Microneedle assembly with sensing and immobilizing structures for wearable sensing apparatus

Abstract

A microneedle assembly (1) comprising a sensing needle structure (2) and an immobilizing needle structure (4). The sensing needle structure (2) comprises a plurality of sensing microneedles (3), at least one sensing microneedle (3) comprising an electrochemical sensor electrode. The immobilizing needle structure (4) comprises a plurality of immobilizing microneedles (5). Each immobilizing microneedle (5) comprises a surface section (6) configured to increase friction between the immobilizing microneedle (5) and body tissue compared to a corresponding friction between the sensing microneedle (3) and the body tissue. The sensing microneedles (3) and the immobilizing microneedles (5) are distributed across an assembly surface (7) configured to contact the body tissue. The surface section (6) may be configured to increase friction without damaging body tissue when extracted. A wearable sensing apparatus (9), such as a skin patch, an earring, glasses, a smartwatch, a bracelet, or a necklace, comprises the microneedle assembly (1).

Description

[0001] MICRONEEDLE ASSEMBLY WITH SENSING AND IMMOBILIZING STRUCTURES FOR WEARABLE

[0002] SENSING APPARATUS

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to a microneedle assembly for wearable sensing apparatus, and more particularly to a microneedle assembly comprising sensing microneedles for continuous monitoring of body analytes. The disclosure furthermore relates to a wearable sensing apparatus comprising the microneedle assembly.

[0005] BACKGROUND

[0006] Continuous monitoring of body analytes, such as glucose, has become increasingly important in managing various health conditions. Wearable sensors have emerged as a promising technology for providing real-time data on vital parameters and body analytes. These devices typically utilize sensing elements that interface with the body to detect and measure specific substances or parameters.

[0007] Traditional continuous glucose monitors (CGMs) employ relatively long sensing filaments, often around 5 mm in length, which are inserted through the skin. The application of these sensors typically requires a sharp needle, ranging from 7 to 10 mm in length, for insertion. This approach can cause discomfort, pain, or even bleeding for the user, potentially leading to reduced compliance with continuous monitoring regimens.

[0008] To address these issues, researchers have proposed the use of sub-millimeter sensing probes, commonly referred to as microneedles. These microneedles offer the potential for less invasive and more comfortable continuous monitoring. However, the reduced penetration depth of microneedles introduces new challenges. The sensor area at sub-millimeter skin depth requires precise positioning, as even slight movements of the microprobes can result in significant changes in the output signal.

[0009] Current designs of sensing microprobes often rely on skin adhesives to maintain the correct position of the sensors. However, the natural bending and stretching of the skin can still cause the probes to shift position within the skin. In extreme cases, this movement may result in the needles being positioned in a passive skin layer, leading to inaccurate or faulty sensor readings.

[0010] Existing approaches to improve microneedle stability within the skin have their own limitations. Some designs incorporate backward-facing spirals or barbs on the microneedles to increase friction with the surrounding tissue. While these features can enhance stability, they may cause damage to the skin tissue during sensor removal. Additionally, the complex shapes required for such designs can be challenging to manufacture using conventional large-scale fabrication methods.

[0011] Hence, there is a need for an improved microneedle assembly suitable for wearable sensing devices.

[0012] SUMMARY

[0013] It is an object to provide an improved microneedle assembly for wearable sensing devices. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

[0014] According to a first aspect, a microneedle assembly is provided. The microneedle assembly comprises a sensing needle structure comprising a plurality of sensing microneedles, at least one sensing microneedle comprising an electrochemical sensor electrode; and an immobilizing needle structure comprising a plurality of immobilizing microneedles, each immobilizing microneedle comprising a surface section configured to increase friction between said immobilizing microneedle and body tissue compared to a corresponding friction between said sensing microneedle and said body tissue, said sensing microneedles and said immobilizing microneedles being distributed across an assembly surface configured to contact said body tissue.

[0015] This microneedle assembly provides the advantage of increased stability and accuracy for continuous analyte sensing by combining sensing microneedles with immobilizing microneedles that create additional friction within the skin, reducing relative movement between the sensing microneedles and the surrounding tissue.

[0016] In a possible implementation form of the first aspect, a free end of the sensing microneedle and / or an elongated part of the sensing microneedle is coated with a functional layer, facilitating functional capabilities of the microneedles.

[0017] In a further possible implementation form of the first aspect, the free end of the microneedle is at least partially coated with a biosensitive material or provided with a structure made of biosensitive material, facilitating the sensing capabilities of the microneedles.

[0018] In a further possible implementation form of the first aspect, the biosensitive material is coated with a layer of protective material or at least partially surrounded by a structure made of protective material, providing mechanical protection of the biosensitive material.

[0019] In a further possible implementation form of the first aspect, the elongated part of the sensing microneedle is coated with a functional layer of sensing, insulating, adhesive, and / or sealing material, facilitating for example sensing capabilities or other properties.

[0020] In a further possible implementation form of the first aspect, the sensing microneedle comprises at least one recessed area. Such recesses protect the biosensitive material from mechanical forces, e.g. shear force, that occur during skin penetration. When the biosensitive material is deposited in a recess, it does not protrude from the surface of the microneedle, thus the mechanical damage during skin penetration may be reduced.

[0021] In a further possible implementation form of the first aspect, the sensing needle structure comprises at least one sensing microneedle array, each sensing microneedle array comprises at least one counter electrode, one working electrode, and one reference electrode. This allows the electrodes to be addressed individually.

[0022] In a further possible implementation form of the first aspect, the sensing needle structure comprises at least three sensing microneedle arrays, and each sensing microneedle array comprises only counter electrodes, only working electrodes, or only reference electrodes, electrodes within one sensing microneedle array being electrically interconnected by a portion of the sensing needle structure. This allows several electrodes to be addressed simultaneously.

[0023] In a possible implementation form of the first aspect, the immobilizing microneedles are arranged altematingly, individually or in alternating rows, with sensing microneedles. This arrangement allows for optimal distribution of immobilizing and sensing functions across the assembly surface, potentially improving overall sensor performance and stability.

[0024] In a further possible implementation form of the first aspect, the immobilizing needle structure comprises at least one array of immobilizing microneedles, and / or the sensing needle structure comprises at least one array of sensing microneedles. Organizing the microneedles into arrays can simplify manufacturing processes and allow for more precise control over the distribution and density of each microneedle type.

[0025] In a further possible implementation form of the first aspect, the sensing needle structure is attached to the immobilizing needle structure by means of adhesive. Using adhesive to attach the sensing and immobilizing structures provides a secure connection while allowing for separate optimization and manufacture of each component.

[0026] In a further possible implementation form of the first aspect, the surface section of the immobilizing microneedle comprises a coating of expandable material configured to generate an expansion of a cross-section of the immobilizing microneedle when contacting body fluid; and / or an expanded section wherein the immobilizing microneedle has an increased cross-section relative the remainder of the immobilizing microneedle. These features enhance the friction-increasing capabilities of the immobilizing microneedles, improving their ability to anchor the assembly in place without causing tissue damage.

[0027] In a further possible implementation form of the first aspect, the coating comprises a swelling material configured to swell when in contact with liquid. A swelling material provides a dynamic response to the skin environment, potentially improving the long-term stability of the microneedle assembly.

[0028] In a further possible implementation form of the first aspect, the expanded surface section is deformable. A deformable expanded section can adapt to skin movement and reduce discomfort during wear and removal of the microneedle assembly.

[0029] In a further possible implementation form of the first aspect, the immobilizing needle structure further comprises a base structure, the base structure being perforated and each perforation being configured to accommodate one of the sensing microneedles, the immobilizing microneedle(s) protruding from non-perforated sections of the perforated base structure. This configuration allows for precise alignment and integration of the sensing and immobilizing microneedles, potentially simplifying assembly and improving overall device performance.

[0030] In a further possible implementation form of the first aspect, the base structure is a reinforcement structure, the reinforcement structure being configured to abut the sensing needle structure and / or the immobilizing needle structure when assembled such that each microneedle extends through, and protrudes from, one of said perforations. This allows a solution that is simple to manufacture and which is durable as the reinforcement structure stabilizes the microneedles during skin puncturing and fixes the microneedles during assembly and processing. Furthermore, the reinforcement structure provides electrical insulation between individual microneedles or rows of microneedles.

[0031] In a further possible implementation form of the first aspect, the microneedle assembly comprises a base structure, the immobilizing microneedle(s) and the sensing microneedle(s) being attached to the base structure. A common base structure for both types of microneedles can provide mechanical stability and simplify the overall assembly process.

[0032] In a further possible implementation form of the first aspect, the sensing needle structure comprises a planar section, and each sensing microneedle is an electrode extending from a surface of the planar section. This facilitates manufacturing the needle structure as a single-piece body.

[0033] In a further possible implementation form of the first aspect, the sensing needle structure comprises conductive material and the planar section is configured to electrically connect the electrodes to an electric device or system, facilitating interconnection between electrodes and other parts such as a sensor system. In a further possible implementation form of the first aspect, the base structure comprises electrically insulating material. An electrically insulating base structure can prevent interference between sensing microneedles and improve the accuracy of analyte measurements.

[0034] In a further possible implementation form of the first aspect, the reinforcement structure comprises a planar sheet of insulating material, each perforation of the reinforcement structure comprising a throughgoing opening extending through the planar sheet in a direction perpendicular to a main plane of the planar sheet; and a hollow body of the insulating material extending from the planar sheet in the direction perpendicular to the main plane, the throughgoing opening and the hollow body being coaxially aligned to form a channel configured to accommodate one of the microneedles. This fixates the microneedles in the correct position during skin puncturing and sensor fabrication. Furthermore, the hollow bodies insulate the microneedles electrically from each other and from external factors (e.g. sweat).

[0035] In a further possible implementation form of the first aspect, the sensing microneedles have a first length and the immobilizing microneedles have a second length, the first length being different from the second length. Different lengths for sensing and immobilizing microneedles allow for optimization of each type for its specific function, potentially improving overall device performance.

[0036] According to a second aspect, a wearable sensing apparatus is provided. The wearable sensing apparatus comprises the microneedle assembly according to the first aspect. Incorporating the microneedle assembly into a wearable sensing apparatus enables continuous, real-time monitoring of analytes in a compact and user-friendly form factor.

[0037] In a possible implementation form of the second aspect, the wearable sensing apparatus is configured to continuously monitor blood glucose. Continuous glucose monitoring provides valuable real-time data for diabetes management, potentially improving patient outcomes and quality of life.

[0038] In a further possible implementation form of the second aspect, the wearable sensing apparatus further comprises at least one of an analog frontend for signal amplification and filtering, an analog-to-digital converter, a microprocessor, a battery, a wireless communication module and antenna, a temperature sensor, and a printed circuit board. These additional components enable the wearable sensing apparatus to process, store, and transmit sensor data, enhancing its functionality and usefulness for users and healthcare providers.

[0039] In a further possible implementation form of the second aspect, the wearable sensing apparatus is a skin patch, an earring, glasses, a smartwatch, a bracelet, or a necklace. These form factors provide users with various options for wearing the sensing apparatus, potentially improving comfort and adherence to continuous monitoring regimens.

[0040] These and other aspects will be apparent from the embodiments described below.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

[0043] Fig. 1 illustrates orthogonal views of an immobilizing needle structure, in accordance with an example of the embodiments of the disclosure; Fig. 2 shows orthogonal views of a sensing needle structure, in accordance with an example of the embodiments of the disclosure:

[0044] Fig. 3 illustrates an exploded view of the microneedle assembly, in accordance with an example of the embodiments of the disclosure;

[0045] Fig. 4 shows an orthogonal side view of the assembled microneedle assembly, in accordance with an example of the embodiments of the disclosure;

[0046] Fig. 5 shows a cutaway view of the microneedle assembly inserted into body tissue, in accordance with an example of the embodiments of the disclosure;

[0047] Fig. 6 illustrates a side view of a microneedle assembly with a curved base structure, in accordance with an example of the embodiments of the disclosure;

[0048] Fig. 7 shows a cross-sectional view of a wearable sensing apparatus incorporating the microneedle assembly, in accordance with an example of the embodiments of the disclosure,

[0049] Fig. 8 shows a schematic side view of a part of a microneedle assembly in accordance with an example of the embodiments of the disclosure;

[0050] Figs. 9a and 9b show schematic, detailed views of a sensing microneedle in accordance with examples of the embodiments of the disclosure.

[0051] DETAILED DESCRIPTION

[0052] The present invention relates to a microneedle assembly 1 comprising a sensing needle structure 2 comprising a plurality of sensing microneedles 3, at least one sensing microneedle 3 comprising an electrochemical sensor electrode; and an immobilizing needle structure 4 comprising a plurality of immobilizing microneedles 5, each immobilizing microneedle 5 comprising a surface section 6 configured to increase friction between the immobilizing microneedle 5 and body tissue compared to a corresponding friction between the sensing microneedle 3 and the body tissue, the sensing microneedles 3 and the immobilizing microneedles 5 being distributed across an assembly surface 7 configured to contact the body tissue.

[0053] This microneedle assembly addresses the challenges associated with continuous analyte monitoring in wearable sensors. By combining sensing microneedles with immobilizing microneedles, the assembly enhances the stability and accuracy of continuous analyte sensing. The immobilizing microneedles create additional friction within the skin, reducing relative movement between the sensing microneedles and the surrounding tissue. This approach mitigates the issues associated with the shifting position of the sensing microneedles within the skin due to natural bending and stretching of the skin, thereby improving the reliability of the sensor readings.

[0054] As shown in Figs. 3 and 4, the microneedle assembly 1 includes a sensing needle structure 2 and an immobilizing needle structure 4. The sensing needle structure 2 comprises a plurality of sensing microneedles 3. At least one of these sensing microneedles 3 includes an electrochemical sensor electrode, which may be used to detect various body analytes, such as glucose. The sensing microneedles 3 may be arranged in at least one row, as shown in Fig. 2, and have a tapered shape which facilitates their penetration into the skin.

[0055] Each sensing microneedle 3 may comprise a free end 3a, configured to penetrate the skin of the user / wearer, and an elongated part 3b, see Figs. 8 and 9. The free end 3a and / or the elongated part 3b of the sensing microneedle 3 may be coated with a functional layer.

[0056] The free end 3a of the microneedle 4 may be at least partially coated with a biosensitive material (not shown) or be provided with at least one structure made of biosensitive material 10 as illustrated in Figs. 9a and 9b. The biosensitive material may be coated with a layer of protective material (not shown) or at least partially surrounded by a structure made of protective material 11 as illustrated in Fig. 9a, providing mechanical protection of the biosensitive material.

[0057] The elongated part 3b of the sensing microneedle may be coated with a functional layer of sensing, insulating, adhesive, and / or sealing material. This surface below the functionalized free end or tip may be covered with an uncured polymer, e.g. an adhesive, that serves as an insulator and a sealant. The sensing microneedle 3 may also comprise at least one recessed area. Recesses may be made in the insulating coating, for example by making a pattern using laser ablation. Recesses may also be created by micromaching cavities and / or depressions on the microneedle’s surface. The purpose of such depressions is to further protect the biosensitive material from mechanical forces, e.g. shear force, that occur during skin penetration. When the biosensitive material is deposited in a depression, it does not protrude from the surface of the microneedle 4, thus the mechanical damage during the skin penetration may be reduced.

[0058] The immobilizing needle structure 4, shown in Fig. 1 , comprises a plurality of immobilizing microneedles 5. Each immobilizing microneedle 5 includes a surface section 6 that is configured to increase friction between the immobilizing microneedle 5 and body tissue. This increased friction helps to keep the microneedle assembly 1 in place within the skin, reducing the likelihood of the sensing microneedles 3 moving relative to the skin. The immobilizing microneedles 5 may also be arranged in at least one row and have a tapered shape similar to the sensing microneedles 3.

[0059] The immobilizing needle structure 4 may comprise at least one array of immobilizing microneedles 5 , and / or the sensing needle structure 2 may comprise at least one array of sensing microneedles 3. This arrangement allows for a high density of microneedles across the assembly surface 7, potentially improving the overall performance of the microneedle assembly 1.

[0060] The immobilizing needle structure 4 may further include a base structure 8. The base structure 8 may be perforated, as illustrated in Fig. 1, with each perforation 12 being configured to accommodate one of the sensing microneedles 3. The immobilizing microneedles 5 protrude from non-perforated sections of the perforated base structure 8. This arrangement allows for the integration of the sensing needle structure 2 and the immobilizing needle structure 4 into a single microneedle assembly 1 , simplifying the overall assembly process and enhancing the stability of the microneedle assembly 1 within the skin.

[0061] The base structure 8 may also or instead be a reinforcement structure, separate or part of the immobilizing needle structure 4 or of the sensing needle structure 2, comprising at least one perforation array. Each perforation 12 of the perforation array(s) is configured to accommodate an individual microneedle 3, 5. The reinforcement structure therefore comprises perforations 12 that correspond in number and layout to the number and layout of at least a part of the microneedles. The reinforcement structure may be configured to abut sensing needle structure 2 and / or the immobilizing needle structure 4, when assembled, such that each microneedle 4 extends through, and protrudes from, one of the perforations 12. The reinforcement structure may comprise a planar sheet, optionally made of insulating material. Each perforation 12 of the reinforcement structure may comprise a throughgoing opening extending through the planar sheet in a direction perpendicular to a main plane of the planar sheet.

[0062] The base structure and / or reinforcement structure may also comprise a hollow body 13, for example, a cylinder, of insulating material that extends from the planar sheet in the direction perpendicular to the main plane, as shown in Fig. 8. The perforation 12 and the hollow body 13 are coaxially aligned to form a channel configured to accommodate one of the microneedles 3, 5.

[0063] The sensing needle structure 2 may be a single-piece body comprising the sensing microneedles 3. A planar section of the sensing needle structure 2 may be a sacrificial part that is used for manipulating multiple microneedles during manufacture and assembly, and which is subsequently removed. Removal of the sacrificial part allows each microneedle to be addressed individually.

[0064] Each sensing microneedle 3 may be an electrode extending from the surface of the planar section. The sensing needle structure 2 may comprise conductive material. The sensing microneedles 3 may comprise a conductive material. The planar section may be configured to electrically connect the electrodes to an electric device or system such as an electric source or electronic amplifier. The electrodes may be electrically separated.

[0065] The sensing needle structure 2 may comprise at least one sensing microneedle array. Each microneedle array 3 may comprise at least one counter electrode, one working electrode, and one reference electrode.

[0066] The sensing needle structure 2 may comprise at least three sensing microneedle arrays, and in turn each sensing microneedle array may comprise only counter electrodes, only working electrodes, or only reference electrodes. The electrodes within one sensing microneedle array are electrically interconnected by a portion of the sensing needle structure 2. The electrical connection to the remaining system may be performed using low- temperature contacting methods such as slot connectors, spring-loaded pins, or electrically conductive glue.

[0067] The immobilizing microneedles 5 may be arranged altematingly, individually or in alternating rows, with the sensing microneedles 3. This arrangement allows for optimal distribution of immobilizing and sensing functions across the assembly surface 7, potentially improving overall sensor performance and stability.

[0068] The surface section 6 of the immobilizing microneedle 5 may comprise a coating of expandable material. This material is configured to generate an expansion of a cross-section of the immobilizing microneedle 5 when contacting body fluid. This feature enhances the friction-increasing capabilities of the immobilizing microneedles 5, improving their ability to anchor the assembly in place without causing tissue damage.

[0069] The surface section 6 of the immobilizing microneedle 5 may comprise an expanded section, as illustrated in Fig. 5, wherein the immobilizing microneedle 5 has an increased cross-section relative to the remainder of the immobilizing microneedle. This expanded section may further enhance the friction between the immobilizing microneedle 5 and the body tissue, providing additional stability to the microneedle assembly 1 within the skin.

[0070] The microneedle assembly 1, as shown in Figs. 5 and 6, may be inserted into body tissue such that the assembly surface 7 contacts the outer layer of the body tissue. The sensing microneedles 3 and immobilizing microneedles 5 penetrate the tissue, with the surface section 6 of each immobilizing microneedle 5 designed to increase friction within the skin. This increased friction helps to keep the microneedle assembly 1 in place within the skin, reducing the likelihood of the sensing microneedles 3 moving relative to the skin. This arrangement provides a stable platform for continuous analyte sensing, potentially improving the reliability of sensor readings.

[0071] The sensing microneedles 3 may have a first length and the immobilizing microneedles 5 may have a second length, with the first length being different from the second length. This difference in length may be designed to optimize the performance of the microneedle assembly 1, with the sensing microneedles 3 and immobilizing microneedles 5 each penetrating to a depth within the skin that is optimal for their respective functions.

[0072] As shown in Fig. 7, the microneedle assembly 1 may be incorporated into a wearable sensing apparatus 9. The wearable sensing apparatus 9 encloses the microneedle assembly 1 within a protective housing. The microneedle assembly 1 may be positioned at the bottom of the wearable sensing apparatus 9, with the microneedles extending downward. The base structure 8 of the microneedle assembly 1 may be integrated into the bottom surface of the wearable sensing apparatus 9. The sensing microneedles 3 and immobilizing microneedles 5 may protrude from the base structure 8, ready to interface with the skin when the wearable sensing apparatus 9 is applied.

[0073] The wearable sensing apparatus 9 may be configured to continuously monitor blood glucose. This continuous monitoring may provide real-time data on the user's blood glucose levels, potentially improving the management of conditions such as diabetes.

[0074] The wearable sensing apparatus 9 may further comprise at least one of an analog frontend for signal amplification and filtering, an analog-to-digital converter, a microprocessor, a battery, a wireless communication module and antenna, a temperature sensor, and a printed circuit board. These components may provide the necessary functionality for the wearable sensing apparatus 9 to process and transmit the data collected by the sensing microneedles 3.

[0075] The wearable sensing apparatus 9 may take various forms, including but not limited to a skin patch, an earring, glasses, a smartwatch, a bracelet, or a necklace. These different forms may provide users with a range of options to choose from, potentially improving user comfort and adherence to continuous glucose monitoring regimens.

[0076] The sensing microneedles 3 may have functionalized tips for detecting body analytes. This functionalization may involve the application of specific coatings or materials to the tips of the sensing microneedles 3, which interact with the body analytes to generate a detectable signal. The signal may then be processed by the wearable sensing apparatus 9 to provide a measurement of the concentration of the body analyte. This feature allows the microneedle assembly 1 to provide continuous, real-time monitoring of body analytes, potentially improving the management of conditions such as diabetes.

[0077] The surface section 6 of the immobilizing microneedle 5 may be deformable. This deformability may be achieved through the use of materials that can change shape or size in response to external forces or conditions. For example, the surface section 6 may comprise a material that swells when in contact with body fluid. This swelling increases the cross-section of the immobilizing microneedle 5, enhancing the friction between the immobilizing microneedle 5 and the body tissue. This feature helps to keep the microneedle assembly 1 in place within the skin, reducing the likelihood of the sensing microneedles 3 moving relative to the skin.

[0078] The immobilizing microneedles 5 may have wider sections in the middle part to lock inside the stretchable dermis layer. This feature further enhances the friction between the immobilizing microneedle 5 and the body tissue, providing additional stability to the microneedle assembly 1 within the skin. The wider sections may be designed to engage with the dermis layer of the skin, which is known to be stretchable and can accommodate the wider sections of the immobilizing microneedles 5. The wearable sensing apparatus 9 may be pressed into the skin such that the tips of the microneedle array, which protrude from the bottom side of the sensor system, penetrate through the skin at most 1 mm and at least around 200 pm or at least through the entire epidermis layer. This depth of penetration ensures that the sensing microneedles 3 are in contact with the interstitial fluid, which contains the body analytes to be detected. At the same time, the immobilizing microneedles 5 are also in contact with the skin, providing the necessary friction to keep the microneedle assembly 1 in place. This arrangement allows for continuous, reliable monitoring of body analytes, potentially improving the accuracy and reliability of the sensor readings.

[0079] The microneedle assembly 1 may be assembled using alternative methods. For instance, individual needles or rows of needles with immobilizing and sensing functionality can be assembled into a microneedle array using an electrically insulating microneedle holder. This holder serves to keep the individual needles or rows of needles firmly in place, ensuring the stability of the microneedle assembly 1. The use of an electrically insulating holder may also provide additional benefits, such as preventing electrical interference between the sensing microneedles 3 and the immobilizing microneedles 5, potentially improving the accuracy of the sensor readings.

[0080] The microneedle assembly 1 may, as previously mentioned, comprise a base structure 8. The immobilizing microneedles 5 and the sensing microneedles 3 may be attached to the base structure 8. This base structure 8 may be made of an electrically insulating material, providing further protection against electrical interference. The base structure 8 also provides mechanical stability to the microneedle assembly 1 , simplifying the overall assembly process.

[0081] In certain embodiments, the sensing needle structure 2 may be attached to the immobilizing needle structure 4 using adhesive. This adhesive attachment ensures a secure connection between the sensing needle structure 2 and the immobilizing needle structure 4, enhancing the stability of the microneedle assembly 1 within the skin. The use of adhesive may also simplify the assembly process, as it eliminates the need for additional mechanical fasteners or complex assembly techniques.

[0082] The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0083] The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

Claims

CLAIMS1. A microneedle assembly (1) comprising-a sensing needle structure (2) comprising a plurality of sensing microneedles (3), at least one sensing microneedle (3) comprising an electrochemical sensor electrode; and-an immobilizing needle structure (4) comprising a plurality of immobilizing microneedles (5), each immobilizing microneedle (5) comprising a surface section (6) configured to increase friction between said immobilizing microneedle (5) and body tissue compared to a corresponding friction between said sensing microneedle (3) and said body tissue, said sensing microneedles (3) and said immobilizing microneedles (5) being distributed across an assembly surface (7) configured to contact said body tissue.

2. The microneedle assembly (1) according to claim 1, wherein a free end (3a) of said sensing microneedle (3) and / or a elongated part (3b) of said sensing microneedle (3) is coated with a functional layer.

3. The microneedle assembly (1) according to claim 1 or 2, wherein said free end (3a) of said sensing microneedle (3) is at least partially coated with a biosensitive material or provided with a structure made of bio sensitive material (10).

4. The microneedle assembly (1) according to claim 3, wherein said biosensitive material is coated with a layer of protective material or at least partially surrounded by a structure made of protective material (11).

5. The microneedle assembly (1) according to any one of the previous claims, wherein said immobilizing microneedles (5) are arranged altematingly, individually or in alternating rows, with sensing microneedles (3).

6. The microneedle assembly (1) according to any one of the previous claims, wherein said immobilizing needle structure (4) comprises at least one array of immobilizing microneedles (5), and / or said sensing needle structure (2) comprises at least one array of sensing microneedles (3).

7. The microneedle assembly (1) according to any one of the previous claims, wherein said sensing needle structure (2) is attached to said immobilizing needle structure (4) by means of adhesive.

8. The microneedle assembly (1) according to any one of the previous claims, wherein said surface section (6) of said immobilizing microneedle (5) comprises-a coating of expandable material configured to generate an expansion of a cross-section of said immobilizing microneedle(5) when contacting body fluid; and / or-an expanded section wherein said immobilizing microneedle (5) has an increased cross-section relative the remainder of said immobilizing microneedle.

9. The microneedle assembly (1) according to claim 8, wherein said coating comprises a swelling material configured to swell when in contact with liquid.

10. The microneedle assembly (1) according to claim 8 or 9, wherein said expanded surface section (6) is deformable.

11. The microneedle assembly (1) according to any one of the previous claims, wherein said immobilizing needle structure (4) further comprises a base structure (8), said base structure (8) being perforated and each perforation (12) being configuredto accommodate one of said sensing microneedles (3), said immobilizing microneedle(s) (5) protruding from non-perforated sections of said perforated base structure (8).

12. The microneedle assembly (1) according to claim 11, wherein said base structure (8) is a reinforcement structure, the reinforcement structure being configured to abut the sensing needle structure (2) and / or the immobilizing needle structure (4) when assembled such that one of said immobilizing microneedle(s) (5) and / or said sensing microneedle(s) (3) extends through, and protrudes from, one of said perforations (12).

13. The microneedle assembly (1) according to any one of claims 1 to 10, wherein said microneedle assembly (1) comprises a base structure (8), said immobilizing microneedle(s) (5) and said sensing microneedle(s) (3) being attached to said base structure (8).

14. The microneedle assembly (1) according to any one of claims 11 to 13, wherein said base structure (8) comprises electrically insulating material.

15. The microneedle assembly (1) according to any one of the previous claims, wherein said sensing microneedles (3) have a first length (LI) and said immobilizing microneedles (5) have a second length (L2), said first length (LI) being different from said second length (L2).

16. A wearable sensing apparatus (9) comprising the microneedle assembly (1) according to any one of claims 1 to 15.

17. The wearable sensing apparatus (9) according to claim 16, configured to continuously monitor blood glucose.

18. The wearable sensing apparatus (9) according to claim 16 or 17, further comprising at least one of an analog frontend for signal amplification and filtering, an analog-to-digital converter, a microprocessor, a battery, a wireless communication module and antenna, a temperature sensor, and a printed circuit board.

19. The wearable sensing apparatus (9) according to any one of claims 16 to 18, wherein said wearable sensing apparatus (9) is a skin patch, an earring, glasses, a smartwatch, a bracelet, or a necklace.

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