Fluid check valve for gas discharge and fluid system

Abstract

A fluid check valve for venting gas from a fluid system includes a retainer defining a fluid opening having an upstream side and a downstream side, a hydrophilic porous material retained by the retainer and positioned to cover the fluid opening, and a hydrophobic porous material retained by the retainer, covering the fluid opening, and positioned adjacent to the hydrophilic porous material. One side of the hydrophilic porous material is in fluid communication with the upstream side of the opening, and one side of the hydrophobic porous material is in fluid communication with the downstream side of the opening. The hydrophilic porous material is configured to retain liquid from the upstream side and prevent passage of gas from the downstream side to the upstream side, and the hydrophobic porous material is configured to prevent passage of liquid from the upstream side to the downstream side.

Description

Technical Field

[0001] The present disclosure generally relates to the discharge and sealing of fluid systems. More specifically, the present disclosure relates to a check valve for discharging gas from a fluid system while preventing the outflow of liquid.

Background Art

[0002] Depending on the situation, it can be useful to be able to selectively remove fluid from a container or channel system and prevent the fluid from re-entering that area. For example, this can be achieved using one or more valves such as check valves, safety valves, and / or pressure relief valves. These valves are typically mechanical valves that can be manufactured from metals such as steel or brass. As such, they cannot be easily miniaturized and typically have a diameter greater than 5 mm.

[0003] Furthermore, there are several applications or desirable applications where it is necessary or desirable to be able to selectively remove gas from a system while retaining liquid within the system. For example, it may be necessary to remove oxygen from a system to prevent oxidation of the remaining liquid. One approach to addressing this need is to evacuate the system of liquid and gas and then seal the system. However, evacuating the system may be undesirable or impractical because of the use of vacuum pumps, valves, and / or gas manifolds.

[0004] Microfluidic systems typically involve the movement of liquid within channels that are less than 3 mm wide. In this context, when a liquid is loaded into a fluid line (or conduit), gas is typically simultaneously evacuated through an outlet or drain. In the case of a dead-end fluid system, the discharge can be effected by the diffusion of air through a permeable material such as polydimethylsiloxane (PDMS).

[0005] Due to the small size of the microfluidic channels, the presence of air bubbles in the fluid line can have a significant impact on the system. Air bubbles can disrupt the optical properties of the system due to the mismatch between the refractive index of air and that of the liquid, which can be important in some applications. The presence of air in undesirable regions of the device can have an adverse effect on the process being carried out. For example, air bubbles in a micro bioreactor can cause cells to dry out and die. In systems that require accurate and uniform flow rate control, it is important to completely fill the fluid line with the desired liquid. The local reduction in the effective fluid cross-sectional area caused by air bubbles in the channel can disrupt the system by locally increasing the flow rate, shear rate, and pressure drop. For these reasons, it is often necessary to effectively remove air bubbles in microfluidic systems.

[0006] It may be desirable to obtain a rapid assessment of the rheological properties of a patient's blood. Knowledge of such rheological properties is valuable in evaluating the administration of coagulants and anticoagulants to a patient. It can also predict the likelihood of bleeding or thromboembolic events in people who tend to bleed or have a high risk of coagulation. Further situations where it is important to know the rheological properties of blood include the monitoring of patients during and after the reversal of anticoagulation during surgery. Changes in blood rheology also occur in patients suffering from sepsis and can indicate the presence of that condition at an early stage. If sepsis is detected early enough, the treatment of that condition can be relatively straightforward.

[0007] No statement contained in this specification as to any document, act, material, device, article, etc. shall be taken as an admission that any of these constitutes prior art base forming a part of the prior art as of the priority date of each of the appended "claims" or was common general knowledge in the field related to this disclosure.

Summary of the Invention

[0008] Some embodiments relate to a fluid check valve for discharging gas from a fluid system, the fluid check valve comprising A retainer defining a fluid opening having an upstream side and a downstream side, a hydrophilic porous material held by the retainer and arranged to cover the fluid opening, a hydrophobic porous material held by the retainer, covering the fluid opening, and arranged adjacent to the hydrophilic porous material, and one surface of the hydrophilic porous material is in fluid communication with the upstream side of the opening, and one surface of the hydrophobic porous material is in fluid communication with the downstream side of the opening, the hydrophilic porous material is configured to hold liquid from the upstream side and prevent gas from passing from the downstream side to the upstream side, and the hydrophobic porous material is configured to prevent liquid from passing from the upstream side to the downstream side.

[0009] The hydrophilic porous material may be disposed upstream of the hydrophobic porous material.

[0010] At least one of the hydrophilic porous material and the hydrophobic porous material may define a plurality of pores, and the plurality of pores have a median pore diameter in the range of about 0.1 micron to about 10 microns. In some embodiments, the plurality of pores have a median pore diameter of less than about 1 micron. The hydrophilic porous material may define a plurality of first pores having a second median pore size of less than about 0.5 micron. The hydrophobic porous material may define a plurality of second pores having a second median pore size of less than about 0.3 micron.

[0011] The hydrophobic porous material and the hydrophilic porous material are in direct contact with each other. In some embodiments, the hydrophobic porous material and the hydrophilic porous material are separated from each other. The hydrophobic porous material and the hydrophilic porous material may be separated from each other by a distance greater than about 0 mm and less than about 2 mm. The hydrophobic porous material and the hydrophilic porous material may be separated by a material that allows fluid passage or permeation. In some embodiments, the hydrophobic porous material and the hydrophilic porous material are separated by a void.

[0012] The retention body may include a first portion and a second portion, the first and second portions being joined together and cooperatively retaining a hydrophilic porous material and a hydrophobic porous material. The first and second portions may be shaped to form a friction fit or may be joined together.

[0013] One of the first portion and the second portion may be shaped to define a recess, and the other section of the first portion and the second portion is shaped to fit within the recess so as to join the first portion and the second portion together. The recess may have a size that tapers along the depth of the recess. At least a portion of each of the hydrophilic porous material and the hydrophobic porous material may be located within the recess.

[0014] The first portion includes an upstream surface that fluidly connects with an upstream side having at least a portion of a frustoconical shape or a concave shape, thereby assisting the passage of gas from the upstream side to the downstream side.

[0015] The hydrophilic porous material may include a hydrophilic membrane. The hydrophobic porous material may include a hydrophobic membrane. In some embodiments, the hydrophobic membrane and / or the hydrophilic membrane includes a polytetrafluoroethylene substrate.

[0016] The hydrophilic porous material may include a hydrophilic coating. The hydrophobic porous material may include a hydrophobic coating.

[0017] When the hydrophilic porous material is exposed to liquid, the fluid check valve may prevent the passage of gas from the downstream side to the upstream side with a backflow pressure limit of about -80 kPa.

[0018] The hydrophobic porous material may be configured to prevent the passage of liquid from the upstream side to the downstream side with a leak pressure limit of about 250 kPa. In some embodiments, the hydrophobic porous material is configured to prevent the passage of liquid from the upstream side to the downstream side with a leak pressure limit of about 150 kPa. In some embodiments, the hydrophobic porous material is configured to prevent the passage of liquid from the upstream side to the downstream side with a leak pressure limit of about 100 kPa.

[0019] Some embodiments relate to a self-sealing fluid discharge system, the self-sealing fluid discharge system comprising a fluid tube including an inner surface, and a fluid check valve as described herein, the fluid check valve being adapted within the fluid tube and forming a fluid seal with the inner surface of the fluid tube to separate the fluid tube into an upstream side including gas and liquid and a downstream side receiving gas.

[0020] The fluid tube defines a plurality of ports in fluid communication with the upstream side to enable pressure measurement. The fluid tube defines an inlet in fluid communication with the upstream side to enable injection of fluid into the upstream side.

[0021] The fluid system may further include a plunger adapted to fit within the fluid tube, the plunger including the fluid check valve. The fluid system may further include an automatic motion control system configured to engage the plunger to control movement of the plunger.

[0022] In some embodiments, the fluid system further includes a baffle component located within the fluid tube adjacent to a first portion to facilitate flow of liquid along the inner surface of the fluid tube.

[0023] Throughout this specification, the words "comprise", "comprises" or "comprising", or variations such as "include", "includes" or "including", are to be understood to mean that they include the stated element, detail or step, or group of elements, details or steps, but do not exclude any other element, detail or step, or group of elements, details or steps.

[0024] Embodiments are described in more detail below by way of example, with reference to the accompanying drawings which are briefly described below.

Brief Description of the Drawings

[0025]

Figure 1

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Figure 6

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Figure 8

Figure 9

[0026] The present disclosure generally relates to the discharge and sealing of fluid systems. More specifically, the present disclosure relates to a check valve for discharging gas from a fluid system while preventing the outflow of liquid.

[0027] The rheological properties of blood can be measured using a microfluidic device. Patent application No. PCT / GB2017 / 053393, previously filed by the applicant of the present invention, discloses an example of such a device. By controlling the flow rate of the sample fluid within the measurement section of the device, viscosity and shear rate can be calculated from an appropriate fluid device. For example, the fluid device may comprise a pumping device for controlling the flow rate of a sample flowing through a measurement unit where the pressure drop within a channel of defined dimensions is measured. Using the known pressure drop, known flow rate, and known channel dimensions, viscosity and shear rate can be calculated. The flow rate is controlled by a syringe pump, and the pressure drop across the entire measurement channel is performed using a differential pressure sensor. In order to measure the full spectrum of viscosity characteristics of a non-Newtonian fluid such as blood (i.e., a fluid that varies with shear rate), the flow rate may vary gradually over time according to a sine wave pattern.

[0028] However, if air bubbles are trapped in the fluid system between the syringe and the measurement channel, the applied change in flow rate and the resulting variable pressure experienced across the entire fluid line cause the air bubbles to compress and decompress. Thus, the air bubbles will have their volume decreased and increased due to the pressure changes. This will then result in a significant difference between the flow rate generated by the movement of the syringe pump and the actual flow rate of the sample passing through the fluid line where the pressure difference is measured. Since the flow rate considered in the viscosity calculation is defined only by the movement of the piston of the syringe pump, the aforementioned difference in flow rate between the volume change of the syringe and the flow rate of the liquid within the channel where the pressure is measured results in an unacceptable error in the calculated viscosity. Thus, this error will invalidate the measurement. Further, if air bubbles are trapped within the measurement section of the channel, less liquid than expected will be measured and / or the effective cross-sectional area of the channel will decrease. This results in a significant error in the calculated viscosity and / or invalidates the viscosity calculation using the physical / absolute cross-sectional size of the channel. This emphasizes the importance of removing air bubbles from the system.

[0029] Referring to FIG. 1, a fluid check valve 100 for discharging gas from a fluid pipe 101 is shown. The fluid check valve 100 includes a holding body 110 that defines a fluid opening 111 having an upstream side 112 and a downstream side 113.

[0030] The fluid check valve 100 also includes a hydrophilic porous material 120 held by the holding body 110 and disposed to cover the fluid opening 111, and a hydrophobic porous material 130 held by the holding body 110 and disposed to cover the fluid opening 111 adjacent to the hydrophilic porous material 120. The hydrophilic porous material 120 is positioned upstream of the hydrophobic porous material 130.

[0031] One surface 121 of the hydrophilic porous material 120 is in fluid communication with the upstream side 112 of the opening 111, and one surface 131 of the hydrophobic porous material 130 is in fluid communication with the downstream side 113 of the opening 111.

[0032] The hydrophilic porous material 120 is configured to hold liquid from the upstream side 112 and prevent gas from passing from the downstream side 113 to the upstream side 112. The hydrophobic porous material 130 is configured to prevent liquid from passing from the upstream side 112 to the downstream side 113.

[0033] If the upstream side 112 of the fluid pipe 101 initially contains only gas (or mainly gas) and liquid 180 is injected into the upstream side 112 of the fluid pipe 101, the liquid includes a liquid surface 181, and the liquid surface 181 can push the gas out from the upstream side 112 through the opening 111, the hydrophilic porous material 120, and the hydrophobic porous material 130 so that the gas passes through the downstream side 113. Next, when the liquid 180 is injected into the upstream side 112 again, the liquid surface 181 and the liquid 180 can enter and be held by the hydrophilic porous material 120. The hydrophilic porous material 120 having the held liquid 180 prevents and / or stops the passage of gas through the hydrophilic porous material 120. The hydrophilic porous material 120 can have, for example, a strong capillary pressure that helps hold a liquid with a high surface tension within its mesh.

[0034] In some embodiments, the retained liquid 180 is difficult to remove from the hydrophilic porous material 120. Thus, the fluid check valve 100 can be considered a single-use check valve because it can actually expel only gas until the hydrophilic porous material 120 holds the liquid 180 and further gas expulsion is impeded or prevented. However, if the liquid 180 is removed from the hydrophilic porous material 120 (e.g., by evaporating, heating, or otherwise drying the hydrophilic porous material 120), the fluid check valve 100 can be reused.

[0035] After the liquid enters the hydrophilic porous material 120, at least a portion of the liquid 180 can pass through the hydrophilic porous material 120 and enter the space (or void) created by the gap 140 and / or contact the hydrophobic porous material 130. However, the liquid 180 is impeded from passing through the hydrophobic porous material 130. The hydrophobic porous material 130 can have a strong repulsive pressure that prevents a liquid with a high surface tension from entering its mesh. The impediment to the liquid 180 passing through the hydrophobic porous material 130 (or the fluid resistance of the hydrophobic porous material 130 to the passage of the liquid 180 therethrough) can be due to the degree of hydrophobicity of the hydrophobic porous material 130, the pore size of the hydrophobic porous material 130, and the surface tension of the particular liquid 180 being measured / tested. This minimizes fluid loss from the fluid system 200, thereby reducing the amount of fluid required to operate the fluid system 200. This provides the advantage of reducing the cost associated with the reagent and minimizing the amount of blood sample required for the measurement. The ability of the hydrophobic porous material 130 to allow gas to pass through takes advantage of the difference in viscosity between the gas and the liquid 180.

[0036] The hydrophobic porous material 130 can be particularly suitable, for example, for preventing the passage of polar liquids. The liquid 180 retained by the fluid check valve 100 can include any one or more of a non-Newtonian fluid, blood (whole blood), serum, and plasma.

[0037] The fluid check valve 100 does not include movable parts. This can bring the advantages of improving its reliability and reducing its manufacturing cost. Also, the simplicity of its design allows it to be manufactured in dimensions suitable for microfluidic applications. The fluid check valve 100 can be sized, for example, to fit within the microfluidic channel of the fluid tube 101. The exposed area of the fluid check valve 100 can be an area equivalent to a circle with a diameter of less than about 3 mm. The total area of the fluid check valve 100 exposed to the fluid from the upstream side 112 can be about 0.4 mm 2 ~ about 10 mm 2 It can be. However, in some embodiments, the total area of the fluid check valve 100 exposed to the fluid from the upstream side 112 can be about 0.01 mm 2 ~ about 100 mm 2 It is. In some embodiments, the total area of the fluid check valve 100 exposed to the fluid from the upstream side 112 can be about 0.4 mm 2 ~ about 80 mm 2 It is. The total area of the fluid check valve 100 exposed to the fluid from the upstream side 112 can be about 0.4 mm 2 ~ about 20 mm 2 It can be.

[0038] The area of the opening 111 can be smaller than the exposed area of the fluid check valve 100.

[0039] Both the hydrophilic porous material 120 and the hydrophobic porous material 130 can be arranged in a "row" between the upstream side and the downstream side, and (when the hydrophilic porous material 120 holds the liquid) can cooperatively prevent (or limit) the passage of gas from the downstream side 113 and prevent the passage of liquid from the upstream side 112. The hydrophilic porous material 120 can be disposed upstream of the hydrophobic porous material 130.

[0040] The hydrophilic porous material 120 and the hydrophobic porous material 130 can be arranged such that the hydrophobic porous material 130 is in fluid connection with the upstream side 112 through the hydrophilic porous material 120.

[0041] The hydrophilic porous material 120 can define a plurality of pores (not shown) having a pore size distribution. The median diameter of the pores (first pores) can be greater than about 2 nm. In some embodiments, the first pores of the hydrophilic porous material 120 have a median diameter in the range of about 2 nm to about 10 microns. The hydrophilic porous material 120 can include an ultrafiltration (or nanoporous) filter. In some embodiments, the first pores of the hydrophilic porous material 120 have a median diameter in the range of about 0.1 micron to about 10 microns. In some embodiments, the first pores of the hydrophilic porous material 120 have a median diameter in the range of about 0.2 micron to about 1 micron. The first pores of the hydrophilic porous material 120 can have a median diameter of about 0.5 micron, such as 0.45 micron.

[0042] The surface of the hydrophilic porous material 120 has an affinity for the liquid 180, but the porous structure of the hydrophilic porous material 120 can also prevent the passage of the liquid 180 due to the surface tension of the liquid 180. However, when the pressure exceeds the threshold pressure, the liquid 180 can pass through the hydrophilic porous material 120 and be retained therein. The threshold pressure can be, for example, about 25 kPa, and the largest pores have a size equivalent to a circle with a diameter of about 0.45 micron.

[0043] When the hydrophilic porous material 120 holds liquid in a plurality of pores across the opening 111, thereby clogging or blocking the pores and forming at least a part of the airtight seal, the hydrophilic porous material 120 (and thus the check valve 100) can substantially prevent the passage of gas from the downstream side 113 to the upstream side 112 up to a pressure limit (leakage pressure limit or backflow pressure limit). The backflow pressure limit is the negative pressure limit of the upstream side 112 with respect to the downstream side 113. The backflow pressure limit can be about -100 kPa (<-100 kPa pressure or a negative pressure greater than the backflow pressure limit will result in gas leakage to the upstream side 112). In some embodiments, the backflow pressure limit can be about -80 kPa.

[0044] The pore diameter, along with the affinity that the hydrophilic porous material has for retaining liquid, is understood to affect the backflow pressure limit. The hydrophilic porous material 120 can be selected with a pore size of a specific size in order to achieve a desired backflow pressure limit. For example, using the following equation for capillary pressure, the maximum pore diameter of radius r is determined to achieve a specific backflow pressure limit P L can be achieved.

Equation

[0045] The sealing of the hydrophilic porous material 120 and the retainer 110 also needs to withstand pressure up to at least the leakage pressure.

[0046] When the hydrophilic porous material 120 holds liquid in a plurality of pores that cross only a part of the opening 111, the passage of gas can be blocked, thereby forming an airtight seal and sufficiently blocking the flow of fluid (i.e., gas) from the downstream side 113 to the upstream side 112 up to the backflow pressure limit, but not enough to prevent it completely.

[0047] The hydrophilic porous material 120 and the hydrophobic porous material 130 can be separated by a gap 140, and the distance between the opposing surfaces of the hydrophilic porous material 120 and the hydrophobic porous material 130 can be less than about 2 mm. The gap 140 can be filled with a material that allows the passage or permeation of fluid (i.e., a material that can form a structure), a mechanical scaffold, or a packing material (i.e., a fluid-conductive material (not shown)). The fluid-conductive material can be, for example, a porous material having pores with a diameter greater than about 5 microns. A fluid-conductive material having a pore size of about 5 microns can allow more fluid to pass through to the hydrophobic porous material 130 compared to a material having smaller pores. Although this is generally not desirable, by using a pore size of about 5 microns, this process that allows fluid to pass through to the hydrophobic porous material 130 can be made faster and can have the advantage of being performed at a lower operating pressure.

[0048] In some embodiments, the gap 140 is a void that can be filled with a gas or a liquid, or a void that can be at least partially filled with a liquid. The gap 140 can be regarded as a "dead volume".

[0049] In some embodiments, the structure of the gap 140 can define a funnel (not shown) whose cross-sectional size contracts and then increases along the length of the funnel. The funnel can also include an intermediate tube length of a fixed diameter. For example, the funnel can contract from a diameter of 3 mm to 1 mm over a length of 0.5 mm, then contract to a tube with a diameter of 1 mm and a length of 9 mm, and then the funnel can expand to 3 mm over a length of 0.5 mm. This is equivalent to a dead volume with a diameter of 3 mm and a length of about 1 mm. The funnel space can be filled with a scaffold material, which will provide greater mechanical stability to the hydrophilic porous material 120 and the hydrophobic porous material 130 while reducing the volume available for the liquid and further reducing the dead volume.

[0050] In some embodiments, the hydrophilic porous material 120 and / or the hydrophobic porous material 130 can be arranged such that their opposing surfaces 122, 132 are not parallel to each other. The opposing surfaces 122, 132 can also generally be non-planar and can have a curved or undulating shape. In these situations, the distance by which the hydrophilic porous material 120 and / or the hydrophobic porous material 130 are separated is regarded as the maximum distance between the opposing surfaces 122, 132.

[0051] In some embodiments, the hydrophilic porous material 120 and the hydrophobic porous material 130 are in direct contact with each other. This has the advantage of eliminating the gap 140 and reducing the volume of space in the check valve 100 that can contain liquid that can flow back to the upstream side 112 when the upstream side is under negative pressure with respect to the downstream side 113. In some embodiments, the dead volume can be less than 1 microliter.

[0052] The hydrophobic porous material 130 may define a plurality of pores (not shown) having a pore size distribution. The median diameter of the pores (second pores) can be greater than about 2 nm. In some embodiments, the second pores of the hydrophobic porous material 130 have a median diameter in the range of about 2 nm to about 10 microns. The hydrophobic porous material 130 may include an ultrafiltration (or nanoporous) filter. In some embodiments, the second pores of the hydrophobic porous material 130 have a median diameter in the range of about 0.1 micron to about 10 microns. In some embodiments, the second pores of the hydrophobic porous material 130 have a median diameter in the range of about 0.1 micron to about 0.5 micron. In some embodiments, the second pores of the hydrophobic porous material 130 have a median diameter in the range of about 0.1 micron to about 0.3 micron. For example, the second pores of the hydrophobic porous material 130 can have a median diameter of about 0.2 micron (such as a nominal diameter of 0.22 micron).

[0053] The hydrophobic porous material 130 can have a strong repulsive pressure that prevents a liquid with a high surface tension from entering its mesh. Advantageously, a pore size of less than 10 microns enables the hydrophobic porous material 130 to prevent the passage of some liquids to the downstream side 113 up to a pressure limit (e.g., a burst pressure limit or a break pressure limit, or a leakage pressure limit) suitable for normal microfluidic operating conditions. The leakage pressure limit can be about 250 kPa (a pressure greater than 250 kPa means allowing the liquid to escape to the downstream side 113 through the hydrophobic porous material 130). In some embodiments, the leakage pressure limit can be about 150 kPa. In some embodiments, the leakage pressure limit can be about 100 kPa.

[0054] It is understood that the hydrophobic material also affects the leakage pressure limit. For example, the membrane can be formed from a polymer such as polytetrafluoroethylene (PTFE) and can have a leakage pressure limit of at least about 250 kPa. The seal between the hydrophilic porous material 130 and the retainer 110 also needs to withstand a pressure up to at least the leakage pressure.

[0055] In some embodiments, one or both of the hydrophilic porous material 120 and the hydrophobic porous material 130 may include a membrane. The membrane may form, for example, a substrate of the material. The membrane may include a mesh that defines pores. The membrane may be the same or similar to those found in commercially available syringe filters, for example.

[0056] The hydrophilic porous material 120 may include a hydrophilic coating or hydrophilic layer on a substrate to form a hydrophilic membrane. The hydrophilic membrane may be the same or similar to those found in commercially available filters such as the Nuclepore™ filter provided by Whatman, the Virtek™ vent provided by Porex Filtration Group, and other filters provided by Sterlitech Corp., Advantec MFS Inc., and GVS S.p.A.

[0057] The hydrophilic porous material 120 may have a strong capillary pressure to maintain a liquid (such as a high surface tension liquid) inside its pores and / or its mesh. The surface tension depends on the type of the liquid 180 and the material from which the hydrophilic porous material 120 is formed. For example, when the liquid 180 contains ethanol, after the hydrophilic porous material 120 holds the liquid 180, the hydrophilic porous material 120 may not function well to prevent the passage of gas. In another example, when the liquid 180 contains hexane, the liquid may not pass through the hydrophilic porous material 120.

[0058] The hydrophobic porous material 130 may include a hydrophobic coating or hydrophobic layer on a substrate to form a hydrophobic membrane. The hydrophobic membrane may have a strong repulsive pressure capable of preventing and / or impeding a liquid (such as a high surface tension liquid) from entering its pores and / or its mesh. The hydrophobic membrane may be the same or similar to those found in commercially available filters such as the Nuclepore™ filter provided by Whatman, the Virtek™ vent provided by Porex Filtration Group, and other filters provided by Sterlitech Corp., Advantec MFS Inc., and GVS S.p.A.

[0059] The fluid check valve 100 is configured (e.g., sized and shaped) to fit within and be positioned within the fluid pipe 101. The fluid check valve 100 may include an outer surface 150 of the fluid, and the outer surface 150 engages at least a portion of the inner surface 102 of the fluid pipe 101 to seal the fluid pipe 101 (resulting in a fluid seal) and separate the fluid pipe 101 into an upstream side 112 and a downstream side 113.

[0060] The seal formed between the check valve 100 and the inner surface 102 prevents gas from passing from the upstream side 112 to the downstream side 113, except through the opening 111. However, when the hydrophilic porous material 120 holds liquid across the opening 111, gas passage from the upstream side 112 to the downstream side 113 is impeded or prevented.

[0061] Referring to FIG. 2, the check valve 200 may further include a sealing member such as an O-ring 252. The sealing member may engage the outer surface 250 of the holder 210, and when the check valve 200 is positioned within the fluid pipe 101, the sealing member may also engage at least a portion of the inner surface 102 of the fluid pipe 101 to seal the fluid pipe 101, whereby fluid can only pass from the upstream side 112 to the downstream side 113 through the opening 111 and the fluid check valve 100.

[0062] In some embodiments, the outer surface 250 of the holder 210 may define a recess or groove 251 for holding a sealing member. The recess or groove 251 may extend circumferentially around the holder 210.

[0063] Figure 3 shows a self-sealing discharge fluid system 300 that includes a fluid tube 301 and a plunger 360 that includes a fluid check valve 310. The plunger 360 and the fluid check valve 310 are adapted to fit within the fluid tube 301. When the plunger 360 fits within the fluid tube 301, an outer surface 350 of the plunger 360 engages an inner surface 302 of the fluid tube 301 to seal the fluid tube 301 and, together with the opening 311, separates the fluid tube 301 into an upstream side 312 and a downstream side 313. A fluid seal between the inner surfaces 302 of the fluid tube 301 separates the fluid tube into an upstream side for containing gas and liquid and a downstream side for receiving gas.

[0064] Advantageously, when the upstream side 312 is filled with a liquid (not shown), the fluid check valve 310 allows any gas inside the upstream side 312 to be discharged out of the upstream side 312 and pass through to the downstream side 313, prevents or stops the passage of the liquid, and prevents or stops any gas from returning from the downstream side 313 to the upstream side 312.

[0065] The plunger 360 defines a discharge path 361 that is in fluid connection with the downstream side 313, guides the gas that has passed from the upstream side 312 to the downstream side 313, and can allow and / or permit the gas to pass through the plunger 361.

[0066] The plunger 360 can be configured to displace along the fluid tube 301 while maintaining a seal with the fluid tube 301. The outer surface 350 can be formed from, for example, a polymeric material. Thus, the plunger 360 can act to push the liquid within the upstream side 312 and move along the fluid tube 301.

[0067] The plunger 360 can include a flange 363 that assists in applying a force to the plunger 360 to displace the plunger 360.

[0068] The fluid tube 301 may include a fluid outlet 303 such that liquid can be extruded from the upstream side 312 by the plunger 360. The fluid check valves 100, 200, 310 can remove gas from the upstream side 312 and prevent the gas from re-entering the upstream side 312, so the fluid system 300 can assist in providing accurate distribution of the liquid.

[0069] Figures 4, 5, and 6 show a fluid system 400 including a fluid tube 101 and a plunger 460 including a fluid check valve 410 and a plunger stick 462. At least a portion of the fluid check valves 100, 200, 310, 410, and the plunger stick 462 are adapted to fit within the fluid tube 101.

[0070] The holder 411 may include a first portion 414 and a second portion 415. The first portion 414 and the second portion 415 are configured to be coupled and / or interconnected with each other. Either the first portion 414 or the second portion 415 may be shaped to define a recess 416 into which the other portion fits internally. For example, the first portion 414 may be shaped to define the recess 416, and the second portion 415 may be shaped to fit within the recess 416.

[0071] The recess 416 and the other of the first portion 414 or the second portion 415 may have a lateral dimension such as a diameter D that tapers along the depth of the recess 416. The recess 416 may have, for example, a frustoconical shape or a truncated pyramidal shape. In some embodiments, the recess 416 may not have a constant lateral dimension. For example, the recess may have a cylindrical, square, or rectangular shape.

[0072] At least a portion (or all) of one or both of the hydrophilic porous material 420 and the hydrophobic porous material 430 may be located within the recess 416. In some embodiments, the first portion 414 and the second portion 415 are coupled and / or interconnected with each other and cooperatively hold the hydrophilic porous material 420 and the hydrophobic porous material 430.

[0073] In some embodiments, a friction fit is formed between the first portion 414 or the second portion 415. The shape of the recess 416 and the shape of the other of the first portion 414 or the second portion 415 may assist in forming the friction fit. The shape of the other of the first portion 414 or the second portion 415 may complement the shape of the recess 416.

[0074] In some embodiments, the first portion 414 or the second portion 415 are joined together by any one of chemical bonding, heat sealing, and adhesives. The first portion 414 or the second portion 415 may be removably or fixedly attached to each other.

[0075] In some embodiments, the hydrophilic porous material 420 and the hydrophobic porous material 430 may be held by the holder 411 by pressurization, pinching, imprinting, and deformation of the materials 420, 430, and by melting, ultrasonic welding, thermal welding, laser welding, overmolding, etc. Alternatively, the hydrophilic porous material 420 and the hydrophobic porous material 430 may be formed directly (e.g., injection molding) inside one or more of the first portion 414 or the second portion 415.

[0076] The fluid check valve 410 may be held by a plunger plastic 462 by two or more tabs 463 on the downstream surface 412 of the holder 411. The contact surface 464 of the plunger plastic 462 may be shaped to complement and engage the tab 463.

[0077] The fluid check valve 410 may include an inner conduit 417 that defines a fluid passage on the downstream side 113 of the hydrophobic porous material 430. Since the cross-sectional shape of the inner conduit 417 may be different from the contact surface 464 of the plunger plastic, when the fluid check valve 410 is held by the plunger plastic 462, the outlet 418 is defined to allow gas to escape from the inner conduit 417.

[0078] The fluid check valve 410 may include a flange 419 that holds the O-ring 452. For example, the second portion 415 may include the flange 419. The flange 419 may extend circumferentially around the second portion 415. In some embodiments, the first portion 414 may include a lip 421 that further holds the O-ring 452. The lip 421 may extend circumferentially around the second portion 415 when interconnected with the first portion 414. The flange 419, the lip 421, and the outer surface 450 of the second portion 415 may together hold the O-ring 452.

[0079] Referring to FIGS. 7 and 8, a fluid system 700 including a fluid check valve 710 within a fluid tube 101 is shown. The fluid check valve 710 includes a first portion 711 and a second portion 715. The first portion 711 may include an upstream surface 712 that fluidly connects with the upstream side 112 of the fluid tube 101 having a laterally decreasing dimension T. For example, the upstream surface 712 may include at least a portion of a frustoconical shape, a truncated pyramidal shape, or a concave shape, thereby assisting the passage of gas from the upstream side 112 to the downstream side 113. The upstream surface 712 may have at least a portion of an inverse spherical shape.

[0080] In some embodiments, the fluid systems 300, 400, 700 may also include a structure (not shown), such as a baffle, within the fluid channel defined by the fluid tube 101, thereby facilitating the flow of liquid along the inner surface 102 of the fluid tube 101 and reducing the risk of air bubbles being trapped at the upstream side 112 near the inner surface 102. The baffle may be attached to, for example, either the fluid tube 101 or any of the fluid check valves 100, 310, 410, 710.

[0081] In some embodiments, to reduce the risk of bubbles being trapped near the inner surface 102 of the fluid tube 101, the contact angle between the surface 181 of the liquid 180 and the inner surface 102 of the fluid tube 101 and / or the fluid check valves 100, 310, 410, 710 can be increased by forming the inner surface 102 of the fluid tube 101 with a hydrophilic material and / or by forming the retainer 110 of the fluid check valves 100, 310, 410, 710 with a hydrophobic material.

[0082] The inner surface 102 formed from a hydrophilic material (e.g., poly(methyl methacrylate), PMMA) can advantageously act to establish a concave meniscus that fills the fluid tube 101 with the liquid 180.

[0083] In some embodiments, the fluid check valves 100, 310, 410, 710 (or at least the upstream surface 712) are formed from or coated with a hydrophobic material (e.g., polyethylene, PE) to minimize early wicking of the upstream surface 712 of the fluid check valves 100, 310, 410, 710. Otherwise, early wicking would result in wetting of the hydrophilic porous medium 120 before complete gas expulsion.

[0084] Referring to FIG. 9, a fluid device 900 is shown that includes a fluid tube 901 that defines a channel 902, a first syringe 910A, and a second syringe 910B. The first syringe 910A and the second syringe 910B each comprise a fluid system 300, 400, 700 as described above. The upstream sides 112, 312 of the fluid systems 300, 400, 700 are in fluid connection with the channel 902. The fluid tube 901 further includes a fluid inlet 903. The fluid inlet 903 can be adapted to receive an inlet plunger 990, and the inlet plunger 990 can be used to push liquid through the channel 901 and the upstream sides 112, 312 of the fluid systems 300, 400, 700 and discharge gas through the downstream sides 113, 313 from the fluid tube 901.

[0085] The fluid tube 901 includes two or more ports 904 that are fluidly connected to the channel 902, enabling pressure measurements of different parts of the chamber. The chamber can include cross-sections of different regions, thereby enabling rheology measurements from pressure measurements during the operation of the plungers 360, 460. The operation of the plungers 360, 460 results in changing flow rates and pressures within the channel 902. Thus, the plungers 360, 460 can function as syringe pumps. When the pressure is lower than the leakage pressure limit, the liquid remains within the channel, and when the magnitude of the negative pressure is smaller than the magnitude of the backflow pressure limit, gas does not enter the channel 902.

[0086] The fluid system 900 may further include an automatic motion control system (not shown) configured to engage with the plungers 360, 460 to control (actuate) the movement of the plungers 360, 460. For example, the automatic motion control system may control the reciprocating motion of the plungers 360, 460.

[0087] Also, the absence of moving parts in the fluid check valves 310, 410 of the plungers 360, 460 can provide the advantage of shortening the time required to discharge gas from the fluid tube 901 having microfluidic dimensions (e.g., less than about 3 mm). This is particularly important for rheology applications involving blood-related liquids to limit blood clotting and / or coagulation, and the maximum time allowed for sample injection, gas discharge, and measurement implementation can be about 30 seconds. The fluid check valves 310, 410 may, for example, require less than about 10 seconds to discharge gas from the fluid tube 101.

[0088] It is understood by those skilled in the art that many variations and / or modifications can be made to the above-described embodiments without departing from the broad general scope of the present disclosure. Accordingly, the present embodiments should be considered illustrative in all respects and not restrictive.

Prior Art Documents

Patent Documents

[0089]

Patent Document 1

Claims

**Claim 1** A fluid pipe including an inner surface, and a fluid check valve for discharging gas from a fluid system, wherein the fluid check valve includes a retainer defining a fluid opening having an upstream side and a downstream side, a hydrophilic porous material held by the retainer and disposed to cover the fluid opening, a hydrophobic porous material held by the retainer, covering the fluid opening, and disposed adjacent to the hydrophilic porous material, one surface of the hydrophilic porous material is in fluid communication with the upstream side of the opening, and one surface of the hydrophobic porous material is in fluid communication with the downstream side of the opening, the hydrophilic porous material is configured to hold liquid from the upstream side and prevent gas from passing from the downstream side to the upstream side, and the hydrophobic porous material is configured to prevent liquid from passing from the upstream side to the downstream side, the fluid check valve fits within the fluid pipe and forms a fluid seal with the inner surface of the fluid pipe, separating the fluid pipe into an upstream side containing gas and liquid and a downstream side receiving the gas, a plunger adapted to fit within the fluid pipe, the plunger including the fluid check valve, a self-sealing discharge fluid system. **Claim 2** The self-sealing discharge fluid system according to claim 1, wherein the hydrophilic porous material is disposed upstream of the hydrophobic porous material. **Claim 3** The self-sealing discharge fluid system according to claim 1 or 2, wherein at least one of the hydrophilic porous material and the hydrophobic porous material defines a plurality of pores, and the plurality of pores have a median pore diameter in the range of 0.1 micron to 10 microns. **Claim 4** The self-sealing discharge fluid system according to claim 3, wherein the plurality of pores have a median pore diameter of less than 1 micron. **Claim 5** The self-sealing discharge fluid system according to any one of claims 1 to 4, wherein the hydrophobic porous material and the hydrophilic porous material are in direct contact with each other. **Claim 6** The self-sealing discharge fluid system according to any one of claims 1 to 4, wherein the hydrophobic porous material and the hydrophilic porous material are separated from each other. **Claim 7** The self-sealing discharge fluid system according to claim 6, wherein the hydrophobic porous material and the hydrophilic porous material are separated from each other by a distance greater than 0 mm and less than 2 mm. **Claim 8** The self-sealing fluid discharge system according to any one of claims 6 or 7, wherein the hydrophobic porous material and the hydrophilic porous material are separated by a material that allows the passage or permeation of a fluid.

9. The self-sealing fluid discharge system according to any one of claims 6 or 7, wherein the hydrophobic porous material and the hydrophilic porous material are separated by voids.

10. The self-sealing fluid discharge system according to any one of claims 1 to 9, wherein the holding body includes a first portion and a second portion, the first portion and the second portion are joined together, and the hydrophilic porous material and the hydrophobic porous material are held in cooperation.

11. The self-sealing fluid discharge system according to claim 10, wherein one of the first portion and the second portion is shaped to define a recess, and a part of the other of the first portion and the second portion is shaped to fit within the recess so as to join the first portion and the second portion together.

12. The self-sealing fluid discharge system according to claim 11, wherein the first portion and the second portion are shaped to form a friction fit or are joined to each other.

13. The self-sealing fluid discharge system according to claim 11 or 12, wherein the recess has a size that tapers along the depth of the recess.

14. The self-sealing fluid discharge system according to any one of claims 11 to 13, wherein at least a part of each of the hydrophilic porous material and the hydrophobic porous material is located within the recess.

15. The self-sealing fluid discharge system according to any one of claims 10 to 14, wherein the first portion includes an upstream surface that is in fluid connection with the upstream side having at least a part of a frustoconical shape or a concave shape, and assists the passage of gas from the upstream side to the downstream side.

16. The self-sealing fluid discharge system according to any one of claims 1 to 15, wherein the hydrophilic porous material includes a hydrophilic membrane.

17. The self-sealing fluid discharge system according to any one of claims 1 to 16, wherein the hydrophobic porous material includes a hydrophobic membrane.

18. The self-sealing fluid discharge system according to any one of claims 1 to 17, wherein the hydrophilic porous material includes a hydrophilic coating.

19. The self-sealing fluid discharge system according to any one of claims 1 to 18, wherein the hydrophobic porous material includes a hydrophobic coating.

20. When the hydrophilic porous material is exposed to a liquid, the fluid check valve prevents the passage of gas from the downstream side to the upstream side with a backflow pressure limit of -80 kPa. The self-sealing discharge fluid system according to any one of claims 1 to 19.

21. The hydrophobic porous material is configured to prevent the passage of the liquid from the upstream side to the downstream side with a leakage pressure limit of 150 kPa. The self-sealing discharge fluid system according to any one of claims 1 to 20.

22. The fluid pipe defines a plurality of ports in fluid communication with the upstream side and enables pressure measurement within the upstream side of the fluid pipe. The fluid system according to any one of claims 1 to 21.

23. The fluid pipe defines an inlet in fluid communication with the upstream side and enables injection of fluid into the upstream side. The self-sealing discharge fluid system according to any one of claims 1 to 22.

24. The self-sealing discharge fluid system according to any one of claims 1 to 23, further comprising an automatic motion control system configured to engage with the plunger and control the movement of the plunger.

25. The self-sealing discharge fluid system according to any one of claims 10 to 15, further comprising a baffle component located within the fluid pipe adjacent to the first portion to facilitate the flow of liquid along the inner surface of the fluid pipe.

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