one or more features / components / devices disclosed herein (e.g., device / structure 100, device / structure 200, device / structure 400, device / structure 600, device / structure 700, device / structure 800, device / structure 1000, and / or device / structure 1200). In some embodiments, each unit 1310 includes one or more features / components / devices disclosed herein. In some embodiments, at least one unit is identical to another unit of the multiple units. In some embodiments, at least one unit is different from the other unit(s) of the multiple units.

[0137] 14, a device 1400 (e.g., a disk) according to some exemplary embodiments of the present disclosure is shown. The device 1400 is rotatable about an axis of rotation, such as a vertical axis of rotation 1403. In some embodiments, the device 1400 can be rotated at a speed of at least about 1000 rpm, at least about 1200 rpm, at least about 1400 rpm, at least about 1600 rpm, at least about 1800 rpm, at least about 2000 rpm, at least about 2200 rpm, at least about 2400 rpm, at least about 2600 rpm, at least about 2800 rpm, at least about 2900 rpm, at least about 3000 rpm, at least about 3500 rpm, at least about 4000 rpm, at least about 4500 rpm, at least about 5000 rpm, at least about 5500 rpm, at least about 6000 rpm, at least about 6500 rpm, or at least about 7000 rpm during one or more processes. In some embodiments, the device 1400 can be rotated at a speed of up to about 500 rpm, up to about 600 rpm, up to about 700 rpm, up to about 800 rpm, up to about 900 rpm, up to about 1000 rpm, up to about 1200 rpm, up to about 1400 rpm, up to about 1600 rpm, up to about 1800 rpm, up to about 2000 rpm, up to about 2200 rpm, up to about 2400 rpm, up to about 2600 rpm, up to about 2800 rpm, up to about 2900 rpm, up to about 3000 rpm, up to about 3500 rpm, up to about 4000 rpm, up to about 4500 rpm, or up to about 5000 rpm during one or more processes.

[0138] In some embodiments, device 1400 (e.g., a disk) includes multiple units, such as units 1410-1, 1410-2, and 1410-3, arranged circumferentially. In some embodiments, device 1400 includes 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 units. In some embodiments, units 1410 include one or more features / components / devices disclosed herein (e.g., device / structure 100, device / structure 200, device / structure 400, device / structure 600, device / structure 700, device / structure 800, device / structure 1000, and / or device / structure 1200). In some embodiments, each unit 1410 includes one or more features / components / devices disclosed herein. In some embodiments, at least one unit is identical to another unit of the multiple units. In some embodiments, at least one unit is different from the other unit(s) of the multiple units.

[0139] Example workflow(s)

[0140] Referring to FIG. 15 , an exemplary workflow 1500 is illustrated according to some exemplary embodiments of the present disclosure. Workflow 1500 can be performed on any of the suitable devices disclosed herein (e.g., device 1300 or device 1400). Workflow 1500 can also be automated. Furthermore, while a specific specimen (e.g., whole blood) is used in describing the workflow, it should be noted that the present disclosure is not limited thereto. Other samples, such as those disclosed herein, may also be used. Furthermore, the processes disclosed herein and illustrated in workflow 1500 can, but need not, be performed completely or in the order in which they are presented.

[0141] Workflow 1500 may be configured to perform one or more assays, including, but not limited to, a white blood cell (WBC) assay, a red blood cell (RBC) assay, and / or a hemoglobin (HgB) assay. In some embodiments, workflow 1500 may be configured to perform multiple assays, for example, any two or all of a WBC assay, an RBC assay, and a hemoglobin assay. In some embodiments, workflow 1500 may be configured to perform one or more additional or optional processes, such as a self-calibration process.

[0142] In some embodiments, workflow 1500 includes process 1502 of loading a buffer (e.g., water) into a device (e.g., device 1400). Loading of the buffer can be performed while the device is stationary or while spinning at a slow speed. In embodiments in which multiple assays are being run, buffer can be loaded for all assays to be run. As a non-limiting example, Figure 16A-1 (schematic) and Figure 16A-2 (photograph) illustrate loading of buffer into device 1400.

[0143] In some embodiments, workflow 1500 includes process 1504 of loading a sample (e.g., blood) into the device. Sample loading can be performed when the device is stationary or rotating at a slow speed. Sample loading can also be performed before, in parallel with, or after buffer loading. In embodiments where multiple assays are being performed, buffers can be loaded for all assays to be performed. As a non-limiting example, Figure 16B-1 (schematic) and Figure 16B-2 (photograph) illustrate loading a sample (e.g., blood) into device 1400. In some embodiments, a sample is loaded into the device and passed through a stepped capture channel(s) for all assays (e.g., device / structure 200 disclosed herein).

[0144] In some embodiments, workflow 1500 includes a buffer overflow process 1506. In this process, the device (e.g., device 1400) is spun, optionally at a predefined speed profile. In embodiments in which multiple assays are performed, buffer overflow can be performed in parallel for all assays (e.g., metering is performed for all assays approximately simultaneously). As a non-limiting example, Figure 16C-1 (schematic) and Figure 16C-2 (photograph) illustrate buffer overflow according to the design of device 1400.

[0145] In some embodiments, workflow 1500 includes a process 1508 of spilling a sample (e.g., blood). In this process, a device (e.g., device 1400) is spun, possibly at a predefined speed profile. In some embodiments, the sample is flowed or spilled through a hematocrit column, such as a bubble-free, closed-ended stepped channel (e.g., device 700 disclosed herein). In embodiments in which multiple assays are performed, sample spilling can be performed in parallel for all assays (e.g., metering is performed for all assays approximately simultaneously). As a non-limiting example, Figure 16D-1 (schematic) and Figure 16D-2 (photograph) illustrate sample spilling according to the design of device 1400.

[0146] In some embodiments, workflow 1500 includes process 1510 of metering a sample (e.g., blood). In this process, a device (e.g., device 1400) is spinning, possibly at a predefined speed profile. In some embodiments, during this process, a valve (e.g., device / structure 100) is breached. The sample is directed through a constricted channel (e.g., device / structure 800) into a mixing chamber (e.g., device / structure 400 or device / structure 600). In embodiments in which multiple assays are performed, sample metering can be performed in parallel for all assays (e.g., metering occurs for all assays approximately simultaneously). As a non-limiting example, Figures 16E-1 (schematic) and 16E-2 (photograph) illustrate sample metering according to the design of device 1400.

[0147] In some embodiments, workflow 1500 includes process 1512, which meters buffer. In this process, the device (e.g., device 1400) is spun, possibly at a predefined speed profile. In some embodiments, during this process, a valve (e.g., device / structure 100) is breached. The buffer is directed through a constricted channel (e.g., device / structure 800) into a mixing chamber (e.g., device / structure 400 or device / structure 600). In embodiments in which multiple assays are performed, buffer metering may be performed in parallel for all assays (e.g., metering is performed for all assays approximately simultaneously). In some embodiments, this process also involves flushing one or more sample chambers. As a non-limiting example, Figure 16F-1 (schematic) and Figure 16F-2 (photograph) illustrate buffer metering according to the design of device 1400.

[0148] In some embodiments, workflow 1500 includes process 1514 of capturing excess sample and / or spilling the sample (e.g., blood). In this process, the spin is accelerated (e.g., the rotational speed of the device is increased). In some embodiments, any excess sample is captured. In some embodiments, any excess sample is spilled onto the hematocrit column. By way of non-limiting example, Figure 16G-1 (schematic) and Figure 16G-2 (photograph) illustrate capturing excess sample and / or spilling the sample according to the design of device 1400.

[0149] In some embodiments, workflow 1500 includes process 1516, which mixes the metered sample with the metered buffer. In some embodiments, mixing is accomplished by alternately accelerating and decelerating the spin of the device (e.g., by alternately increasing and decreasing the rotational speed of the device). Increasing / decreasing the rotational speed of the device (e.g., device 1400) can be repeated as desired, programmed, or until the solutions are adequately / sufficiently mixed. In some embodiments, increasing / decreasing the rotational speed of the device can be repeated about 10 times, about 20 times, about 30 times, about 40 times, about 50 times, or about 60 times. In embodiments in which multiple assays are performed, the volumes of solutions for different assays can be different. However, devices disclosed herein (e.g., device 1400) are configured such that mixing efficiency is similar for all assays. This allows mixing for all assays to be performed in parallel (e.g., at approximately the same time and / or approximately the same number of times for all assays).

[0150] In some embodiments, mixing is accomplished using the laws of inertial motion, e.g., by increasing the rotational speed of the device relative to device / structure 400 and device / structure 600 as disclosed herein to a threshold speed and then suddenly stopping the spin (e.g., reducing the rotational speed to a low level or zero), thereby pushing the liquid to one side. This motion occurs entirely in one direction. This not only mixes the buffer with the sample, but also dissolves the respective lyophilized reagents (e.g., lyo-beads) in the chambers. As a non-limiting example, Figures 16H-1 (schematic) and 16H-2 (photograph) illustrate the mixing of a metered amount of sample with a metered amount of buffer according to the design of device 1400.

[0151] In some embodiments, the mixing process melts lyophilized beads in a mixing chamber configured for a WBC assay. The melted lyophilized beads lyse RBCs and / or stain platelets for fluorescent imaging, if desired. In some embodiments, the sample or solution becomes translucent. In some embodiments, the WBCs are also tagged for fluorescent imaging. In some embodiments, the mixing process melts lyophilized beads in a mixing chamber configured for an RBC assay. In some embodiments, the melted lyophilized beads stain platelets for fluorescent imaging, if desired. In some embodiments, the mixing process melts lyophilized beads in a mixing chamber configured for an HgB assay. In some embodiments, the melted lyophilized beads lyse all cells, for example, into a homogenous translucent mixture for imaging and / or hemoglobin absorbance measurement by other methods.

[0152] In some embodiments, workflow 1500 includes process 1518, which delivers the mixture (e.g., the solution after the mixing process) to one or more detection channels (e.g., device / structure 1200) for measurement. In some embodiments, the mixture is delivered to the respective imaging channel by accelerating the device spinning to a threshold speed in the opposite direction (e.g., the direction opposite to that used for mixing) and then abruptly stopping to push the mixture in the direction of spin. In some embodiments, the device is then spun at a slower speed to fill (e.g., completely fill) one or more detection channels or chambers with the mixture. As a non-limiting example, Figure 16I-1 (schematic) and Figure 16I-2 (photograph) illustrate the delivery of the mixture to one or more detection channels according to the design of device 1400.

[0153] In some embodiments, workflow 1500 includes process 1520 of measuring the optical density (OD) of HgB. In some embodiments, measuring the optical density (OD) of HgB is performed using methods disclosed herein or similar methods. In some embodiments, the detection channel is a stepped optical channel (e.g., device / structure 1200). As a non-limiting example, Figures 16I-1 (schematic) and 16I-2 (photograph) illustrate measuring the OD of HgB according to the design of device 1400.

[0154] Workflow 1500 can include one or more additional, optional, or alternative processes. For example, in some embodiments, workflow 1500 includes a process that enables a WBC assay (e.g., for measuring the number of white blood cells in a blood sample). In some embodiments, workflow 1500 includes an additional or optional process of sedimenting cells in one or more imaging channels configured for a WBC assay, as illustrated in Figure 16J-1 (schematic) and Figure 16J-2 (photograph). After the cells have sedimented in the imaging channel(s), each of the one or more imaging channels is imaged and / or the images are analyzed for a WBC assay (e.g., WBC count).

[0155] In some embodiments, workflow 1500 includes a process that enables an RBC assay (e.g., for measuring the number of red blood cells in a blood sample). For example, in some embodiments, workflow 1500 includes an additional or optional process of settling cells in one or more imaging channels configured for an RBC assay, as illustrated in Figure 16K-1 (schematic) and Figure 16K-2 (photograph). After the cells have settled in the imaging channel(s), each of the one or more imaging channels is imaged and / or the images are analyzed for the RBC assay.

[0156] In some embodiments, workflow 1500 includes a process that enables hematocrit measurement (e.g., measuring the hematocrit level or percentage of red blood cells in a blood sample). For example, in some embodiments, workflow 1500 includes an additional or optional process of separating plasma from the blood sample. Plasma can be separated from the blood sample (e.g., the blood sample from the sample spill) by spinning the device at high speed after all other assays have been performed (e.g., after the detection channels for all other assays have been imaged), as illustrated in Figure 16L-1 (schematic) and Figure 16L-2 (photograph).

[0157] In some embodiments, workflow 1500 includes a process that enables self-calibration. Self-calibration may be performed in accordance with method 900 and / or device / structure 1000 disclosed herein. By way of non-limiting example, Figures 16M-1 (schematic), 16M-2 (photograph), and 16M-3 (photograph) illustrate self-calibration in accordance with the design of device 1400, which includes one or more devices / structures 1000 or structures similar to device / structure 1000.

[0158] The devices and methods disclosed herein can be used in a variety of applications, including, but not limited to, clinical chemistry, immunoassays, and hematology. Examples of clinical chemistry, immunoassays, and / or hematology are disclosed in WO2018 / 119437, WO2018 / 140719, WO2022 / 029731, and WO2022 / 029732, the contents of each of which are incorporated herein by reference in their entirety. The devices and methods disclosed herein can be operated or performed by systems similar to those disclosed in U.S. Patent Application No. 17 / 371,746, the contents of which are incorporated herein by reference in their entirety.

[0159] Description of the subject technology as a clause

[0160] Various examples of aspects of the present disclosure are described for convenience as numbered clauses (1, 2, 3, etc.) and are provided as examples and not as limitations on the subject technology.

[0161] Clause 1. A valve comprising: a first channel having a first inlet and a first outlet, the first inlet connected to an upstream chamber and having a cross section perpendicular to a flow direction that is the same as or smaller than that of the upstream chamber, thereby forming a hydrophobic junction with the upstream chamber at the first inlet; and a compartment connected to the first outlet of the first channel, the compartment having a cross section perpendicular to the flow direction that is larger than that of the first outlet of the first channel, thereby forming a hydrophilic junction at the first outlet of the first channel.

[0162] Clause 2. The valve of clause 1, further comprising a second channel having a second inlet and a second outlet, wherein the second inlet is connected to the compartment and the second outlet is connected to a downstream chamber.

[0163] Clause 3. The valve of clause 2, wherein the second channel has the same cross section perpendicular to the flow direction as the first channel.

[0164] Clause 4. The valve of clause 2, wherein the second channel has a cross section perpendicular to the flow direction that is different from the first channel.

[0165] Clause 5. The valve of any one of clauses 2 to 4, wherein the second channel is longer than the first channel.

[0166] Clause 6. The valve of any preceding clause, wherein the compartment is deeper, wider, or both, than the first channel.

[0167] Clause 7. A valve according to any preceding clause, wherein the compartment is cylindrical.

[0168] Clause 8. The valve of clause 7, wherein the compartment has a circular, elliptical, oval, or polygonal cross section.

[0169] Clause 9. A device comprising a valve according to any preceding clause and the upstream chamber, wherein a portion of the upstream chamber adjacent the first inlet of the first channel of the valve is tapered to smooth the transition between the upstream chamber and the first inlet of the first channel of the valve.

[0170] Clause 10. The device of clause 9, wherein the tapered portion of the upstream chamber has a trapezoidal cross section parallel to the flow direction.

[0171] Clause 11. A device described in any one of clauses 9 to 10, wherein the tapered portion of the upstream chamber is configured at least in part based on a fluid to be processed by the device.

[0172] Clause 12. A device described in any one of clauses 9 to 11, wherein the tapered portion of the upstream chamber has an angle of about -10 degrees to -30 degrees, about -30 degrees to -60 degrees, or about -60 degrees to -80 degrees relative to the first channel.

[0173] Clause 13. A device comprising: an axis of rotation; a channel for transporting a fluid by rotating the device about the axis of rotation, the channel including an inlet, an outlet radially outward of the inlet relative to the axis of rotation, and a first portion between the inlet and the outlet; and a structure connected to a first side of the first portion of the channel, the structure configured to (i) enable transport of the fluid when the device rotates at a first speed, (ii) collect fluid residue when the device rotates at a second speed greater than the first speed, and (iii) capture the collected fluid residue within the structure when the device is subjected to acceleration, deceleration, or both.

[0174] Clause 14. The device of clause 13, wherein the structure includes a pocket for accommodating the fluid residue and a chamber connecting the pocket to the first side of the first portion of the channel and having a depth greater than the first portion of the channel and the pocket, thereby acting as a valve between the first portion of the channel and the pocket.

[0175] Clause 15. A device described in any one of clauses 13 to 14, wherein at least a portion of the structure is positioned radially outward of the first portion of the channel, and the radially innermost point at the junction formed by the chamber and the first side of the first portion of the channel defines the maximum allowable level of fluid residue.

[0176] Clause 16. The device of clause 15, wherein a second side of the first portion of the channel is positioned radially inward of the maximum allowable level of fluid residue.

[0177] Clause 17. The device of any one of clauses 13 to 16, wherein the first portion of the channel is curved.

[0178] Clause 18. A device comprising an axis of rotation and a mixing chamber having curved sides not coaxial with said axis of rotation, the mixing chamber configured to inertially mix fluids containing two or more different components.

[0179] Clause 19. A method comprising: (A) obtaining a device comprising an axis of rotation and a mixing chamber having a curved side that is not coaxial with the axis of rotation, the mixing chamber containing a fluid having two or more distinct components; (B) accelerating the device to a first velocity in a direction toward the curved side of the mixing chamber; and (C) suddenly decelerating the device such that the fluid moves toward the curved side of the mixing chamber by inertia, the curved side of the mixing chamber converting the motion of the fluid into a circular motion to create a vortex, thereby promoting mixing of the two or more distinct components in the fluid.

[0180] Clause 20. The method of clause 19, further comprising: (D) repeating said accelerating (B) and said decelerating (C) one or more times.

[0181] Clause 21. The method of any one of clauses 19 to 20, wherein said slowing down (C) brings said device to a complete stop.

[0182] Clause 22. The method of any one of clauses 19 to 21, wherein the deceleration (C) is carried out at a deceleration rate of at least 500 rpm / s, at least 1000 rpm / s, at least 1500 rpm / s, at least 2000 rpm / s, or at least 2500 rpm / s, at least 3000 rpm / s, at least 5000 rpm / s, 10000 rpm / s, at least 50000 rpm / s, or more.

[0183] Clause 23. The method of any one of clauses 19 to 22, wherein the volume of the fluid is at most 50%, at most 55%, at most 60%, at most 65%, or at most 70% of the volume of the mixing chamber.

[0184] Clause 24. The method of any one of clauses 19-23, wherein the first rate is based at least in part on the type of fluid, the amount of fluid, the shape of the mixing chamber, or any combination thereof.

[0185] Clause 25. The method of any one of clauses 19-24, wherein the mixing chamber comprises a path opposite the curved side and not coaxial with the axis of rotation, and the method further comprises (E) accelerating the device at a second velocity in a direction toward the path, and (F) suddenly decelerating the device such that the fluid moves by inertia toward the path of the mixing chamber.

[0186] Clause 26. The method of clause 25, wherein the second rate is based at least in part on the type of fluid, the amount of fluid, the shape of the mixing chamber, or any combination thereof.

[0187] Clause 27. A method comprising: (A) obtaining a device having an axis of rotation and a chamber having a path not coaxial with the axis of rotation, the chamber containing a fluid; (B) accelerating the device in a direction toward the path of the chamber; and (C) suddenly decelerating the device such that the fluid moves toward the path of the chamber by inertia.

[0188] Clause 28. A capillary channel comprising an open end, a closed end positioned radially outward of the open end relative to an axis of rotation, and first, second, and third lanes, wherein the first lane has an inlet at the open end for receiving a fluid, and the third lane has an outlet at the open end for discharging air, the second lane being formed between and connected to the first and third lanes, the second lane having a flow resistance different from that of the first and third lanes, whereby the fluid first flows through the first lane from the open end to the closed end, and then flows through the second lane, the third lane, or both, from the closed end to the open end, facilitating bubble-free priming.

[0189] Clause 29. The capillary channel of clause 28, wherein the first, second, and third lanes collectively form a stepped cross-section perpendicular to the length of the capillary channel.

[0190] Clause 30. The capillary channel of clause 29, wherein said first and third lanes are deeper than said second lane.

[0191] Clause 31. The capillary channel of clause 30, wherein the first and third lanes are substantially identical to each other.

[0192] Clause 32. The capillary channel of clause 30, wherein said first and third lanes are different from each other.

[0193] Clause 33. A capillary channel according to any one of clauses 29 to 32, wherein at least two of the first, second and third lanes have the same width.

[0194] Clause 34. A capillary channel according to any one of clauses 29 to 33, wherein at least two of the first, second and third lanes have different widths.

[0195] Clause 35. A device comprising a rotating shaft, a ventilation port, and a capillary channel according to any one of clauses 28 to 34, wherein the outlet of the third lane of the capillary channel is connected to the ventilation port.

[0196] Clause 36. A device comprising a chamber and a channel connected to said chamber for delivering a fluid to said chamber, said chamber and said channel collectively forming a junction that minimizes or eliminates capillary flow as said fluid exits an outlet of said channel and enters said chamber.

[0197] Clause 37. The device of clause 36, wherein the channel includes a protruding portion that forms at least a portion of the junction.

[0198] Clause 38. A device as described in clause 37, wherein the protruding portion comprises a U-shaped wall portion on either side of the channel at the outlet of the channel.

[0199] Clause 39. A device as described in clause 37, wherein the protruding portion comprises V-shaped walls on either side of the channel at the outlet of the channel.

[0200] Clause 40. A device described in any one of clauses 36 to 39, wherein the wall of the chamber adjacent the outlet of the channel is curved radially inward relative to the outlet of the channel so as to form at least a part of the junction.

[0201] Clause 41. A device described in any one of clauses 36 to 40, wherein the junction causes the fluid to flow from the outlet of the channel into the chamber in the direction of centrifugal force.

[0202] Clause 42. A method comprising: (A) obtaining a device comprising a structure filled with an absorbing dye, the structure comprising a first portion having a first depth and a second portion having a second depth, the first depth and the second depth being different from one another, but a nominal depth difference between the first depth and the second depth being known; (B) measuring a first optical density of the absorbing dye in the first portion of the structure and a second optical density of the absorbing dye in the second portion of the structure; (C) calculating an optical density difference between the first optical density and the second optical density; (D) calculating a ratio of the optical density difference to the nominal depth difference, the ratio representing the product of the extinction coefficient and concentration of the absorbing dye; and (E) using the ratio to determine the first depth of the first portion of the structure, the second depth of the second portion of the structure, the depth of an additional structure of the device, or any combination thereof.

[0203] Clause 43. The method of clause 42, wherein said obtaining (A) comprises obtaining said device comprising said structure and filling said structure with said absorbing dye.

[0204] Clause 44. A device comprising one or more features, each of said features comprising a first portion having a first depth and a second portion having a second depth, said first depth and said second depth being different from one another, but with a known nominal depth difference between said first depth and said second depth, thereby allowing self-calibration of the depth of features of said device independent of variations in the manufacture of said device.

[0205] Clause 45. The device of clause 44, wherein the one or more structures include a first structure and a second structure at different locations on the device.

[0206] Clause 46. The device of clause 45, wherein the nominal depth difference of the first structure is the same as that of the second structure.

[0207] Clause 47. The device of clause 45, wherein the nominal depth difference of the first structure is different from the second structure.

[0208] Clause 48. A method comprising: (A) obtaining a device having a structure positioned in a path of a mixture having a first component, the structure including a first portion having a first depth and a second portion having a second depth, the first depth and the second depth being different from one another, but a nominal depth difference between the first depth and the second depth being known; (B) measuring a first optical density of the first component in the first portion of the structure and a second optical density of the first component in the second portion of the structure; (C) calculating an optical density difference between the first optical density and the second optical density; and (D) determining a concentration of the first component in the mixture based at least in part on the optical density difference and the nominal depth difference.

[0209] Clause 49. The method of clause 48, wherein the concentration of the first component in the mixture is determined by comparing the optical density difference to a calibration curve in an optical path corresponding to the nominal depth difference.

[0210] Clause 50. (E) The method of Clause 49, further comprising, prior to said determining (D), creating said calibration curve, wherein said creating (E) comprises (i) preparing a series of standard solutions containing known concentrations of said first component, (ii) measuring the absorbance of each of said standard solutions at one or more specific wavelengths for said first component in one or more optical paths, thereby obtaining a plurality of absorbance values, and (iii) plotting said absorbance values ​​against the corresponding concentrations of said first component to create said calibration curve for each of said one or more optical paths.

[0211] Clause 51. The method of clause 50, wherein said measuring of absorbance is performed using a spectrophotometer or a microfluidic device.

[0212] Clause 52. The method of clause 48, wherein the extinction coefficient of the first component is known and the concentration of the first component in the mixture is calculated by dividing the optical density difference by the nominal depth difference and the extinction coefficient of the first component.

[0213] Clause 53. The method of any one of clauses 48 to 52, wherein the first component is hemoglobin.

[0214] Clause 54. A device comprising a structure positioned in a path of a mixture having a first component, the structure including a first portion having a first depth and a second portion having a second depth, the first depth and the second depth being different from one another, but with a known nominal depth difference between the first depth and the second depth, thereby enabling measurement of the concentration of the first component independent of variations in manufacturing of the device.

[0215] Clause 55. A system for operating a device described in any of the preceding clauses or for carrying out a method described in any of the preceding clauses.

[0216] Terminology and References Cited The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the claims. As used in the description of embodiments and in the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will be understood that terms such as "left" or "right," "top" or "bottom," "lower" or "upper," "inner" or "outer," "inside" or "outside," etc. are used to describe features of exemplary embodiments with reference to the location of the features as displayed in the figures. While terms such as "first" and "second" may be used herein to describe various elements, it will be understood that these elements should not be limited by these terms. These terms are used merely to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without changing the meaning of the description, as long as the terms "first element" and "second element" are consistently re-titled.

[0217] As used herein, the term "and / or" refers to and includes any and all possible combinations of one or more of the associated listed items. Furthermore, it will be understood that the terms "include," "includes," "including," "comprise," "comprises," and / or "comprising," when used herein, specify the presence of stated features, entities, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, entities, steps, operations, elements, components, and / or groups thereof.

[0218] The terms "about" or "approximately" are used herein to provide a literal rationale for a number that is close to or approximately the same as the number that follows the term, as well as the number itself. When determining whether a number is close to or approximately the same as a specifically stated number, an unstated nearby or approximate value may be a number that, in the context in which it is presented, is a substantial equivalent of the specifically stated number. All numerical values ​​and ranges disclosed herein are understood to be approximate values ​​and ranges, regardless of whether "about" is used in conjunction with them. The term "about" used in conjunction with a numerical value herein is also understood to refer to a value that may be ±0.01% (inclusive), ±0.1% (inclusive), ±0.5% (inclusive), ±1% (inclusive), ±2% (inclusive), ±3% (inclusive), ±5% (inclusive), ±10% (inclusive), or ±15% (inclusive) of the numerical value. Moreover, when a range of numerical values ​​is disclosed herein, it is to be understood that every number falling within that range is also specifically disclosed.

[0219] The term "if," as used herein, shall be interpreted to mean "when" or "upon" or "in response to determining" or "in response to detecting" or "pursuant to a determination that," as appropriate, depending on the context. Similarly, the phrase "when determined to" or "when [a described condition or event] is detected," as used herein, shall be interpreted to mean "when determined to" or "in response to determining" or "upon detecting [a described condition or event]" or "in response to detecting [a described condition or event]" or "pursuant to a determination that [a described condition or event] has been detected," as appropriate, depending on the context.

[0220] When a reference number is given the notation "i-th," the reference number refers to a general component, set, or embodiment. For example, "unit i" refers to the i-th unit of a plurality of units.

[0221] All references cited in this specification are incorporated herein by reference in their entirety for all purposes to the same extent as if each individual publication or patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety for all purposes.

Claims

1. A valve, a first channel having a first inlet and a first outlet, the first inlet being connected to an upstream chamber and having a cross section perpendicular to the flow direction that is the same as or smaller than that of the upstream chamber, thereby forming a hydrophobic junction with the upstream chamber at the first inlet; a compartment connected to the first outlet of the first channel, the compartment having a cross section perpendicular to the flow direction that is larger than the first outlet of the first channel, thereby forming a hydrophilic junction at the first outlet of the first channel; The valve.

2. 10. The valve of claim 1, further comprising a second channel having a second inlet and a second outlet, the second inlet connected to the compartment and the second outlet connected to a downstream chamber.

3. The valve of claim 1 , wherein the compartment is deeper, wider, or both, than the first channel.

4. A valve according to claim 1; the upstream chamber, the device, wherein a portion of the upstream chamber adjacent the first inlet of the first channel of the valve is tapered to smooth the transition between the upstream chamber and the first inlet of the first channel of the valve.

5. The device of claim 4 , wherein the tapered portion of the upstream chamber has a trapezoidal cross section parallel to the flow direction.

6. A device, A rotation axis; a channel for transporting a fluid by rotating the device about the axis of rotation, the channel including an inlet, an outlet radially outward of the inlet relative to the axis of rotation, and a first portion between the inlet and the outlet; a structure connected to a first side of the first portion of the channel, the structure configured to (i) allow transport of the fluid when the device rotates at a first speed, (ii) collect fluid residue when the device rotates at a second speed greater than the first speed, and (iii) capture the collected fluid residue within the structure when the device is subjected to acceleration, deceleration, or both; The device comprising:

7. 7. The device of claim 6, wherein the structure comprises: a pocket for containing said fluid residue; a chamber connecting the pocket to the first side of the first portion of the channel and having a depth greater than the first portion of the channel and the pocket, thereby acting as a valve between the first portion of the channel and the pocket; The device comprising:

8. 7. The device of claim 6, At least a portion of the structure is positioned radially outward of the first portion of the channel; a radially innermost point at a junction formed by the chamber and the first side of the first portion of the channel defines a maximum allowable level of fluid residue; The device.

9. The device of claim 8 , wherein a second side of the first portion of the channel is positioned radially inward of the maximum allowable level of fluid residue.

10. The device of claim 6 , wherein the first portion of the channel is curved.

11. (A) obtaining a device comprising an axis of rotation and a mixing chamber having curved sides that are not coaxial with the axis of rotation, wherein the mixing chamber contains a fluid comprising two or more distinct components; (B) accelerating the device in a direction toward the curved side of the mixing chamber to a first velocity; and (C) suddenly decelerating the device so that the fluid moves by inertia toward the curved side of the mixing chamber, the curved side of the mixing chamber converting the motion of the fluid into a circular motion and creating a vortex, thereby promoting mixing of the two or more distinct components in the fluid. A method comprising:

12. 12. The method of claim 11, (D) repeating said accelerating (B) and said decelerating (C) one or more times.

13. the mixing chamber having a path opposite the curved side that is not coaxial with the axis of rotation, and the method further comprising: (E) accelerating the device at a second velocity in a direction toward the path; and (F) suddenly decelerating the device so that the fluid moves by inertia toward the passageway of the mixing chamber.

13. The method of claim 12, further comprising:

14. (A) obtaining a device having an axis of rotation and a chamber having a path that is not coaxial with the axis of rotation, the chamber containing a fluid; (B) accelerating the device in a direction toward the path of the chamber; and (C) suddenly decelerating the device so that the fluid moves by inertia toward the passageway of the chamber. A method comprising:

15. A capillary channel, an open end; a closed end positioned radially outward of the open end relative to the axis of rotation; first, second, and third lanes; the first lane having an inlet at the open end for receiving a fluid; the third lane having an outlet at the open end for discharging air; the second lane is formed between the first lane and the third lane and is connected to the first lane and the third lane, and the second lane has a flow resistance different from that of the first lane and the third lane, whereby the fluid first flows through the first lane from the open end to the closed end, and then flows through the second lane, the third lane, or both from the closed end to the open end, facilitating bubble-free priming; The capillary channel.

16. 16. The capillary channel of claim 15, wherein the first, second, and third lanes collectively form a stepped cross section perpendicular to the length of the capillary channel.

17. 17. The capillary channel of claim 16, wherein the first and third lanes are deeper than the second lane.

18. a chamber; a channel connected to the chamber for delivering a fluid to the chamber, The device, wherein the chamber and the channel collectively form a junction that minimizes or eliminates capillary flow as the fluid exits the outlet of the channel and enters the chamber.

19. The device of claim 18 , wherein the channel includes a protruding portion that forms at least a portion of the junction.

20. 20. The device of claim 19, wherein the protruding portions comprise U-shaped or V-shaped walls on either side of the channel at the outlet of the channel.

21. 21. The device of claim 20, wherein a wall of the chamber adjacent the outlet of the channel curves radially inward relative to the outlet of the channel to form at least a portion of the junction.

22. 22. The device of claim 21, wherein the junction causes the fluid to flow from the outlet of the channel into the chamber in the direction of centrifugal force.

23. (A) obtaining a device comprising a structure filled with an absorbing dye, the structure including a first portion having a first depth and a second portion having a second depth, the first depth and the second depth being different from one another, but with a known nominal depth difference between the first depth and the second depth; (B) measuring a first optical density of the absorber dye in the first portion of the structure and a second optical density of the absorber dye in the second portion of the structure; (C) calculating an optical density difference between the first optical density and the second optical density; (D) calculating a ratio of the optical density difference to the nominal depth difference, the ratio representing the product of the extinction coefficient and the concentration of the absorbing dye; and (E) using the ratio to determine the first depth of the first portion of the feature, the second depth of the second portion of the feature, a depth of an additional feature of the device, or any combination thereof. A method comprising:

24. 24. The method of claim 23, wherein said obtaining (A) comprises: obtaining the device comprising the structure; and filling the structure with the absorbing dye; The method comprising:

25. A device comprising one or more structures, The device, wherein each of the features includes a first portion having a first depth and a second portion having a second depth, the first depth and the second depth being different from one another, but with a known nominal depth difference between the first depth and the second depth, thereby enabling self-calibration of the depth of the features of the device regardless of variations in manufacturing of the device.

26. 26. The device of claim 25, wherein the one or more structures include a first structure and a second structure at different locations on the device.

27. (A) obtaining a device comprising a structure positioned within a path of a mixture having a first component, the structure including a first portion having a first depth and a second portion having a second depth, the first depth and the second depth being different from one another, but with a known nominal depth difference between the first depth and the second depth; (B) measuring a first optical density of the first component in the first portion of the structure and a second optical density of the first component in the second portion of the structure; (C) calculating an optical density difference between the first optical density and the second optical density; and (D) determining a concentration of the first component in the mixture based at least in part on the optical density difference and the nominal depth difference. A method comprising:

28. 28. The method of claim 27, wherein the concentration of the first component in the mixture is determined by comparing the optical density difference to a calibration curve in an optical path corresponding to the nominal depth difference.

29. 30. The method of claim 28, further comprising: (E) generating the calibration curve prior to said determining (D), wherein said generating (E) comprises: (i) preparing a series of standard solutions containing known concentrations of said first component; (ii) measuring the absorbance of each of the standard solutions at one or more specific wavelengths for the first component in one or more optical paths, thereby obtaining a plurality of absorbance values; and (iii) plotting the absorbance values ​​against the corresponding concentrations of the first component to generate the calibration curve for each of the one or more optical paths. The method comprising:

30. 28. The method of claim 27, the attenuation coefficient of the first component is known; The method, wherein the concentration of the first component in the mixture is calculated by dividing the optical density difference by the nominal depth difference and the extinction coefficient of the first component.

31. 18. The capillary channel of any one of claims 15 to 17, wherein a biological sample comprising a mixture of aqueous and non-aqueous biological components is moved from the inlet port to the outer measurement chamber by means of inertial and centrifugal forces for analysis and evaluation.

32. 32. The capillary channel of claim 31, wherein the mixture is a mixture of body fluid and cells.

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