Capillary action-based pressure threshold sensor for liquids, and method and apparatus using the same.

Abstract

Capillary-based pressure threshold sensors are provided that take advantage of the properties of hydrophobic, superhydrophobic, oleophilic, and biphobic porous membranes to detect when a fluid passes through the membrane when the pressure across the membrane rises above the breakthrough pressure of the fluid. Exemplary implementations provide different configurations of capillary-based pressure threshold sensors and how they can be used in drug delivery devices or other fluid delivery devices to detect occlusions or other fluid flow conditions.

Description

Technical Field

[0001] The present disclosure broadly relates to a detection system capable of detecting excessive pressure events in fluid lines or channels. The present disclosure also relates to a capillary-based pressure threshold sensor for liquids that utilizes the properties of a porous membrane to detect when fluid passes through the membrane when the pressure across the membrane rises above the breakthrough pressure of the fluid.

Background Art

[0002] Fluid delivery devices such as infusion pumps and infusion sets are known to deliver drugs or medications to patients over a long period of time. Examples of infusion pumps include portable pumps (e.g., portable pumps), wearable pumps or patch pumps, and larger non-portable infusion pumps in a medical environment. An exemplary infusion set includes a catheter assembly connected to a pump (e.g., a MiniMed Paradigm® insulin pump manufactured by Medtronic) by a tubing set.

[0003] These fluid delivery devices typically include one or more flow paths, such as tubing connected to an infusion set, or flow paths within an infusion set, including a catheter. Infusion pumps may have internal flow paths that move fluids, such as medications, from a container to a catheter. Obstructions can occur in these flow paths. Obstructions can be caused by biological, pharmacological, and / or mechanical obstructions, for example, mechanical problems with the infusion device or by the fluid itself. Finding partial or complete obstructions is important in drug delivery applications, as failure to find an obstruction may result in the patient not receiving the prescribed amount of medication. One potential failure mode that can be caused by an obstructed flow path is a pressure increase that can cause leakage in the flow path, preventing subsequent medication administration (one or more times). Increased pressure in a fluid delivery system can also cause other problems, such as pump mechanism immobilization, pump mechanism deceleration and resulting increase in overall delivery time, pump mechanism damage due to increased force required to overcome the increased pressure, pump mechanism stall, and increased power consumption due to the pump mechanism operating at higher pressures.

[0004] Therefore, an element is needed to detect blockage or pressure in the flow path. Considerations for integrating pressure sensing elements into wearable or disposable medical devices include reliability, stability, component size and ability to be integrated into the device, cost, power consumption, need for (re)calibration, and required computing power. Existing pressure sensors may be too expensive to add to injection devices while maintaining the target cost of the device, and / or too unreliable to detect overpressure conditions, and / or may require specially sized hardware to read the values ​​measured by the sensor, and / or may require excessive computing power to analyze the data provided by the pressure sensor. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2008 / 0129475 [Patent Document 2] U.S. Patent No. 10398852 [Patent Document 3] U.S. Patent No. 9782536 [Patent Document 4] International Publication No. 2016048878 [Overview of the Initiative]

[0006] The aforementioned problems and other issues are overcome by the exemplary embodiment, and further advantages are realized.

[0007] Exemplary embodiments of the present disclosure provide pressure detectors that can be miniaturized to achieve a small mounting area, use off-the-shelf or specially developed materials to meet specific requirements, achieve a very low-cost product, represent a fail-safe element in a flow path when configured to be the weakest point in a fluid delivery system, have low power consumption (e.g., zero power consumption in some embodiments), require low computational power (e.g., zero computational power in some embodiments), are idle, and do not require calibration.

[0008] An exemplary embodiment provides a method for fabricating a capillary action-based pressure threshold sensor, comprising: selecting a first porous medium having porous properties that allow fluid to leak from a first side of the porous medium to an opposing second side thereof, wherein the leakage occurs when the fluid pressure exceeds a fluid breakthrough pressure threshold of the porous medium; and providing a fluid sensing element positioned at least proximal to the second side of the porous medium and configured to detect the presence of at least a target fluid on the second side of the porous medium.

[0009] According to an exemplary embodiment, the fluid detection element is selected from a passive fluid detection element and an active fluid detection element, the passive fluid detection element remains inactive until the target fluid leaks through the porous medium and reaches a second opposing side of the porous medium, and the active fluid detection element provides different outputs to distinguish between a first state in which the target fluid has not yet leaked through the porous medium and a second state in which the target fluid has leaked through the porous medium.

[0010] According to an exemplary embodiment, the fluid detection element includes an indicator element configured to change state when a target fluid leaks through a porous medium to a second side, the changing state being selected from a color display and a change in color display.

[0011] According to an exemplary embodiment, the method further includes coating a first porous medium with a thermally responsive material to detect a state selected from a specified temperature and a specified pressure change of a target fluid.

[0012] According to an exemplary embodiment, the thermally responsive material is poly-N-isopropylacrylamide (PNIPAM).

[0013] According to exemplary embodiments, the porous properties of the medium are selected from pore size, thickness, material, surface shape, coating, and contact angle with the fluid.

[0014] According to an exemplary embodiment, the method further includes forming a seal over a hole in the flow path, exposing the porous medium to the fluid in the flow path, and configuring a first aspect to prevent the fluid from leaking out of the capillary action-based pressure threshold sensor.

[0015] According to an exemplary embodiment, the fluid sensing element comprises at least two electrodes, and the method further includes providing an affinity second porous medium positioned between an affinity porous medium and the fluid sensing element such that the second porous medium is selected to have different conductivity when dry and when wetted by the fluid in the flow path, and the electrodes are passive and configured not to be activated until the fluid leaking through the porous medium exceeds a threshold.

[0016] According to an exemplary embodiment, providing a fluid detection element includes providing an electrode fabricated from a contact pad on a printed circuit board (PCB).

[0017] According to an exemplary embodiment, the method further includes thermal crimping the PCB via a thermal crimping pin configured to maintain proximity to a second porous medium and to maintain direct contact with the porous medium.

[0018] According to an exemplary embodiment, the fluid sensing element includes at least two electrodes, and the method further includes acting the electrodes as passive switches that are open until they come into contact with a fluid and close.

[0019] According to an exemplary embodiment, providing a switch includes providing electrodes made of contact pads on a printed circuit board (PCB).

[0020] According to an embodiment of the exemplary model, the method further includes connecting one electrode to a ground pin of the microcontroller and the other electrode to an input pin of the microcontroller.

[0021] According to an embodiment of the exemplary model, the method further includes connecting one electrode to an output pin of a microcontroller and the other electrode to an input pin of a microcontroller.

[0022] According to an aspect of an exemplary embodiment, the method further includes connecting one of the electrodes to a positive rail of a power supply or a reference voltage having a common ground with the microcontroller, and connecting the other electrode to an input pin of the microcontroller.

[0023] According to an aspect of an exemplary embodiment, the method further includes connecting a pull-up resistor between the positive rail of the power supply or the reference voltage of the microcontroller and the input pin.

[0024] According to an aspect of an exemplary embodiment, the method further includes connecting a pull-down resistor between the input pin and a negative rail connected to a negative or ground terminal of the microcontroller.

[0025] According to an aspect of an exemplary embodiment, the resistor has a resistance of about 1 kΩ to 100 MΩ.

[0026] According to an aspect of an exemplary embodiment, the porous medium is selected from a hydrophobic medium, a superhydrophobic medium, an oleophobic medium, and a porous medium with both non-affinities.

[0027] According to an aspect of an exemplary embodiment, the method further includes selecting, at least, a second porous medium disposed at least proximally to a first side of the first porous medium so as to contact the target fluid before the target fluid leaks through the first porous medium, and the second porous medium has a porous property that allows the fluid to easily penetrate the second porous medium, and a porous property that prevents the gas from passing through the second porous medium after the target fluid penetrates the second porous medium until the gas exceeds the intrusion pressure of the second porous medium.

[0028] According to an exemplary embodiment, the method further includes selecting an auxiliary porous medium positioned at least proximal to the opposite side of the first porous medium so as to be in contact with the target fluid before the target fluid leaks through at least the first porous medium, the second porous medium having one or more porous properties that allow the fluid to easily penetrate the second porous medium and enhance contact between the target fluid and the fluid sensing element.

[0029] An exemplary embodiment provides a method using a capillary action-based pressure threshold sensor, the method comprising: selecting an overpressure threshold to be detected in a fluid; selecting a capillary action-based pressure threshold sensor comprising a porous medium having at least one porous property and a fluid breakthrough overpressure threshold associated with the overpressure threshold, wherein the capillary action-based pressure threshold sensor allows fluid to leak from one side through the medium to the other side when the fluid pressure crossing the medium exceeds the fluid breakthrough overpressure threshold, and arranging the capillary action-based pressure threshold sensor such that at least one side of the porous medium is in contact with the fluid in which the overpressure event is detected.

[0030] According to an exemplary embodiment, the method further includes providing a flow path and selecting a location where an overpressure event should be detected by a capillary action-based pressure threshold sensor.

[0031] According to an exemplary embodiment, the method further includes providing a fluid vessel and selecting a location where an overpressure event is detected by a capillary action-based pressure threshold sensor.

[0032] According to an exemplary embodiment, the method further includes providing a hole at a selected location and sealing the hole by fixing a porous medium over it.

[0033] According to an exemplary embodiment, the method further includes welding a porous medium to a material forming a channel.

[0034] According to an exemplary embodiment, a capillary action-based pressure threshold sensor includes at least two electrodes, and the method further includes causing the electrodes to act as passive switches that are open until they are closed in contact with a fluid.

[0035] According to an exemplary embodiment, the method further includes activating a notification when a passive switch is closed.

[0036] According to an exemplary embodiment, starting is selected from providing an input associated with a notification to a microcontroller connected to an electrode and generating a notification by inducing a change in a notification element in response to a fluid coming into contact with at least one side of a porous medium.

[0037] According to an embodiment of the exemplary model, the method further includes connecting one electrode to a ground pin of a microcontroller and connecting the other electrode to an input pin of a microcontroller.

[0038] According to an embodiment of the exemplary model, the method further includes connecting one electrode to an output pin of a microcontroller and the other electrode to an input pin of a microcontroller.

[0039] According to an exemplary embodiment, the method further includes connecting one electrode to the positive rail of a power supply having a common ground with the microcontroller, and connecting the other electrode to an input pin of the microcontroller.

[0040] According to an exemplary embodiment, the method further includes connecting pull-up resistors to the positive rail or reference voltage of the power supply for the microcontroller and input pins.

[0041] According to an exemplary embodiment, the method further includes connecting a pull-down resistor between an input pin and a negative rail connected to a negative or ground terminal of a microcontroller.

[0042] According to an exemplary embodiment, the resistor has a resistance of approximately 1 k ohm to 100 M ohms.

[0043] According to exemplary embodiments, the porous medium is selected from hydrophobic, superhydrophobic, oleophobic, and both inaffeminate porous media.

[0044] According to exemplary embodiments, the porous properties of the medium are selected from pore size, thickness, material, surface shape, coating, and contact angle with the fluid.

[0045] An exemplary embodiment provides a capillary action-based pressure threshold sensor comprising: a porous medium having at least one porous property and a fluid breakthrough pressure threshold that allows fluid to leak from a first side to its opposing second side when the fluid pressure exceeds a fluid breakthrough threshold of the porous medium; and a fluid detection element positioned at least proximal to the second side of the porous medium and configured to detect the presence of at least a target fluid on the second side of the porous medium.

[0046] According to an exemplary embodiment, the capillary action-based pressure threshold sensor further comprises two electrodes in contact with a second side surface of a porous medium.

[0047] According to exemplary embodiments, the porous medium is selected from hydrophobic, superhydrophobic, oleophobic, and both inaffeminate porous media.

[0048] According to an exemplary embodiment, at least one porous property of the porous medium is selected from pore size, thickness, material, surface shape, coating, and contact angle with fluid.

[0049] According to an exemplary embodiment, the porous medium is a first porous medium, further comprising a second porous medium positioned at least proximal to a first side of the first porous medium so as to be in contact with the target fluid before the target fluid leaks through the first porous medium, the second porous medium having one or more porous properties that allow the fluid to easily penetrate the second porous medium and prevent the gas from passing through the second porous medium after penetrating with the target fluid until the gas exceeds the intrusion pressure of the second porous medium.

[0050] According to an exemplary embodiment, the capillary action-based pressure threshold sensor includes at least an auxiliary porous medium positioned at least proximal to the opposite side of the first porous medium so as to contact the target fluid before the target fluid leaks through the first porous medium, the second porous medium having one or more porous properties that allow the fluid to easily penetrate the second porous medium and enhance contact between the target fluid and the fluid sensing element.

[0051] According to an exemplary embodiment, the auxiliary porous medium is selected from hydrophilic media, superhydrophilic media, lipophilic media, and biaffinity porous media.

[0052] According to an exemplary embodiment, the auxiliary porous medium is selected from a material that swells upon contact with the fluid in the channel, and the fluid sensing element acts as a passive switch activated by the swelling of the second porous medium.

[0053] According to an exemplary embodiment, the fluid detection element comprises two electrodes in contact with an auxiliary porous medium.

[0054] According to an exemplary embodiment, the auxiliary porous medium is selected to have different conductivity when dry and when wetted by the fluid in the channel.

[0055] According to an exemplary embodiment, the fluid detection element comprises two electrodes, which are contact pads on a printed circuit board (PCB).

[0056] According to an exemplary embodiment, the PCB is heat-crimped via a heat-crimping pin to be in close proximity to and maintain direct contact with the second porous medium.

[0057] According to an exemplary embodiment, the fluid sensing element includes at least two electrodes that act as passive switches, which remain open until they come into contact with a fluid and close.

[0058] According to an exemplary embodiment, the capillary action-based pressure threshold sensor further includes an indicator element configured to change state when a target fluid leaks through a porous medium to a second side of the porous medium, the changing state being selected from a color indication and a change in color indication.

[0059] According to an exemplary embodiment, when the fluid sensing element is closed, it generates a notification that can be processed by a microcontroller connected to the electrode.

[0060] According to an exemplary embodiment, one electrode is connected to the ground pin of the microcontroller, and the other electrode is connected to the input pin of the microcontroller.

[0061] According to an exemplary embodiment, one electrode is connected to an output pin of the microcontroller, and the other electrode is connected to an input pin of the microcontroller.

[0062] According to an exemplary embodiment, one electrode is connected to the positive rail of a power supply having a common ground with the microcontroller, and the other electrode is connected to an input pin of the microcontroller.

[0063] According to an exemplary embodiment, the capillary action-based pressure threshold sensor further comprises a pull-down resistor connected between the input pin and a negative rail connected to the negative or ground terminal of the microcontroller.

[0064] According to an exemplary embodiment, the capillary action-based pressure threshold sensor further comprises a microcontroller and a pull-up resistor connected to the positive rail of a power supply or reference voltage for the input pin.

[0065] According to an exemplary embodiment, the pull-up resistor has a resistance of approximately 1 kΩ to 100 MΩ.

[0066] According to an exemplary embodiment, the fluid detection element is passive and remains unactivated until the target fluid leaks through the porous medium and reaches a second side opposite the porous medium.

[0067] According to an exemplary embodiment, the fluid detection element is active and provides different outputs to distinguish between a first state in which the target fluid has not yet leaked through the porous medium and a second state in which the target fluid has leaked through the porous medium.

[0068] According to an exemplary embodiment, a capillary action-based pressure threshold sensor further comprises a thermally responsive material covering a first porous medium, and detects a state selected from a specified temperature and a specified pressure change in a target fluid.

[0069] According to an exemplary embodiment, the thermally responsive material is poly-N-isopropylacrylamide (PNIPAM).

[0070] Additional and / or other embodiments and advantages of the exemplary embodiments will be described in the following description, become apparent from the description, or may be known through the practice of the exemplary embodiments. Exemplary embodiments may include an apparatus having one or more of the above embodiments and / or one or more of their features or combinations, and a method for operating such an apparatus. Exemplary embodiments may include, for example, features and / or combinations of the above embodiments described in the appended claims. [Brief explanation of the drawing]

[0071] The above and / or other aspects and advantages of the exemplary embodiments will be more readily apparent from the following detailed description in conjunction with the accompanying drawings. [Figure 1A] Figure 1A shows a side view of a capillary action-based pressure threshold sensor configured according to an exemplary embodiment. [Figure 1B] Figure 1B shows a side view of a capillary action-based pressure threshold sensor, according to an exemplary embodiment, which, once wetted / pre-primed, prevents air from being introduced into the flow path as a result of negative pressure in the flow path. [Figure 2A] Figure 2A shows an exemplary hydrophobic porous medium in the capillary action-based pressure threshold sensor shown in Figure 1A. [Figure 2B] Figure 2B shows an example of a hydrophilic porous medium in the capillary action-based pressure threshold sensor shown in Figure 1B, which is wetted by a liquid and prevents air from entering the medium by capillary force. [Figure 3A] Figure 3A shows a capillary action-based pressure threshold sensor configured according to an exemplary embodiment, representing two different states: below the pressure threshold and above the pressure threshold, respectively. [Figure 3B] Figure 3B shows a capillary action-based pressure threshold sensor configured according to an exemplary embodiment, representing two different states: below the pressure threshold and above the pressure threshold, respectively. [Figure 4] Figure 4 shows a printed circuit board with electrodes for a capillary action-based pressure threshold sensor configured according to an exemplary embodiment. [Figure 5A] Figure 5A is a block diagram of a capillary action-based pressure threshold sensor that provides output to a processor, configured according to an exemplary embodiment. [Figure 5B] Figure 5B is a block diagram of a capillary action-based pressure threshold sensor that provides an output to a passive indicator, according to an exemplary embodiment. [Figure 6]Figure 6 is a flowchart illustrating an exemplary method using a capillary action-based pressure threshold sensor configured according to an exemplary embodiment. [Figure 7A] Figure 7B shows the contact angles of liquids in contact with different surfaces that are flat and textured. [Figure 7B] Figure 7B shows the contact angles of liquids in contact with different surfaces that are flat and textured. [Figure 8] Figure 8 illustrates the penetration of air and water in an exemplary hydrophobic fiber membrane. [Figure 9] Figure 9 shows different locations for installing a capillary action-based pressure threshold sensor, configured according to an exemplary embodiment, in the flow path of an exemplary injection set. [Figure 10] Figure 10 shows different locations for installing a capillary action-based pressure threshold sensor, configured according to an exemplary embodiment, in the flow path of an exemplary injection set. [Figure 11] Figure 11 shows different locations for installing a capillary action-based pressure threshold sensor configured according to an exemplary embodiment in the flow path of an exemplary injection set. [Figure 12] Figure 12 is a perspective view of an exemplary injection pump. [Figure 13] Figure 13 is a perspective view of the injection pump shown in Figure 12, with the housing cover removed to expose exemplary pump components on the base plate. [Figure 14] Figure 14 shows different locations for installing a capillary action-based pressure threshold sensor, configured according to an exemplary embodiment, in the flow path of an exemplary injection set. [Figure 15] Figure 15 shows different locations for installing a capillary action-based pressure threshold sensor configured according to an exemplary embodiment in the flow path of an exemplary injection set. [Figure 16A] Figure 16A shows different locations for installing a capillary action-based pressure threshold sensor, configured according to an exemplary embodiment, in the flow path of an exemplary injection set. [Figure 16B] Figure 16B shows different locations for installing a capillary action-based pressure threshold sensor configured according to an exemplary embodiment in the flow path of an exemplary injection set.

[0072] Throughout the drawings, similar reference numbers are understood to refer to similar elements, features, and structures. [Modes for carrying out the invention]

[0073] The following describes in detail exemplary embodiments shown in the attached drawings. The embodiments described herein are illustrative of exemplary embodiments, but are not limited to those shown in the drawings.

[0074] This disclosure provides a capillary action-based pressure threshold sensor 200 using a hydrophobic porous material or medium 208, and medium-specific properties of a fluid breakthrough pressure (e.g., a capillary action-based pressure threshold) for detecting a desired overpressure state or event in a given application, such as detecting overpressure in a flow channel in a fluid delivery application. Figures 1A and 1B show exemplary capillary action-based pressure threshold sensors 200 implemented in a flow channel 202 formed of a material such as a polymer material to surround a fluid 204, respectively. As will be described in more detail below, the sensor 200 in the flow channel 202 is used to detect when the membrane 208 and an optional membrane 214 are damaged after the fluid pressure in the flow channel exceeds a specified threshold, for example, as an indicator of blockage or other condition.

[0075] Figure 2A shows a partial view of exemplary media 208, 214 used in the sensor 200, having a first side surface 210 in contact with the liquid 204 and a second side surface 212 in contact with a gas such as air. The capillary action-based pressure threshold sensor 200 for liquids utilizes the properties of an inaffiliative porous medium as membrane 208 (e.g., hydrophobic, superhydrophobic, oleophobic, and biaffiliative porous membranes) and, optionally, the properties of an affinity porous medium as membrane 214 (e.g., hydrophilic, superhydrophilic, oleophobic, and biaffiliative porous membranes) to detect when the pressure crossing membrane 208 or membrane 214 rises above the breakthrough pressure of the fluid 204, thereby detecting when the fluid 204 passes through membrane 208 or membrane 214. The capillary pressure p is a function of the contact angle, surface tension, and effective radius of the interface with respect to the following equation:

[0076]

number

[0077] In the case of a porous membrane, the fluid breakthrough pressure is determined by the capillary pressure of the equivalent maximum pore 215 defined by the corresponding adjacent fibers 213 in the membrane, as shown in Figure 2A. The equivalent maximum pore is the smallest pore through which the liquid must pass in a given penetration path between the fibers 213, from one side 210 to the other side 212 of the membrane. In addition to hydrophilic porous membranes and / or expansive materials 214a, Figure 2B shows an affinity porous medium for membrane 214b, which, when wetted with liquid 204, prevents air from entering the medium 214 by capillary force. It can be understood that the capillary pressure can be positive (e.g., affinity porous medium) or negative (non-affinity porous medium). Negative capillary pressure prevents the passage of liquid but allows the passage of gas, while positive capillary pressure facilitates the passage of liquid but prevents the passage of gas once wetted with liquid.

[0078] Referring to Figures 1A, 3A, and 3B, according to an exemplary embodiment, the capillary action-based pressure threshold sensor 200 is formed by using a hydrophobic, superhydrophobic, oleophobic, or biaphobic porous medium (i.e., also referred to as an “aphobic porous medium”) for a hydrophobic membrane 208 that comes into contact with the fluid 204 in the fluid line or channel 202. For example, Figure 3A shows the operation of the sensor 200 when the sensed fluid is below the fluid breakthrough pressure threshold, and Figure 3B shows the operation of the sensor 200 when the sensed fluid is above the fluid breakthrough pressure threshold. In one exemplary embodiment, the hydrophobic membrane 208 is a superhydrophobic porous membrane that seals an opening 206 formed along the channel 202. The sensor 200 includes a fluid detector or fluid detection element 216 (e.g., a passive switch or an active switch including electrodes 218a, b) for detecting the presence of a target fluid 204 positioned in close proximity to or in direct contact with the porous membrane 208, and for detecting the presence of the fluid 204 after the fluid has passed through the membrane 208. For example, the switch 216 can be a gold terminal or a membrane switch. A desired fluid breakthrough pressure can be obtained by selecting the properties of the porous medium used as the membrane 208 (e.g., in particular, pore size, thickness, material, surface shape, coating, and contact angle with the fluid), which is the pressure at which the pressure difference between the two sides 210, 212 of the porous membrane 208 overcomes the capillary pressure that prevents the pores from being blocked by the fluid.

[0079] Referring again to Figures 1B, 3A, and 3B, a second porous membrane 214 (also referred to as the “affinity porous medium”) is optionally interposed between the fluid detector 216 and the non-affinity porous medium 208, allowing the fluid 204 to diffuse in a controlled manner and optimize its detection by the fluid detector 216. In one embodiment, once the affinity porous medium 214 comes into contact with the fluid, it expands to further improve contact with the fluid detector 216 and optimize detection. In another embodiment, the expanding affinity porous medium 214 acts mechanically to activate an exemplary fluid detector element 216 (e.g., a switch). In an exemplary embodiment, the non-affinity porous medium 208 is welded to a polymer material forming a flow channel 202 so as to seal an opening 206 formed by holes in the polymer material that give access to the fluid line or flow channel 202. In an exemplary embodiment, the fluid detector 216 is formed by two electrodes 218a, b that are in direct contact with the affinity porous medium 214. The affinity porous medium 214 is selected such that its electrical conductivity when dry differs from that when wet with fluid 204. As a result, the presence of the fluid can be detected by a change in resistance between the two measuring electrodes 218a and 218b. If the fluid 204 has low electrical conductivity (e.g., pure water), an ionic compound (such as a salt) can be placed in the path between the fluid 202 and the electrodes 218a and 218b of the fluid detector 216 to increase the electrical conductivity of the fluid 204 and enable its detection. Using the pogo pins 229 and adjacent contact pads 228 in Figures 1A and 1B, the circuit (i.e., electrodes 218a and 218b) can be connected to a separate PCB containing a microcontroller or other components.

[0080] As shown in Figures 3A and 3B, ventilated electrodes 218a and 218b can be used. For example, vias 220 located at the positions of sensing electrodes 218a and 218b allow air to escape and effectively guide the fluid 204 into contact with the electrodes. Ventilated electrodes 218a and 218b are advantageous in that they avoid pockets of trapped air or bubbles at the electrodes, which could interfere with proper electrical contact and thus impair the detection of the fluid 204.

[0081] Referring to Figures 3A, 3B, and 4, in an exemplary embodiment, electrodes 218a, b are made of contact pads on a printed circuit board (PCB) 222. The PCB 222 is heat-crimped by heat-crimping pins 22 to maintain close contact with the affinity porous medium 214, which is in direct contact with the non-affinity porous medium 208. The electrodes 218a, b of the fluid detector 216 can function as open switches that close when in contact with the fluid 204 to produce a notification that can be processed by a microcontroller 226 or other type of processing device, as shown in Figure 5A, or they can generate a passive notification using a passive indicator 230, as shown in Figure 5B. One electrode 218a may be connected to the ground pin of the microcontroller 226, and the other electrode 218b may be connected to the input pin of the microcontroller 226. A pull-up resistor 232 having a high value (e.g., 100 k ohms) may be connected to the positive rail of a power supply (not shown). The pull-up resistors are in the range of 1 kΩ to 100 MΩ and may have values ​​for the impedance of the wet / dry electrodes 234 schematicly shown in Figure 5A. The pull-up and pull-down resistors can be used interchangeably by appropriately connecting the electrodes 218a, b and pins of the microcontroller 226. Such embodiments have the advantage of extremely low power consumption of the sensor 200, unless an overpressure condition or event occurs in the fluid line 202 where the sensor 200 is located. In another exemplary embodiment, the fluid 204 reduces the conductivity sensed by electrodes 218a, b, and produces a detectable event in the same manner as described above. In the exemplary embodiment, one electrode may be connected to an output pin of the microcontroller and the other electrode to an input pin of the microcontroller. According to an aspect of the exemplary embodiment, one electrode is connected to the positive rail of a power supply having a common ground with the microcontroller, and the other electrode is connected to an input pin of the microcontroller. In another embodiment, the electrodes are supplied with an AC signal instead of, or without, a DC bias.

[0082] It should be understood that the description of the fluid detector 216 in this specification is, for example, as a functional switch for a specific purpose, and not necessarily as an electrical component. For example, the resistance of a fluid detector 216 operating as a “close switch” is relatively high (e.g., several kilohms depending on the structure of the electrode 218, such as their materials and the properties of the fluid). According to exemplary embodiments of this specification, the electrode 218 is used as a capacitive sensor.

[0083] Furthermore, according to an exemplary embodiment, the fluid detection element 216 is passive and remains unactivated until the target fluid leaks through the porous medium and reaches a second side opposite the porous medium. According to an alternative embodiment, the fluid detection element 216 is active and provides different outputs or readings (e.g., in the case of a processor) to distinguish between a first state in which the target fluid 202 has not yet leaked through the porous medium 208 and a second state in which the target fluid 204 has leaked through the porous medium 208. In an exemplary embodiment, the presence of fluid can be detected by an optical sensor, a capacitive sensor, an inductive sensor, or a humidity sensor 216. In the embodiment illustrated in Figure 5B, the fluid detector 216 operates directly with a marker (e.g., the presence of fluid 204 triggers a color change in a material associated with the fluid detector 216, which acts as a fully passive marker) without using a processor as illustrated in Figure 5A. The passive marker can act as an optical or visual marker that visually indicates (e.g., to the user's naked eye) a change in state, such as a change in color, from when the fluid detector 216 is not in contact with the fluid 204 until the fluid leaks through the membrane(s) 208 and the fluid detector 216, or otherwise comes into contact with the membrane(s) 208 and the fluid detector 216. Such embodiments are useful, for example, in smartphones or other devices having an IPX8 specification, where if the fluid detector 216, located within the housing or case of a smartphone or other IPX8s specification device, is exposed to a fluid pressure higher than the IPX8 specification, a passive marker associated with the fluid detector 216 occurs, thereby invalidating the guarantee n.

[0084] Figure 4 shows the PCB 222 providing wiring between electrodes 218a, b and vias for wired connection to pins of the processing unit 226, but the sensor 200 can provide at least wireless communication capability to communicate state changes of the fluid detector 216 to the processing unit 226. For example, there are several techniques currently used to power wireless sensors, such as providing wireless power inductively, through radio frequency energy transfer, or capacitively, as described in Patent Document 1. This patent publication recommends RFID or SOW for powering the sensor. One of these techniques can be used to provide sufficient power and signal amplification to enable wireless transmission of information from the sensor 200 (e.g., notification from the fluid detector 216 that fluid has been sensed and therefore switch 216 has been activated) to a questioner in a device in which the sensor 200 is deployed (e.g., a drug delivery device) or another device (e.g., a user interface). Alternatively, the fluid detector 216 may be configured passively.

[0085] In another exemplary embodiment, the affinity porous medium 214 in Figure 1A and the affinity porous medium 214a in Figure 1B are expandable affinity materials that mechanically operate the switch when they expand (for example, as a result of fluid 204 leaking through them). The affinity porous medium 214 can be a porous material that expands or swells when absorbing the liquid 204, such as a hydrophilic membrane and / or expandable membrane 214, thereby forcing close contact of the affinity porous medium 214 with the electrodes 218a,b. The expandable affinity material can be, for example, anhydrous hydrogel, foam, or sponge-like material. Anhydrous hydrogel can be further filled with salts or materials that increase the conductivity of the liquid filling material to improve the reliability of fluid detection through the electrodes.

[0086] According to another exemplary embodiment, the capillary action-based pressure threshold sensor 200 is a disposable sensor (for example, it is no longer usable once the fluid 204 leaks into the membrane and the fluid detector 216 is activated). In another embodiment, the capillary action-based pressure threshold sensor 200 can be reused after the fluid 204 that has passed through the non-affinity porous medium 208 has receded from the area examined by the fluid detector 216.

[0087] According to another exemplary embodiment, a non-affinity porous medium (not shown) having a higher fluid breakthrough pressure than the non-affinity porous medium 208 is positioned on top of the sensor 200 to encapsulate the sensing region and prevent any fluid 204 from leaking beyond the sensing region, and also to provide a barrier to avoid moisture condensation that could produce false detections. According to another exemplary embodiment, contact between electrodes 218a, b and affinity porous medium 214 can be improved by having electrodes 218a, b have a rough surface, and / or having a conductive material that forms a wavy surface on affinity porous medium 214, and / or having a conductive material impregnated into affinity porous medium 214, such as a conductive adhesive that connects the porous material 214 to the individual electrodes 218a, b without short-circuiting the electrodes, and / or having interlocking electrodes. According to another exemplary embodiment, the sensor 200 may have multiple sensor configurations with two or more electrodes 218a, b. Different electrodes can be configured and functionalized to detect a variety of fluid properties, including advanced fluid properties that can be further analyzed, for example, by electrochemical measurements and / or impedance spectroscopy. As a further example, a thermosensitive material for hydrophobic films (e.g., poly-N-isopropylacrylamide or PNIPAM) can be used. In one exemplary embodiment, a material with a contact angle that changes depending on a particular condition may be selected to combine the detection of multiple factors in addition to overpressure in the fluid line. For example, the porous medium 208 may be composed of or coated with a thermoresponsive material such as PNIPAM to detect either a temperature below a lower critical eutectic temperature (LCST) or a pressure above the fluid breakthrough pressure.

[0088] According to an exemplary embodiment, a method for fabricating and using a capillary action-based pressure threshold sensor 200 is shown in Figure 6. For example, when a certain application is made in a fluid line (e.g., a flow path between a container for storing insulin and a catheter in a drug delivery device) such as a requirement to detect an overpressure condition, an overpressure threshold to be detected in the flow path 202 is selected (block 280). A capillary action-based pressure threshold sensor is selected that comprises a porous medium 208 that allows the fluid to leak through the medium when the fluid pressure exceeds its fluid break-overpressure threshold (block 282). The porous medium 208 has at least one porous property and a fluid break-overpressure threshold related to the overpressure threshold. The capillary action-based pressure threshold sensor 200 is positioned along the fluid line or flow path 202 such that one side 210 of the porous medium 208 is in contact with the fluid 204 in the flow path 202 (block 284). The sensor 200 has electrodes 218a and 218b on the opposite side 212 of the medium 208, and electrodes 218a and 218b can act as an open switch that is closed in contact with the fluid 204 (block 286). The closing of the switch 216 produces a notification (e.g., an optical or color change display by the passive type switch 216, or an output to the processing unit 226 from the active type switch 216) (block 288). The capillary action-based pressure threshold sensor 200 is useful for detecting pressure in different types of fluid lines 202 with respect to different types of fluids and different types of fluid devices or systems, and should therefore be understood to be not limited to drug delivery devices and fluid pharmaceutical products.

[0089] Here, several exemplary materials for fabricating a capillary action-based pressure threshold sensor 200 are described. For example, a superhydrophobic porous membrane (e.g., MilliporeSuruVent® PVDF membrane) can be used as the medium 208. The fluid detector 216 can be fabricated, for example, with a conductive pad or conductive wiring in contact with a membrane switch located on a rigid or flexible PCB 222, which is, for example, a liquid (e.g., applicable to pegfilgrastim and insulin). The conductive pad can be, but is not limited to, gold / copper / tin / silver / silver chloride materials. Table 1 below gives an example of porous membrane properties and the corresponding fluid breakthrough pressure (psi) for one type of superhydrophobic material, SureVentPVDF. It should be understood that the relationship between pore size, thickness, and fluid breakthrough pressure can vary from those shown in Table 1. For example, the water breakthrough pressure may differ for different materials or coatings (i.e., resulting in different contact angles) having the same pore size and thickness properties as in Table 1.

[0090] [Table 1]

[0091] A capillary action-based pressure threshold sensor 200 configured according to an exemplary embodiment can be implemented in a flexible or rigid flow channel 202. A configuration comprising a hydrophobic porous membrane 208 (e.g., comprising an optional hydrophilic material 214), a fluid detection system or element 216 (e.g., electrodes 218a, b, or mechanical, optical, or other types of switches) can potentially be integrated anywhere in the flow channel, as long as the porous membrane 208 is in contact with the fluid 204 in the fluid line 202 where overpressure detection is required or desired.

[0092] The underlying technical principles of exemplary embodiments of the capillary action-based pressure threshold sensor 200 are the capillary pressure of an incompatible porous medium 208 (e.g., a hydrophobic medium) and the conductivity of the porous mediums 208, 214 when wetted with a liquid solution. According to one exemplary embodiment, the fluid 204 is conductive and flows across the incompatible porous membrane 208, and detection of an overpressure event is performed by closing the open circuit 216 via a change in the resistance of an optional second medium 214 (e.g., a sponge material). If an optional second medium 214 is not used in the sensor 200, the fluid 204 itself replaces the air in the gap between electrodes 218a, b, closing the circuit between the electrodes. According to another exemplary embodiment, one of the electrodes 218a, b is excited (e.g., using capacitance to a DC circuit) and the measurement is performed. In any case, an overpressure event can be identified by measuring the change in the impedance of the medium in the region of electrodes 218a, b due to the saturation of the fluid.

[0093] As described above, several factors can be considered when selecting an incompatible porous material for medium 208 to achieve a desired pressure threshold for applications where it is required to detect overpressure events, provided that the medium 208 has porous properties and a corresponding breakthrough pressure. For example, medium 208 can be a superhydrophobic porous membrane. Different properties of the incompatible porous material (e.g., roughness, pore size, material, coating, film thickness, etc.) can influence the decision regarding whether it has a breakthrough pressure corresponding to a desired pressure threshold that is required to be detected when exceeded.

[0094] Capillary action is a key factor characterizing the nature of the interaction between fluids and porous materials. Fibrous materials with negative capillary pressure are hydrophobic and can be used as membranes or as water-resistant barriers for a variety of applications. Detailed capillary pressure prediction is also important for the proper design of gas diffusion layers (GDLs) for fuel cells or other applications involving liquid-liquid or gas-liquid separation. Figure 8 is a magnified view of the air-water interface subjected to burst instability near the bottom of the membrane. Surfaces with a hydrophobic tendency can be enhanced to superhydrophobic by adding roughness, or more precisely, a specific type of surface morphology, as shown by the exemplary fibrous membrane in Figure 8. When a hydrophobic fibrous membrane (e.g., a distillation membrane used in direct contact membrane distillation) is brought into contact with water, the hydrophobic fibers resist the penetration of water into the membrane's pores (spaces between fibers). Nevertheless, an immersed hydrophobic membrane cannot remain dry under increased pressure. This occurs because the interface between the water outside the membrane and the air inside the membrane becomes unstable due to excessive pressure, allowing water to enter the membrane's pores (i.e., the membrane's capillary pressure cannot balance the intrusion pressure). Generally, the pressure at which water enters a membrane is called the liquid intrusion pressure, liquid breakthrough pressure, or water breakthrough pressure (in the case of an aqueous solution).

[0095] Figures 7A and 7B illustrate the relationship between Young's equation and the characterization of media as hydrophobic or hydrophilic. Surface tension γLV relates to the existence of an interface between liquid and vapor and is just one example of interfacial tension. When a liquid droplet is on a solid, two further interfaces, solid-liquid and solid-vapor, are involved, giving interfacial tensions γSL and γSV. The balance of these three interfacial forces determines whether the droplet on the solid is eventually stretched into a thin film or remains a droplet, and if so, the extent of its contact area on the solid surface. On a smooth, flat surface, the interaction energy per unit area of ​​a dry surface is γSV, but on the same surface covered with a thin layer of liquid, there are two interfaces where the interaction energy per unit area is related to the combination of γSL + γSV. Therefore, the condition for forming a film on a smooth, flat surface is that the energy decreases according to equation (1) below.

[0096] S = γSL + γLV - γSV > 0 Here, S is defined as the spreading force.

[0097] If no film is formed and the droplet remains partially wet on the surface, an equilibrium contact angle θe exists at the edge of the droplet. This is the tangential angle of the liquid-vapor interface in the three-phase (solid-liquid-vapor) contact line. The contact angle is independent of the droplet size and is described by Young's equation (2).

[0098]

number

[0099] Furthermore, regarding hydrophobicity, hydrophilicity, and superhydrophobicity, a perfectly hydrophilic (or wettable) surface is one on which a film is formed based on equation (1), and for S=0, equation (2) shows that the threshold for this corresponds to θe=0°. A perfectly hydrophobic surface is energetically unfavorable for any contact between droplets, which corresponds to θe=180°. Therefore, all droplets with a finite contact angle between these two values ​​are partially wetted. In general, a solid surface is considered hydrophilic if the water contact angle is less than 90°, and hydrophobic if the water contact angle is greater than 90°. Surfaces / materials with a water contact angle greater than 150° are generally called superhydrophobic.

[0100] A surface with hydrophobic tendencies can be enhanced to superhydrophobicity by adding roughness, or more precisely, by adding a specific type of surface morphology. This can be seen as a physical amplification of the surface's chemical properties. The contact angle can be increased far beyond what is possible with chemical properties alone, sometimes approaching 180°. Conversely, chemical materials alone can decrease the contact angle closer to 0° than expected. The amplification effect of surface morphology can be understood in a similar way to the derivation of Young's equation. The shape and degree of roughness of the surface morphology, and the contact angle of the selected liquid to the selected material, all affect wetting and dehumidification. Wenzel's equation predicts that the contact angle decreases with roughness at contact angles below 90° and increases at higher contact angles, but due to the bridging effect, surfaces with lower intrinsic contact angles show an increase in the contact angle with roughness. The shape of the roughness is important in causing bridging. These factors allow for a wide range of design possibilities when designing materials for specific purposes, such as the non-affinity porous medium 208 and the optional affinity porous medium 214 used in the capillary action-based pressure threshold sensor 200.

[0101] This disclosure utilizes the fluid breakthrough pressure characteristics of a non-affinity porous medium 208 to enable detection of fluid 204 leaking through the medium on the opposite side 212 of the porous medium, thereby enabling detection when the pressure in the fluid line 202 rises above a predetermined threshold. Unlike solutions involving the use of active sensors for continuous measurement of pressure in a fluid line, the capillary action-based pressure threshold sensor 200 according to the exemplary embodiments described herein is extremely compact, allows for a very small footprint that can be easily integrated into small devices, requires little data processing and computing power, has no moving parts, has a very low dead volume, is cost-effective, can be manufactured with minimal assembly steps, consumes very low power, can be mass-produced, and can be used to detect a specific pressure threshold without the use of any pressure transducer.

[0102] Here, exemplary mountings of a capillary action-based pressure threshold sensor 200 in a fluid line 202 of different types of apparatus are described according to exemplary embodiments. Figures 9, 10, and 11 show different locations for mounting the capillary action-based pressure threshold sensor 200 in the flow path of an exemplary injection set, respectively. The exemplary injection sets are described in jointly owned Patent Documents 2 and 3, which are incorporated herein by reference in their entirety, respectively.

[0103] Figures 9 and 10 show the sensor 200 located on the hub of the infusion set. Figure 11 shows the sensor 200 attached (e.g., welded) to the tubing of the infusion set. Figures 9 and 11 show wireless communication between the sensor 200 and the processor 226. In Figure 10, the device 120 comprises a housing 122 and a housing adhesive portion 124, as well as a needle hub 126 and a needle hub adhesive portion 128. A flexible connector 130 is provided between the outer housing 122 and the needle hub 126 and can be configured to house, for example, the sensor 200. The two hubs 122 and 126 can be attached to the surface of the skin as a single device, and the inner hub 126 can be configured to maintain the position of the catheter 134 relative to the tissue into which the catheter 134 is inserted.

[0104] Figure 12 is a perspective view of an exemplary infusion pump in which a capillary action-based pressure threshold sensor 200 may be installed. Patch pump 1 is described in jointly owned Patent Document 4, which is incorporated herein in whole by reference. Pump 1 has a housing 10 including a main cover 2, the main cover 2 being liquid-sealed, or preferably sealed against a base 9. The base 9 holds various components. Figure 13 shows some of the main components of patch pump 1 in a perspective view with the main cover 2 and container 4 removed for clarity. According to one embodiment, an infusion port 43 is a conduit for supplying a drug to the container 4. In some embodiments, the infusion port 43 may include a portion that functions as part of the flow path of the drug coming out of the container 4. A receptacle 32 is connected by a tube to an insertion mechanism 7, for example, to transfer the drug to the insertion mechanism 7 before injection into the patient's skin. Patch pump 1 preferably includes a container 4 for containing a drug (such as insulin), a pump 3 for pumping the drug out of the container 4, and a force sensing resistor 30 for detecting a pressure value in the drug flow path. The patch pump 1 also preferably includes electronic equipment 8 for programming and operating the patch pump 1, and an insertion mechanism 7 for inserting a cannula 47 into the patient's skin to deliver the drug.

[0105] The capillary action-based pressure threshold sensor 200 can be used in place of, or in addition to, the existing pressure sensor 30 in the exemplary injection pump 1, and the sensor 200 can be used at different locations in the flow path of a fluid delivery or transport device. For example, Figure 14 shows the capillary action-based pressure threshold sensor 200 deployed along the tube of the insertion mechanism 7. Figure 15 shows the bottom surface 22 of the base 9 of the patch pump 1. The bottom surface 22 of the base 9 includes first and second fluid paths 24, 26. The first and second fluid paths 24, 26 provide flow paths between various components of the patch pump 1, such as the container 4, the injection port 43, the force sensing resistor 30, the pump 3, and the insertion mechanism 7. The capillary action-based pressure threshold sensor 200 can be deployed along either or both of the first fluid path 24 and the second fluid path 26, as shown in Figure 15. The capillary action-based pressure threshold sensor 200 can be mounted, for example, at an opening in the film covering the path. The base plate may also have vias for connecting the sensor 200 to a processor included in the electronic device 8.

[0106] According to another embodiment, the patch pump may have a fluid path plate 34 located inside the patch pump 1 1 12 to provide a drug flow path, as shown in Figures 16A and 16B. The fluid path plate 34 includes a first fluid path 36 and a second fluid path 38 of the plate, encapsulated by a fluid path cover 28, which is omitted for clarity. The fluid paths 36, 38 of the plate transport drug fluid through the inside 12 of the patch pump 1 to various components. A capillary action-based pressure threshold sensor 200 can be mounted, for example, in an opening in the cover. The fluid path plate 34 may also have vias for connecting the sensor 200 to a processor included in the electronic equipment 8.

[0107] Those skilled in the art will understand that the application of this disclosure is not limited to the detailed structures and component arrangements described above or illustrated in the drawings. The embodiments described herein are not limited to other embodiments and can be performed or implemented in various ways. Furthermore, it should be understood that the expressions and terms used herein are for illustrative purposes only and should not be considered limiting. The use of “includes,” “equipped,” or “has,” and their variations herein, means to include additional items in addition to those enumerated herein and their equivalents. Unless otherwise specified, the terms “connected,” “joined,” and “mounted,” and their variations herein, are used broadly and include direct and indirect connections, joints, and mountings. Furthermore, the terms “connected,” and “joined,” and their variations, are not limited to physical or mechanical connections or joints. Additionally, terms such as top, bottom, base, and upper surface are relative and used to aid the illustrations, but are not limiting.

[0108] The components of the illustrated apparatus, system, and method adopted according to the illustrated embodiments can be implemented, at least in part, as digital electronic circuits, analog electronic circuits, or computer hardware, firmware, software, or a combination thereof. These components can be implemented as computer program products, such as computer programs, program code, or computer instructions, clearly embodied in an information medium or machine-readable storage device for execution by or control of data processing devices such as a programmable processor, computer, or multiple computers.

[0109] Computer programs are written in any form of programming language, including compiled or interpreted languages, and can be deployed as standalone programs or modules, in any form including components, subroutines, or other units suitable for use in a computer environment. Computer programs can be deployed to run on one computer or multiple computers at one site, or they can be distributed across multiple sites and interconnected by a communication network. Furthermore, functional programs, code, and code segments for implementing exemplary embodiments can be readily interpreted by a programmer skilled in the art to which the exemplary embodiments belong as being within the scope of the claims illustrated by the exemplary embodiments. The steps of a method relating to an exemplary embodiment of the present invention can be performed by one or more programmable processors that execute computer programs, code, or instructions for performing a function (e.g., by manipulating input data and / or generating output). For example, the steps of a method can also be performed by a special-purpose logic circuit such as an FPGA (Field-Programmable Gate Array) or ASIC (Application-Specific Integrated Circuit), and the apparatus of the exemplary embodiment can be implemented as such.

[0110] Various exemplary logic blocks, modules, and circuits described in connection with embodiments disclosed herein may be implemented or run by a general-purpose processor, a digital signal processor (DSP), an ASIC, an FPGA, or other programmable logic device, discrete gates, or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computer devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or other such configurations.

[0111] Processors suitable for executing computer programs include, for example, both general-purpose and dedicated microprocessors, and any one or more processors in any type of digital computer. Generally, a processor receives instructions and data from read-only memory and / or random-access memory. Essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also includes, or is operablely coupled to, one or more mass storage devices for storing data, such as magnetic, magneto-optical disks, or optical disks, or both. Information media suitable for embodying computer program instructions and data include, for example, electrically programmable read-only memory or ROM (EPROM), electrically erasable programmable ROM (EEPROM), semiconductor memory devices such as flash memory devices, and all forms of non-volatile memory, including data storage disks (magnetic disks, internal hard disks, or removable disks, magneto-optical disks, CD-ROMs, and DVD-ROM disks, etc.). Processors and memory can be supplemented or incorporated into special-purpose logic circuits.

[0112] Those skilled in the art will understand that information and signals can be represented using any of the various different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips, which may be referenced throughout the above description, can be represented by voltage, electric current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0113] Those skilled in the art will further understand that various exemplary logic blocks, modules, circuits, and algorithmic steps described in connection with the embodiments disclosed herein may be implemented as electronic devices, computer software, or a combination of both. To clearly demonstrate this compatibility between hardware and software, various exemplary components, blocks, modules, circuits, and steps have been described above in general terms of their function. Whether such functions are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functions in various ways for each specific application, but such a decision on implementation should not be construed as deviating from the scope of the claims illustrated by the exemplary embodiments. Software modules may reside in random access memory (RAM), flash memory, ROM, EPROM, EEPROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. The exemplary storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium. Alternatively, the storage medium may be integrated into the processor. In other words, the processor and storage medium may reside within an integrated circuit or be implemented as separate components.

[0114] Computer-readable non-temporary media include all types of computer-readable media, including magnetic storage media, optical storage media, flash media, and solid-state storage media. It should be understood that software can be installed on a central processing unit (CPU) device and sold with it. Alternatively, software can be acquired and loaded onto a CPU device, which includes acquiring the software through physical media or distribution systems, such as from a server owned by the software creator or from a server not owned by the software creator but used by them. Software can be stored on a server for distribution, for example, over the internet.

[0115] The above description and figures are intended for illustrative purposes only and are not intended to limit the invention in any way except as set forth in the following claims. Those skilled in the art will be particularly aware that various technical aspects of various elements of the various exemplary embodiments described above can be readily combined in many other ways, and all such combinations are considered to be within the scope of the claims.

Claims

1. A method for fabricating a capillary action-based pressure threshold sensor, The selection of a first porous medium having porous properties that allow fluid to leak from a first side of the first porous medium to an opposing second side through the first porous medium, wherein the leakage occurs when the fluid pressure exceeds the fluid breakthrough pressure threshold of the first porous medium. To provide a fluid detection element positioned at least proximal to the second surface of the first porous medium and configured to detect the presence of at least a target fluid on the second surface of the first porous medium, Methods that include...

2. The fluid detection element is selected from a passive fluid detection element and an active fluid detection element. The passive fluid detection element does not operate until the target fluid leaks through the first porous medium and reaches the opposing second side surface of the first porous medium, and The active fluid detection element provides different outputs to distinguish between a first state in which the target fluid has not yet leaked through the first porous medium and a second state in which the target fluid has leaked through the first porous medium, and / or The fluid detection element includes an indicator element configured to change state when a target fluid leaks through a first porous medium to the second side, the changing state being selected from a color display and / or a change in color display. The method further includes, and / or, coating the first porous medium with a thermally responsive material to detect a state selected from a specified temperature and a specified pressure change of the target fluid. The method according to claim 1, further comprising coating the first porous medium with a thermoresponsive material to detect a state selected from a specified temperature and a specified pressure change of a target fluid, wherein the thermoresponsive material is poly-N-isopropylacrylamide (PNIPAM).

3. The method according to claim 1, wherein the porous properties of the first porous medium are selected from pore size, thickness, material, surface shape, coating, and contact angle with the fluid.

4. The method according to claim 1, further comprising forming a seal over a hole in the flow path to expose the first porous medium to the fluid in the flow path and to configure the first side to prevent the fluid from leaking out of the capillary action-based pressure threshold sensor.

5. The fluid detection element includes at least two electrodes, To provide a second porous medium with affinity, positioned between a first porous medium with a non-affinity and the fluid detection element, such that the second porous medium is selected to have different conductivity when dry and when wet with fluid in the flow path, thereby controllingly distributing the fluid leaking through the first porous medium to a sensor, The present invention further includes providing two electrodes that contact the second side of a first porous medium, wherein the electrodes are passive and configured not to be activated until a fluid leaking through the first porous medium exceeds a threshold, and / or Providing a fluid detection element includes providing an electrode fabricated on a contact pad on a printed circuit board (PCB), and / or The method according to claim 1, further comprising thermal crimping the PCB via a thermal crimping pin configured to maintain proximity to the second porous medium and to maintain direct contact with the first porous medium.

6. The method according to claim 1, further comprising: the fluid detection element comprising at least two electrodes, and the electrodes acting as passive switches that are open until they come into contact with a fluid and close.

7. Providing a switch includes providing electrodes made of contact pads on a printed circuit board (PCB), and / or The method further includes connecting one electrode to a ground pin of a microcontroller and the other electrode to an input pin of a microcontroller, and / or The method further includes connecting one electrode to an output pin of a microcontroller and the other electrode to an input pin of a microcontroller, and / or The method further includes connecting one electrode to the positive rail of a power supply having a common ground with the microcontroller, and connecting the other electrode to an input pin of the microcontroller, and / or The method further includes connecting a pull-up resistor between the positive rail of the microcontroller's power supply or reference voltage and the input pin, and / or The method further includes connecting a pull-down resistor between the input pin and the negative rail connected to the negative or ground terminal of the microcontroller, and / or The method according to claim 6, wherein the resistor has a resistance of approximately 1 kΩ to 100 MΩ.

8. The method according to claim 1, wherein the first porous medium is selected from a hydrophobic medium, a superhydrophobic medium, an oleophobic medium, and a porous medium that is both incompatible.

9. The method further includes selecting a second porous medium positioned at least proximal to a first side of the first porous medium so as to be in contact with the target fluid before the target fluid leaks through the first porous medium, The second porous medium is Porous properties that allow the fluid to easily penetrate the second porous medium, and Having porous properties that prevent the gas from passing through the second porous medium after the target fluid has penetrated the second porous medium, until the gas exceeds the intrusion pressure of the second porous medium, and / or The method according to claim 1, further comprising selecting a second porous medium located at least proximal to the opposite side of the first porous medium so as to come into contact with the target fluid before the target fluid leaks through at least the first porous medium, wherein the second porous medium has one or more porous properties that allow the fluid to easily penetrate the second porous medium and enhance contact between the target fluid and the fluid detection element.

10. A method using a capillary action-based pressure threshold sensor, Selecting an overpressure threshold detected by the fluid, Select a capillary action-based pressure threshold sensor comprising a porous medium having at least one porous property and a fluid breakthrough overpressure threshold related to the overpressure threshold, wherein the capillary action-based pressure threshold sensor allows fluid to leak from one side through the porous medium to the other side when the fluid pressure crossing the porous medium exceeds the fluid breakthrough overpressure threshold. The capillary action-based pressure threshold sensor is positioned such that the opposite side of the porous medium is in contact with the fluid where the overpressure event is detected, To provide a fluid detection element positioned at least proximal to the opposite side of a porous medium and configured to detect the presence of at least a target fluid on the opposite side of the porous medium, Methods that include...

11. The further includes providing a flow path and selecting a location where an overpressure event should be detected by a capillary action-based pressure threshold sensor, and / or The method further includes providing a fluid container and selecting a location where an overpressure event is detected by a capillary action-based pressure threshold sensor, and / or The method further includes providing a hole at a selected location and sealing the hole by fixing a porous medium over it, and / or The method according to claim 10, further comprising welding a porous medium to a material forming a channel.

12. A capillary action-based pressure threshold sensor includes at least two electrodes, and further includes, and / or, having the electrodes act as passive switches that remain open until they come into contact with a fluid and close. The method further includes, and / or, activating a notification when a passive switch is closed. The activation is selected from and / or from providing an input associated with the notification to a microcontroller connected to an electrode, and generating a signal by inducing a change in a signaling element in response to the fluid coming into contact with at least one side of a porous medium. The method further includes connecting one electrode to a ground pin of a microcontroller and the other electrode to an input pin of a microcontroller, and / or The method further includes connecting one electrode to an output pin of a microcontroller and the other electrode to an input pin of a microcontroller, and / or The method further includes connecting one electrode to the positive rail of a power supply having a common ground with the microcontroller, and / or connecting the other electrode to an input pin of the microcontroller. The method further includes, and / or, connecting pull-up resistors to the positive rail or reference voltage of the power supply for the microcontroller and input pins. The method further includes connecting a pull-down resistor between the input pin and the negative rail connected to the negative or ground terminal of the microcontroller, and / or The method according to claim 10, wherein the resistor has a resistance of approximately 1 k ohm to 100 M ohms.

13. The porous medium is selected from hydrophobic mediums, superhydrophobic mediums, oleophobic mediums, and porous mediums with both apathy and / or The method according to claim 10, wherein the porous properties of the porous medium are selected from pore size, thickness, material, surface shape, coating, and contact angle with the fluid.

14. A capillary action-based pressure threshold sensor, A first porous medium having at least one porous property and a fluid breakthrough pressure threshold that allows fluid to leak from its first side to its opposing second side when the fluid pressure exceeds the fluid breakthrough threshold of the first porous medium, A fluid detection element is positioned at least proximal to a second surface of a first porous medium and configured to detect the presence of at least a target fluid on the second surface of the first porous medium. A pressure threshold sensor equipped with the following features.

15. The invention further comprises two electrodes in contact with a second side surface of the first porous medium, and / or The first porous medium is selected from hydrophobic media, superhydrophobic media, oleophobic media, and porous media of both inaffiliations, and / or The pressure threshold sensor according to claim 14, wherein at least one porous property of the first porous medium is selected from pore size, thickness, material, surface shape, coating, and contact angle with fluid.

16. The present invention further comprises, at least, a second porous medium positioned at least proximal to a first side of the first porous medium so as to be in contact with the target fluid before the target fluid leaks through the first porous medium, wherein the second porous medium has one or more porous properties that allow the fluid to easily penetrate the second porous medium and prevent the gas from passing through the second porous medium after it has penetrated with the target fluid until the gas exceeds the intrusion pressure of the second porous medium, and / or The pressure threshold sensor according to claim 14, further comprising a second porous medium positioned at least proximal to the opposite side of the first porous medium so as to be in contact with the target fluid before the target fluid leaks through the first porous medium, wherein the second porous medium has one or more porous properties that allow the fluid to easily penetrate the second porous medium and enhance the contact between the target fluid and the fluid detection element.

17. The second porous medium is selected from hydrophilic media, superhydrophilic media, lipophilic media, and biaffinity porous media, and / or The second porous medium is selected from a material that swells upon contact with the fluid in the channel, and the fluid sensing element acts as a passive switch activated by the swelling of the second porous medium, and / or The fluid detection element comprises two electrodes in contact with a second porous medium, and / or The second porous medium is selected to have different conductivity when dry and when wetted by the fluid in the channel, and / or The fluid detection element comprises two electrodes consisting of contact pads on a printed circuit board (PCB), and / or The pressure threshold sensor according to claim 16, wherein the PCB is heat-crimped via a heat-crimping pin to be in close proximity to a second porous medium and to maintain direct contact with a first porous medium.

18. The fluid detection element includes at least two electrodes that act as passive switches that remain open until they come into contact with the fluid and close, and / or The sensor further comprises an indicator element configured to change state when a target fluid leaks through a first porous medium to a second side surface of the first porous medium, the changing state being selected from a color display and / or a change in color display. When the fluid detection element is closed, it generates a notification that can be processed by a microcontroller connected to the electrode, and / or One electrode is connected to the ground pin of the microcontroller, and the other electrode is connected to the input pin of the microcontroller, and / or One electrode is connected to an output pin of the microcontroller, and the other electrode is connected to an input pin of the microcontroller, and / or One electrode is connected to the positive rail of the power supply, which has a common ground with the microcontroller, and the other electrode is connected to an input pin of the microcontroller, and / or The sensor further comprises a pull-down resistor connected between the input pin and a negative rail connected to the negative or ground terminal of the microcontroller, and / or The sensor further comprises a pull-up resistor connected to the positive rail of the power supply or reference voltage for the microcontroller and input pin, and / or The pressure threshold sensor according to claim 14, wherein the pull-up resistor has a resistance of approximately 1 kΩ to 100 MΩ.

19. The fluid detection element is passive and remains unactivated until the target fluid leaks through the first porous medium and reaches the second side opposite the first porous medium, or The pressure threshold sensor according to claim 14, wherein the fluid detection element is active and provides different outputs to distinguish between a first state in which the target fluid has not yet leaked through the first porous medium and a second state in which the target fluid has leaked through the first porous medium.

20. The system further comprises a thermally responsive material covering a first porous medium, which detects a state selected from a specified temperature and a specified pressure change in a target fluid, and / or The pressure threshold sensor according to claim 14, wherein the thermally responsive material is poly-N-isopropylacrylamide (PNIPAM).

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