Device for dynamically monitoring blood supply disorder after flap transplantation based on MEMS capacitive sensor and use method

Abstract

The invention discloses a skin flap transplantation post-operation blood supply disorder dynamic monitoring device based on an MEMS capacitive sensor and a using method, the device comprises a fitting layer and a sensor layer, the fitting layer is of a three-layer structure, and stable fitting and biocompatibility of the device and a skin flap area are achieved; the sensor layer comprises a signal monitoring module and a signal transmission module, the signal monitoring module forms an array by a plurality of capacitive sensing units, and skin flap tissue swelling is converted into a capacitance signal with position identification through the MEMS parallel plate capacitance principle; after being processed and converted, the capacitance signal is wirelessly transmitted to external equipment through low-power-consumption Bluetooth. And medical personnel judge the blood supply disorder and the occurrence area after the skin flap operation based on the capacitance signal change trend. The device disclosed by the invention integrates miniaturization and integration, can monitor in real time, reduces manpower consumption, provides data support for early intervention of blood supply disorder, and is suitable for post-operation clinical monitoring of skin flap transplantation.

Description

Technical Field

[0001] This invention relates to the fields of microelectromechanical systems and medical technology, specifically a dynamic monitoring device for postoperative blood supply disorders after flap transplantation based on MEMS capacitive sensors. Background Technology

[0002] Skin flap transplantation is a tissue repair method that involves transplanting skin and subcutaneous tissue with their own independent blood supply system completely from the donor site to the recipient site. It is one of the most important treatments for soft tissue trauma and chronic wounds. Postoperative blood circulation is a key monitoring focus after skin flap transplantation, with a vascular disorder incidence rate as high as 40%. Failure to accurately identify and intervene early can lead to irreversible necrosis of the transplanted flap, forcing patients to undergo secondary surgery, and in severe cases, even resulting in amputation or permanent loss of function. Therefore, dynamic monitoring of the transplanted flap area is crucial for postoperative management and the implementation of intervention measures.

[0003] Currently, clinical medical staff mainly rely on manual assessment and instrumental monitoring of flap color, temperature, and tissue edema to indirectly assess the blood supply status of transplanted flaps. However, differences in subjective perception and experience levels among observers can lead to a lack of standardized and objective monitoring results, making it difficult to form accurate quantitative judgments. Furthermore, frequent bedside observations consume a significant amount of limited medical human resources. Instrumental monitoring often uses technologies such as infrared thermometers, semiconductor skin thermometers, and far-infrared thermal imagers to monitor flap temperature changes to indirectly reflect flap blood perfusion. However, these temperature monitoring methods can only observe the surface temperature of the flap and are easily affected by environmental factors and the flap's own metabolic state, resulting in insufficient stability and accuracy, making them unreliable as a basis for judging flap blood supply disorders.

[0004] Micro-Electro-Mechanical Systems (MEMS), as a multidisciplinary technology, integrates cutting-edge achievements from microfabrication technology, materials science, electronics, and other disciplines. It boasts advantages such as miniaturization, integration, and intelligence, and is widely used in biomedical monitoring. Based on this, this invention proposes a dynamic monitoring device and method for skin flap transplantation based on a MEMS capacitive sensor. This device is integrated into the skin or inner dressing surface of the skin flap transplantation area. The dynamic changes in capacitance respond to the swelling trend of the skin flap tissue, thereby indirectly and objectively reflecting the blood supply status of the flap. This enables real-time, accurate, and objective dynamic monitoring of the transplanted skin flap after surgery, meeting the urgent need for "early detection and early intervention" in clinical practice. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a dynamic monitoring device and method for blood supply disorders after flap transplantation based on MEMS capacitive sensors, which solves the problems of lack of objectivity or insufficient stability and accuracy in the existing technology of manual assessment or instrument monitoring of blood supply disorders after flap transplantation.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a dynamic monitoring device for blood supply disorders after flap transplantation based on MEMS capacitive sensors, comprising an adhesive layer and a sensor layer, wherein the sensor layer is tightly attached to the side of the adhesive layer away from the flap transplantation area. The bonding layer is used to stably adhere the sensor layer to the skin or inner dressing surface of the flap transplantation area. It consists of release paper, medical pressure-sensitive adhesive layer and medical-grade transparent polyurethane film protective layer stacked sequentially from the side closest to the flap to the outside. The sensor layer includes a signal monitoring module and a signal transmission module, which are electrically connected by a metal wire and are both encapsulated with biocompatible polyimide. The signal monitoring module consists of an array of multiple capacitive sensing units. Each sensing unit is identified by a unique coordinate code. The capacitive sensing unit is a flexible substrate, a bottom electrode, a polyimide capacitor film layer and a top electrode stacked in sequence. It is used to detect changes in the electrode spacing d or the effective overlap area S caused by the swelling of the flap tissue and convert them into a capacitive signal with a position identifier. The signal transmission module is used to process and convert the capacitance signal and then wirelessly transmit it to an external device. The external device infers the tissue swelling trend based on the change trend of the capacitance signal, thereby determining the blood supply disorder after flap surgery.

[0007] In a preferred embodiment, the array layout of the signal monitoring module is a regular hexagon or rectangle, the spacing between adjacent capacitive sensing units is 0.5mm-2mm, and the number of units is adapted to the size of the flap transplantation area. The geometric centers of the flexible substrate, bottom electrode, polyimide capacitor film layer, and top electrode coincide, and the layers are bonded together by medical-grade silicone adhesive.

[0008] In a preferred embodiment, the flexible substrate is one of polydimethylsiloxane, polyimide, or hydrogel, with a thickness of 50-200 μm and an elongation at break of not less than 300%. The top electrode and the bottom electrode are planar symmetrical and identical in shape. They are fabricated using titanium nitride, gold, or platinum thin films via MEMS patterning processes, with a thickness of 50-200 nm and an effective area of ​​5 mm². 2 -20mm 2 The sheet resistance is no greater than 5Ω / sq.

[0009] In a preferred embodiment, one surface of the polyimide capacitor film layer covers the bottom electrode, and the other surface is connected to the top electrode. It undergoes adaptive deformation synchronously with the deformation of the flexible substrate, changing the distance d between the top electrode and the bottom electrode or the effective overlap area S.

[0010] In a preferred embodiment, the signal transmission module includes a signal conditioning submodule, an analog-to-digital conversion submodule, a wireless transmission submodule, and a power supply unit connected in sequence. The signal conditioning submodule has a built-in capacitor-to-voltage conversion circuit, an amplifier circuit, and a filter circuit. The capacitor-to-voltage conversion circuit has a detection range of 0.1pF-10pF, the amplifier circuit has an amplification factor of 50-200 times, and the filter circuit is a second-order RC low-pass filter circuit with a cutoff frequency of 5Hz-20Hz. The analog-to-digital conversion submodule is a successive approximation ADC with a sampling frequency of 1Hz-100Hz, used to convert analog voltage signals into digital signals. The wireless transmission submodule adopts Bluetooth Low Energy technology, with a transmission rate of 1Mbp / s-2Mbp / s, a power consumption of less than 10mW, and a communication distance of not less than 5m. The power supply unit is a miniature button battery.

[0011] In a preferred embodiment, the capacitive signal output by the capacitive sensing unit of the signal monitoring module is converted into a voltage signal by the signal conditioning submodule, amplified and noise filtered out, then converted into a digital signal by the analog-to-digital conversion submodule, and finally transmitted to an external device through the wireless transmission submodule.

[0012] In a preferred embodiment, the metal guide wire is made of Au or Ag, with a diameter of 0.1-0.2 mm, and is covered with a polyimide insulating layer with a thickness of 5-10 μm. One end is connected to the signal conditioning submodule, and the other end is connected to the top electrode and the bottom electrode, respectively.

[0013] In a preferred embodiment, the external device calculates the swelling trend of the skin flap tissue based on the following parallel plate capacitance formula: ; In the formula: ε 0 is the vacuum permittivity; ε r The relative permittivity of the polyimide capacitor film layer; S is the effective area of ​​the electrode plate; d represents the distance between the electrodes, used to reflect the trend of tissue changes after flap transplantation.

[0014] In a preferred embodiment, the medical-grade transparent polyurethane film protective layer is breathable, the medical pressure-sensitive adhesive layer is a low-allergenic formula, and the shape and area of ​​the adhesive layer are adapted to the sensor layer.

[0015] The method of using the above-mentioned device includes the following steps: S1. Check the integrity of the device to confirm that the medical pressure-sensitive adhesive layer is free from contamination, the sensor layer is undamaged, and the wireless transmission submodule can communicate normally. S2. Clean the monitoring area, remove the release paper, and attach the device to the skin or inner dressing of the flap transplantation area. S3. Initiate the connection between external devices and the wireless transmission submodule to ensure real-time data reception; S4. Based on the changing trend of capacitance signals received from external devices, determine whether there is blood supply obstruction and the obstruction area after flap surgery.

[0016] The present invention provides a dynamic monitoring device and method for blood supply disorders after flap transplantation based on a MEMS capacitive sensor. By adopting the above structure and method, it has the following beneficial effects: (1) Unlike traditional manual assessment or temperature monitoring, based on the MEMS capacitive sensing principle, it infers tissue deformation by quantifying changes in capacitance value, directly correlates with blood supply status, and achieves local area positioning with array layout, avoiding subjective errors and environmental interference, and the monitoring results are more accurate and objective. (2) The device is integrated into the skin flap or dressing and can monitor continuously for several days in real time. It uses Bluetooth low power wireless transmission, which does not require wired connection and does not affect the patient's activities. The data is directly uploaded to external devices, reducing the frequency of bedside observation by medical staff and improving monitoring efficiency. (3) All components are made of biocompatible materials. The encapsulation layer prevents the intrusion of body fluids. The flexible substrate can change synchronously with tissue deformation, adapting to the dynamic environment of the flap area. Long-term use has no risk of skin irritation or sensitization. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the signal monitoring module in this invention.

[0019] Figure 3 This is a flowchart illustrating the operation of the signal transmission module in this invention.

[0020] In the diagram: bonding layer 1, release paper 11, medical pressure-sensitive adhesive layer 12, medical-grade transparent polyurethane film protective layer 13, sensor layer 2, signal monitoring module 21, flexible substrate 211, top electrode 212, polyimide capacitor film layer 213, bottom electrode 214, signal transmission module 22, signal conditioning submodule 221, analog-to-digital conversion submodule 222, wireless transmission submodule 223, power supply unit 224. Detailed Implementation

[0021] Example 1: Combined with appendix Figure 1-3 For example, consider a device suitable for small hand flap transplantation areas (10mm × 10mm): The core of the monitoring device consists of an adhesive layer 1 and a sensor layer 2, which are tightly and seamlessly bonded together using medical-grade silicone adhesive. The overall structure is thin and lightweight, and will not compress the transplanted skin flap area or restrict the patient's movement. The adhesive layer 1 adopts a three-layer composite design of "release paper 11 - medical pressure-sensitive adhesive layer 12 - medical-grade transparent polyurethane film protective layer 13", with an overall thickness controlled at 0.15mm. Its shape is completely consistent with that of the sensor layer 2, which ensures stable fixation of the sensor layer 2 and avoids discomfort caused by excessive thickness. Release paper 11 is made of PET material with a thickness of 0.08mm. It is adhered to the side of the medical pressure-sensitive adhesive layer 12 away from the protective layer. It needs to be peeled off before use to protect the adhesive layer's stickiness and prevent contamination during storage and transportation. The medical pressure-sensitive adhesive layer 12 uses low-allergenic acrylic adhesive with a thickness of 30μm and an adhesive strength set at 1.2N / cm². This adhesive layer has passed the ISO10993-10 skin sensitization test, with an irritation index ≤0.3. Even if it is applied to sensitive postoperative skin areas for a long time, it will not cause adverse reactions such as redness, swelling, or itching. The medical-grade transparent polyurethane film protective layer 13 is 0.04mm thick and has a strength of ≥500g / (m³). 2 The high breathability (24h) effectively reduces sweat buildup in the skin flap area and provides physical protection for the underlying sensor layer 2, preventing damage to the components from external friction.

[0022] The sensor layer 2, with a thickness of 1.5 mm, contains a signal monitoring module 21 and a signal transmission module 22, which are stably electrically connected via a metal guide wire. The entire sensor layer 2 is encapsulated in a 20 μm thick biocompatible polyimide layer (encapsulation layer 225), which effectively prevents bodily fluids from invading the electronic components, ensuring the safety and stability of the device during clinical use. The signal monitoring module 21 adopts a 3×3 rectangular array layout, consisting of 9 independent capacitive sensing units. Adjacent sensing units are spaced 1 mm apart, and each unit has a unique coordinate code (1,1)-(3,3), corresponding to different local locations within the flap transplantation area, achieving full-area coverage monitoring of the flap. The interlayer structure of each capacitive sensing unit, from bottom to top, consists of a flexible substrate 211, a bottom electrode 214, a polyimide capacitor film layer 213, and a top electrode 212. The geometric centers of each layer are completely coincident, and the layers are bonded together with a 3μm thick medical-grade silicone adhesive. This bonding method ensures that each layer can transmit deformation synchronously when the skin flap tissue deforms, avoiding signal deviation caused by interlayer slippage. The flexible substrate 211 is made of polydimethylsiloxane (PDMS), with a thickness of 100 μm and an elongation at break of 350%. It can deform synchronously with the swelling of the skin flap tissue, and its biocompatibility meets the GB / T16886.1 standard, allowing direct contact with the skin or dressings. The top electrode 212 and the bottom electrode 214 are designed as a planar symmetrical circular structure with a diameter of 3.6 mm and an effective area of ​​10 mm². They are made of titanium nitride thin film with a thickness of 80 nm and a sheet resistance of 3 Ω / sq, prepared by magnetron sputtering. This material has excellent conductivity and resistance to body fluid corrosion, and can maintain stable electrical performance over a long period of time. The polyimide capacitor film layer 213 is 25 μm thick and has a dielectric constant of 3.8 (at 25℃). Within the human body temperature range of 30-40℃, the dielectric constant fluctuation is ≤±2%, which can avoid the drift of the capacitance signal caused by temperature changes and ensure the accuracy of monitoring data.

[0023] The signal transmission module 22 is integrated into the edge area of ​​the flexible substrate 211, without covering the array area of ​​the signal monitoring module 21. This layout avoids local pressure on the skin flap and reduces interference from electronic components to the capacitive signal acquisition. The module consists of a signal conditioning circuit 221, an analog-to-digital converter 222, a Bluetooth module 223, and a power supply battery 224 connected in series. The signal conditioning circuit 221 incorporates a capacitor-to-voltage conversion circuit, an amplifier circuit, and a second-order RC low-pass filter circuit. The capacitor-to-voltage conversion circuit uses a charge amplifier structure with a detection range of 0.1pF-10pF, which can accurately capture changes in electrode spacing as small as 0.01mm. The amplifier circuit uses an instrumentation amplifier AD8221 with a magnification factor set to 100, which can amplify weak voltage signals from the mV level to the V level for easy subsequent processing. The filter circuit has a cutoff frequency of 10Hz, which can effectively filter out 50Hz power frequency interference in the environment and high-frequency noise generated by human movement, retaining only the effective signals related to skin flap swelling. The analog-to-digital converter module 222 uses a 12-bit successive approximation ADC (ADS7822) with a sampling frequency of 10Hz. It generates a reference voltage sequentially from the most significant bit to the least significant bit through a successive approximation register, repeatedly comparing it with the input analog signal to determine the value of each bit. The conversion accuracy is ≤±1LSB, ensuring that the digital signal accurately reflects capacitance changes. The converted digital signal is transmitted via the Universal Asynchronous Receiver / Transmitter (UART) protocol at a baud rate of 9600bps. The Bluetooth module 223 uses the BLE 5.0 protocol chip nRF52832, with a transmission rate of 1Mbps, power consumption of 8mW, and a communication distance of 8m. It supports real-time connections with external devices such as medical monitors and smartphones, with a data transmission latency ≤80ms and a bit error rate ≤10%. -5 This meets the needs of real-time clinical monitoring. The power supply battery 224 uses a CR2032 micro button battery with a capacity of 225mAh. It is connected to the various power components of the signal transmission module 22 through metal contacts. A single power supply can support the device to work continuously for 9 days, eliminating the need for frequent battery replacements and meeting the long-term monitoring needs after flap surgery.

[0024] The metal wires are made of 99.99% pure gold wire with a diameter of 0.15 mm and are covered with an 8 μm thick polyimide insulating layer. One metal wire connects the signal conditioning circuit 221 to the top electrode 212, and the other metal wire connects the signal conditioning circuit 221 to the bottom electrode 214. This connection method can ensure lossless transmission of capacitive signals, while the insulating layer can prevent electrochemical corrosion caused by direct contact between the metal wires and the skin, further improving the biosafety of the device.

[0025] The working process of the device in this embodiment follows the complete chain of "tissue deformation - capacitance signal - digital signal - blood supply discrimination". When blood circulation disorder occurs after the transplanted flap surgery, causing tissue swelling, the thickness of the local area of ​​the flap increases by 0.05mm, which will cause the flexible base 211 of the signal monitoring module 21 to bulge synchronously. The deformation of the flexible base 211 stretches the polyimide capacitor film layer 213, causing the distance d between the top electrode 212 and the bottom electrode 214 to increase from the initial 25μm to 30μm.

[0026] According to the parallel plate capacitance formula: ; in, ε 0 = 8.85 × 10 -12 F / m; ε r =3.8; S=10mm 2 =10 -5 m 2 .

[0027] The capacitance value C decreases from the initial 13.1pF to 10.9pF, completing the precise conversion from "blood supply state - tissue deformation - capacitance signal". Subsequently, the capacitance-to-voltage conversion circuit of the signal conditioning circuit 221 converts the above capacitance change into a 0.3V voltage signal. After being amplified 100 times by the amplifier circuit, a 30V analog signal is obtained. Then, the 50Hz power frequency interference (residual noise ≤5mV) is filtered out by the filter circuit. The analog-to-digital conversion module 222 converts the filtered analog signal into a 12-bit digital signal (corresponding to the value 2457) and sends it to the Bluetooth module 223 via the UART protocol. The Bluetooth module 223 wirelessly transmits the digital signal to the external device at a rate of 1Mbp / s. After receiving the digital signal, the external device uses a built-in algorithm to infer the capacitance value change trend.

[0028] In this embodiment, taking the sensing unit at coordinates (2,2) of the corresponding flap center region as an example, the following graded risk determination process is executed: If the capacitance value of the sensing unit drops below a preset first threshold for medical personnel for one hour, where the first threshold is a preset percentage of the baseline capacitance value, the device determines that there is a "suspicious risk" and automatically issues an early warning. If the capacitance value does not drop further in the following hour of monitoring, the "suspicious risk" determination is maintained, and the coordinate area of ​​the sensing unit is marked on the display module. If, during the period of “suspected risk”, the capacitance value further decreases by more than a preset second threshold, which is a preset percentage of the capacitance baseline value, and the second threshold is greater than the first threshold, then it is determined to be “blood supply obstruction risk”, and the coordinate area where the obstruction occurs is displayed on the display module. When the capacitance value of the sensing unit drops significantly beyond a preset second threshold for one consecutive hour, the device directly identifies it as a "risk of blood supply obstruction" and displays the coordinates of the obstruction on the display module. Medical personnel can use the trend of the warning information to detect changes in the blood supply of the transplanted flap tissue early and implement timely intervention to prevent further aggravation of the blood supply obstruction.

[0029] Example 2: Based on Example 1, the device was fabricated using conventional MEMS micromachining technology and a layered bonding process. The fabrication process first involved the fabrication of the signal monitoring module 21: A PDMS flexible substrate 211 with a thickness of 100 μm was prepared by molding process. After plasma treatment, a titanium nitride thin film was deposited on its surface by magnetron sputtering process, and then the bottom electrode 214 was formed by photolithography-etching process. The polyimide capacitor film layer 213 was bonded to the surface of the bottom electrode 214 with medical grade silicon-based adhesive to ensure geometric center alignment. The top electrode 212 is prepared by repeating magnetron sputtering and photolithography-etching processes on the surface of the polyimide capacitor thin film layer 213, ensuring that it is planar symmetrical with the bottom electrode 214.

[0030] Next, the signal transmission module 22 will be integrated: A wire groove is etched in the edge region of the flexible substrate 211, and a metal wire is embedded in the groove. One end is connected to the top electrode 212 / bottom electrode 214, and the other end is connected to the signal conditioning circuit 221. The signal conditioning circuit 221, the analog-to-digital conversion module 222, and the Bluetooth module 223 are integrated onto the flexible substrate 211 using a flip-chip bonding process, and the metal spring of the power supply battery 224 is welded on. A 20μm thick polyimide encapsulation layer was coated on the surface of the signal transmission module 22 using a spin-coating process and then baked and cured at 120℃.

[0031] Finally, assemble the bonding layer 1: The medical-grade transparent polyurethane film protective layer 13 is bonded to the side of the sensor layer 2 away from the electrode using an adhesive; a medical pressure-sensitive adhesive layer 12 is coated on the surface of the protective layer, and then release paper 11 is attached to complete the assembly of the overall device.

[0032] After the device is assembled according to the above steps and sterilized to meet medical standards, it is then attached to the skin surface of the sterilized skin flap transplantation area.

[0033] In terms of wireless transmission performance, the Bluetooth communication range is 8m, the data transmission latency is 75ms, and the bit error rate is 8×10⁻⁶. -6It meets the wireless coverage and real-time requirements in clinical wards; in terms of battery life, the CR2032 button battery can support the device to work continuously for 9 days without needing to be replaced, which is suitable for the critical monitoring cycle of 7-10 days after flap surgery.

[0034] In terms of clinical compatibility, the device is only 1.65mm thick (0.15mm for the adhesive layer + 1.5mm for the sensor layer). The flexible substrate can deform synchronously with the movement of the skin flap, without affecting the patient's daily hand activities. It is compatible with the clinical dressing change process. When changing the dressing, the device can be directly peeled off, and the device can be re-fixed after the new dressing is applied. There is no risk of the metal guidewire and the encapsulation layer falling off. All components that come into contact with the skin (medical pressure-sensitive adhesive, PDMS, polyimide) have passed biocompatibility tests and have no sensitization or cytotoxicity issues, so they can be safely used in clinical practice.

Claims

1. A dynamic monitoring device for postoperative blood supply disorder in skin flap transplantation based on MEMS capacitive sensors, characterized in that: It includes an adhesive layer (1) and a sensor layer (2), wherein the sensor layer (2) is tightly attached to the side of the adhesive layer (1) away from the flap transplantation area; The bonding layer (1) is used to stably attach the sensor layer (2) to the skin or inner dressing surface of the flap transplantation area. It consists of release paper (11), medical pressure-sensitive adhesive layer (12) and medical-grade transparent polyurethane film protective layer (13) stacked sequentially from the side closest to the flap to the outside. The sensor layer (2) includes a signal monitoring module (21) and a signal transmission module (22). The signal monitoring module (21) and the signal transmission module (22) are electrically connected by a metal wire and are both encapsulated with biocompatible polyimide. The signal monitoring module (21) consists of an array of multiple capacitive sensing units. Each sensing unit is identified by a unique coordinate code. The capacitive sensing unit is a flexible substrate (211), a bottom electrode (214), a polyimide capacitive film layer (213), and a top electrode (212) stacked in sequence. It is used to detect changes in the electrode spacing d or the effective overlap area S caused by the swelling of the skin flap tissue and convert them into a capacitive signal with a position identifier. The signal transmission module (22) is used to process and convert the capacitance signal and then wirelessly transmit it to an external device. The external device infers the tissue swelling trend based on the change trend of the capacitance signal, and then determines the blood supply disorder after the flap surgery.

2. The device for dynamic monitoring of blood supply disorders after flap transplantation based on MEMS capacitive sensors according to claim 1, characterized in that: The array layout of the signal monitoring module (21) is a regular hexagon or rectangle, and the spacing between adjacent capacitive sensing units is 0.5mm-2mm. The number of units is adapted to the size of the flap transplantation area. The geometric centers of the flexible substrate (211), bottom electrode (214), polyimide capacitor film layer (213) and top electrode (212) coincide, and the layers are bonded together by medical-grade silicone adhesive.

3. The device for dynamic monitoring of blood supply disorders after flap transplantation based on MEMS capacitive sensors according to claim 1, characterized in that: The flexible substrate (211) is made of one of polydimethylsiloxane, polyimide or hydrogel, with a thickness of 50-200 μm and an elongation at break of not less than 300%. The top electrode (212) and the bottom electrode (214) are planar symmetrical and have the same shape. They are made of titanium nitride, gold or platinum metal thin films, fabricated by MEMS patterning process, with a thickness of 50-200 nm and an effective area of ​​5 mm. 2 -20mm 2 The sheet resistance is no greater than 5Ω / sq.

4. The device for dynamic monitoring of blood supply disorders after flap transplantation based on MEMS capacitive sensors according to claim 1, characterized in that: The polyimide capacitor film layer (213) has one surface covered with the bottom electrode (214) and the other surface connected to the top electrode (212). It undergoes adaptive deformation synchronously with the deformation of the flexible substrate (211), changing the distance d between the top electrode (212) and the bottom electrode (214) or the effective overlap area S.

5. The device for dynamic monitoring of blood supply disorders after flap transplantation based on MEMS capacitive sensors according to claim 1, characterized in that: The signal transmission module (22) includes a signal conditioning submodule (221), an analog-to-digital conversion submodule (222), a wireless transmission submodule (223), and a power supply unit (224) connected in sequence. The signal conditioning submodule (221) has a built-in capacitor-to-voltage conversion circuit, an amplifier circuit and a filter circuit. The capacitor-to-voltage conversion circuit has a detection range of 0.1pF-10pF, the amplifier circuit has an amplification factor of 50-200 times, and the filter circuit is a second-order RC low-pass filter circuit with a cutoff frequency of 5Hz-20Hz. The analog-to-digital conversion submodule (222) is a successive approximation ADC with a sampling frequency of 1Hz-100Hz, used to convert analog voltage signals into digital signals; The wireless transmission submodule (223) adopts Bluetooth Low Energy technology, with a transmission rate of 1Mbp / s-2Mbp / s, a power consumption of less than 10mW, and a communication distance of not less than 5m; The power supply unit (224) is a miniature button battery.

6. The device for dynamic monitoring of blood supply disorders after flap transplantation based on MEMS capacitive sensors according to claim 1, characterized in that: The capacitance signal output by the capacitive sensing unit of the signal monitoring module (21) is converted into a voltage signal by the signal conditioning submodule (221), amplified and noise filtered out, and then converted into a digital signal by the analog-to-digital conversion submodule (222), and then transmitted to an external device through the wireless transmission submodule (223).

7. The device for dynamic monitoring of blood supply disorders after flap transplantation based on MEMS capacitive sensors according to claim 1, characterized in that: The metal guide wire is made of Au or Ag, with a diameter of 0.1-0.2 mm and a surface covered with a polyimide insulating layer with a thickness of 5-10 μm. One end is connected to the signal conditioning submodule (221), and the other end is connected to the top electrode (212) and the bottom electrode (214) respectively.

8. The device for dynamic monitoring of blood supply disorders after flap transplantation based on MEMS capacitive sensors according to claim 1, characterized in that: The external device calculates the trend of flap tissue swelling based on the following parallel plate capacitance formula: ； In the formula: ε 0 is the vacuum permittivity; ε r is the relative permittivity of the polyimide capacitor film layer (13); S is the effective area of ​​the electrode plate; d represents the distance between the electrodes, used to reflect the trend of tissue changes after flap transplantation.

9. The device for dynamic monitoring of blood supply disorders after flap transplantation based on MEMS capacitive sensors according to claim 1, characterized in that: The medical-grade transparent polyurethane film protective layer (13) is breathable, the medical pressure-sensitive adhesive layer (12) is a low-allergenic formula, and the shape and area of ​​the bonding layer (1) are adapted to the sensor layer (2).

10. A method of using the apparatus according to any one of claims 1-9, characterized in that... Includes the following steps: S1. Check the integrity of the device and confirm that the medical pressure-sensitive adhesive layer (12) is free from contamination, the sensor layer (2) is undamaged, and the wireless transmission submodule (223) can communicate normally. S2. Clean the monitoring area, remove the release paper (11), and attach the device to the skin or inner dressing surface of the flap transplantation area. S3. Initiate the connection between the external device and the wireless transmission submodule (223) to ensure real-time data reception; S4. Based on the changing trend of capacitance signals received from external devices, determine whether there is blood supply obstruction and the obstruction area after flap surgery.

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