Check valves with color change and pressure detection

Abstract

The present invention relates to a check valve comprising an upper housing that defines an inlet of the check valve and a lower housing that has a support portion and defines an outlet of the check valve. The check valve further includes a chamber interposed between and defined by the upper and lower housings to fluidly connect the inlet and outlet, and a flexible diaphragm mounted in the chamber. The flexible diaphragm selectively permits fluid flow in a first direction and prevents fluid reflux in a second direction opposite to the first. The flexible diaphragm includes a color-changing material, and when the flexible diaphragm rests on the support portion and bends due to the force of the fluid flowing in the first direction, the flexible diaphragm exhibits a color change.

Description

Check valves with color change and detection PRESSURE Field of Invention This description relates in general to check valves, and more particularly to valve elements of check valves capable of changing color to visually indicate permeability when subjected to fluid flow pressure. Background of the Invention IV infusion sets are commonly used in infusion therapy to deliver medication from a pre-filled container, such as an IV bottle or bag containing the desired medication, to a patient. Typically, the intravenous tubing is connected to a catheter and inserted into the localized area to be treated. Patients are commonly given IV solutions that are initially provided in an IV bottle or bag and then dripped into the patient's vein through an IV line. Typically, an injection port is provided along the IV line and adapted to work with a syringe to allow an injectable solution to be added to the IV solution. A check valve is also commonly included in the IV line to allow fluid to flow only in the direction of the patient. This ensures that the injectable flows downstream. Ref.: 344040 towards the patient, not upstream towards the intravenous reservoir. To check the permeability of conventional check valves, the IV line currently has to be opened to access and examine the check valve. The description provided in the background section should not be assumed to pertain to the aforementioned technique simply because it is mentioned in or associated with it. The background section may include information describing one or more aspects of the technology in question. Brief Description of the Invention According to various embodiments of the present description, a check valve may include an upper housing defining a check valve inlet, a lower housing comprising a support portion and defining a check valve outlet, and a chamber interposed between and defined by the upper and lower housings to fluidly connect the inlet and outlet. The check valve may further include a flexible diaphragm mounted in the chamber to selectively permit fluid flow in a first direction and prevent backflow of fluid in a second direction opposite to the first. The flexible diaphragm may Μλ / a / zuzj / uujui □ include a color-changing material, wherein when the flexible diaphragm sits on the support portion and bends due to the force of the fluid flowing in the first direction, the flexible diaphragm exhibits a color change. According to several aspects of the present description, a check valve may include a valve chamber comprising an inlet port at one end, an outlet port at one end, and an internal surface defining a convex roof and side walls of the chamber. The check valve may further include a flexible diaphragm supported within the valve chamber. The flexible diaphragm may include a plurality of layers of transparent material that exhibits a color change when the flexible diaphragm is seated in the valve chamber and flexes due to the force of the fluid flowing from the inlet port to the outlet port. It is understood that other configurations of the technology in question will be readily apparent to those skilled in the art from the following detailed description, which illustrates and describes several configurations of the technology in question. As will be understood, the technology in question is capable of other and different configurations, and its various details can be modified in several other aspects, all without departing from the scope of the technology in question. Consequently, the ML / a / ZUZ J / UU dUl J figures and detailed description should be considered illustrative and non-restrictive in nature. Brief Description of the Figures The following figures are included to illustrate certain aspects of the modalities and should not be seen as exclusive modalities. The related matter described is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will be presented to those experienced in the technique and who benefit from this description. Figure 1 illustrates an IV extension assembly that includes a check valve, according to some embodiments of the present description. Figure 2 illustrates a cross-sectional view of a check valve in an open state, according to some embodiments of the present description. Figure 3 illustrates a cross-sectional view of a check valve coupled to a male luer fitting, according to some embodiments of the present description. Figure 4 illustrates a cross-sectional view of the check valve of Figure 3 along line 4-4, according to some modalities of the present description. Figure 5 illustrates a cross-sectional view of a check valve in a closed state, according to MA / a / zuzj / uujui □ some modalities of the present description. Detailed Description of the Invention The detailed description below outlines several configurations of the technology in question and is not intended to represent the only configurations in which it can be practiced. The detailed description includes specific details to provide a comprehensive understanding of the technology. Consequently, dimensions regarding certain aspects may be provided as non-limiting examples. However, it will be evident to those experienced in the technique that the technology can be practiced without these specific details. In some cases, well-known structures and components are shown in block diagram form to avoid obscuring the concepts of the technology. It should be understood that the present description includes examples of the technology in question and does not limit the scope of the appended claims. Several aspects of the technology in question will be described below according to specific, but not limiting, examples. Various embodiments described herein may be carried out in different forms and variations, and according to a desired application or implementation. This description relates in general to ML / a / zuzj / uujui □ check valves, and more particularly, for example and without limitation, with check valves capable of changing color to visually indicate permeability when subjected to fluid flow pressure. According to some embodiments, a check valve includes an upper housing that defines a check valve inlet, a lower housing that defines a check valve outlet, and a chamber interposed between and defined by the upper and lower housings to fluidly connect the inlet and outlet. A flexible diaphragm may be mounted in the chamber to selectively allow fluid flow from the inlet to the outlet and to prevent fluid backflow (reverse flow) from the outlet to the inlet. In some embodiments, the flexible diaphragm may be in the form of a disc or other circular plate and may be made of a color-changing material. When the flexible diaphragm rests on a support portion of the lower housing and bends or arches due to the pressure of the fluid flowing from the inlet to the outlet, the flexible diaphragm may change color. Structurally, the flexible diaphragm may consist of a plurality of stacked layers of transparent material. When the flexible diaphragm is exposed to a current pressure MA / a / zuzj / uujui □ above (i.e., a pressure applied by a fluid flowing from inlet to outlet), the flexible diaphragm bends, arches, or deforms, such that light is reflected at each interface between adjacent layers of the flexible diaphragm. The reflected light produces colors in the visible spectrum on the flexible diaphragm that a user / caretaker can observe as an indication of fluid flow, thus indicating the permeability of the check valve. In some models, the upper housing includes an internal surface that defines the camera's side walls. These side walls may have a convex shape that acts as a magnifying lens, allowing the flexible diaphragm's color change to be magnified and more easily observed. Advantageously, due to the convex shape of the upper housing's inner walls, which act like a magnifying lens, the flexible diaphragm's color change is easily visible from the outside without opening the fluid line. This color change indicates the check valve's permeability and can confirm to the user or caregiver that fluid is indeed flowing through the check valve as intended. Even more advantageously, the user or caregiver can confirm the presence of net upstream pressure (indicating flow through the check valve) simply by observing the flexible diaphragm's color change. This eliminates the need for a separate pressure sensor to confirm the valve's operation. MA / a / zuzj / uujui □ fluid flow. Figure 1 illustrates an IV extension assembly including a check valve 100, according to some embodiments of the present description. As shown, the IV assembly 1 includes a primary fluid system 11 and a secondary fluid system 25. An IV pump (not shown) receives fluid from the primary fluid system 11 and the secondary fluid system 25 through a primary IV line 5 and can control and dispense fluids therefrom to a patient 50. In some embodiments, the primary fluid system 11 may include a primary fluid source, such as a primary fluid bag 10, which may contain saline or other medicinal fluid or drug for administration to the patient 50. As illustrated, the primary IV line 5 carries the primary fluid from a drip chamber 13 to the check valve 100. As will be described later with reference to the following figures, the check valve 100 may be arranged in the primary IV line 5 and permit fluid flow from the primary fluid bag 10 to the IV pump (not illustrated) while preventing reverse flow (counterflow) of fluid from the secondary fluid system 25 into the primary fluid bag 10.According to some embodiments, the secondary fluid system 25 includes a secondary fluid source, such as a secondary fluid bag 20, which may contain drugs or other secondary fluid to be administered to the patient 50 for treatment. As shown, the IV assembly 1 may further include a secondary IV line 7 that carries the flow from the drip chamber 22 to the check valve 100. Figure 2 illustrates a cross-sectional view of a check valve in an open state, according to some embodiments of the present description. Referring to Figure 2, the check valve 100 may include an axially extending body 101 defining a central longitudinal axis X. In some embodiments, the body 101 may be made of a chemical-resistant material that may have magnifying properties. The body 101 may be made of a material capable of providing superior clarity and light transmission. For example, in some embodiments, the body material may be made of an acrylic polymer. The body 101 may be a generally cylindrical (or tubular) structure and may include an upper housing 10 and a lower housing 15. The upper housing 10 may include a first end portion 12 and an axially opposite second end portion 14.As illustrated, a radial extension of the upper housing 10 in the second end portion 14 may be greater than the radial extension of the same in the first end portion 12. The lower housing 15 may include one. MA / a / zuzj / uujui □ upstream internal surface 16, and the second end portion 14 and the upstream internal surface 16 of the lower housing 15 can be axially contacted with each other to cooperatively form a check valve chamber 30 100. In some embodiments, the upper housing 10 may include an inlet 20 of the check valve 100 at the first end 12, and the lower housing 15 may include an outlet 25 of the check valve 100. The body 101 may define an internal flow passage 18 that extends axially between the inlet 20 and the outlet 25 and is in fluid communication with it. As understood, the check valve 100 may permit fluid to flow from inlet 20 to outlet 25 (as indicated by the arrows in Figure 2) and minimize, or otherwise limit, fluid flow from outlet 25 to inlet 20 (as indicated by the arrows in Figure 5). As shown, the upper housing 10 and the lower housing 15 may define the chamber 30 for fluidly connecting the inlet 20 and the outlet 25. Figure 3 illustrates a cross-sectional view of a check valve coupled to a male luer fitting, according to some embodiments of the present description. Figure 4 illustrates a cross-sectional view of the check valve of Figure 3 along line 4-4, according to some embodiments of the present description. The valve MA / a / zuzj / uujui □ Check valve 100 of the various modalities described herein may be placed in different locations on the IV assembly 1, according to the desired purpose. For example, in some modalities, check valve 100 may be placed below the drip chamber 13 to prevent any potential backflow into the primary IV line 5. In some modalities, as shown in Figure 3, check valve 100 may be incorporated into or otherwise attached to a connector, for example, a male luer connector 23 at the end of the IV assembly closest to the patient 50. When attached to the connector 23, check valve 100 may be used to prevent backflow of the patient's blood into the intravenous set 1. In the represented modalities, a flexible diaphragm 35 can be mounted in the chamber 30 to selectively allow fluid flow from inlet 20 to outlet 25 and prevent fluid reflux (reverse flow) from outlet 25 to inlet 20. According to some embodiments, the flexible diaphragm 35 may be in the form of a disc or any other circular plate. As shown, the flexible diaphragm 35 can be mounted on a support portion 28 of the lower housing 14. In particular, the support portion 28 may include a central opening 44 and a plurality of axially extending slots 46 through which fluid flows from the inlet 20 and into the cavity 30, and the outlet 25 may enter in the open state of the check valve 100. As depicted, the flexible diaphragm 35 may be made of a color-changing material. As mentioned herein, a color-changing material is defined as a material that, when subjected to an axial load, is capable of reflecting light to display vibrant colors in the visible spectrum. Consequently, when the flexible diaphragm 35 rests on the support portion 28 and bends due to the force of the fluid flowing in the direction from inlet 20 to outlet 25, the flexible diaphragm 35 changes or exhibits a different color. In particular, in some embodiments, the flexible diaphragm 35 may be made of a plurality of layers of transparent material. For example, the flexible diaphragm 35 may be made of a plurality of ultrathin layers of transparent materials, which may be periodically stacked to form the disc-shaped flexible diaphragm 35.In some embodiments, each layer of transparent material within the flexible, disc-shaped diaphragm can be on the order of a few hundred nanometers thick. In some embodiments, the transparent material can be a transparent rubber material or any other similar material capable of bending or deforming under a load. In some forms, the flexible diaphragm 35 may be made of a resistive pressure-sensing material that MA / a / zuzj / uujui □ has a hollow sphere microstructure such as, but without limitation, a microstructured elastic conductive polymer thin-film material. In some versions, the flexible diaphragm 35 may consist of a touch-sensitive sensor film. In still other versions, the flexible diaphragm 35 may be made of a material with hollow spheres in its structure, where the hollow spheres can be pressed together, causing the flexible diaphragm 35 to change color. In some embodiments, the upper housing 10 includes an internal surface having a first part that defines a roof 40 and a second part that defines the side walls 42 of the chamber 30. As shown, the part of the internal surface that defines the side walls 42 may have a convex shape. Furthermore, in some embodiments, the side walls 42 are made of a transparent material to allow visual observation of the color change. Advantageously, the convex shape of the side walls 42 acts as a magnifying lens, making it easier to enlarge and observe the color change of the flexible diaphragm 35. In operation, when the flexible diaphragm 35 formed by the plurality of transparent layers is exposed to an upstream fluid pressure (i.e., a pressure applied by a fluid flowing from the inlet 20 to the (ML / a / zuzj / uujui □ exit 25), the flexible diaphragm 35 can be bent, arched, or otherwise deformed, such that light is reflected at each interface between adjacent layers of the flexible diaphragm. The reflected light produces colors in the visible spectrum in the flexible diaphragm 35 that can depend on the geometric properties and material composition of the transparent layers of the flexible diaphragm 35. For example, with layers of constant thickness, the light reflected at the interfaces between adjacent layers of the flexible diaphragm 35 can interact to enhance some colors in the visible spectrum, e.g., red, while diminishing the brightness of other colors. Consequently, when bent due to upstream fluid pressure, the flexible diaphragm 35 formed by transparent layers can appear or exhibit a certain color, depending on the thickness of the layers within the flexible diaphragm 35. According to various embodiments, the flexible diaphragm 35 can be made of a pressure-sensitive material. For example, the flexible diaphragm 35 can be made of a plurality of layered, pressure-sensitive photonic fibers, such that when subjected to upstream pressure, at a specific desired pressure, the fibers of the flexible diaphragm 35 can reflect a readily distinguishable color. To this effect, the flexible diaphragm 35 can be designed to change color when the fluid flow from the MA / a / zuzj / uujui □ inlet port to outlet port exerts a normal pressure on the flexible diaphragm that is greater than or equal to a predetermined pressure threshold. Accordingly, several embodiments of the present description provide a check valve 100 having a flexible diaphragm 35 that changes color when it is bent, arched, or otherwise deformed due to upstream fluid pressure that is substantially perpendicular or normal to the flexible diaphragm 35. The upstream pressure causes the flexible diaphragm 35 to bend or tilt toward the outlet 25. As depicted, the flexible diaphragm 35 can curve further outward in a central portion thereof where the fluid pressure is more concentrated or stronger. Once the flexible diaphragm 35 is bent or arched while seated in the support portion 28, light is reflected at each interface between adjacent layers of the flexible diaphragm 35. The reflected light produces colors in the visible spectrum on the flexible diaphragm 35. In some modalities, as illustrated in the figures, the color change may be more intense in the central part of the flexible diaphragm where the fluid pressure is more concentrated and become less intense towards the outer periphery of the flexible diaphragm 35. For example, a caregiver may see different colors of varying intensities depending on the magnitude of the upstream fluid pressure. Μλ / a / zuzj / uujui □ Advantageously, due to the convex shape of the inner walls 42 of the upper housing 10, which act as a magnifying lens, the color change of the flexible diaphragm 35 can be easily observed from the outside without opening the fluid line. This color change indicates the permeability of the check valve 100 and can confirm to the user or caregiver that fluid is indeed flowing through the check valve 100 as indicated. Even more advantageously, the user or caregiver can confirm that there is net upstream pressure (indicating flow through the check valve 100) simply by observing the visual color change of the flexible diaphragm 35. Therefore, the need for a separate pressure sensor to confirm fluid flow is obvious. Figure 5 illustrates a cross-sectional view of a check valve 100 in a closed state, according to some embodiments of the present description. As shown, and as described above, the upper housing 10 may include an internal surface having a first part defining a roof 40 and a second part defining the side walls 42 of the chamber 30. In some embodiments, the roof 40 defines a sealing surface of the check valve 100. As illustrated in Figure 5, in the closed state of the check valve 100, the flexible diaphragm 35 makes contact with the roof 40. Because the flexible diaphragm 35 makes contact with the internal surface defining the roof 40, reverse flow (reflux) of fluid from the outlet 25 to the inlet 20 is restricted or prevented. During operation, when downstream pressure (i.e., pressure applied by a fluid flowing from outlet 25 to inlet 20) is applied to the flexible diaphragm 35, the flexible diaphragm 35 can move toward and make contact with the roof 40 to block fluid communication between inlet 20 and chamber 30, thereby restricting fluid reflux from outlet 25 to inlet 20. Preventing or restricting fluid reflux is advantageous because it restricts undesirable particles, for example, contained in a drug distributed from a secondary route, from flowing back through the flexible diaphragm 35, thus preventing the patient from receiving the proper concentration of the drug dose or timely drug administration. In one or more embodiments of the description, a check valve comprises an upper housing defining a check valve inlet; a lower housing comprising a support portion and defining a check valve outlet; a chamber interposed between and defined by the upper and lower housings for fluidly connecting the inlet and outlet; and a flexible diaphragm Μλ / a / zuzj / uujui □ mounted in the chamber to selectively allow fluid flow in a first direction and prevent fluid backflow in a second direction opposite to the first direction, the flexible diaphragm comprising a color-changing material, wherein when the flexible diaphragm sits on the support portion and bends due to the force of the fluid flowing in the first direction, the flexible diaphragm exhibits a color change. In some aspects of the description, the flexible diaphragm comprises a plurality of periodically stacked layers of a transparent material. In some aspects of the description, the upper housing comprises an internal surface having a first part defining a roof and a second part defining the side walls of the chamber; and the portion of the internal surface defining the side walls of the chamber comprises a convex shape. In some aspects of the description, the convex side walls comprise a transparent material to allow visual observation of the color change. In some aspects of the description, the convex shape of the side walls forms a magnifying material to enhance the visual observation of the color change. In terms of description, the flexible diaphragm comprises a disc shape. In terms of description, the flexible diaphragm comprises a pressure sensor. MA / a / zuzj / uujui □ In aspects of the description, the flexible diaphragm comprises pressure-sensitive photonic fibers. In aspects of the description, the flexible diaphragm changes color when the fluid flows in the first direction that has a pressure greater than or equal to a predetermined pressure. In aspects of the description, the flexible diaphragm changes color when subjected to a compressive force oriented substantially perpendicular to the flexible diaphragm. In aspects of the description, the flexible diaphragm comprises a transparent rubber material. In one or more embodiments of the description, a check valve comprises a valve chamber comprising an inlet port at an inlet end, an outlet port at an outlet end, and an internal surface defining a convex roof and side walls of the chamber; and a flexible diaphragm supported within the valve chamber, wherein the flexible diaphragm comprises a plurality of layers of transparent material exhibiting a color change when the flexible diaphragm is seated in the valve chamber and bent due to the force of the fluid flowing from the inlet port to the outlet port. In terms of description, the convex side walls comprise a transparent material to allow visual observation of the color change. In terms of description, the convex shape of the side walls forms MA / a / zuzj / uujui □ A magnifying material to enhance the visual observation of color change. In this description, the flexible diaphragm comprises a disc shape. In this description, the flexible diaphragm comprises a pressure sensor. In this description, the flexible diaphragm comprises pressure-sensitive photonic fibers. In this description, the flexible diaphragm changes color when the fluid flow from the inlet port to the outlet port is greater than or equal to a predetermined pressure. In this description, the flexible diaphragm changes color when subjected to a fluid force oriented perpendicular to the flexible diaphragm. In this description, the transparent material comprises a transparent rubber material. This description is provided to enable anyone experienced in the technique to practice the various aspects described herein. The description provides several examples of the technology in question, and the technology in question is not limited to these examples. Several modifications to these aspects will be readily apparent to those experienced in the technique, and the generic principles defined herein can be applied to other aspects. A reference to a singular item is not intended to mean one and only one unless specifically stated, but rather one or more. Unless otherwise stated Μλ / a / zuzj / uujui □ specifically the opposite, the term some refers to one or more. Masculine pronouns (e.g., his) include feminine and neuter genders (e.g., her, for feminine or something) and vice versa. Titles and subtitles, if any, are used only for convenience and do not limit invention. The word "exemplary" is used herein to mean "serves as an example" or "serves as an illustration." Any aspect or design described herein as exemplary should not necessarily be interpreted as preferred or advantageous over other aspects or designs. In one respect, several alternative configurations and operations described herein may be considered at least equivalent. As used herein, the phrase "at least one of" preceding a list of items, with the term "or" separating any of the items, modifies the list as a whole, rather than each individual item. The phrase "at least one of" does not require the selection of at least one item; rather, the phrase allows for a meaning that includes at least one of any of the items, and / or at least one of any combination of the items, and / or at least one of each item. For example, the phrase "at least one of A, B, or C" could refer to: only A, only B, or only C; or any combination of A, B, and C. iviA / a / ¿u¿ó / uuóu ij A phrase, such as "aspect," does not imply that such an aspect is essential to the technology in question or that such an aspect applies to all configurations of the technology in question. A description related to an aspect may apply to all configurations, or to one or more configurations. An aspect may provide one or more examples. A phrase, such as "an aspect," may refer to one or more aspects and vice versa. A phrase, such as "modality," does not imply that such a modality is essential to the technology in question or that such a modality applies to all configurations of the technology in question. A description related to a modality may apply to all modalities, or to one or more modalities. A modality may provide one or more examples. A phrase, such as "a modality," may refer to one or more modalities and vice versa.A phrase such as "configuration" does not imply that such a configuration is essential to the technology in question or that such a configuration applies to all configurations of the technology in question. A description related to a configuration may apply to all configurations, or to one or more configurations. A configuration may provide one or more examples. A phrase "such configuration" may refer to one or more configurations and vice versa. In one respect, unless otherwise stated, all measurements, values, classifications, positions, magnitudes, MA / a / zuzj / uujui □ Sizes and other descriptions set forth in this description, including the claims that follow, are approximate, not exact. In one respect, they are intended to have a reasonable range consistent with the functions to which they relate and with what is customary in the art to which they belong. The specific order or hierarchy of steps or operations in the described processes or methods is understood to be an illustration of exemplary methods. Based on implementation preferences or scenarios, the specific order or hierarchy of steps, operations, or processes may be rearranged. Some steps, operations, or processes may be performed simultaneously. In some implementation preferences or scenarios, certain operations may or may not be performed. Some or all steps, operations, or processes may be performed automatically, without user intervention. The attached method claims present elements of the various steps, operations, or processes in a sample order and are not intended to be limited to the specific order or hierarchy presented. All structural and functional equivalents of the elements of the various aspects described throughout this description that are known or will be known later by those experienced in the technique are expressly incorporated herein as a reference and it is intended that ML / a / zuzj / uujui □ are included by the claims. Furthermore, nothing described herein is intended to be dedicated to the public, regardless of whether such description is explicitly mentioned in the claims. No element of a claim shall be construed in accordance with the provisions of 35 U.S.C. §112(f) unless the element is expressly mentioned using the phrase "means to" or, in the case of a method claim, the element is mentioned using the phrase "step to." Additionally, to the extent the term "include," "have," or similar is used, such term is intended to be inclusive in a manner similar to the term "comprise," as "comprise" is construed when employed as a transitional word in a claim. The title, background, abstract, brief figure descriptions, and summary description are hereby incorporated into the description and are provided as illustrative examples, not as restrictive descriptions. They are presented with the understanding that they shall not be used to limit the scope or meaning of the claims. Furthermore, in the Detailed Description, it can be seen that the description provides illustrative examples, and the various features are grouped into several modes for the purpose of simplification. This method of description should not be construed as reflecting an intention that the claimed object requires more features than are expressly mentioned in each claim. Rather, as reflected in the following claims, the inventive matter lies in at least all the features of a single described configuration or operation.The following claims are hereby incorporated into the Detailed Description, and each claim is presented on its own as a separate related claim matter. The claims are not intended to be limited to the matters described herein, but should be given their full scope in accordance with the language of the claims and to encompass all legal equivalents. However, none of the claims purports to cover, nor should they be construed as covering, any related matter that does not meet the requirement of 35 U.S.C. § 101, 102, or 103. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A check valve characterized in that it comprises: an upper housing defining an inlet of the check valve; a lower housing comprising a support portion and defining an outlet of the check valve; a chamber interposed between and defined by the upper and lower housings for fluidly connecting the inlet and outlet; and a flexible diaphragm mounted in the chamber to selectively permit fluid flow in a first direction and prevent backflow of fluid in a second direction opposite to the first direction, the flexible diaphragm comprising a color-changing material, wherein when the flexible diaphragm is seated on the support portion and bent due to the force of the fluid flowing in the first direction, the flexible diaphragm exhibits a color change.

2. The check valve according to claim 1, characterized in that the flexible diaphragm comprises a plurality of periodically stacked layers of a transparent material.

3. The check valve according to claim 1, characterized in that: the upper housing comprises an internal surface having a first part defining a roof and a second part defining the side walls of the chamber; and the part of the internal surface defining the side walls of the chamber has a convex shape.

4. The check valve according to claim 3, characterized in that the convex side walls comprise a transparent material to allow visual observation of the color change.

5. The check valve according to claim 4, characterized in that the convex shape of the side walls forms a magnifying material to improve the visual observation of the color change.

6. The check valve according to claim 1, characterized in that the flexible diaphragm comprises a disc shape.

7. The check valve according to claim 1, characterized in that the flexible diaphragm comprises a pressure sensor.

8. The check valve according to claim 1, characterized in that the flexible diaphragm comprises pressure-sensitive photonic fibers. MA / a / zuzj / uujui □ 9. The check valve according to claim 1, characterized in that the flexible diaphragm changes color when the fluid flows in the first direction that has a pressure greater than or equal to a predetermined pressure.

10. The check valve according to claim 1, characterized in that the flexible diaphragm changes color when subjected to a compressive force oriented substantially perpendicular to the flexible diaphragm.

11. The check valve according to claim 1, characterized in that the flexible diaphragm comprises a transparent rubber material.

12. A check valve characterized in that it comprises: a valve chamber comprising an inlet port at an inlet end, an outlet port at an outlet end, and an internal surface defining a convex roof and side walls of the chamber; and a flexible diaphragm held within the valve chamber, wherein the flexible diaphragm comprises a plurality of layers of transparent material exhibiting a color change when the flexible diaphragm is seated in the valve chamber and bent due to the force of a fluid flowing from the inlet port to the outlet port.

13. The check valve according to claim 12, characterized in that the convex side walls comprise a transparent material to allow visual observation of the color change.

14. The check valve according to claim 12, characterized in that the convex shape of the side walls forms a magnifying material to improve the visual observation of the color change.

15. The check valve according to claim 12, characterized in that the flexible diaphragm comprises a disc shape.

16. The check valve according to claim 15, characterized in that the flexible diaphragm comprises a pressure sensor.

17. The check valve according to claim 16, characterized in that the flexible diaphragm comprises pressure-sensitive photonic fibers.

18. The check valve according to claim 12, characterized in that the flexible diaphragm changes color when the fluid flow from the inlet port to the outlet port is greater than or equal to a predetermined pressure.

19. The check valve according to claim 12, characterized in that the flexible diaphragm MA / a / zuzj / uujui □ changes color when subjected to a fluid force oriented normal to the flexible diaphragm.

20. The check valve according to claim 12, characterized in that the transparent material comprises a transparent rubber material.

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