Backflow relief for subcutaneous infusion devices

Abstract

Systems and methods for mitigating backflow in subcutaneous infusion devices are disclosed. A medical device may include a base having a surface configured to be placed against a skin of a patient; and a subcutaneous assembly coupled to the base and configured to be inserted through the skin of the patient when the surface of the base is placed against the skin of the patient. The subcutaneous assembly includes an infusion cannula defining a lumen extending through the infusion cannula and configured to infuse fluid through the lumen, and a sensor configured to sense a biological analyte. An expandable member (e.g., an expandable material) is coupled to a radially outer surface of the subcutaneous component. The expandable member is configured to expand in a radially outward direction when bodily fluid is present, thereby at least partially blocking a flow path from the distal end portion of the infusion cannula to the sensor.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 642,576, filed May 3, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This technology generally relates to medical devices, and more specifically to subcutaneous infusion devices. Background Technology

[0004] This disclosure generally relates to subcutaneous sensors and infusion devices and systems, such as, but not limited to, infusion kits, injection ports, patch pump devices, or other medical devices and systems having at least one subcutaneous sensor probe and also configured for subcutaneous delivery of infusion media or other fluids. Additional examples relate to methods of using such devices and systems.

[0005] Modern medical technology allows for the monitoring or sensing of certain biological conditions using one or more analytical sensors inserted subcutaneously into a medical device. For example, subcutaneous sensors are commonly used to monitor blood glucose levels as part of diabetes treatment. A continuous glucose monitor (CGM) can monitor a patient's blood glucose levels over a period of time. Additionally, certain diseases or conditions can be treated by subcutaneously delivering medications or other substances into a patient's body via infusion kits, injection ports, patch pumps, or other medical devices. For example, diabetes is typically treated by delivering a predetermined amount of insulin to the patient at appropriate times. Some patients with a CGM may require multiple insulin injections per day.

[0006] Some patients use sensor devices to detect or monitor biological conditions or analytes associated with those conditions (such as, but not limited to, blood glucose levels) and may also benefit from infusion kit devices to deliver infusion media (such as, but not limited to, insulin) for treatment or in response to detected or monitored biological conditions or analytes. However, the installation and use of two devices (a sensor device and an infusion kit device), each with one or more subcutaneous components, can be inconvenient and uncomfortable for patients.

[0007] Therefore, certain exemplary medical devices as described herein may include one or more sensors and one or more infusion cannulas in a single medical device, the sensors and cannulas being configured to facilitate the sensing or monitoring of one or more biological conditions or analytes, as well as the subcutaneous infusion of drugs or other infusion media. In some examples, at least one sensor and at least one infusion cannula are configured for combined insertion at a single location at the insertion site via a single insertion needle. By employing a device including sensors for detecting one or more biological conditions or analytes and an infusion cannula for infusing the infusion media in a single device as described herein, the area occupied by the device worn by the patient can be reduced, and / or the number of needle insertions can be reduced. These aspects can result in reduced foreign body reactions and / or can produce sites with minimal scarring in the dermis.

[0008] However, for medical devices configured as described herein (for delivering infusion media at or near the subcutaneous site of a sensor element), reducing or minimizing interference of the infusion media with sensor operation may be beneficial. For example, stabilizers in insulin (or other infusion media) may interfere with the sensor signal. Additionally, the volume of insulin (or other infusion media) infused during bolus administration may dilute local tissue glucose (or other parameters), resulting in sensor signal attenuation and therefore inaccurate readings. One or more of these effects are referred to herein as interference effects. Therefore, certain examples described herein are configured to increase isolation between the infusion cannula and the sensor (e.g., by increasing functional separation between the outlet opening of the infusion cannula and the working electrode of the sensor), for example by mitigating backflow of the media delivered via the infusion cannula, while simultaneously enabling the device to deliver the infusion media at or near the same insertion site as the sensor.

[0009] The specific examples described herein offer additional advantages and overcome problems encountered when arranging the sensor and infusion cannula in the same device or inserting the sensor element and infusion cannula into a single insertion needle. Summary of the Invention

[0010] Typically, in some embodiments according to the present technology, the medical device includes: a base having a first surface configured to rest against a patient's skin; and a subcutaneous assembly coupled to the base and extending away from the first surface. The subcutaneous assembly is configured to be inserted through the patient's skin at an insertion site when the first surface of the base rests against the patient's skin. The subcutaneous assembly includes: an infusion cannula defining a lumen extending through the infusion cannula and configured to infuse fluid through the lumen and allow the fluid to flow out from a distal opening of the infusion cannula; a sensor configured to sense a bioanalyte corresponding to a biological condition; and an expandable member coupled to a radially outer surface of the subcutaneous assembly. The expandable member is configured to extend radially outward in the presence of bodily fluid, thereby at least partially obstructing the flow path from the distal opening of the infusion cannula to the sensor.

[0011] In some embodiments, the expandable member comprises a biocompatible hydrogel and / or an expandable polymer. The expandable member may include an inner expandable layer having a first radial thickness and an outer barrier layer having a second radial thickness less than the first radial thickness, such that the outer barrier layer has a higher elastic modulus than the inner expandable layer. In some embodiments, the expandable member is coupled to at least a distal end portion of the infusion cannula. The expandable member may extend circumferentially around the infusion cannula. Alternatively or additionally, the expandable member is disposed only along a portion of the infusion cannula extending distally beyond the distal end of the sensor. In some cases, the expandable member is disposed above at least a portion of the sensor. Optionally, the sensor includes at least one electrode, and the expandable member does not extend above the at least one electrode.

[0012] In some embodiments, the expandable member is configured to expand in the radially outward direction to at least twice its size in its unexpanded state. The expandable member may include a coating having an unexpanded thickness of less than about 40 micrometers and an expanded thickness of at least 80 micrometers in the presence of bodily fluids. In some embodiments, the infusion cannula has at least one surface feature configured to receive the expandable member thereon. The surface feature may include a recess, groove, protrusion, or other suitable structure. Optionally, the sensor includes at least one electrode, wherein the at least one electrode is spaced at least about 5 mm from the distal end of the infusion cannula. In some specific embodiments, the subcutaneous assembly is configured to be inserted via a single insertion needle.

[0013] Typically, in some embodiments according to the present technology, the medical device includes a housing and an infusion cannula. The housing is configured to be placed over a patient's skin, and the infusion cannula is coupled to the housing and configured to extend through the patient's skin when the housing is placed over the patient's skin. The infusion cannula includes a tubular member defining a lumen through the tubular member and an opening at a distal end portion. The medical device further includes a sensor coupled to the housing and configured to extend through the patient's skin when the housing is placed over the patient's skin. The sensor includes a working electrode arranged such that the working electrode is spaced at least 5 mm from the opening at the distal end portion of the infusion cannula. An expandable material is disposed above the radially outer surface of the infusion cannula and is configured to expand in the presence of bodily fluid to mitigate backflow of infusion fluid dispensed through the opening of the infusion cannula.

[0014] In some embodiments, the expandable material extends circumferentially around the infusion cannula. The expandable material may be disposed only along a portion of the infusion cannula extending distally beyond the distal end of the sensor. Optionally, the expandable material is disposed above at least a portion of the sensor. The infusion cannula may include at least one surface feature configured to receive the expandable material thereon.

[0015] Typically, in some embodiments according to this technology, a method includes positioning a medical device such that its base is positioned against a patient's skin, and a subcutaneous component of the medical device penetrates the patient's skin and extends into the patient's body so that the subcutaneous component comes into contact with bodily fluids. The subcutaneous component includes an infusion cannula and a sensor. The method further includes allowing an expandable member coupled to the radially outer surface of the subcutaneous component to expand radially outward in the presence of bodily fluids. Fluid is dispensed through a distal opening of the infusion cannula, and the expandable member mitigates backflow of the dispensed fluid along the proximal direction of the infusion cannula.

[0016] In some embodiments, the sensor includes a working electrode, and an expandable member is disposed between the distal opening of the infusion cannula and the working electrode of the sensor. This expandable member can expand radially outward to at least twice its size in its unexpanded state. Optionally, setting up the medical device involves positioning the base against the patient's skin and then inserting the subcutaneous component under the patient's skin via a single insertion needle.

[0017] Other technical features will be obvious to those skilled in the art based on the following figures, detailed embodiments and claims. Attached Figure Description

[0018] Many aspects of this disclosure can be better understood by referring to the following accompanying drawings. The components in the drawings are not necessarily drawn to scale. Rather, the focus is on clearly illustrating the principles of this disclosure.

[0019] Figure 1A This is a side view of a medical device including a subcutaneous component according to an embodiment of the present technology.

[0020] Figure 1B yes Figure 1A An enlarged perspective view of the subcutaneous component of the medical device shown in the image.

[0021] Figure 1C yes Figure 1B An enlarged perspective view of the distal end portion of the subcutaneous assembly shown in the image.

[0022] Figure 2A This is a schematic side view of a medical device for delivering subcutaneous fluid via an infusion cannula according to an embodiment of the present technology.

[0023] Figure 2B This is a schematic side view of a medical device for delivering subcutaneous fluid via an infusion cannula with expandable components to alleviate reflux, according to an embodiment of the present technology.

[0024] Figures 3A to 3D Various configurations of a subcutaneous assembly with expandable components according to embodiments of the present technology are shown.

[0025] Figure 4A This is a side sectional view of an infusion sleeve with expandable components according to an embodiment of the present technology.

[0026] Figure 4B yes Figure 4A The diagram shows a top sectional view of an infusion sleeve with expandable components.

[0027] Figure 5 This is a top sectional view of another exemplary infusion sleeve with expandable components according to an embodiment of the present technology.

[0028] Figure 6A This is a perspective view of the distal portion of an infusion cannula with surface features according to an embodiment of the present technology.

[0029] Figure 6B It is an embodiment of the present technology having an expandable member disposed within a surface feature. Figure 6A The infusion cannula shown is a cross-sectional view.

[0030] Figure 7 This is a cross-sectional view of another exemplary infusion sleeve with surface features according to an embodiment of the present technology.

[0031] Figure 8A This is a cross-sectional view of an infusion sleeve having surface features and an expandable component in an unexpanded state, according to an embodiment of the present technology.

[0032] Figure 8B It has surface features and is in an extended structure. Figure 8A A cross-sectional view of the infusion sleeve of the expandable component shown.

[0033] Figure 9A This is a perspective view of the distal portion of an infusion cannula with surface features according to an embodiment of the present technology.

[0034] Figure 9B This is a cross-sectional view of an infusion sleeve having an expandable member disposed within a surface feature, according to an embodiment of the present technology.

[0035] Figure 9C It is a side sectional view of an infusion sleeve with an expandable component in an unexpanded state.

[0036] Figure 9D It is in an extended state. Figure 9C The side sectional view of the infusion sleeve of the expandable component shown.

[0037] Figure 10 This is a perspective view of the distal portion of an infusion cannula with surface features according to an embodiment of the present technology.

[0038] Figure 11 This is a perspective view of the distal portion of an infusion cannula with surface features according to an embodiment of the present technology.

[0039] Figure 12 This is a perspective view of the distal portion of an infusion cannula with surface features according to an embodiment of the present technology. Detailed Implementation

[0040] I. Overview

[0041] One challenge with fluid infusion devices (such as infusion kits, patch pumps, or the like) is the tendency of subcutaneously delivered fluid to flow backward after exiting the cannula (e.g., diffuse in the direction opposite to the flow through the cannula). This backflow or leakage of the infused fluid can have detrimental consequences. First, the accumulation of fluid around the outer surface of the cannula can widen the radial gap between the outer surface of the cannula and the surrounding tissue due to elastic deformation or damage to the tissue surrounding the cannula. Additionally, fluid leakage can lead to problems with effective absorption in the subcutaneous tissue, as a portion of the infused fluid may not reach the intended delivery site. This can result in wasted fluid, requiring a larger dose to be effective in the patient. In the case of medications such as insulin, this also increases costs for the patient. These challenges are amplified with shorter cannulas (e.g., less than 10 mm in length), and especially with microneedles (e.g., ranging in length from 0.5 mm to 2.5 mm). While the use of microneedles can allow for faster insulin absorption, the benefits are diminished when leakage due to backflow occurs. Additionally, when the sensor is placed near the infusion cannula, fluid backflow from the cannula may pose an additional risk of interfering with the sensor's ability to detect bioanalytes corresponding to biological conditions (e.g., glucose concentration).

[0042] This technology addresses these and other problems by providing an expandable component coupled to the distal portion of the infusion cannula. The expandable component can be configured to expand radially after subcutaneous insertion of the infusion cannula. In its expanded state, the expandable component mitigates backflow of fluid discharged from the infusion cannula. In various embodiments, the expandable component can take the form of a biocompatible polymer, such as a hydrogel, or other suitable material configured to expand or otherwise enlarge in the presence of a biofluid. In embodiments involving combined infusion and sensor devices, the expandable component can be at least partially disposed between the sensor and the outlet of the infusion cannula, such that the expandable component reduces fluid transfer from the infusion cannula toward the sensor, thereby reducing interference with sensor operation due to fluid backflow.

[0043] II. Exemplary medical device including infusion cannula and sensor

[0044] Figure 1AA side view of a medical device 100 is shown. This device may be a combined continuous glucose monitoring (CGM) sensor and fluid delivery device, such as an infusion kit, which can be coupled to a separate pump unit. In some embodiments, the medical device 100 may be in the form of a patch pump, in which the pump mechanism is integrated with the CGM sensor and the fluid delivery device. The medical device 100 includes a base 101 having a lower surface 103 configured to contact and adhere to a patient's skin. The base 101 may be made of a flexible material to conform to the contours of the patient's body, thereby ensuring a secure and comfortable fit. The medical device 100 further includes a subcutaneous component 105 extending away from the base 101. This subcutaneous component 105 is configured to penetrate the patient's skin to infuse fluids, such as insulin or other medications, for continuous glucose monitoring.

[0045] Figure 1B Provided Figure 1A The enlarged perspective view of the subcutaneous assembly 105 shown reveals its main components. The subcutaneous assembly 105 includes an infusion cannula 107 and a sensor 109, which are arranged close to each other. This close arrangement facilitates easy insertion and patient comfort, as it requires only a single insertion site and minimizes skin irritation. In an alternative arrangement, the infusion cannula 107 and the sensor 109 may be spaced apart from each other across the base 101.

[0046] The infusion cannula 107 includes an elongated body 115 having a distal end 117. The elongated body 115 of the infusion cannula 107 may be made of a flexible biocompatible material, such as polytetrafluoroethylene (PTFE), polyethylene, polyether block amide (PEBA), or other suitable materials to ensure patient comfort and safety.

[0047] Figure 1C An enlarged perspective view of the distal end portion of the subcutaneous assembly 105 is provided. The infusion cannula 107 defines a through passage at a distal opening 119 terminating at the distal end 117 of the infusion cannula 107, through which fluids such as insulin or other medications can exit the infusion cannula 107 and be delivered to the patient's subcutaneous tissue. The size and shape of the distal opening 119 can be optimized to control the flow rate and distribution pattern of the infusion fluid.

[0048] like Figure 1B and Figure 1CAs shown, sensor 109 includes an elongated body 111 carrying a plurality of electrodes 113. These electrodes 113 are used to measure bioanalytes (e.g., glucose levels in the patient's interstitial fluid) within the body, thereby enabling continuous analyte monitoring. In operation, when the subcutaneous assembly 105 is inserted into the patient's body, one or more of the individual electrodes 113 are configured to make electrical contact with a biofluid or tissue. In various examples, electrodes 113 may include at least one working electrode, at least one reference electrode, and at least one control electrode. In one example, the working electrode may be configured to provide a positive current response when an analyte (e.g., glycerol, phenol, and / or m-cresol) arrives at the working electrode. In other examples, electrodes 113 may have other configurations with one or more electrodes. The number of individual electrodes 113 can vary, for example, having 2, 3, 4, 5, 6, 7, 8, 9, or more electrodes 113.

[0049] exist Figures 1A to 1C In the example shown, electrode 113 is disposed on the side of sensor body 111 facing away from infusion sleeve 107. By arranging electrode 113 on that side of sensor body 111, electrode 113 can be oriented to face away from infusion sleeve 107, which can help increase the separation or isolation of electrode 113 from the distal opening 119 of infusion sleeve 107.

[0050] In the illustrated embodiment, the infusion cannula 107 has an axial length approximately equal to the axial length of the sensor 109. In other examples, the infusion cannula 107 may have an axial length longer than the axial length of the sensor 109, or it may be provided with an axial length shorter than the axial length of the sensor 109, to increase the separation distance between the distal opening 119 of the infusion cannula 107 and the electrode 113 of the sensor 109. Alternatively or additionally, the medical device 100 may be implemented with an angled insertion direction, for example, to achieve a greater separation or isolation distance or improved patient comfort (or both).

[0051] In any of the examples described herein, the infusion cannula 107 may be configured with one or more openings through the sidewall of the cannula for discharging the infusion medium. Such sidewall openings may be provided instead of... Figure 1CThe distal opening 119 shown may be a supplement to this distal opening. In certain examples, one or more openings may be provided on the side of the infusion cannula 107 opposite to the sensor 109 (in the opposite direction of the sensor). In some examples, the distal end 117 of the infusion cannula 107 may be closed to allow the infusion medium to drain only from one or more sidewall openings, and not from the distal end of the cannula 107. By arranging the openings on one side of the infusion cannula 107, the openings may be oriented opposite to the sensor 109, such that the infusion medium is completely (or partially) drained in a direction away from the sensor 109, to help increase the separation or isolation of the sensor 109 from the infusion medium outlet of the infusion cannula 107.

[0052] III. Exemplary scalable component for mitigating backflow

[0053] Figure 2A A medical device 100 is depicted positioned above a patient's skin 201, with a subcutaneous component 105 penetrating into the patient's skin. In the example shown, the distal end of sensor 109 is spaced apart from the distal end 117 of infusion cannula 107 by a distance D1. In other embodiments, the distal end 117 of infusion cannula 107 may be aligned with the distal end of sensor probe 109, and the working electrode of sensor 109 may be spaced apart from the distal end 117 of infusion cannula 107 by a distance D1. While close proximity of infusion cannula 107 and sensor 109 is advantageous for ease of insertion and patient comfort, it may lead to problems associated with backflow. Figure 2A As shown, the fluid 203 delivered via the infusion cannula 107 can diffuse and backflow in a proximal direction (e.g., toward the skin 201). This backflow includes diffusion toward the area adjacent to the electrode 113 of the sensor 109, which can interfere with the accuracy of readings obtained by the electrode 113, such as glucose level readings. The presence of the infusion fluid 203 near the electrode 113 can alter the local glucose concentration and lead to erroneous measurement results. In various examples, the distance D1 can be at least about 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or greater. In some embodiments, the distance D1 is no greater than about 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, 1 mm or less.

[0054] Figure 2B An arrangement to mitigate the reflux problem is presented, showing the medical device 100 and... Figure 2AThe infusion cannula 107 is similarly positioned, but now features an expandable member 200 positioned above the distal end portion of the infusion cannula 107. In various examples, the expandable member 200 is an expandable material configured to expand radially in the presence of a biofluid. In operation, the expandable member 200 mitigates backflow of the fluid 203, which prevents or reduces the amount of fluid 203 that comes into contact with or otherwise interferes with the readings obtained via the electrodes 113 of the sensor 109. Upon exposure to the interstitial fluid, the expandable member 200 expands and forms a barrier that helps confine the fluid 203 to the area around the distal end 117 of the infusion cannula 107, thereby minimizing the likelihood of the fluid 203 reaching and interfering with the electrodes 113 of the sensor 109. This also reduces the likelihood of localized glucose dilution, which could be another cause of erroneous low readings of the sensor value via the sensor 109. In addition to reducing the risk of interference with the electrodes 113, the expandable member 200 also promotes greater lateral dispersion of the fluid 203, thereby increasing the surface area to volume ratio of the fluid, which will result in increased absorption.

[0055] The expandable component 200 can be a hydrogel or other polymer that exhibits significant swelling or other expansion when exposed to aqueous fluids. By controlling the backflow of the infusion fluid 203, the expandable component 200 helps maintain the accuracy of the glucose readings obtained by the sensor 109, while still allowing for tight placement of the infusion cannula 107 and the sensor 109 to improve patient comfort and ease of use.

[0056] Figures 3A to 3D Various configurations of the subcutaneous assembly 105 with the expandable member 200 are shown. These figures illustrate different configurations of the expandable member 200 relative to the distal end 117 of the infusion cannula 107 and the electrode 113 of the sensor 109.

[0057] exist Figure 3A In this configuration, the expandable member 200 is positioned at the distal end 117 of the infusion cannula 107. The expandable member 200 extends axially from the distal end 117 but does not reach the proximal end of the sensor 109, and therefore does not axially overlap with the electrode 113. This configuration allows the expandable member 200 to mitigate backflow of the infusion fluid while maintaining separation between the expandable member 200 and the electrode 113.

[0058] Figure 3B It shows the relationship with Figure 3ACompared to a further axially extended expandable member 200, in this arrangement, the expandable member 200 reaches the proximal end of the electrode 113 on the sensor 109, for example, covering a single electrode 113. The expandable member 200 may extend partially or completely circumferentially around the subcutaneous assembly 105. The expandable member 200 provides a larger barrier to prevent fluid backflow, while still leaving at least some individual electrodes 113 uncovered.

[0059] exist Figure 3C In this configuration, the expandable member 200 extends further axially to the location where multiple electrodes 113 are covered, but at least one individual electrode 113 remains uncovered. This configuration provides a more comprehensive barrier to prevent fluid backflow because the expandable member 200 covers a significant portion of the axial length of the electrode 113. However, the expandable member 200 does not cover all electrodes 113, leaving at least one electrode uncovered.

[0060] Figure 3D An expandable member 200 is depicted that extends only around the infusion cannula 107 and not around the sensor 109. In this configuration, the electrode 113 of the sensor 109 may be completely uncovered by the expandable member 200. In this arrangement, the expandable member 200 provides extensive obstruction to prevent fluid backflow without covering the electrode 113.

[0061] Figures 3A to 3D The different configurations shown illustrate various options for positioning the expandable member 200 relative to the electrode 113 of the infusion cannula 107 and sensor 109. The optimal configuration for a given application will depend on various factors, such as the specific design of the medical device, the nature of the expandable member 200 and the electrode 113 of the sensor 109, and the desired balance between reflux mitigation and maintaining separation between the expandable member 200 and the electrode 113. Additionally, while the expandable member 200 is depicted in each case as extending fully to the distal end 117 of the infusion cannula 107, in some embodiments, the expandable member 200 does not extend to the distal end 117 but is axially spaced from the distal end 117 of the infusion cannula 107. Furthermore, while the expandable member 200 is depicted as a cylindrical body with uniform radial dimensions, in various embodiments, the expandable member 200 may have varying cross-sectional profiles, such as tapering distally or proximally, bending, undulation, and / or surface features such as protrusions, bulges, recesses, grooves, or other suitable constructions.

[0062] Figure 4AA side sectional view of an infusion cannula 107 equipped with an expandable member 200 is shown. As described above, the infusion cannula 107 may include an elongated body 115 having a distal end 117. The expandable member 200 is disposed above the distal end portion of the infusion cannula 107 and surrounds the body 115 in the region near the distal end 117.

[0063] In the example shown, the expandable member 200 takes the form of a multi-layered assembly, including an inner portion 401 and a surrounding outer portion 403. The inner portion 401 acts as the primary expansion element, while the outer portion 403 serves as a stiffer barrier layer to prevent excessive expansion and maintain the mechanical integrity of the expandable member 200 in its expanded state. In both the unexpanded and expanded states, the radial thickness of the inner portion 401 is greater than the radial thickness of the outer portion 403. Additionally, the outer portion 403 may have a higher elastic modulus (e.g., Young's modulus) compared to the inner portion 401.

[0064] The expandable member 200 can be configured to expand to at least twice its initial radial dimension when exposed to an aqueous fluid. In various embodiments, the expandable member 200 can achieve a radial dimension that is 3, 4, 5, 6, 7, 8, 9, or even 10 times larger than its radial dimension in its expanded configuration. The unexpanded thickness of the expandable member 200 can range from about 10 micrometers to 500 micrometers, with specific examples being about 20 micrometers, 30 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, 90 micrometers, 100 micrometers, 110 micrometers, 120 micrometers, 130 micrometers, 140 micrometers, 150 micrometers, 160 micrometers, 170 micrometers, 180 micrometers, 190 micrometers, or 200 micrometers.

[0065] Suitable materials for the inner portion 401 include poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA), which are water-soluble polymers composed of hydrophilic polymer chains. These polymers exhibit significant expansion upon contact with aqueous fluids, making them ideal for forming a plug around the infusion sleeve 107 to mitigate backflow and interference with the electrodes of adjacent sensors. Thickeners, such as sodium alginate, can be mixed with PEO or PVA to increase the mechanical integrity of the inner portion 401 upon hydration and further enhance backflow resistance. A specific example involves using a combination of 2.3% PEO, 0.4% sodium alginate, and 7% PVA (w / v) to coat the sleeve 107 using a dip-coating technique.

[0066] Other examples of biocompatible hydrogels suitable for the inner portion 401 include polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), polyacrylamide-chitosan hydrogel, poly(2-hydroxyethyl methacrylate) (PHEMA), and hyaluronic acid (HA). Additionally, NAFION (a fluoropolymer-copolymer based on sulfonated tetrafluoroethylene) and NAFION composite films can be used as interference-inhibiting membranes to reduce the influence of insulin excipients on the glucose sensor. In one example, the inner portion 401 may comprise NAFION, PEO, and sodium alginate with a thickness of approximately 25 to 30 micrometers, while the outer portion 403 may be PVA with a thickness of approximately 5 micrometers.

[0067] To ensure proper retention of the expandable member 200 on the infusion sleeve 107, an adhesive material may be provided between the inner portion 401 and the outer surface of the body 115. Examples of suitable adhesive materials include 3-(trimethoxysilyl)propyl methacrylate, poly(ethylene glycol) bis(carboxymethyl) ether, poly(ethylene glycol) diglycidyl ether, or any other material that promotes adhesion between the radially inner surface of the expandable member 200 and the radially outer surface of the infusion sleeve 107.

[0068] Figure 4B Provided Figure 4A The diagram shows a top sectional view of the infusion sleeve 107 and the expandable member 200. In this example, the body 115 of the infusion sleeve 107 has a triangular cross-section. The expandable member 200 is applied as a coating around the body 115 to conform to the triangular shape of the body. The inner portion 401 of the expandable member 200 has a triangular cross-section that matches the shape of the body 115, while the outer portion 403 has a circular cross-section surrounding the inner portion 401.

[0069] Figure 5 Another example of the infusion cannula 107 and the expandable member 200 is shown. In this embodiment, the body 115 of the infusion cannula 107 has a circular cross-section. The expandable member 200 is applied as a substantially uniform coating around the body 115, resulting in both the inner portion 401 and the outer portion 403 of the expandable member 200 having circular cross-sections. This configuration demonstrates the adaptability of the expandable member 200 to different cross-sectional shapes of the infusion cannula 107.

[0070] In both examples, the expandable component 200 can be designed to expand to multiples of its initial radial dimension when exposed to an aqueous fluid. Specific materials selected for the inner portion 401 and outer portion 403, such as PEO, PVA, sodium alginate, NAFION (a fluoropolymer-polymer copolymer based on sulfonated tetrafluoroethylene), and other biocompatible hydrogels, enable significant expansion while ensuring safety for long-term use. The multi-layered design of the expandable component 200 (where the inner portion 401 acts as the primary expansion element and the outer portion 403 serves as a barrier layer) allows for controlled expansion and maintained mechanical integrity in the expanded state.

[0071] Figure 6A and Figure 6B An infusion cannula 107 is shown having a plurality of surface features 601 formed in the body 115 of the cannula. Figure 6A A perspective view of the infusion cannula 107 is provided, while Figure 6B A cross-sectional view of the infusion cannula is shown. Surface feature 601 may take the form of a recess, groove, indentation, pawl, or other similar feature that can accommodate expandable material to form expandable member 200. In the example shown, surface feature 601 is a semi-cylindrical recess extending axially along a portion of the body 115 of the infusion cannula 107. These cylindrical recesses may terminate proximally at the distal end 117 of the body 115, or, in alternative embodiments, they may extend together with the distal end 117 of the infusion cannula 107.

[0072] Depending on the desired characteristics of the expandable member 200, the surface feature 601 can take various forms and shapes. As a complement or alternative to the illustrated semi-cylindrical recess, the surface feature 601 can be partially spherical or elliptical, or have a rectangular, triangular, or other prismatic cross-sectional shape. Furthermore, the surface feature 601 can extend axially, circumferentially, helically, or in any other suitable manner around the body 115 of the infusion sleeve 107. The number and arrangement of the surface features 601 can also be varied to achieve a specific extended profile and mechanical properties of the expandable member 200.

[0073] like Figure 6B As depicted, the expandable members 200, formed of material received within surface feature 601, are substantially flush with the radially outer surface of the infusion sleeve 107 in a pre-expanded state. Upon exposure to an aqueous fluid, the expandable members 200 expand radially outward, such that the radially outer surface of each expandable member 200 protrudes beyond the radially outermost surface of the body 115 of the infusion sleeve 107. This expansion helps to secure the infusion sleeve 107 in place and prevent fluid backflow.

[0074] Figure 7Another example of an infusion cannula 107 with surface feature 601 is presented. In this case, the infusion cannula 107 has a circular cross-section, and the surface feature 601 is a recess with a semi-circular cross-section. The circular cross-section of the infusion cannula 107 allows the surface feature 601 to be distributed more evenly around the circumference of the body 115.

[0075] Surface features 601 can be arranged in various patterns to achieve desired expansion characteristics. For example, surface features 601 can be arranged in a linear array along the length of the infusion sleeve 107, or they can be staggered to provide more uniform expansion. Additionally, surface features 601 can be grouped into multiple sets, where each set has a different size, shape, or orientation to produce a specific expansion profile. The spacing between surface features 601 can also be adjusted to control the overall expansion of the expandable member 200 and the mechanical properties of the infusion sleeve 107.

[0076] Figure 8A A cross-sectional view of the infusion cannula 107 is shown, in which the expandable member 200 is disposed around the outer surface of the cannula in an unexpanded state. A recessed surface feature 601 causes the radial thickness of the expandable member 200 to be greater in the region aligned with the surface feature 601. This variation in thickness allows the expandable member 200 to expand in a controlled manner upon exposure to fluid.

[0077] Figure 8B An infusion sleeve 107 with an expandable member 200 in an extended state is shown. Due to the increased thickness of the expandable member 200 in the region aligned with surface feature 601, those portions of the expandable member 200 protrude radially outward beyond other portions of the expandable member 200 during expansion. The outermost surface of this protrusion creates a wavy extended profile, which can be customized by selecting an appropriate number, geometry, and arrangement of surface features 601 around the infusion sleeve 107.

[0078] Surface feature 601 can be designed to facilitate specific expansion characteristics. For example, a larger or deeper surface feature 601 can result in a larger local expansion of the expandable member 200, while a smaller or shallower surface feature 601 can provide a wider expansion. The orientation of surface feature 601 can also affect the expansion profile, with axially oriented features promoting longitudinal expansion and circumferentially oriented features promoting radial expansion.

[0079] In addition to enhancing properties, surface feature 601 can also be used to improve the mechanical properties of the infusion tubing 107. By strategically placing surface feature 601, the flexibility, stability, and kink resistance of the infusion tubing 107 can be improved. For example, surface feature 601 arranged in a spiral pattern can increase the flexibility of the tubing while maintaining its structural integrity.

[0080] The combination of the expandable member 200 and the surface feature 601 on the infusion cannula 107 offers several advantages. The expandable member 200 helps secure the infusion cannula 107 in place, prevents fluid backflow, and potentially reduces irritation to surrounding tissues. The surface feature 601 allows for customization of the expansion profile and mechanical properties of the infusion cannula 107, enabling optimization for specific applications and patient needs.

[0081] In some embodiments, the surface feature of the infusion cannula 107 may take the form of a recessed portion, wherein the recess extends circumferentially around the body 115 of the infusion cannula 107. Such a circumferential recess allows for the arrangement of an expanded, thicker member 200 above the body 115 of the infusion cannula 107 in its unexpanded state without increasing the overall radial outermost dimension of the infusion cannula 107 for subcutaneous insertion. Examples of such a circumferential recess are shown in... Figures 9A to 12 As shown in the image.

[0082] Figure 9A A perspective view of the distal portion of the infusion cannula 107 is presented, which has a surface feature 901 in the form of a circumferentially extending recess at the distal end of the cannula 107. The recess 901 is designed to accommodate an expandable member 200, which may be formed of a swellable material. Placing the recess 901 at the distal end of the infusion cannula 107 allows the expandable member 200 to be targeted and expanded in this region.

[0083] Figure 9B A cross-sectional view of an infusion cannula 107 is shown, which has an expandable member 200 disposed within a recess 901. The expandable member 200 fills the recess 901 and creates a smooth outer surface flush with the non-recessed portion of the infusion cannula 107 in its unexpanded state. As shown, the expandable member 200 has an unexpanded thickness D2 above the infusion cannula 107. This configuration minimizes the overall profile of the infusion cannula 107 during insertion, thereby reducing patient discomfort and tissue trauma.

[0084] Figure 9C and Figure 9D Side sectional views of the infusion cannula 107 in its unexpanded and expanded states are shown respectively. In the unexpanded state ( Figure 9C Under these conditions, the expandable member 200 has a first thickness D2 in the farthest region (also as...). Figure 9BAs shown in the diagram, the first thickness covers the recessed surface feature 901. Conversely, the expandable member 200 has a smaller thickness D3 in the region near the surface feature 901. This variation in thickness is due to the presence of the recess 901, which allows for the placement of a larger volume of expandable material in the farthest region.

[0085] When the expandable component 200 is exposed to fluid and expands ( Figure 9D The thickness variation becomes more pronounced. A portion of the surface feature 901 covering the recess of the expandable member 200 exhibits an increased thickness D4, while the proximal portion extends to a smaller thickness D5 (which is still increased relative to thickness D3). This configuration results in the distal segment of the expandable member 200 defining the radially largest portion, thereby effectively forming a plug to mitigate backflow of fluid discharged from the distal end 117 of the infusion sleeve 107.

[0086] The circumferentially extending recess 901 can be modified in various ways to achieve different expansion profiles and mechanical properties. For example, the depth and width of the recess 901 can be adjusted to control the amount of expandable material that can be accommodated, thereby affecting the degree of expansion. In addition, the recess 901 can be formed with different cross-sectional shapes, such as rectangles, triangles, or semicircles, to produce specific expansion geometries.

[0087] Figure 10 A perspective view of the distal portion of the infusion cannula 107 is presented, which has surface feature 1001 in the form of a circumferentially extending recess. Figures 9A to 9D The recessed part 901 is different. Figure 10 The surface feature 1001 does not extend to the distal end 117 of the infusion cannula 107. Instead, the recess 1001 extends along length D6, leaving a non-recessed portion 1003 of the body 115 distal to the surface feature 1001. This non-recessed portion 1003 has a length D7 and may have a radial outermost dimension similar to other non-recessed portions of the body 115, such as those located proximal to the recessed surface feature 1001.

[0088] The presence of the non-recessed portion 1003 distal to surface feature 1001 offers several advantages. First, it helps secure the expandable member 200 within the area covering surface feature 1001, particularly during proximal withdrawal of the infusion cannula 107. Second, the non-recessed portion 1003 helps maintain the structural integrity of the distal end 117 of the infusion cannula 107, thereby preventing potential collapse or deformation of the cannula tip during insertion.

[0089] Figure 11A perspective view of another exemplary infusion cannula 107 is shown, which has a surface feature 901 in the form of a circumferentially extending recess. This infusion cannula 107 and the recess 901 are similar to... Figures 9A to 9D The main difference between those described in the text is that... Figure 11 The infusion sleeve 107 has a generally cylindrical cross-sectional shape. This cylindrical geometry can result in a more uniform distribution of the expandable members 200 around the circumference of the infusion sleeve 107, thereby potentially enhancing the sealing effect and reducing fluid backflow.

[0090] Figure 11 The cylindrical cross-section of the infusion cannula 107 also provides opportunities to modify the surface feature 901 in different ways. For example, the recess 901 can be formed as a continuous helical groove extending along the distal portion of the infusion cannula 107, rather than a single circumferential recess. This helical configuration can provide a more progressive extended profile and can improve the flexibility of the infusion cannula 107 in the distal region.

[0091] Figure 12 A perspective view of the distal portion of another exemplary infusion cannula 107 is presented, which has a surface feature 1001 in the form of a circumferentially extending recess, adjacent to a non-recessed portion 1003 of the body 115. This infusion cannula 107 and recess 1001 are similar to... Figure 10 The main difference between those described in the text lies in the cylindrical cross-sectional shape of the infusion sleeve 107.

[0092] IV. in conclusion

[0093] Although these devices and methods are described in the context of drug infusion devices (such as infusion kits or patch pumps), it should be understood that these techniques are equally applicable to a wide range of fluid delivery devices, whether other medical or non-medical devices delivering fluids. For example, this technology can also be applied to devices for delivering other drugs, such as, for instance, pain-masking medications, chemotherapy and other cancer-related drugs, antibiotics, hormones, GLP-1, glucagon, and various other drugs, including macromolecules and proteins that may require high levels of delivery precision. This technology can also be applied to devices for delivering non-drug fluids.

[0094] The description of embodiments of this technology is not intended to be exhaustive or to limit the technology to the exact forms disclosed above. Where the context permits, singular or plural terms may also include plural or singular terms respectively. While specific embodiments and examples of this technology have been described above for illustrative purposes, those skilled in the art will recognize that various equivalent modifications can be made within the scope of this technology. For example, although the steps are presented in a given order, alternative embodiments may perform the steps in a different order. The various embodiments described herein may also be combined to provide other embodiments.

[0095] As used herein, the terms “overall,” “substantially,” “about,” and similar terms are used as approximate terms rather than as terms of degree, and are intended to take into account the inherent biases of the measured or calculated values ​​that will be recognized by one of ordinary skill in the art.

[0096] Furthermore, the term "comprising" is used throughout to mean that at least the listed features are included, without excluding any larger number of the same features and / or other features of additional types. It should also be understood that specific embodiments have been described herein for illustrative purposes, but various modifications may be made without departing from the present technology. Additionally, while advantages associated with certain embodiments of the present technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments are required to exhibit such advantages to fall within the scope of the present technology. Therefore, this disclosure and associated technology may cover other embodiments not explicitly shown or described herein.

Claims

1. A medical device, the medical device comprising: A base having a first surface configured to rest against the patient's skin; A subcutaneous assembly, the subcutaneous assembly being coupled to the base and extending away from the first surface, the subcutaneous assembly being configured to be inserted through the patient's skin at an insertion site when the first surface of the base is placed against the patient's skin, the subcutaneous assembly comprising: An infusion cannula, the infusion cannula defining a lumen extending through the infusion cannula and configured to infuse fluid through the lumen and allow the fluid to flow out from a distal opening of the infusion cannula; Sensors configured to sense bioanalytes corresponding to biological conditions; and An expandable member is coupled to the radially outer surface of the subcutaneous assembly, wherein the expandable member is configured to expand in a radially outward direction in the presence of body fluid, thereby at least partially blocking the flow path from the distal opening of the infusion cannula to the sensor.

2. The medical device of claim 1, wherein the expandable component comprises a biocompatible hydrogel.

3. The medical device of claim 1, wherein the expandable component comprises an expandable polymer.

4. The medical device of claim 1, wherein the expandable member comprises an inner expandable layer having a first radial thickness and an outer barrier layer having a second radial thickness less than the first radial thickness, wherein the outer barrier layer has a higher elastic modulus than the inner expandable layer.

5. The medical device of claim 1, wherein the expandable member is coupled to at least the distal end portion of the infusion cannula.

6. The medical device of claim 1, wherein the expandable member extends circumferentially around the infusion cannula.

7. The medical device of claim 1, wherein the expandable member is provided only for a portion extending distally along the infusion cannula beyond the distal end of the sensor.

8. The medical device of claim 1, wherein the expandable member is disposed above at least a portion of the sensor.

9. The medical device of claim 1, wherein the sensor includes at least one electrode, and wherein the expandable member does not extend over the at least one electrode.

10. The medical device of claim 1, wherein the expandable member extends in the radially outward direction to at least twice its size in its unexpanded state.

11. The medical device of claim 1, wherein the expandable component comprises a coating having an unexpanded thickness of less than about 40 micrometers and an expanded thickness of at least 80 micrometers in the presence of bodily fluids.

12. The medical device of claim 1, wherein the infusion cannula includes at least one surface feature configured to receive the expandable member thereon.

13. The medical device of claim 12, wherein the at least one surface feature includes a recess.

14. The medical device of claim 1, wherein the sensor comprises at least one electrode, and wherein the at least one electrode is spaced at least about 5 mm from the distal end of the infusion cannula.

15. The medical device of claim 1, wherein the subcutaneous component is configured to be inserted via a single insertion needle.

16. A medical device, the medical device comprising: A housing configured to be placed over the patient's skin; An infusion cannula, coupled to the housing and configured to extend through the patient's skin when the housing is placed over the patient's skin, the infusion cannula including a tubular member defining a lumen through the tubular member and an opening at a distal end portion; A sensor, coupled to the housing and configured to extend through the patient's skin when the housing is placed over the patient's skin, the sensor including a working electrode, wherein the working electrode is spaced at least 5 mm from the opening at the distal end portion of the infusion cannula; and An expandable material is disposed above the radial outer surface of the infusion cannula, the expandable material being configured to expand in the presence of body fluid to mitigate backflow of the infusion fluid distributed through the opening of the infusion cannula.

17. The medical device of claim 16, wherein the expandable material extends circumferentially around the infusion cannula.

18. The medical device of claim 16, wherein the expandable material is disposed only along a portion of the infusion cannula extending distally beyond the distal end of the sensor.

19. The medical device of claim 16, wherein the expandable material is disposed above at least a portion of the sensor.

20. The medical device of claim 16, wherein the infusion cannula includes at least one surface feature configured to receive the expandable material thereon.

21. A method, the method comprising: A medical device is positioned such that its base is positioned against the patient's skin and its subcutaneous component penetrates the patient's skin and extends into the patient's body so that the subcutaneous component comes into contact with bodily fluids. The subcutaneous component includes an infusion cannula and a sensor. An expandable member attached to the radially outer surface of the subcutaneous assembly is allowed to extend in the radially outward direction in the presence of the body fluid; as well as Fluid is distributed through the distal opening of the infusion cannula, wherein the expandable member mitigates backflow of the distributed fluid along the proximal direction of the infusion cannula.

22. The method of claim 21, wherein the sensor includes a working electrode, and wherein the expandable member is disposed between the distal opening of the infusion cannula and the working electrode of the sensor.

23. The method of claim 21, wherein the expandable member expands in the radially outward direction to at least twice the size of its unexpanded state.

24. The method of claim 21, wherein setting the medical device comprises setting the base against the patient's skin and then inserting the subcutaneous component under the patient's skin via a single insertion needle.

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