Wound monitoring bandage and method based on flexible passive inductance-capacitance resonance sensing

Abstract

The invention belongs to the technical field of medical sensing, and relates to a wound monitoring bandage and method based on flexible passive inductance-capacitance resonance sensing. Comprising a contact wound dressing; the sensor assembly comprises a first transparent dressing packaging layer, a second transparent dressing packaging layer and an LC resonance sensor, the first transparent dressing packaging layer and the second transparent dressing packaging layer are arranged in a stacked mode, the LC resonance sensor is packaged between the first transparent dressing packaging layer and the second transparent dressing packaging layer, and the LC resonance sensor is of a planar spiral structure; the second transparent dressing packaging layer is arranged at the top of the contact wound dressing; and the transparent dressing fixing layer covers and fixes the sensor assembly and the contact wound dressing. The problems that in the prior art, wound healing state evaluation depends on subjective experience, continuous real-time monitoring cannot be achieved, the healing environment is prone to being damaged and infection is caused by frequent dressing replacement are solved, and the dual functions of objective, continuous and non-invasive monitoring on the wound healing process and active healing promotion are achieved.

Description

Technical Field

[0001] This invention belongs to the field of medical sensing technology, and relates to a wound monitoring bandage and method based on flexible passive inductive-capacitive resonant sensing. Background Technology

[0002] Wound healing is a complex physiological process involving multiple stages, including inflammatory response, tissue proliferation, and tissue remodeling. In clinical practice, accurately assessing the wound healing status is crucial for optimizing treatment plans and improving patient prognosis. Currently, clinical practice mainly relies on healthcare professionals' subjective judgment of wound size, color, and exudate characteristics through visual observation, palpation, and dressing changes. This method has significant limitations. On the one hand, the assessment results are heavily influenced by personal experience, are highly subjective, and lack objective quantitative evidence. On the other hand, existing assessment methods are intermittent, failing to provide continuous, real-time monitoring of the wound condition and easily overlooking key dynamic changes during the healing process. Furthermore, frequent dressing changes not only disrupt the moist healing environment of the wound but may also increase the risk of infection, thus interfering with or even delaying the healing process.

[0003] To overcome the shortcomings of traditional assessment methods, the medical monitoring field has recently begun exploring the integration of sensing technology with wound dressings to achieve objective, continuous, and non-invasive monitoring of wound conditions. Among various sensing mechanisms, electrical sensing technology has attracted much attention due to its high sensitivity to changes in tissue physiological states. Existing research has focused on monitoring key parameters such as wound pH, temperature, humidity, and bacterial biomarkers. However, existing electrical sensing solutions mostly rely on active electronic components, requiring built-in power supplies and wired signal acquisition and transmission. This results in complex system structures, high costs, and large sizes, making the overall dressing bulky and uncomfortable, severely impacting patients' daily activities and limiting its clinical promotion and application.

[0004] Against this backdrop, wireless passive sensing technology offers a new direction for overcoming the technical bottlenecks of active sensors. Among them, sensors based on the inductor-capacitor (LC) resonance principle exhibit unique advantages. Their working mechanism lies in the fact that the resonant circuit composed of an inductor and a capacitor has a specific resonant frequency. When external environmental parameters (such as dielectric constant and conductivity) change, it causes a shift in the resonant frequency or a change in the amplitude of the resonant peak. By detecting these changes in characteristics through an external reading device, the wound environment state can be inferred. This type of sensor requires no built-in power supply or physical connection, achieving true passivity and wireless functionality, and possesses excellent potential for clinical applications.

[0005] Although LC resonant sensing is relatively mature in theory, it still faces many challenges in practical wound monitoring applications, including insufficient biocompatibility and mechanical properties of the sensor, poor signal stability and anti-interference ability, and low measurement repeatability, which restrict its transformation into practical applications and products. Therefore, there is an urgent need to develop a wireless passive sensing system that combines good biocompatibility, stable sensing performance, and suitability for long-term wound environment monitoring. Summary of the Invention

[0006] To address the problems in existing technologies, this invention provides a wound monitoring bandage and method based on flexible passive inductive-capacitive resonant sensing, achieving the dual functions of objective, continuous, and non-invasive monitoring of the wound healing process and actively promoting healing. To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing, comprising: Contact wound dressing; The sensor assembly includes a first transparent dressing encapsulation layer, a second transparent dressing encapsulation layer, and an LC resonant sensor encapsulated between the first transparent dressing encapsulation layer and the second transparent dressing encapsulation layer, wherein the LC resonant sensor has a planar spiral structure; the second transparent dressing encapsulation layer is disposed on the top of the contact wound dressing. A transparent dressing fixation layer covers and secures the sensor assembly to the contact wound dressing.

[0007] Preferably, the planar projected area of ​​the transparent dressing fixation layer is larger than the planar projected area of ​​the contact wound dressing; a biocompatible adhesive layer is provided on the lower surface of the transparent dressing fixation layer in the area outside the periphery of the contact wound dressing.

[0008] Preferably, it further includes alignment marks disposed on the outer surface of the transparent dressing fixing layer, the center of the alignment marks being coaxial with the center of the planar spiral structure of the LC resonant sensor.

[0009] Preferably, the contact wound dressing comprises an anti-adhesive isolation layer, an absorbent pad, and a breathable base fabric stacked sequentially; the second transparent dressing encapsulation layer is disposed on top of the breathable base fabric.

[0010] Preferably, the transparent dressing encapsulation layer is a medical transparent dressing.

[0011] Preferably, the planar spiral structure is a mosquito coil-type structure.

[0012] Preferably, the mosquito coil-like structure includes two adjacent spiral coils; wherein one spiral coil is made of molybdenum and the other spiral coil is made of zinc.

[0013] Preferably, the thickness of the LC resonant sensor is 10~100μm.

[0014] Preferably, the dimensions of both the first transparent dressing encapsulation layer and the second transparent dressing encapsulation layer are larger than the dimensions of the LC resonant sensor.

[0015] Secondly, the present invention provides a wound monitoring method based on flexible passive inductive-capacitive resonant sensing, comprising the following steps: The bandage is attached to the wound to be tested, so that the contact wound dressing is in direct contact with the wound surface, and the LC resonant sensor is fixed to the central area of ​​the wound through the transparent dressing fixation layer. The detection antenna of the external reading device is spatially aligned with the LC resonant sensor fixed at the center of the wound. The detection antenna transmits a scanning signal to the LC resonant sensor and receives the response signal from the LC resonant sensor to obtain the forward transmission coefficient S21 spectrum of the LC resonant sensor; Extract the resonant frequency characteristics and / or resonant amplitude characteristics of the LC resonant sensor from the spectrum of the forward transmission coefficient S21; Based on the changes in the resonant frequency characteristics and / or resonant amplitude characteristics, the changes in the dielectric properties of the wound tissue are monitored, thereby assessing the wound healing status.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention's LC resonant sensor requires no built-in power supply or wired connection; energy acquisition and signal transmission are achieved solely through electromagnetic coupling, greatly simplifying the system structure and reducing cost and size. The transparent dressing encapsulation layer covering the sensor creates an effective physical barrier, preventing high-conductivity wound exudate from directly contacting the sensor and avoiding signal attenuation, resonant peak broadening, or disappearance due to liquid load. Simultaneously, while isolating interference, the sensor still allows for sensitive detection of changes in the dielectric properties of underlying tissue through electromagnetic fields, ensuring reliable monitoring signals. Furthermore, upon contact with exudate, the sensor can generate a galvanic cell effect based on its material properties, releasing metal ions that promote healing, thus providing auxiliary therapeutic functions in addition to monitoring.

[0017] Furthermore, the sensor used in this invention is made of biodegradable molybdenum and zinc metals, which not only has excellent biocompatibility and environmental friendliness, effectively avoiding the long-term biotoxicity risks of traditional non-degradable materials, but also fundamentally solves the key problem of active sensors relying on battery replacement and generating electronic waste.

[0018] Furthermore, the "mosquito coil-shaped" planar spiral structure combines excellent mechanical flexibility with superior electromagnetic performance. Its extremely high flexibility ensures that the sensor conformally fits the human skin and wound surface, effectively adapting to bending and stretching caused by body movements, and significantly reducing measurement errors caused by mechanical deformation. At the same time, this structure achieves a balance between high inductance and distributed capacitance within a limited area, and the resulting optimized electromagnetic field distribution concentrates energy on the sensing area, thus exhibiting extremely high sensitivity to minute changes in the dielectric constant and conductivity of wound tissue, ultimately achieving a significant improvement in monitoring performance.

[0019] Furthermore, by fixing the sensor to the center of the wound and employing a standardized measurement method that aligns the external detection antenna with the center of the sensor, combined with the inherent symmetrical magnetic field distribution of the planar spiral structure, a stable and reliable detection system was constructed. This "center-to-center" alignment strategy effectively suppresses signal fluctuations caused by minute offsets in the relative position, angle, or distance between the antenna and the sensor, ensuring high consistency and comparability of data collected at different time points, and providing a solid guarantee for long-term accurate tracking of the dynamic changes in wound healing. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a wound monitoring bandage based on flexible passive LC resonant sensing in an embodiment of the present invention; Figure 2 This refers to the AutoCAD software drawing of the sensing shape in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the wound monitoring process based on flexible passive LC resonant sensing in Embodiment 2 of the present invention; Figure 4 This is a sensor response diagram in Example 3 of the present invention when exposed to different amounts of PBS in vitro; Figure 5 This is a sensor response diagram when exposed to skin and wound areas in Embodiment 3 of the present invention; Figure 6 A is the sensor response diagram for wound infection day 0 in Embodiment 3 of the present invention; Figure 6 B is the sensor response diagram of wound infection 1 day after embodiment 3 of the present invention; Figure 6C is the sensor response diagram of the wound infection 2 days after embodiment 3 of the present invention; Figure 6 D is the sensor response diagram of the wound infection 3 days after embodiment 3 of the present invention; Figure 6 E is the sensor response diagram of the wound infection 6 days after embodiment 3 of the present invention; Figure 6 F is the sensor response diagram of wound infection 7 days after embodiment 3 of the present invention; Figure 6 G is the sensor response diagram of the wound infection 9 days after embodiment 3 of the present invention; Figure 6 H is the sensor response diagram of the wound infection 11 days after embodiment 3 of the present invention; Figure 6 J is the sensor response diagram of wound infection 13 days after embodiment 3 of the present invention; Figure 7 A is a graph showing the change of resonant frequency over time during the wound healing process in Embodiment 3 of the present invention; Figure 7 B is a graph showing the correlation between resonant frequency and wound area during the wound healing process in Embodiment 3 of the present invention; Figure 8 A is a graph showing the change of peak amplitude over time during the wound healing process in Embodiment 3 of the present invention; Figure 8 B is a correlation diagram between the peak amplitude and the wound area during the wound healing process in Embodiment 3 of the present invention; Figure 9 This is a diagram illustrating wound treatment using sensors in Embodiment 3 of the present invention; Figure 10 This is a wound area diagram of the sensor part promoting wound healing in Embodiment 3 of the present invention.

[0022] The components are: 1. First transparent dressing encapsulation layer; 2. LC resonant sensor; 3. Second transparent dressing encapsulation layer; 4. Contact wound dressing; 5. Transparent dressing fixation layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0029] The present invention will now be described in further detail with reference to the accompanying drawings: The first objective of this invention is to provide a wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing, comprising: 4. Contact wound dressing; The sensor assembly includes a first transparent dressing encapsulation layer 1, a second transparent dressing encapsulation layer 3 stacked together, and an LC resonant sensor 2 encapsulated between the first transparent dressing encapsulation layer 1 and the second transparent dressing encapsulation layer 3, wherein the LC resonant sensor 2 has a planar spiral structure; the second transparent dressing encapsulation layer 3 is disposed on the top of the contact wound dressing 4. A transparent dressing fixation layer 5 covers and fixes the sensor assembly to the contact wound dressing 4.

[0030] The wound monitoring bandage described in this invention achieves stable and reliable wireless monitoring through a sophisticated multi-layered design. Its core is a sensor assembly composed of two transparent dressing encapsulation layers. This protects the internal planar spiral-structured LC resonant sensor from direct interference from wound exudate, ensuring signal clarity and stability. Simultaneously, it allows the sensor's electromagnetic field to effectively penetrate, sensitively detecting changes in the dielectric properties of the underlying tissue. The contact wound dressing acts as a buffer layer between the sensor and the wound, absorbing excess exudate and providing a moist healing environment while preventing adhesion between new tissue and the sensor, ensuring measurement stability and patient comfort. The outermost transparent dressing fixation layer firmly integrates and secures the entire assembly at the center of the wound, minimizing signal fluctuations caused by component displacement or slippage. This ensures the consistency and comparability of data collected at different time points, laying a solid foundation for accurately tracking the dynamic progress of wound healing.

[0031] The planar projected area of ​​the transparent dressing fixation layer 5 is larger than that of the contact wound dressing 4. A biocompatible adhesive layer is provided on the lower surface of the transparent dressing fixation layer 5, in the area outside the periphery of the contact wound dressing 4. By expanding the coverage area of ​​the transparent dressing fixation layer 5 and utilizing the biocompatible adhesive layer at its edge, a superior fixation of the entire monitoring component is achieved. It firmly "locks" the sensor component and the contact wound dressing 4 in the center of the wound, effectively resisting displacement, lifting, or detachment caused by daily body activities or clothing friction.

[0032] The wound monitoring bandage of this invention also includes alignment marks disposed on the outer surface of the transparent dressing fixation layer 5, the center of which is coaxial with the center of the planar spiral structure of the LC resonant sensor 2. By setting alignment marks on the outer surface of the transparent dressing fixation layer 5, which is coaxial with the center of the LC resonant sensor 2, an intuitive and accurate visual alignment target is provided for the external readout antenna. This design simplifies the monitoring operation process, ensuring that the antenna can achieve rapid and accurate "center alignment" with the sensor during each measurement, thereby maximizing the excitation of the sensor's resonant response and acquiring the strongest signal.

[0033] The contact wound dressing 4 comprises a non-adhesive isolation layer, an absorbent pad, and a breathable base fabric stacked sequentially; the second transparent dressing encapsulation layer 3 is disposed on top of the breathable base fabric. The bottom non-adhesive isolation layer gently conforms to the wound surface, effectively preventing adhesion to newly formed granulation tissue and avoiding secondary damage during replacement; the absorbent pad is responsible for quickly absorbing and locking in excess exudate, maintaining a clean and appropriately humid healing environment for the wound, while preventing excessive liquid accumulation from interfering with sensor operation; the upper breathable base fabric provides a flat and stable adhesion substrate for the upper sensor encapsulation layer.

[0034] For example, the LC resonant sensor 2 has a mosquito coil-shaped structure (it can also be concentric circle, square, etc.), and is manufactured using laser cutting technology. This technology has the advantages of high precision, the ability to process complex patterns, and suitability for high-speed mass production. The mosquito coil-shaped structure is essentially a resonant unit formed by the coupling of a planar spiral inductor and a distributed capacitor. Its tightly wound spiral design achieves a longer wire path within a limited planar area, thus obtaining a higher inductance value without increasing the sensor size, successfully achieving a balance between high inductance and small size. Simultaneously, the distributed capacitance naturally formed between each spiral wire in this structure constitutes an inherent integrated "inductor-capacitor" resonant circuit, allowing it to operate without the need for additional independent capacitor components. From a mechanical performance perspective, the continuous smooth curve structure of the mosquito coil shape can uniformly distribute stress, giving it excellent mechanical durability against bending, tension, and torsion. In terms of electromagnetic performance, its symmetrical circular structure generates a highly symmetrical magnetic field distribution. This not only reduces the stringent requirements for the alignment accuracy of the readout antenna, but also maintains a strong signal strength even with slight offsets, thereby improving the robustness and ease of use of the monitoring system. More importantly, this structure can concentrate the electromagnetic field energy in its center and the area near the coil plane. When the dielectric constant and conductivity of the wound tissue change, it will directly disturb this concentrated electromagnetic field, thereby causing a significant and measurable shift in the resonant frequency and amplitude. This effectively amplifies the signal changes and ultimately significantly improves the sensor's sensitivity to monitoring subtle physiological changes during wound healing.

[0035] The LC resonant sensor 2 is made of a soft and biodegradable metallic material. The aforementioned mosquito coil-shaped structure includes two adjacent spiral coils; one spiral coil is made of molybdenum, and the other is made of zinc. The thickness of the LC resonant sensor 2 is 10~100μm. In the physiological environment of the body, the material not only has good biocompatibility, but also accelerates its synergistic degradation through the galvanic cell effect of molybdenum and zinc, ultimately being eliminated by the body through a safe pathway, achieving bioabsorbability of the device. Simultaneously, this sub-millimeter-thin thickness combined with the planar spiral structure significantly reduces the overall bending stiffness of the sensor, resulting in a very small bending radius and excellent flexibility. This ensures that the sensor can maintain a stable and conformal fit to irregular human wound surfaces, effectively adapting to body movements and fully meeting the core requirements for mechanical reliability of flexible electronic devices in wearable monitoring applications.

[0036] The transparent dressing encapsulation layer is a medical transparent dressing (including but not limited to 3M transparent dressings and PCL encapsulation film), which is sterile, waterproof, and breathable. On the one hand, it acts as a reliable physical barrier, effectively isolating external contaminants and liquids from intrusion and preventing wound infection. At the same time, its breathability creates a suitable moist healing environment for the wound. On the other hand, it completely seals the LC resonant sensor in a stable and isolated microenvironment, which effectively prevents high-conductivity wound exudate from directly contacting the sensor and causing signal distortion, while not hindering the sensor from sensitively sensing changes in the dielectric properties of the underlying tissue through the electromagnetic field. This ensures the accuracy and reliability of the monitoring signal in the complex and ever-changing wound environment.

[0037] The dimensions of the first transparent dressing encapsulation layer 1 and the second transparent dressing encapsulation layer 3 are both larger than the dimensions of the LC resonant sensor 2, which can ensure that the LC resonant sensor 2 is completely sealed inside the dressing. Its edge forms a closed adhesive area, which effectively blocks wound exudate from seeping in from the side and prevents liquid from directly contacting the sensor, thus preventing signal short circuit or attenuation.

[0038] A second objective of this invention is to provide a wound monitoring method based on flexible passive inductive-capacitive resonant sensing, comprising the following steps: The bandage is attached to the wound to be tested, so that the contact wound dressing 4 is in direct contact with the wound surface, and the LC resonant sensor 2 is fixed to the central area of ​​the wound by the transparent dressing fixing layer 5. The detection antenna of the external reading device is spatially aligned with the LC resonant sensor 2 fixed at the center of the wound. The detection antenna transmits a scanning signal to the LC resonant sensor 2 and receives the response signal from the LC resonant sensor 2 to obtain the forward transmission coefficient S21 spectrum of the LC resonant sensor 2. Extract the resonant frequency characteristics and / or resonant amplitude characteristics of the LC resonant sensor 2 from the spectrum of the forward transmission coefficient S21; Based on the changes in the resonant frequency characteristics and / or resonant amplitude characteristics, the changes in the dielectric properties of the wound tissue are monitored, thereby assessing the wound healing status.

[0039] This invention utilizes the electromagnetic coupling principle of a passive LC sensor. By analyzing the resonant frequency and amplitude characteristics in the spectrum of its forward transmission coefficient S21, it can sensitively capture changes in dielectric properties caused by alterations in wound tissue composition. This non-invasive, continuous monitoring mechanism successfully transforms traditional subjective, intermittent wound assessment into objective, quantitative, dynamic process tracking, providing a reliable technical means for accurately determining the healing stage and promptly detecting abnormalities.

[0040] Example 1 The preparation method of the mosquito coil-type LC resonant sensor wound monitoring bandage includes the following steps: S1, Sensor fabrication First, a mosquito coil-shaped planar spiral structure pattern was designed using AutoCAD and other drawing software. This pattern is a symmetrical spiral with six turns of wire, an outer diameter of approximately 10.5 mm, a line width of 1.1 mm, and a line spacing of 400 μm. Then, molybdenum and zinc metal foils with thicknesses of 10 μm and 100 μm respectively were selected as sensor materials. A precision laser cutting system (process parameters set as follows: power 55 W, cutting speed 7 mm / s, repeat count 2 times) was used to precisely machine the above pattern onto the metal foils, thereby obtaining a burr-free, structurally complete flexible LC resonant sensor. Figure 2 As shown.

[0041] S2, Sensor Packaging The fabricated flexible LC resonant sensor is placed in the center of an adhesive layer of a medical transparent dressing (e.g., 3MTegaderm transparent dressing) with a diameter of approximately 11 mm. Another transparent dressing of the same size is then placed on top, completely sealing the sensor between the two layers to form a complete encapsulation. This entire process must be performed in a sterile environment to ensure the sterility of the sensor after encapsulation. This encapsulation layer is not only effectively waterproof and breathable, but more importantly, it isolates the sensor from direct contact with wound exudate, preventing signal interference.

[0042] S3, Placement of contact wound dressing layer A contact wound dressing (typically consisting of layers of an anti-adhesive barrier, an absorbent pad, and a breathable base fabric) is placed beneath the encapsulated sensor. This dressing absorbs excess wound exudate, providing the sensor with a stable and appropriately humidified measurement interface while preventing the sensor from adhering to newly formed granulation tissue.

[0043] S4, Overall Fixation Finally, precisely place the encapsulated sensor assembly directly above the center of the wound dressing, and secure the entire assembly (covering the underlying wound dressing and the encapsulated sensor) to the wound using a larger (e.g., 3 cm × 3 cm) transparent fixation dressing (such as 3M Tegaderm dressing). This step minimizes signal errors caused by sensor displacement during use, ensuring the stability and reliability of the monitoring data.

[0044] Example 2 The test method for wound monitoring bandages based on mosquito coil-type LC resonant sensors includes the following steps: The bandage is attached to the wound to be tested, so that the contact wound dressing 4 is in direct contact with the wound surface, and the LC resonant sensor 2 is fixed to the central area of ​​the wound by the transparent dressing fixing layer 5. like Figure 3 As shown, a dual-port vector network analyzer (VNA) is used as the reading device, and the VNA's probe antenna is spatially aligned with the LC resonant sensor 2 fixed at the center of the wound, while maintaining a reading distance of about 2-3 mm. The detection antenna transmits a scanning signal to the LC resonant sensor 2 and receives the response signal from the LC resonant sensor 2 to obtain the forward transmission coefficient S21 spectrum of the LC resonant sensor 2. Extract the resonant frequency characteristics and / or resonant amplitude characteristics of the LC resonant sensor 2 from the spectrum of the forward transmission coefficient S21; Based on the changes in the resonant frequency characteristics and / or resonant amplitude characteristics, the changes in the dielectric properties of the wound tissue are monitored, thereby assessing the wound healing status.

[0045] Example 3 To systematically verify the comprehensive performance of the wound monitoring bandage described in this invention, we conducted a series of experiments, including in vitro simulation, in vivo response, long-term monitoring, and verification of therapeutic functions.

[0046] (1) The sensor’s sensitivity to dielectric environment and the anti-interference capability of the packaging structure were evaluated through in vitro experiments.

[0047] The wound monitoring bandage as described in Example 1 was placed horizontally on isolated mouse skin. Different volumes (0 μL, 5 μL, 10 μL) of phosphate-buffered saline (PBS, pH 7.4, to simulate wound exudate) were carefully dropped onto the underside of the bandage, opposite the sensor location, using a pipette. After each drop, the solution was allowed to stand for 1 minute until it stabilized before measurement. The VNA and probe antenna described in Example 2 were used. The probe antenna was kept aligned with the sensor center at a fixed distance (approximately 2 mm), and the S21 characteristic curve was scanned and recorded after each PBS drop.

[0048] Experimental results are as follows Figure 4 As shown, when 0 μL of PBS (i.e., in a dry state) is added, the S21 curve exhibits a clear and sharp resonance peak. As the volume of the PBS droplet increases, the dielectric environment of the sensor changes, causing a systematic leftward shift (towards lower frequencies) of the resonance frequency; correspondingly, the high conductivity of PBS introduces losses, resulting in a significant decrease in the amplitude of the resonance peak.

[0049] Although the resonant frequency and peak amplitude changed, the resonant peak remained clearly discernible and did not broaden or disappear. This fully demonstrates the crucial role of the transparent dressing encapsulation layer: it allows the sensor's electromagnetic field to penetrate and sense changes in the external dielectric environment, while effectively preventing signal short circuits and complete annihilation caused by direct contact between high-conductivity liquids and the sensor, ensuring the robustness and measurability of the sensor's signal in a real wound environment.

[0050] (2) Verify the sensor’s ability to distinguish tissue states through in vivo experiments.

[0051] Five-week-old female Kunming rats were selected, and a 10 mm full-thickness skin defect model was created on their backs. The wound monitoring bandage described in Example 1 was fixed to the normal skin area and the center of the wound area of ​​the mouse, respectively. At each measurement point, the sensor was ensured to be in good contact with the skin, and the reading antenna was aligned with the center of the sensor. At each location, the S21 parameter was scanned using a VNA. The experimental results are as follows: Figure 5 As shown, normal skin exhibits a higher resonant frequency and a larger peak amplitude. This is because relatively healthy skin tissue has lower water content and ion concentration, resulting in a lower dielectric constant and conductivity, and a weaker loading effect on the resonant circuit. The resonant frequency in the wound area shifts significantly to the left (towards lower frequencies), and the peak amplitude decreases markedly. This is because wound tissue, in the early stages of healing, is rich in highly conductive exudate, blood, and inflammatory cells. The higher dielectric constant and conductivity of these components strongly alter the electromagnetic field distribution of the sensor, increasing energy loss and thus leading to a decrease in resonant frequency and peak amplitude.

[0052] The results show that the sensor described in this invention can respond sensitively and reliably to two distinctly different dielectric environments: normal skin and wound tissue. This significant and consistent difference provides a reliable physical basis for subsequent continuous monitoring of the wound's transition from the high-humidity inflammatory phase to the low-humidity healing phase.

[0053] Through the above series of experiments, from in vitro to in vivo, it has been demonstrated that the sensor described in this invention has the ability to sense dielectric changes, possesses stability against exudate interference, and has the sensitivity to distinguish different tissue states in vivo, fully meeting the technical requirements as a core component of a wound monitoring bandage.

[0054] (3) Monitoring the wound healing status in the body using sensors.

[0055] During wound healing, the dielectric constant and conductivity of the tissue undergo systematic changes due to variations in the composition of blood and exudate. Therefore, it is essential to monitor the wound daily and calculate and record the wound area throughout the entire healing process. Figures 6-8 As shown, the resonant frequency and peak amplitude exhibit a regular increasing trend as the wound heals. Figure 6 A-J show the LC sensor resonant frequency and peak-to-peak amplitude data obtained throughout the entire process, from wound modeling (Day 0) to infection worsening (Day 1–Day 2), and then gradual healing (Day 3–Day 13) (the light blue curve represents normal healthy skin, and the purple curve represents the infected wound). Theoretically, the resonant frequency and peak-to-peak amplitude of the sensor located on normal healthy skin should remain relatively stable throughout the study. However, in the early stages (Day 0–Day 2), due to the presence of more blood and wound exudate, and the diffusion of some exudate to the surrounding healthy area, even the sensor on normal skin exhibited a lower resonant frequency. For the sensor located in the wound area, these two parameters typically increase gradually as the wound heals. The increase in resonant frequency can be attributed to the decrease in water content during wound healing, which reduces the sensor's self-capacitance and thus increases the resonant frequency. Therefore, the resonant frequency further decreased during Day 1–Day 2, reflecting the continued increase in exudate due to the worsening infection. Starting from Day 3, as the wound gradually heals, the resonant frequency begins to slowly rise, and the peak-to-peak amplitude increases significantly in the later stages of healing. This phenomenon can be attributed to the sensitivity of the peak-to-peak amplitude to changes in the conductivity of its surrounding environment. Figure 7 A and 8A show the curves of resonant frequency and resonant peak amplitude as a function of healing time; Figure 7B and 8B demonstrate a strong negative correlation between these two parameters and wound area reduction (i.e., the smaller the wound, the higher the resonant frequency and peak amplitude). By regularly monitoring and recording these parameters (e.g., once a day), healing trend graphs can be plotted, providing clinicians with objective and quantitative assessments of healing status.

[0056] (4) Validation of sensor-assisted therapeutic function.

[0057] like Figure 9 and 10 As shown, in a preferred embodiment of the present invention, since the sensor uses molybdenum and zinc as materials, when the exudate comes into contact with the sensor, the molybdenum and zinc can form a micro galvanic cell in the electrolyte environment. Zinc ions (Zn) 2+ The release of [the sensor] has been shown to promote fibroblast migration, proliferation, and keratinization, thereby accelerating wound healing. Experimental results show that, compared with the control group without the sensor, the treatment group with the sensor of this invention showed a significantly faster rate of wound area reduction, demonstrating that the bandage described in this invention has both monitoring and adjunctive therapeutic functions.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing, characterized in that, include: Contact wound dressing (4); The sensor assembly includes a first transparent dressing encapsulation layer (1) and a second transparent dressing encapsulation layer (3) stacked together, and an LC resonant sensor (2) encapsulated between the first transparent dressing encapsulation layer (1) and the second transparent dressing encapsulation layer (3), wherein the LC resonant sensor (2) has a planar spiral structure; the second transparent dressing encapsulation layer (3) is disposed on the top of the contact wound dressing (4); A transparent dressing fixation layer (5) covers and fixes the sensor assembly to the contact wound dressing (4).

2. The wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing according to claim 1, characterized in that, The planar projection area of ​​the transparent dressing fixation layer (5) is larger than the planar projection area of ​​the contact wound dressing (4); a biocompatible adhesive layer is provided on the lower surface of the transparent dressing fixation layer (5) in the area outside the periphery of the contact wound dressing (4).

3. A wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing according to claim 1, characterized in that, It also includes alignment marks disposed on the outer surface of the transparent dressing fixing layer (5), the center of the alignment marks (6) being coaxial with the center of the planar spiral structure of the LC resonant sensor (2).

4. A wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing according to claim 1, characterized in that, The contact wound dressing (4) includes an anti-adhesive isolation layer, an absorbent pad, and a breathable base fabric stacked in sequence; the second transparent dressing encapsulation layer (3) is disposed on top of the breathable base fabric.

5. A wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing according to claim 1, characterized in that, The transparent dressing encapsulation layer is a medical transparent dressing.

6. A wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing according to claim 1, characterized in that, The planar spiral structure is a mosquito coil-type structure.

7. A wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing according to claim 6, characterized in that, The mosquito coil-like structure includes two adjacent spiral coils; one spiral coil is made of molybdenum and the other spiral coil is made of zinc.

8. A wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing according to claim 7, characterized in that, The thickness of the LC resonant sensor (2) is 10~100μm.

9. A wound monitoring bandage based on flexible passive inductive-capacitive resonant sensing according to claim 1, characterized in that, The dimensions of the first transparent dressing encapsulation layer (1) and the second transparent dressing encapsulation layer (3) are both larger than the dimensions of the LC resonant sensor (2).

10. A wound monitoring method based on flexible passive inductive-capacitive resonant sensing, characterized in that, The bandage according to any one of claims 1 to 9 includes the following steps: The bandage is attached to the wound to be tested, so that the contact wound dressing (4) is in direct contact with the wound surface, and the LC resonant sensor (2) is fixed to the center area of ​​the wound through the transparent dressing fixing layer (5). The detection antenna of the external reading device is spatially aligned with the LC resonant sensor (2) fixed at the center of the wound; The detection antenna transmits a scanning signal to the LC resonant sensor (2) and receives the response signal from the LC resonant sensor (2) to obtain the forward transmission coefficient S21 spectrum of the LC resonant sensor (2); Extract the resonant frequency characteristics and / or resonant amplitude characteristics of the LC resonant sensor (2) from the spectrum of the forward transmission coefficient S21; Based on the changes in the resonant frequency characteristics and / or resonant amplitude characteristics, the changes in the dielectric properties of the wound tissue are monitored, thereby assessing the wound healing status.

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