Flexible breath detection device based on embedded multi-element sensor array and preparation method thereof

Abstract

The application discloses a wearable flexible breath detection device based on an embedded multi-element sensing array and a preparation method. The device comprises a nasal cavity flexible carrier and a multi-element flexible sensing array, and the multi-element flexible sensing array comprises a temperature sensor, a humidity sensor, a respiratory mechanics sensor, an electrochemical sensor, an interface electrode, a PI layer, a PDMS layer and a SiO2 layer. The respiratory mechanics sensor comprises a conductive magnetic hollow microtube array with micro ball pits on the surface, which is used for converting the bending deformation caused by the nasal cavity airflow into resistance change. During preparation, a planar multi-element flexible sensing array and a conductive magnetic hollow microtube array are formed respectively, and then the two are integrated and bonded with the nasal cavity flexible carrier to be curled or bent into a shape. The application can synchronously detect the temperature, humidity, airflow mechanics and exhaled gas components in the area where the nasal cavity breath airflow passes.

Description

Technical Field

[0001] This invention relates to the fields of flexible electronics, wearable physiological monitoring, and respiratory multi-parameter detection technology, specifically to a flexible respiratory detection device based on an embedded multi-element sensor array and its fabrication method. Background Technology

[0002] Temperature, humidity, aerodynamic changes, and exhaled gas composition during respiration reflect the human body's respiratory rhythm and physiological state. Existing wearable respiratory detection devices mostly employ mask-mounted, perinasal, or chest / abdomen-attached designs. Mask-mounted devices, with their detection position relatively far from the nasal airflow source, are easily affected by trapped gas inside the mask, external airflow, and the degree of fit. Perinasal-attached devices are easily interfered with by facial expressions, sweat, skin condition, head movements, and environmental airflow. Chest / abdomen-attached devices primarily reflect respiratory status indirectly through chest and abdominal deformation, making it difficult to directly obtain various parameters of nasal airflow.

[0003] Existing respiratory detection devices typically detect one or a few parameters, such as temperature, humidity, aerodynamics, or exhaled gas composition, making it difficult to simultaneously acquire multidimensional respiratory information at the same wearable location. Furthermore, while the inner side of the nasal cavity inlet is close to the respiratory airflow source and offers a relatively semi-enclosed detection environment, this area is small and has high humidity. Conventional rigid or semi-rigid sensing structures are difficult to adapt to the flexibility of the nasal cavity wall, and integrating multiple sensing units within a limited area can easily lead to bending damage, interface separation, or unstable electrical connections.

[0004] In addition, nasal breathing airflow is characterized by low flow rate and periodic changes. Conventional planar mechanical sensing structures have limited deformation under weak airflow, which may result in weak output signals or inconsistent recovery states after cyclic detection. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible respiratory detection device that can be stably maintained inside the nasal cavity entrance or near the inner wall of the nasal cavity, simultaneously detect multiple respiratory parameters, and generate a repeatable mechanical response under the action of weak nasal airflow.

[0006] To achieve the above objectives, the present invention proposes the following technical solution: a flexible respiratory detection device based on an embedded multi-element sensor array, wherein the flexible respiratory detection device includes a flexible nasal cavity carrier and a multi-element flexible sensor array;

[0007] The nasal flexible carrier is used to hold the multi-element flexible sensor array inside the nasal cavity entrance or near the inner wall of the nasal cavity, so that the detection area of ​​the multi-element flexible sensor array is located in the area through which the nasal breathing airflow passes.

[0008] The multi-element flexible sensor array includes a temperature sensor, a humidity sensor, a respiratory mechanics sensor, an electrochemical sensor, an interface electrode, a PI layer, a PDMS layer, and a SiO2 layer.

[0009] The temperature sensor, humidity sensor, respiratory mechanics sensor, and electrochemical sensor are electrically connected to the interface electrode, the PI layer serves as a flexible insulating substrate that carries each sensor and its interconnection structure, the PDMS layer serves as a temporary support layer, a flexible support layer, or a material layer of the nasal cavity flexible carrier, and the SiO2 layer is disposed at the bonding interface between the PI layer and the PDMS layer.

[0010] The respiratory mechanics sensor includes a conductive magnetic hollow microtube array, which is formed by mixing and solidifying a flexible polymer, magnetic microparticles and conductive fillers. The surface of the conductive magnetic hollow microtube array has micro-spherical pits. The conductive magnetic hollow microtube array is used to bend and deform under the action of nasal breathing airflow and generate a change in resistance, and recovers through its own elasticity and magnetic properties after the breathing airflow disappears.

[0011] Furthermore, in this invention, the temperature sensor includes a serpentine metal electrode extending circumferentially along the flexible nasal cavity carrier, the serpentine metal electrode being used to convert local temperature changes caused by inhalation and exhalation into resistance changes.

[0012] The humidity sensor includes interdigitated electrodes and a humidity-sensitive material layer. The humidity-sensitive material layer covers the surface of the interdigitated electrodes and the gap area between adjacent electrodes, and is used to convert humidity changes in the nasal respiratory microenvironment into electrical signals. The humidity-sensitive material layer includes graphene oxide, polyvinyl alcohol, cellulose nanomaterials, ion gels, or composite materials thereof.

[0013] Furthermore, in this invention, the respiratory mechanics sensor also includes a common conductive magnetic composite substrate integrally formed with the conductive magnetic hollow microtube array. The common conductive magnetic composite substrate is fixed to a preset respiratory mechanics detection area of ​​the PI layer and is electrically connected to the corresponding respiratory mechanics sensing connection electrode in the interface electrode.

[0014] Multiple hollow microtubes in the conductive magnetic hollow microtube array are arranged circumferentially along the flexible nasal carrier. The hollow microtubes protrude from the common conductive magnetic composite substrate, allowing nasal breathing airflow to act on the sidewalls of the hollow microtubes and drive them to bend.

[0015] Furthermore, in this invention, the flexible polymer is PDMS, the magnetic microparticles are neodymium iron boron microparticles, the conductive filler is carbon nanotubes, and the mass ratio of PDMS, neodymium iron boron microparticles and carbon nanotubes is 2:6:1.

[0016] The hollow microtubes are axially magnetized to form an axial magnetic pole distribution, and the diameter of the micro-spherical pits is 5 to 10 micrometers; the inner cavity of the hollow microtubes is used to load sustained-release drugs, humidification materials or functional molecules.

[0017] Furthermore, in this invention, the electrochemical sensor includes at least one working electrode, an Ag / AgCl reference electrode, and a counter electrode, wherein at least one of the working electrodes has a sensitive modification layer on its surface for detecting respiratory-related biomarkers;

[0018] The working electrode includes at least two of the following: hydrogen peroxide working electrode, ethanol working electrode, lactic acid working electrode, and blank working electrode. The blank working electrode is used for differential compensation of non-target signals.

[0019] The sensitive modification layer of the hydrogen peroxide working electrode includes Prussian blue and conductive carbon material; the sensitive modification layer of the ethanol working electrode includes Nafion, multi-walled carbon nanotubes, Meldora blue, alcohol dehydrogenase and oxidized coenzyme I; and the sensitive modification layer of the lactate working electrode includes platinum nanoparticles, chitosan and lactate oxidase.

[0020] Furthermore, in this invention, the flexible nasal carrier is in the form of a ring, semi-ring, tubular or nasal plug structure, and can pass through the nasal inlet after radial compression, and elastically recover and fit the inner side of the nasal inlet after entering the nasal cavity.

[0021] The outer periphery of the nasal cavity flexible carrier is provided with an outwardly protruding anti-fall-off limiting part, which is an annular flange or a partial boss extending along the axial direction of the nasal cavity flexible carrier.

[0022] The nasal cavity flexible carrier is a single nostril structure, or the nasal cavity flexible carrier is a dual nostril integrated structure, the dual nostril integrated structure includes a flexible connecting bridge and two nasal cavity flexible carriers respectively disposed at both ends of the flexible connecting bridge.

[0023] The non-sensitive areas of the multi-element flexible sensor array are provided with an insulating and moisture-proof encapsulation layer, and the detection areas of the temperature sensor, humidity sensor, respiratory mechanics sensor and electrochemical sensor are respectively provided with openings, semi-permeable interfaces or air-permeable and hydrophobic interfaces.

[0024] A method for fabricating a flexible respiratory detection device based on an embedded multi-sensor array, used to fabricate the aforementioned flexible respiratory detection device based on an embedded multi-sensor array, includes:

[0025] Step S1: A planar multi-element flexible sensor array with a PI layer as a flexible insulating substrate is prepared on a temporary support layer. A connection area and interface electrode for a temperature sensor, a humidity sensor, an electrochemical sensor, and a respiratory mechanics sensor are formed in the planar multi-element flexible sensor array. A SiO2 layer is formed on the bonding surface of the PI layer.

[0026] Step S2: Prepare an array of conductive magnetic hollow microtubes with micro-spherical pits on the surface;

[0027] Step S3: Integrate the conductive magnetic hollow microtube array into the preset respiratory mechanics detection area of ​​the planar multi-element flexible sensor array to form a respiratory mechanics sensor, and then combine the planar multi-element flexible sensor array with a nasal cavity flexible carrier formed by a PDMS layer. Finally, roll or bend the composite structure into an embedded wearing structure that fits the inside of the nasal cavity inlet.

[0028] Furthermore, in this invention, step S1 includes:

[0029] PDMS is spin-coated onto a glass substrate and cured to form a temporary support layer. The surface of the temporary support layer is modified. PI material is then spin-coated onto the temporary support layer and cured to form a PI layer.

[0030] A metal thin film is formed on the PI layer and the metal thin film is patterned to form the serpentine electrode of the temperature sensor, the interdigitated electrode of the humidity sensor, the working electrode and counter electrode of the electrochemical sensor, the connection electrode of the respiratory mechanics sensor, and the interface electrode.

[0031] A silver layer is formed in the reference electrode region of the electrochemical sensor, and the silver layer is chlorinated to form an Ag / AgCl reference electrode.

[0032] A PI insulating layer is formed on the metal thin film, and openings are formed in the sensitive area of ​​the humidity sensor, the electrode area of ​​the electrochemical sensor, the connection area of ​​the respiratory mechanics sensor, and the interface electrode.

[0033] A humidity-sensitive material layer is formed at the interdigitated electrode of the humidity sensor, and a sensitive modification layer is formed at the working electrode of the electrochemical sensor.

[0034] The planar multi-element flexible sensor array is peeled off from the temporary support layer and transferred to form a SiO2 layer in the bonding area on the back side of the PI layer.

[0035] Furthermore, in this invention, step S2 includes:

[0036] A resin mold with a micropillar array is formed by 3D printing, and a PVA water-soluble sacrificial film is formed on the surface of the micropillar array.

[0037] PDMS, neodymium iron boron microparticles and carbon nanotubes are mixed to form a conductive magnetic composite slurry, and the conductive magnetic composite slurry is coated on the surface of a micropillar array on which the PVA water-soluble sacrificial film is formed.

[0038] PMMA particles are placed on the surface of the uncured conductive magnetic composite slurry and then thermo-cured. The thermo-cured conductive magnetic composite slurry is then axially magnetized.

[0039] The PVA water-soluble sacrificial film is dissolved in water to form a release gap between the resin mold and the cured conductive magnetic composite slurry. The PMMA particles are dissolved in an organic solvent to form micro-spherical pits on the surface of the conductive magnetic composite slurry.

[0040] The cured conductive magnetic composite slurry is demolded from the resin mold to obtain the conductive magnetic hollow microtube array, and a sustained-release drug, a wetting modifier, or a functional molecule is selectively loaded into the hollow microtube cavity of the conductive magnetic hollow microtube array.

[0041] Furthermore, in this invention, step S3 includes:

[0042] The conductive magnetic hollow microtube array is fixed on the preset respiratory mechanics detection area on the PI layer, and the conductive magnetic hollow microtube array is electrically connected to the corresponding respiratory mechanics sensing connection electrode in the interface electrode.

[0043] A flexible nasal carrier formed by the PDMS layer is prepared. The SiO2 layer and the bonding surfaces of the flexible nasal carrier are treated with oxygen plasma. The treated planar multi-element flexible sensor array is aligned, attached and bonded to the flexible nasal carrier.

[0044] The bonded composite structure is rolled or bent along a predetermined direction to form a ring, semi-ring, tubular or nose plug-like structure.

[0045] The non-sensitive areas of the planar multi-element flexible sensor array are insulated and moisture-proofed, and openings, semi-permeable interfaces, or breathable and hydrophobic interfaces are retained in the detection areas of the temperature sensor, humidity sensor, respiratory mechanics sensor, and electrochemical sensor to obtain the flexible respiratory detection device based on the embedded multi-element sensor array.

[0046] Beneficial effects: The technical solution of this application has the following technical effects:

[0047] This invention uses a flexible nasal carrier to hold a multi-element flexible sensor array inside the nasal cavity entrance or near the inner wall of the nasal cavity. The detection areas of the temperature sensor, humidity sensor, respiratory mechanics sensor, and electrochemical sensor are located within the area through which nasal airflow passes. This allows for the simultaneous acquisition of respiratory temperature, humidity, aerodynamics, and exhaled gas composition information near the nasal airflow source. Compared to detection structures placed on the facial skin surface, this embedded approach reduces the impact of skin sweat, facial expressions, changes in attachment position, and external stray airflow on the detection process, while also increasing the dimensionality of respiratory detection information.

[0048] This invention uses a PI layer to carry various sensors and interconnection structures, and a PDMS layer to form a flexible support or nasal cavity flexible carrier. A SiO2 layer is set at the bonding interface between the PI layer and the PDMS layer, so that the multi-element flexible sensor array can bend with the nasal cavity flexible carrier and maintain the corresponding connection relationship. This is beneficial to improving the bonding stability between the flexible array and the nasal cavity carrier, and enables the device to adapt to the bending wear environment inside the nasal cavity entrance.

[0049] The respiratory mechanics sensor of this invention employs an array of conductive magnetic hollow microtubes formed from flexible polymers, magnetic microparticles, and conductive fillers. When nasal airflow acts on the hollow microtubes, the hollow microtubes bend, causing changes in the conductive network, thereby outputting a resistance signal reflecting changes in respiratory airflow. The hollow structure and the micro-craters on its surface help increase the deformation response under weak airflow. After the airflow disappears, the hollow microtubes can recover through their own elasticity and magnetic properties, facilitating periodic respiratory detection. Attached Figure Description

[0050] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0051] Figure 1 This is a schematic diagram of the overall structure of a wearable flexible respiratory detection device.

[0052] Figure 2 Top view of the wearable flexible respiratory detection device and enlarged view of a respiratory mechanics sensor.

[0053] Figure 3 This is a schematic diagram of the fabrication process for an embedded multi-element sensor array device.

[0054] Figure 4 This is a schematic diagram of the fabrication process for a respiratory mechanics sensor.

[0055] The meanings of the reference numerals in the figure are as follows: 1. Wearable flexible respiratory detection device based on embedded multi-element sensor array; 2. Temperature sensor; 3. Humidity sensor; 4. Respiratory mechanics sensor; 5. Electrochemical sensor; 6. Interface electrode; 7. PI layer; 8. PDMS layer; 9. SiO2 layer. Detailed Implementation

[0056] The embodiments of the invention will be described in detail below with reference to the accompanying drawings to clearly illustrate the structure, purpose, advantages, positional relationship and connection method of each component.

[0057] Example 1: Structure of a wearable flexible respiratory detection device

[0058] This embodiment provides a wearable flexible respiratory detection device 1 based on an embedded multi-element sensor array. The wearable flexible respiratory detection device 1 includes a flexible nasal cavity carrier and a multi-element flexible sensor array. The flexible nasal cavity carrier holds the multi-element flexible sensor array inside the nasal cavity inlet or near the inner wall of the nasal cavity, allowing the multi-element flexible sensor array to be directly located in the area through which nasal breathing airflow passes. This arrangement brings the sensing area close to the nasal airflow source, while utilizing the relatively semi-enclosed space inside the nasal cavity inlet to reduce the influence of external stray airflow, skin sweat, facial expressions, and external probe movement on the detection process.

[0059] In this embodiment, the flexible nasal carrier uses PDMS layer 8 to form a closed annular structure. The diameter of the annular structure is 14 mm, the axial length is 12.2 mm, and the carrier thickness is 0.5 mm. The annular structure is circumferentially continuous and integrally formed without any openings or gaps. Before wearing, the annular flexible nasal carrier can be radially compressed under external force to pass through the nasal inlet. After entering the inner side of the nasal inlet, the flexible nasal carrier relies on the elastic recovery of the PDMS material to make its outer peripheral surface conform to the circumferential soft tissue inside the nasal inlet, thereby maintaining the multi-element flexible sensor array at the predetermined detection position.

[0060] The flexible nasal carrier has an anti-dislodgement limiting part on its outer periphery. This anti-dislodgement limiting part can be an annular flange extending axially along the flexible nasal carrier, or it can be a circumferentially spaced partial protrusion. The outer diameter of the anti-dislodgement limiting part is 0.5–1.0 mm larger than the outer diameter of the main body of the flexible nasal carrier, so that it can be secured to the soft tissue inside the nasal cavity entrance after wearing, reducing the possibility of the carrier slipping deeper into the nasal cavity or accidentally dislodging from the nostril. This anti-dislodgement limiting part does not need to penetrate the nasal cavity tissue; its function is to maintain the wearing position through geometric limiting and flexible contact.

[0061] In the dual-nostril detection implementation, two annular flexible nasal carriers are respectively positioned at both ends of a flexible connecting bridge, which spans below the nasal septum or in the columellar region. The flexible connecting bridge serves both to connect the two flexible nasal carriers and to restrict the movement of a single carrier deeper into the nasal cavity. When detecting breathing in only one nasal cavity, a single flexible nasal carrier can also be used.

[0062] The multi-element flexible sensor array includes a temperature sensor 2, a humidity sensor 3, a respiratory mechanics sensor 4, an electrochemical sensor 5, an interface electrode 6, a PI layer 7, a PDMS layer 8, and a SiO2 layer 9. The temperature sensor 2, humidity sensor 3, respiratory mechanics sensor 4, and electrochemical sensor 5 are arranged on the PI layer 7 according to their respective detection areas and are electrically connected to the interface electrode 6 via interconnects. The interface electrode 6 includes sensor contact electrodes, interconnects, and pads, used to lead the electrical signals of each sensing unit to a flexible interconnect interface or an external detection terminal.

[0063] The PI layer 7 includes a flexible PI insulating substrate for supporting the electrodes and interconnects, and a PI insulating layer covering the interconnect areas. The PI flexible insulating substrate is less than 1 micrometer thick, allowing the planar sensor array to be rolled and bent along with the flexible nasal cavity carrier. The PI insulating layer is 2 micrometers thick, covering the metal interconnects and non-detection areas, while forming openings in the sensitive areas of each sensor and at the interface electrode 6. The PI layer 7 serves as a carrier for the micro-nano fabrication of each sensor and also separates the metal electrodes from the flexible nasal cavity carrier to reduce the direct localized stretching of the interconnect structure during bending.

[0064] In this embodiment, a conductive magnetic hollow microtube array, the sensitive or opening regions of each sensor, a PI insulating layer, a Cr / Au electrode layer, a PI flexible insulating substrate, a SiO2 layer 9, and a PDMS layer 8 are sequentially arranged from the airflow side of the nasal cavity to the side that adheres to the nasal cavity wall. The SiO2 layer 9 has a thickness of approximately 5 nanometers and is disposed at the bonding interface between the back side of the PI flexible insulating substrate and the PDMS layer 8. After activation by oxygen plasma, the SiO2 layer 9 forms a stable bond with the PDMS layer 8, which is used to improve the bonding stability between the ultrathin PI sensor array and the PDMS flexible nasal cavity carrier.

[0065] Temperature sensor 2 employs a resistive temperature detection structure, including a serpentine metal resistor extending circumferentially along the flexible carrier of the nasal cavity. The serpentine metal resistor is formed of a Cr / Au metal layer, wherein the Cr layer is 5 nanometers thick and the Au layer is 50 nanometers thick. The Cr layer is used to improve the adhesion between the Au layer and the PI layer 7, and the Au layer is used to form a temperature-sensitive resistor with stable conductivity.

[0066] The detection area of ​​temperature sensor 2 is 36.0 mm × 2.5 mm, with the 36.0 mm section extending circumferentially along the flexible nasal cavity carrier and the 2.5 mm section extending axially along the flexible nasal cavity carrier. The serpentine metal resistor comprises 20 parallel metal resistor segments connected sequentially by bends, with a linewidth and spacing of 50 micrometers between adjacent resistor lines. This serpentine design increases the effective length of the metal resistor within a limited circumferential area, allowing localized temperature changes caused by exhalation and inhalation to be translated into more noticeable resistance changes.

[0067] The humidity sensor 3 includes interdigitated metal electrodes and a graphene oxide humidity-sensitive film covering the surface of the interdigitated metal electrodes and the gaps between the electrodes. The interdigitated metal electrodes are also formed using Cr / Au metal layers with thicknesses of 5 nm and 50 nm, respectively, and include 12 interlaced electrode fingers. The electrode fingers are 200 μm wide, the spacing between adjacent electrode fingers is 100 μm, and the length of the electrode fingers is 2.0 mm. The humidity detection area measures 34.0 mm × 3.5 mm.

[0068] The graphene oxide humidity-sensitive membrane has a thickness of 5–10 nanometers. When exhaled air enters the nasal cavity, the graphene oxide humidity-sensitive membrane adsorbs water molecules, causing changes in its conductivity, capacitance, or impedance. During inhalation, when the local humidity decreases, some water molecules desorb, and the electrical signal of the humidity sensor 3 recovers accordingly. The interdigitated structure increases the contact length between the humidity-sensitive material and the area of ​​electric field interaction, which is beneficial for detecting periodic changes in respiratory humidity within a limited space.

[0069] The respiratory mechanics sensor 4 is disposed in a region of the multi-element flexible sensor array that can receive direct impact from nasal airflow. The respiratory mechanics sensor 4 includes a conductive magnetic hollow microtube array and a common conductive magnetic composite substrate integrally formed with its bottom. The common conductive magnetic composite substrate is fixed to a preset respiratory mechanics detection area of ​​the PI layer 7 and is electrically connected to the corresponding respiratory mechanics sensing connection electrode in the interface electrode 6, thereby enabling the conductive magnetic hollow microtube array to form a conductive path that can be connected to an external resistance detection circuit.

[0070] The common conductive magnetic composite substrate measures approximately 32.0 mm × 3.0 mm and has a thickness of 100 micrometers. The conductive magnetic hollow microtube array covers an area of ​​approximately 32.0 mm × 2.5 mm. The bottoms of multiple hollow microtubes are integrally formed with and electrically connected to the common conductive magnetic composite substrate. The entire array is connected to the detection circuit via the common conductive magnetic composite substrate and connecting electrodes. The hollow microtubes are arranged circumferentially along the flexible nasal cavity carrier, allowing the airflow generated during nasal exhalation and inhalation to act on the sidewalls of the hollow microtubes.

[0071] Each hollow microtube has an outer diameter of 200 micrometers, an inner diameter of 100 micrometers, a wall thickness of 50 micrometers, a height of 2.0 millimeters, and an aspect ratio of 10. The edge spacing between adjacent hollow microtubes is 100 micrometers. The hollow structure reduces the bending stiffness of the microtube while maintaining its tubular shape, allowing even a small airflow in the nasal cavity to drive the microtube to bend laterally. The hollow microtube is integrally molded with a common conductive magnetic composite substrate, which reduces the risk of detachment or sudden changes in contact resistance at the bottom interface of the microtube during repeated bending.

[0072] The conductive magnetic hollow microtubes are formed by curing a mixture of PDMS, neodymium iron boron microparticles, and multi-walled carbon nanotubes in a mass ratio of 2:6:1. PDMS forms a flexible elastic matrix, allowing the hollow microtubes to bend and elastically recover after the airflow disappears; the neodymium iron boron microparticles impart magnetism to the hollow microtubes; and the multi-walled carbon nanotubes form a conductive network within the PDMS, enabling the bending, stretching, and changes in the internal particle spacing of the hollow microtubes to be converted into changes in electrical resistance.

[0073] After axial magnetization, the hollow microtubes form an axial NS magnetic pole distribution. Nasal exhalation and inhalation act on the sidewalls of the hollow microtubes in a direction approximately perpendicular to the microtube axis, with the airflow direction making an angle of 80–90 degrees with the microtube axis. Since exhalation and inhalation are in opposite directions, this drives the microtubes to bend laterally and medially within the nasal cavity, respectively. During microtube bending, changes in the spacing, contact state, or tunneling distance of the multi-walled carbon nanotube conductive pathways within the PDMS matrix cause the respiratory mechanics sensor 4 to output a resistance signal corresponding to the airflow state. After the airflow effect disappears, the microtubes recover due to the elasticity of the PDMS itself and the magnetic interaction between adjacent magnetic microtubes.

[0074] Each hollow microtube has micro-crates with a diameter of 5–10 micrometers on its outer surface. These micro-crates are formed by the dissolution of PMMA particles that were originally attached to the surface of the uncured composite slurry. The micro-crates transform the surface of the microtube from a smooth surface to one with a concave microstructure. When airflow passes through, this alters the local boundary layer and stress distribution, and creates local stress concentrations around the crates. This makes the hollow microtubes more prone to detectable bending and piezoresistive changes under the same airflow conditions.

[0075] The lumen of the hollow microtube can also serve as a loading space for functional substances. In drug-loaded embodiments, the lumen can be loaded with a thermosensitive hydrogel containing levocetirizine transdermal transporters, rizatriptan protoplasts, or α-cyperone nanoparticles; it can also be loaded with humidification materials or other functional molecules. Lumen loading is an optional function, and the loaded material does not participate in the basic detection circuitry of temperature, humidity, respiratory mechanics, and electrochemical sensors. When no functional substance is present, the hollow microtube lumen remains empty, and respiratory mechanics detection can still be performed.

[0076] The electrochemical sensor 5 employs a three-electrode structure, including a working electrode, an Ag / AgCl reference electrode, and a counter electrode. The electrochemical detection area measures 30 mm × 2.2 mm, and includes four rectangular working electrodes, each 28 mm long and 0.4 mm wide, a reference electrode measuring 0.5 mm × 2.0 mm, and a counter electrode measuring 0.5 mm × 2.0 mm. The minimum spacing between the electrodes is 0.2 mm.

[0077] Three of the four working electrodes are hydrogen peroxide (WE1), ethanol (WE2), and lactic acid (WE3), while the fourth is the blank working electrode (Blank WE). The blank working electrode is a bare gold electrode used to obtain the background current when the target-sensitive modification layer is missing, so as to perform differential processing on the background signal generated by environmental humidity, temperature changes, or non-specific adsorption with the signal from the sensitive working electrode.

[0078] The sensitive modification layer of the hydrogen peroxide working electrode WE1 is formed by combining Prussian blue and conductive carbon paste. Prussian blue is used for the electrocatalytic response to hydrogen peroxide, while the conductive carbon paste provides a conductive pathway and immobilizes the Prussian blue. The sensitive modification layer of the ethanol working electrode WE2 includes Nafion, multi-walled carbon nanotubes, Meldora blue, alcohol dehydrogenase, and oxidized coenzyme I. Multi-walled carbon nanotubes are used to increase the effective electrode area and improve electron transport capacity; Nafion is used for immobilization and sieving; alcohol dehydrogenase is used to recognize and catalyze the ethanol reaction; oxidized coenzyme I participates in the enzymatic reaction; and Meldora blue is used for electron transfer.

[0079] The sensitive modification layer of the lactate working electrode WE3 includes platinum nanoparticles, chitosan, and lactate oxidase. Lactate oxidase is used to recognize and catalyze lactate, platinum nanoparticles enhance the electrocatalytic detection capability of the reaction products, and chitosan immobilizes the enzyme and nanoparticles. Depending on the specific target, the number of working electrodes or the sensitive modification layer can be adjusted to detect ammonia, nitric oxide, volatile organic compounds, glucose, urea, or other respiratory markers.

[0080] The multi-element flexible sensor array employs a partially encapsulated structure. The metal interconnects and pad gaps constitute the fully encapsulated area, which is insulated, moisture-proofed, and protected against biological interfaces by a PI layer 7, PDMS layer 8, SiO2 layer 9, a superhydrophobic and breathable membrane, or a composite layer thereof. The detection areas of temperature sensor 2, humidity sensor 3, respiratory mechanics sensor 4, and electrochemical sensor 5 are partially open areas. Humidity sensor 3 retains its graphene oxide moisture-sensitive membrane for contact with water vapor; electrochemical sensor 5 retains its sensitive modification layer for contact with the exhaled gas or exhaled condensate; and the hollow microtube of respiratory mechanics sensor 4 protrudes from the encapsulation layer and receives airflow.

[0081] Example 2: Fabrication of a planar multi-element flexible sensor array

[0082] Step S11: Prepare a PDMS temporary support layer. A layer of PDMS is spin-coated onto the surface of a clean glass slide at 500 rpm and cured on a hot plate at 80°C for 30 minutes to form the PDMS temporary support layer. The function of the PDMS temporary support layer is to support the ultrathin PI layer 7 during subsequent photolithography, sputtering, etching, and sensitive layer modification processes, preventing wrinkles, curling, or cracking of the PI flexible insulating substrate with a thickness of less than 1 micrometer, while also providing a separable interface for subsequent lift-off and transfer printing.

[0083] Step S12: Prepare the PI flexible insulating substrate. Place the PDMS temporary support layer in a UV lamp box for 3 minutes to modify its surface, allowing the PI solution to spread evenly on the PDMS surface. Then, spin-coat the PI material at 2000 rpm and cure using a gradient temperature method: first pre-baking at 80℃ for 30 minutes, then raising the temperature to 120℃ and holding for 30 minutes, and finally raising the temperature to 250℃ and holding for 60 minutes, followed by natural cooling. This staged curing gradually removes the solvent and completes the PI curing, reducing bubbles, cracking, and uneven thickness caused by rapid heating.

[0084] Step S13: Prepare a Cr / Au metal thin film. A 5 nm thick Cr layer and a 50 nm thick Au layer are sequentially deposited on the surface of a PI flexible insulating substrate using magnetron sputtering. The Cr layer acts as an adhesion layer, reducing the peeling of the Au layer from the PI surface under bending and humid conditions. The Au layer is used to form the conductive structure of the connection areas for the temperature sensor 2, humidity sensor 3, electrochemical sensor 5, and respiratory mechanics sensor 4, as well as the interface electrode 6.

[0085] Step S14: Prepare the Ag / AgCl reference electrode. Expose the pre-defined gold reference electrode region in the electrochemical sensor 5 using photolithography and development, and electroplate an Ag layer in this region. Subsequently, chlorinate the electroplated Ag layer in a 3 mmol / L FeCl3 solution, at least partially converting the Ag layer surface to AgCl. After removing the photoresist, the Ag / AgCl reference electrode is formed. This reference electrode provides a relatively stable reference potential during electrochemical detection.

[0086] Step S15: Patterning of sensing electrodes and interconnect structures. The Cr / Au metal thin film is patterned using photolithography, development, and wet etching to form the serpentine electrode in temperature sensor 2, the interdigitated electrode in humidity sensor 3, the working electrode and counter electrode in electrochemical sensor 5, the connection electrode in respiratory mechanics sensor 4, and the contact electrode, pads, and interconnects in interface electrode 6. Processing different sensing units on the same metal layer reduces the number of re-alignments, allowing the positional relationships between sensing units to be determined by the same layout.

[0087] Step S16: Prepare the PI insulating layer and electrode openings. A layer of PI material is spin-coated onto the surfaces of the electrodes and interconnect structures obtained in step S15, and after curing, a PI insulating layer with a thickness of approximately 2 micrometers is formed. Using photolithography and reactive ion etching, openings are formed at the working electrode, counter electrode, and Ag / AgCl reference electrode of the electrochemical sensor 5, the sensitive area of ​​the humidity sensor 3, the connection area of ​​the respiratory mechanics sensor 4, and the interface electrode 6, while retaining the PI insulating layer above the interconnects. This structure exposes areas that need to come into contact with gas, moisture, or external wires, while enclosing and protecting the metal interconnects that do not need to participate in detection.

[0088] Step S17: Prepare the humidity-sensitive material layer. A graphene oxide aqueous dispersion is spin-coated onto the surface of the interdigitated electrodes and the electrode gaps of the humidity sensor 3 at a speed of 500 rpm. After heating at 60°C for 30 minutes, a graphene oxide humidity-sensitive film with a thickness of 5–10 nanometers is formed. The low-speed spin-coating allows the humidity-sensitive material to enter the interdigitated electrode gaps, and the subsequent heating is used to remove moisture and stabilize the film adhesion.

[0089] Step S18: Peeling, Transfer, and Forming of SiO2 Layer 9. A water-soluble adhesive tape is attached to the side of the planar multi-element flexible sensor array containing the electrodes and sensitive layer. The PI layer 7 and the sensing structure thereon are peeled from the PDMS temporary support layer using the water-soluble adhesive tape. Subsequently, the back side of the water-soluble adhesive tape is fixed to a temporary glass substrate, with the back side of the PI flexible insulating substrate facing upwards, and a SiO2 layer 9 approximately 5 nm thick is magnetron sputtered in the bonding area. After deposition, the water-soluble adhesive tape is dissolved in water, thereby releasing a PI-based multi-element flexible sensor array capable of bonding with the PDMS nasal cavity flexible carrier.

[0090] Step S19: Modify the electrochemical working electrode. For the hydrogen peroxide working electrode WE1, Prussian blue and commercial conductive carbon paste were mixed at a mass ratio of 1:20, stirred at 300 rpm for 10 minutes, and then ultrasonically dispersed for 30 minutes. The resulting mixture was coated onto the surface of WE1 and heated at 80°C for 15 minutes to form a Prussian blue / carbon paste sensitive modification layer.

[0091] For the ethanol working electrode WE2, 5 μL of a 10 mg / mL multi-walled carbon nanotube suspension was drop-coated onto the electrode surface, with ethanol and water in a volume ratio of 7:3 as the dispersion medium. After drying at room temperature, it was covered with a 5% (w / v) Nafion-117 solution and dried again at room temperature. Subsequently, 0.25 mmol / L Meldora Blue was electrochemically polymerized in neutral phosphate buffer using cyclic voltammetry, with a scanning potential range of 0.60 V to +1.30 V and 30 cycles. Finally, 5 μL of a mixture of alcohol dehydrogenase and oxidized coenzyme I was added, and the electrode was air-dried at room temperature to form the ethanol working electrode WE2.

[0092] For the lactic acid working electrode WE3, the electrode was placed in a solution containing 5 mmol / L chloroplatinic acid and 1.5 mmol / L formic acid, and electrodeposited at -0.1 V for 30 seconds to form platinum nanoparticles on the electrode surface. Subsequently, 5 μL of a mixture consisting of 1% chitosan, 40 mg / mL lactate oxidase, and 10 mg / mL bovine serum albumin was drop-coated onto the electrode surface and dried at room temperature to form the lactic acid working electrode WE3.

[0093] Example 3: Fabrication of a conductive magnetic hollow microtube array

[0094] Step S21: Prepare the micropillar array resin mold. The micropillar array resin mold is formed using 3D printing technology. The mold substrate thickness is 1.0 mm, the micropillar diameter is 90 μm, the micropillar height is 2 mm, the edge spacing between adjacent micropillars is 210 μm, and the micropillar height is slightly lower than the mold edge. The mold is irradiated with ultraviolet light for 5 minutes to improve the wettability of the micropillar surface to the PVA aqueous solution, thereby enabling the subsequent sacrificial film to continuously cover the micropillar sidewalls.

[0095] Step S22: Forming a PVA water-soluble sacrificial film. A 15% (w / w) PVA aqueous solution is spin-coated or sprayed onto the surface of the micropillar array, coating the top and sidewalls of the micropillars with the PVA aqueous solution; subsequently, it is dried at 40–60°C to form a PVA water-soluble sacrificial film with a thickness of 5 ± 2 micrometers. The PVA sacrificial film, together with the 90-micrometer diameter micropillars, defines the inner diameter of the hollow microtubes at approximately 100 micrometers, and is subsequently dissolved and removed in water, allowing the solidified inner wall of the microtubes to separate from the mold micropillars.

[0096] Step S23: Prepare and coat the conductive magnetic composite slurry. Mix PDMS prepolymer and curing agent at a mass ratio of 10:1 to form a PDMS composite matrix. Then, prepare the PDMS composite matrix, NdFeB particles with an average particle size of approximately 10 micrometers, and multi-walled carbon nanotubes at a mass ratio of 2:6:1. First, ultrasonically disperse the multi-walled carbon nanotubes in n-hexane, then add the NdFeB particles and PDMS composite matrix; the preferred amount of n-hexane added is 40% of the mass of the PDMS composite matrix.

[0097] The mixture was thoroughly stirred, and under ventilated conditions, some of the n-hexane was pre-evaporated, followed by vacuum degassing to obtain a conductive magnetic composite slurry. This slurry was uniformly coated onto the surface of micropillars with a PVA sacrificial film, ensuring the material layer thickness on the micropillar sidewalls was controlled at 50 ± 5 micrometers, while avoiding complete filling of the gaps between adjacent micropillars. The n-hexane was used to reduce the slurry viscosity and aid in the dispersion of carbon nanotubes; pre-evaporation and vacuum degassing reduced air bubbles and conductive discontinuities within the microtube walls after curing.

[0098] Step S24: Set PMMA particles and heat-cur. Select PMMA powder with a particle size of 5-10 micrometers, load it into a powder spray gun, and spray it evenly for 10 seconds at a distance of about 10 cm from the mold surface, so that the spray amount per unit area is about 0.5 mg / cm². The PMMA particles adhere to the surface of the uncured conductive magnetic composite slurry. After the hexane has fully evaporated, place the entire mold in an 80°C oven and heat for 30 minutes to cure the conductive magnetic composite slurry and temporarily fix the PMMA particles to the surface of the microtubes.

[0099] Step S25, Axial Magnetization. The cured conductive magnetic film, along with the mold, is placed into a capacitive magnetizer. Axial magnetization is performed using a 2000-volt magnetization voltage in a coil with a central magnetic field of 3 Tesla. Magnetization with the mold allows the magnetization direction to be determined while the microtubes remain in a regular upright state, resulting in a basically consistent axial magnetic pole distribution for each microtube.

[0100] Step S26: Dissolve the PVA sacrificial film. Immerse the magnetized mold in deionized water and sonicate it at 80°C for 30 minutes to fully dissolve the water-soluble PVA sacrificial film. After the PVA is dissolved, a physical gap is formed between the mold micropillars and the inner wall of the cured composite material, reducing the possibility of tearing or breaking the high aspect ratio hollow microtubes during subsequent demolding.

[0101] Step S27: Dissolving PMMA particles and forming micro-pits. The mold is placed in acetone and subjected to intermittent ultrasound at 50°C for 30–60 minutes to dissolve the PMMA particles embedded in the composite material surface. After dissolution, micro-pits with a diameter of approximately 5–10 micrometers are left on the outer surface of the microtubes. Intermittent ultrasound promotes the penetration of acetone around the PMMA particles while avoiding excessive mechanical vibration of the microtubes caused by continuous high-intensity ultrasound.

[0102] Step S28, demolding and selective in-tube loading. The conductive magnetic hollow microtube array with micro-spherical pits is removed from the mold to obtain a hollow microtube array with its bottom integrally formed with a common conductive magnetic composite substrate.

[0103] When drug or functional molecule loading is required, the selected drug delivery system is mixed with a thermosensitive hydrogel that gels above 25°C at 4°C to form a flowable liquid hydrogel at low temperatures. Levocetirizine delivery system, rizatriptan protoplast, and α-cyperone nanoparticles can be placed in different sample cells. A hollow microtube array is inverted and placed across the sample cell, then extracted under vacuum at 4°C, allowing the liquid hydrogel to enter the corresponding microtube lumen. After loading, the temperature is raised to the operating temperature, causing the thermosensitive hydrogel to gel and remain within the lumen. This loading process can be omitted if no drug loading is required.

[0104] Example 4: Device Integration and Molding

[0105] Step S31: Integrate the respiratory mechanics sensor 4. Align the conductive magnetic hollow microtube array obtained in step S28 with the preset respiratory mechanics detection area on the PI substrate multi-element flexible sensor array obtained in step S19, so that the common conductive magnetic composite substrate is fixed on the PI layer 7, and the conductive end of the common conductive magnetic composite substrate is reliably in contact with the corresponding respiratory mechanics sensing connection electrode in the interface electrode 6. After fixing, the hollow microtubes protrude towards the nasal airflow side, and the common conductive magnetic composite substrate is located between the hollow microtubes and the PI layer 7.

[0106] Step S32: Prepare a flexible PDMS nasal cavity carrier. A ring-shaped, semi-ring-shaped, tubular, or nasal plug-like mold adapted to the morphology of the inner side of the nasal cavity inlet is formed by 3D printing. Uncured PDMS is poured into or spin-coated into the mold, and after curing and demolding, a PDMS layer 8 is formed.

[0107] Step S33, array bonding. Oxygen plasma treatment is applied to the surface of the SiO2 layer 9 on the PI substrate multi-element flexible sensor array and the bonding surface of the PDMS nasal cavity flexible carrier, respectively. The treatment power is 100 W, the treatment time is 90 seconds, the cavity pressure is 30–50 Pa, and the oxygen flow rate is 20–30 standard mL / min. Oxygen plasma treatment forms active groups on the SiO2 layer 9 and the PDMS surface, providing reaction sites for subsequent interfacial bonding.

[0108] Within 2 minutes of oxygen plasma treatment, the PI-based multi-element flexible sensor array and the PDMS nasal cavity flexible carrier are aligned and bonded together. A bonding pressure of 10–20 kPa is applied, and the mixture is heated at 80°C for 30 minutes to form a stable composite structure. The limited bonding time is to complete interfacial contact before the surface activity decays, the bonding pressure is used to eliminate interfacial gaps, and the heat treatment is used to promote interfacial bonding and stabilization.

[0109] Step S34, Roll-up and partial encapsulation. The bonded planar flexible composite structure is rolled or bent along a predetermined direction to form an annular flexible nasal cavity carrier with a diameter of approximately 14 mm and an axial length of approximately 12.2 mm. The rolling direction should be such that the detection surfaces of each sensor face the nasal airflow channel, and the PDMS layer 8 faces the contact side with the inner wall of the nasal cavity.

[0110] An insulating and moisture-proof encapsulation layer is set in the non-sensitive area to encapsulate the metal interconnects, pad gaps, and flexible substrate interface. Openings, semi-permeable interfaces, or breathable and hydrophobic interfaces are reserved at the corresponding positions of temperature sensor 2, humidity sensor 3, respiratory mechanics sensor 4, and electrochemical sensor 5. After encapsulation, temperature sensor 2, humidity sensor 3, respiratory mechanics sensor 4, and electrochemical sensor 5 are all located in the area through which nasal breathing airflow passes, while the interface electrode 6 can be connected to the signal acquisition end located outside the nasal cavity through a flexible interconnect structure.

[0111] Example 5: Basic Performance Calibration Experiment

[0112] The fabricated wearable flexible respiratory detection device 1 was placed in a test chamber capable of adjusting temperature, humidity, and airflow. The interface electrode 6 was connected to an external resistance detection device and an electrochemical workstation. Before testing, the device was left to stand in a preset environment to allow the baselines of the temperature sensor 2, humidity sensor 3, and respiratory mechanics sensor 4 to stabilize.

[0113] During the calibration of temperature sensor 2, the test temperature was gradually increased from 20℃ to 40℃, with each temperature increment being 2℃. The resistance value of the serpentine metal resistor was recorded at each temperature point, and the test was repeated under dynamic airflow conditions of 0.5–2.0 L / min. This experiment was used to establish the correspondence between temperature and the resistance value of the serpentine resistor, and to confirm that temperature sensor 2 can respond to local temperature changes caused by inhalation and exhalation.

[0114] During the calibration of humidity sensor 3, the relative humidity of the test chamber was adjusted from 10% to 100%, and repeated scanning was performed at 25℃, 30℃, 35℃, and 40℃, respectively, recording the changes in impedance, resistance, or capacitance of the interdigitated electrodes. The purpose of setting multiple temperature conditions is to observe whether the humidity response is affected by temperature changes, providing a calibration basis for the subsequent separate identification and correction of temperature and humidity signals.

[0115] During the calibration of the respiratory mechanics sensor 4, the relative humidity was set to 80%–100% to approximate the high humidity environment inside the nasal cavity. The dynamic airflow rate was set to 0.5–2.0 L / min, and the airflow was periodically applied to the sidewall of the hollow microtube at an angle of 80–90 degrees to the axis of the microtube. The resistance changes, baseline recovery, and signal waveforms during repeated airflow cycles of the respiratory mechanics sensor 4 were recorded at different flow rates. This experiment can confirm whether the conductive magnetic hollow microtube has a detectable piezoresistive response under high humidity and periodic weak airflow conditions.

[0116] During the calibration of electrochemical sensor 5, standard samples containing known concentrations of hydrogen peroxide, ethanol, and lactic acid were provided to the corresponding working electrodes. The electrochemical response was recorded using cyclic voltammetry or chronoamperometry, and the background signal of the blank working electrode was recorded simultaneously. Differential calibration between the sensitive working electrode signal and the blank working electrode signal can reduce the influence of substrate current and nonspecific environmental changes. When a dedicated carbon dioxide working electrode is provided, carbon dioxide calibration can also be performed. In the WE1, WE2, and WE3 structures specified in this embodiment, the main calibration targets are hydrogen peroxide, ethanol, and lactic acid.

[0117] The technical effects and underlying mechanisms embodied in this embodiment are as follows: Firstly, this embodiment enables in-situ detection of multiple parameters inside the nasal cavity inlet from a structural perspective. Temperature sensor 2, humidity sensor 3, respiratory mechanics sensor 4, and electrochemical sensor 5 are all mounted on the same PI layer 7 and maintained within the nasal airflow path along with the PDMS nasal flexible carrier. Therefore, it can acquire signals related to temperature changes, humidity changes, airflow mechanics changes, and exhaled gas composition caused by respiration. Compared to indirect detection methods located on the chest and abdomen, these signals directly originate from nasal airflow; compared to external patching around the nose, the sensing area is independent of the adhesion state to the skin surface.

[0118] The underlying principle is that the inner side of the nasal cavity entrance is close to the source of respiratory airflow. When exhaled air enters this area, it has not yet fully mixed with the surrounding air, and its temperature, humidity, and airflow direction exhibit significant periodic changes. Placing the sensor in this location helps shorten the transmission path of the gas being measured from the nasal airflow source to the sensing interface. This effect is a direct result of the device placement, but its specific anti-interference capability still needs to be verified through experimental data from human wear or simulated nasal cavities.

[0119] The conductive magnetic hollow microtube array can convert weak airflow into a resistance signal because the hollow tubular structure has lower bending stiffness compared to a solid micropillar of the same outer diameter. When airflow acts on the sidewall of the microtube, the outer side of the microtube is under tension and the inner side is under compression, causing changes in the contact distance and conductive pathways between the multi-walled carbon nanotubes inside the PDMS. Thus, mechanical deformation can be converted into a change in resistance that can be output by the interface electrode 6.

[0120] Micro-craters, by altering the surface morphology and local stress distribution of microtubes, can increase the non-uniform stress on the surface during airflow and create local stress concentrations near the edges of the craters. Axially magnetized NdFeB particles give the microtubes a defined magnetization direction; after airflow unloading, the magnetic effect and PDMS elastic recovery together cause the microtubes to return to their initial position. Therefore, the hollow structure, surface micro-craters, piezoresistive conductive network, and magnetic recovery are not entirely independent; they collectively serve the weak airflow response and periodic recovery.

[0121] The interlayer combination of PI layer 7, SiO2 layer 9, and PDMS layer 8 enables the device to simultaneously achieve micro / nano fabrication and flexible wearability. PI layer 7 is suitable for forming fine metal electrodes and interconnects; PDMS layer 8 is flexible and elastic, suitable for forming a nasal cavity wear carrier; SiO2 layer 9, after oxygen plasma treatment, provides bonding conditions for heterogeneous material interfaces. Local packaging isolates the interconnects and pad gaps from the high-humidity environment of the nasal cavity, while not obstructing sensitive areas that must be exposed to airflow, moisture, or the object under test.

[0122] There is a clear sequential synergy between the different steps in the process. The PDMS temporary support layer first provides processing support for the ultrathin PI layer 7; after the sensing electrodes and sensitive layer are completed, water-soluble adhesive tape is used for peeling and transfer to expose the back side of the PI layer 7 and deposit the SiO2 layer 9; the conductive magnetic hollow microtubes are fabricated using independent molds to avoid their high aspect ratio structure undergoing the photolithography, etching, and high-temperature curing processes of the planar array; finally, the microtube array is integrated with the PI planar array and bonded to the pre-formed PDMS nasal cavity carrier. This process sequence can reduce the mutual interference between the microtube structure and the planar micro / nano fabrication process.

[0123] Working principle: During use, the flexible nasal carrier is compressed radially and placed inside the nasal cavity inlet. The flexible nasal carrier elastically recovers and conforms to the inner wall of the nasal cavity, and the anti-fall-off limiting part restricts its axial sliding. Temperature sensor 2, humidity sensor 3, respiratory mechanics sensor 4, and electrochemical sensor 5 face the nasal cavity breathing airflow channel, and interface electrode 6 is connected to the external detection end.

[0124] During exhalation, the warm and humid exhaled airflow passes through a multi-element flexible sensor array. The resistance of the serpentine metal resistor changes with temperature, the graphene oxide humidity-sensitive membrane undergoes an electrical change due to the adsorption of water molecules, and the conductive magnetic hollow microtubes bend under the lateral force of the airflow, resulting in a piezoresistive change. The electrochemical working electrode then generates an electrochemical response to corresponding markers in the exhaled gas or exhaled condensate. During inhalation, the airflow direction, local temperature, and humidity change, causing the microtubes to bend in the opposite direction or return to their original position. Each sensing unit generates a signal corresponding to the inhalation phase.

[0125] After the respiratory airflow weakens or disappears, the conductive magnetic hollow microtube recovers due to the elasticity and magnetism of PDMS; the temperature sensor 2 changes its resistance as the local temperature recovers; the humidity sensor 3 gradually recovers as water molecules desorb; the electrochemical sensor 5 forms a detection circuit through the reference electrode and the counter electrode, and can be combined with a blank working electrode for background differential detection. Thus, the wearable flexible respiratory detection device 1 can simultaneously output signals related to temperature, humidity, respiratory mechanics, and exhaled gas composition inside the nasal cavity inlet, providing a signal basis for multi-parameter detection of respiratory status.

[0126] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A flexible respiratory detection device based on an embedded multi-element sensor array, characterized in that, The flexible respiratory detection device (1) includes a flexible nasal cavity carrier and a multi-element flexible sensor array; The nasal flexible carrier is used to hold the multi-element flexible sensor array inside the nasal cavity entrance or near the inner wall of the nasal cavity, so that the detection area of ​​the multi-element flexible sensor array is located in the area through which the nasal breathing airflow passes. The multi-element flexible sensor array includes a temperature sensor (2), a humidity sensor (3), a respiratory mechanics sensor (4), an electrochemical sensor (5), an interface electrode (6), a PI layer (7), a PDMS layer (8), and a SiO2 layer (9). The temperature sensor (2), humidity sensor (3), respiratory mechanics sensor (4) and electrochemical sensor (5) are electrically connected to the interface electrode (6) respectively. The PI layer (7) serves as a flexible insulating substrate that carries each sensor and its interconnection structure. The PDMS layer (8) serves as a temporary support layer, a flexible support layer or a material layer of the nasal cavity flexible carrier. The SiO2 layer (9) is disposed at the bonding interface between the PI layer (7) and the PDMS layer (8). The respiratory mechanics sensor (4) includes a conductive magnetic hollow microtube array, which is formed by mixing and solidifying a flexible polymer, magnetic microparticles and conductive fillers. The surface of the conductive magnetic hollow microtube array has micro-spherical pits. The conductive magnetic hollow microtube array is used to bend and deform under the action of nasal breathing airflow and generate resistance changes, and recovers through its own elasticity and magnetic action after the action of breathing airflow disappears.

2. The flexible respiratory detection device based on an embedded multi-element sensor array according to claim 1, characterized in that, The temperature sensor (2) includes a serpentine metal electrode extending circumferentially along the flexible carrier of the nasal cavity, the serpentine metal electrode being used to convert local temperature changes caused by inhalation and exhalation into resistance changes; The humidity sensor (3) includes interdigitated electrodes and a humidity-sensitive material layer. The humidity-sensitive material layer covers the surface of the interdigitated electrodes and the gap area between adjacent electrodes, and is used to convert humidity changes in the nasal respiratory microenvironment into electrical signals. The humidity-sensitive material layer includes graphene oxide, polyvinyl alcohol, cellulose nanomaterials, ion gels or composite materials thereof.

3. The flexible respiratory detection device based on an embedded multi-element sensor array according to claim 1, characterized in that, The respiratory mechanics sensor (4) also includes a common conductive magnetic composite substrate integrally formed with the conductive magnetic hollow microtube array. The common conductive magnetic composite substrate is fixed to the preset respiratory mechanics detection area of ​​the PI layer (7) and electrically connected to the corresponding respiratory mechanics sensing connection electrode in the interface electrode (6). Multiple hollow microtubes in the conductive magnetic hollow microtube array are arranged circumferentially along the flexible nasal carrier. The hollow microtubes protrude from the common conductive magnetic composite substrate, allowing nasal breathing airflow to act on the sidewalls of the hollow microtubes and drive the hollow microtubes to bend.

4. The flexible respiratory detection device based on an embedded multi-element sensor array according to claim 3, characterized in that, The flexible polymer is PDMS, the magnetic microparticles are neodymium iron boron microparticles, the conductive filler is carbon nanotubes, and the mass ratio of PDMS, neodymium iron boron microparticles and carbon nanotubes is 2:6:

1. The hollow microtubes are axially magnetized to form an axial magnetic pole distribution, and the diameter of the micro-spherical pits is 5 to 10 micrometers; the inner cavity of the hollow microtubes is used to load sustained-release drugs, humidification materials or functional molecules.

5. The flexible respiratory detection device based on an embedded multi-element sensor array according to claim 1, characterized in that, The electrochemical sensor (5) includes at least one working electrode, an Ag / AgCl reference electrode and a counter electrode, wherein at least one of the working electrodes has a sensitive modification layer for detecting respiratory-related markers on its surface; The working electrode includes at least two of the following: hydrogen peroxide working electrode, ethanol working electrode, lactic acid working electrode, and blank working electrode. The blank working electrode is used for differential compensation of non-target signals. The sensitive modification layer of the hydrogen peroxide working electrode includes Prussian blue and conductive carbon material; the sensitive modification layer of the ethanol working electrode includes Nafion, multi-walled carbon nanotubes, Meldora blue, alcohol dehydrogenase and oxidized coenzyme I; and the sensitive modification layer of the lactate working electrode includes platinum nanoparticles, chitosan and lactate oxidase.

6. The flexible respiratory detection device based on an embedded multi-element sensor array according to claim 1, characterized in that, The flexible nasal carrier has a ring-shaped, semi-ring-shaped, tubular, or nasal plug-like structure, and can pass through the nasal inlet after radial compression. After entering the nasal cavity, it elastically recovers and fits the inside of the nasal inlet. The outer periphery of the nasal cavity flexible carrier is provided with an outwardly protruding anti-fall-off limiting part, which is an annular flange or a partial boss extending along the axial direction of the nasal cavity flexible carrier. The nasal cavity flexible carrier is a single nostril structure, or the nasal cavity flexible carrier is a dual nostril integrated structure, the dual nostril integrated structure includes a flexible connecting bridge and two nasal cavity flexible carriers respectively disposed at both ends of the flexible connecting bridge. The non-sensitive areas of the multi-element flexible sensor array are provided with an insulating and moisture-proof encapsulation layer, and the detection areas of the temperature sensor (2), humidity sensor (3), respiratory mechanics sensor (4) and electrochemical sensor (5) are respectively provided with openings, semi-permeable interfaces or air-permeable and hydrophobic interfaces.

7. A method for fabricating a flexible respiratory detection device based on an embedded multi-element sensor array, used to fabricate the flexible respiratory detection device based on an embedded multi-element sensor array as described in claim 1, characterized in that, include: Step S1: A planar multi-element flexible sensor array with PI layer (7) as a flexible insulating substrate is prepared on a temporary support layer. A connection area and interface electrode (6) of temperature sensor (2), humidity sensor (3), electrochemical sensor (5), and respiratory mechanics sensor (4) are formed in the planar multi-element flexible sensor array. A SiO2 layer (9) is formed on the bonding surface of the PI layer (7). Step S2: Prepare an array of conductive magnetic hollow microtubes with micro-spherical pits on the surface; Step S3: Integrate the conductive magnetic hollow microtube array into the preset respiratory mechanics detection area of ​​the planar multi-element flexible sensor array to form a respiratory mechanics sensor (4), and combine the planar multi-element flexible sensor array with the nasal cavity flexible carrier formed by the PDMS layer (8), and then roll or bend the composite structure into an embedded wearing structure that fits the inside of the nasal cavity inlet.

8. The method for fabricating a flexible respiratory detection device based on an embedded multi-element sensor array according to claim 7, characterized in that, Step S1 includes: PDMS is spin-coated onto a glass substrate and cured to form a temporary support layer. The surface of the temporary support layer is modified. PI material is spin-coated onto the temporary support layer and cured to form a PI layer (7). A metal thin film is formed on the PI layer (7) and the metal thin film is patterned to form the serpentine electrode of the temperature sensor (2), the interdigitated electrode of the humidity sensor (3), the working electrode and counter electrode of the electrochemical sensor (5), the connection electrode of the respiratory mechanics sensor (4), and the interface electrode (6). A silver layer is formed in the reference electrode region of the electrochemical sensor (5), and the silver layer is chlorinated to form an Ag / AgCl reference electrode. A PI insulating layer is formed on the metal thin film, and openings are formed in the sensitive area of ​​the humidity sensor (3), the electrode area of ​​the electrochemical sensor (5), the connection area of ​​the respiratory mechanics sensor (4), and the interface electrode (6). A humidity-sensitive material layer is formed at the interdigitated electrode of the humidity sensor (3), and a sensitive modification layer is formed at the working electrode of the electrochemical sensor (5). The planar multi-element flexible sensor array is peeled off from the temporary support layer and transferred to form a SiO2 layer (9) on the back side of the PI layer (7) in the bonding area.

9. The method for fabricating a flexible respiratory detection device based on an embedded multi-element sensor array according to claim 7, characterized in that, Step S2 includes: A resin mold with a micropillar array is formed by 3D printing, and a PVA water-soluble sacrificial film is formed on the surface of the micropillar array. PDMS, neodymium iron boron microparticles and carbon nanotubes are mixed to form a conductive magnetic composite slurry, and the conductive magnetic composite slurry is coated on the surface of a micropillar array on which the PVA water-soluble sacrificial film is formed. PMMA particles are placed on the surface of the uncured conductive magnetic composite slurry and then thermo-cured. The thermo-cured conductive magnetic composite slurry is then axially magnetized. The PVA water-soluble sacrificial film is dissolved in water to form a release gap between the resin mold and the cured conductive magnetic composite slurry. The PMMA particles are dissolved in an organic solvent to form micro-spherical pits on the surface of the conductive magnetic composite slurry. The cured conductive magnetic composite slurry is demolded from the resin mold to obtain the conductive magnetic hollow microtube array, and a sustained-release drug, a wetting modifier, or a functional molecule is selectively loaded into the hollow microtube cavity of the conductive magnetic hollow microtube array.

10. The method for fabricating a flexible respiratory detection device based on an embedded multi-element sensor array according to claim 7, characterized in that, Step S3 includes: The conductive magnetic hollow microtube array is fixed on the preset respiratory mechanics detection area on the PI layer (7), and the conductive magnetic hollow microtube array is electrically connected to the corresponding respiratory mechanics sensing connection electrode in the interface electrode (6). A flexible nasal carrier formed by the PDMS layer (8) was prepared. The SiO2 layer (9) and the bonding surfaces of the flexible nasal carrier were subjected to oxygen plasma treatment respectively. The treated planar multi-element flexible sensor array was aligned, attached and bonded to the flexible nasal carrier. The bonded composite structure is rolled or bent along a predetermined direction to form a ring, semi-ring, tubular or nose plug-like structure. The non-sensitive areas of the planar multi-element flexible sensor array are insulated and moisture-proofed, and openings, semi-permeable interfaces or air-permeable and hydrophobic interfaces are retained in the detection areas of the temperature sensor (2), humidity sensor (3), respiratory mechanics sensor (4) and electrochemical sensor (5) to obtain the flexible respiratory detection device (1) based on the embedded multi-element sensor array.

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