A wearable dynamic and static blood supply monitoring device and method

Abstract

The present application relates to a kind of wearable dynamic and static blood supply monitoring device and method, the device includes front-end test module and rear-end processing module, the front-end test module is connected with rear-end processing module by front-end rear-end connecting line, the front-end test module is covered on the skin of patient, the front-end test module includes pressure layer and light ray transceiver layer, pressure sensor is arranged on the pressure layer, light emitting diode and photodetector are arranged on the light ray transceiver layer, the pressure layer is connected with light ray transceiver layer by front-end internal connecting line, the two sides of the pressure layer and light ray transceiver layer are provided with package, the rear-end processing module includes signal acquisition processing transmission layer, signal acquisition processing transmission component is arranged on the signal acquisition processing transmission layer, the two sides of the signal acquisition processing transmission layer are provided with package.Compared with prior art, the present application realizes non-invasive real-time monitoring to skin blood supply state, can judge thrombus type in time.

Description

Technical Field

[0001] This invention belongs to the field of medical biosensor technology and relates to a wearable dynamic and static blood circulation monitoring device and method. Background Technology

[0002] Free flap transplantation is a common skin repair technique in reconstructive surgery. It can be used to cover skin wounds caused by trauma, tumor resection, etc., and can also be used to repair large-area skin and soft tissue defects caused by scar correction. Free flap transplantation involves placing a free flap over the affected area and anastomosing the arteries and veins to the main blood vessels of the affected area, enabling continuous blood supply to the flap and the formation of new peripheral blood vessels. With the continuous improvement of microsurgical techniques, the success rate of flap transplantation surgery has reached a high level, with many studies reporting a survival rate of over 95%.

[0003] Although flap transplantation is a relatively mature procedure, its inherent risks should not be ignored. Blood supply disruption is the leading cause of flap transplantation failure. Once it occurs, the transplanted flap can quickly lose its blood supply, leading to microcirculatory disturbances, and if not treated promptly, can result in flap necrosis. Clinically, flap survival rates are negatively correlated with ischemia time; therefore, long-term postoperative blood supply monitoring is crucial for patients.

[0004] Currently, postoperative monitoring methods for transplanted skin flaps are mainly divided into two categories: clinical monitoring and instrumental monitoring. Clinical monitoring methods rely heavily on the physician's clinical experience and include observing the flap's color, surface temperature, capillary reactivity, tissue elasticity, and needle prick bleeding. While clinical observation is highly accurate, it is also highly subjective, dependent on the observer's clinical experience, lacks flexibility, and cannot achieve long-term continuous monitoring. Therefore, there is a lag in assessing sudden situations such as vascular obstruction, potentially leading to missed opportunities for optimal rescue.

[0005] Instrumental monitoring is another method of postoperative monitoring after skin flap transplantation, which can be divided into traditional instrumental monitoring methods and new instrumental monitoring methods. Traditional instrumental monitoring technology relies on large, fixed medical equipment deployed in hospitals, while new instrumental monitoring technology relies on wearable, small, portable electronic devices.

[0006] Currently used traditional monitoring technologies mainly include color Doppler ultrasound, laser Doppler flowmeter, and transcutaneous oxygen saturation meter. Handheld Doppler ultrasound is the most widely used auxiliary instrument. Its principle is that the ultrasound probe emits a series of ultrasound waves into the body, scanning in a specific direction. By monitoring the delay time and intensity of the echoes, the distance and nature of organs can be determined. This data is then processed by a computer to form an ultrasound image. Color Doppler ultrasound operates on the same principle, but for vascular imaging, it adds red and blue colors to distinguish between veins and arteries, allowing for precise quantification of blood inflow and outflow. However, Doppler ultrasound imaging technology has relatively low resolution and requires a certain level of skill from the operator. It needs to be operated and interpreted by professional medical personnel. When monitoring patients after flap transplantation, it is necessary to know the location of the vascular pedicle and anastomosis in advance to quantitatively monitor blood supply. Laser Doppler imaging technology differs slightly from Doppler ultrasound imaging in principle. It is based on transmitting a laser beam through optical fiber. When the laser beam is scattered by the tissue being studied, some light is absorbed. The wavelength of the laser hitting blood cells changes, while the wavelength remains unchanged when hitting stationary tissue. The intensity and frequency distribution of these wavelength changes are directly related to the number and movement speed of blood cells within the monitored volume. This information is recorded and converted into electrical signals for analysis via the receiving optical fiber. Laser Doppler imaging technology has high accuracy in microcirculation monitoring, but its significant drawback is that using a single point for flow analysis can lead to high variability in the measured values. This is because microvessels are inherently non-uniform, and flow can vary spatially and temporally; therefore, it cannot provide information on visible vascular morphology or density measurements. Transcutaneous oxygen partial pressure (TOP) meters are often used to monitor local blood perfusion. Their principle involves heating the local skin with a transcutaneous TOP probe, causing local capillary dilation and maximizing the release of oxygen from the blood through the skin. The TOP value is then measured to indirectly reflect the tissue oxygenation status. However, because this method requires heating the skin and maintaining a high temperature, it cannot achieve long-term monitoring. Furthermore, due to the low amount of oxygen released from the skin and the constraints imposed by various factors, the measurement results are not stable.

[0007] Novel monitoring methods are mostly small, portable wearable monitoring devices, which can be divided into implantable and non-implantable types. Patent US20130116575A1 discloses an implantable Doppler monitor, which is similar in principle to Doppler ultrasound and consists of three parts: a sensor strap, a sound wave transmitter and receiver, and a wireless signal transmission device. The sensor strap fixes the sound wave transmitter and receiver near the vascular anastomosis, and the wireless transmission device sends the received sound wave signal to the external receiver. Hexia Guo's "Wireless implantable optical probe for continuous monitoring of oxygensaturation in flaps and organ grafts" published in Nature Communications ((2022) 13:3009) introduces an injectable flexible probe with a miniature inorganic light-emitting diode and a photodetector, which can measure the absorbance gradient and thus accurately calculate the oxygenation level of various tissues. DiLu's paper, "Implantable, wireless, self-fixing thermal sensors for continuous measurements of microvascular blood flow in flaps and organ grafts," published in *Biosensors and Bioelectronics* (Volume 206, 15 June 2022, 114145), also introduces an implantable blood flow sensor for flap monitoring. Its main principle is to indirectly measure blood flow based on thermodynamics and fluid dynamics through blood flow thermodynamic analysis. The sensor includes a heater and multiple temperature sensors. It calculates microperfusion by heating the flap tissue and measuring the temperature difference. The sensor also features biodegradable barbs to secure the probe to surrounding tissue, facilitating removal after a period of use. However, implantable monitoring devices need to be placed inside the body during surgery and removed after recovery, increasing surgical time and subjecting patients to secondary trauma.

[0008] Compared to implantable flap monitoring devices, non-implantable wearable monitoring devices are more convenient to use. Patent US20220061714A1 discloses a transdermal oxygen partial pressure sensor. This device operates on the same principle as a transdermal oxygen meter, creating an oxygenation membrane that can directly adhere to the skin by coating fluorescent and scattering materials onto a flexible polymer substrate. Combined with a heating element and a miniature LED light source emitter and receiver, it can measure the skin's oxygen partial pressure. However, this device also suffers from the problem of high heating temperatures preventing long-term monitoring. Patent KR20220039478A also discloses a transdermal oxygen partial pressure monitoring sensor. By fixing a sensor patch to a strap that can be filled with liquid or gas, it can achieve better adhesion to different body surfaces. However, due to the strapping fixation method, the sensor cannot be used for monitoring transplanted flaps in certain special areas.

[0009] Bioelectrochemical sensors can also be used to monitor transplanted skin flaps postoperatively by detecting biochemical indicators such as pH, ion concentration, and bacteria. Wonryung Lee, in his paper "Conformable microneedle pH sensors via the integration of two different siloxane polymers for mapping peripheral artery disease" published in *Science Advance* (7 (2021) 6290), introduced a microneedle sensor integrating two different siloxane polymers, where polyaniline deposited on the microneedles can be used to detect the pH value of skin tissue. Yuji Gao, in his paper "A flexible multiplexed immunosensor for point-of-care in situ wound monitoring" published in *Science Advance* (7 (2021) 9614), proposed a microfluidic-based multi-parameter sensor platform that can measure multiple biophysical and chemical parameters of wound fluid. Studies have shown that a wound bed pH below 7.3 may be associated with skin graft failure, but the main cause of flap failure is thrombosis leading to impaired vascular hemodynamics. Therefore, monitoring flap transplantation by detecting wound biochemical indicators is not the optimal approach.

[0010] Measuring skin temperature and comparing skin color are also methods for postoperative monitoring of skin flaps. Patent CN212326377U discloses an integrated skin flap observation and evaluation device, which is divided into two areas: one for displaying skin flap temperature and the other for skin flap color comparison. However, this evaluation device requires manual operation and identification, and does not achieve fully real-time monitoring.

[0011] Patent CN113729654A discloses a skin-attached sensing system for detecting blood flow status of postoperative skin flaps and reconstructed limbs. The system includes a front-end status detection module and a back-end signal processing and output module. The front-end status detection module collects real-time blood oxygen saturation and temperature data of the postoperative skin flap and reconstructed limb, and encapsulates the printed circuit board with a flexible encapsulation layer. After chemical treatment of the flexible encapsulation layer surface, a prepolymerized hydrogel solution is injected for cross-linking to obtain a hydrogel adhesion layer, ensuring long-term close adhesion to the skin while preventing bacterial infection. The back-end signal processing and output module processes the blood oxygen saturation and temperature data and transmits it to a mobile terminal in real time. However, the device described in this patent can only achieve static monitoring of patients after skin flap transplantation. While it can provide alerts based on abnormal oxygen saturation and temperature to indicate the presence of arterial and venous thrombosis, it does not provide a corresponding identification method for the specific location of blood flow thrombosis.

[0012] In summary, based on the research results of existing patented technologies, professional medical equipment is bulky, and doctors prefer clinical monitoring methods, thus limiting the promotion of traditional flap monitoring technology; new monitoring technologies have lower testing accuracy and limited application sites, and may cause secondary trauma to patients, making wearable flap monitoring technology not widely accepted. Summary of the Invention

[0013] The purpose of this invention is to overcome at least one of the defects of the prior art and provide a wearable dynamic and static blood circulation monitoring device and method. This invention realizes non-invasive real-time monitoring of the blood circulation status of the skin and can promptly determine the type of thrombus.

[0014] The objective of this invention can be achieved through the following technical solutions:

[0015] One of the technical solutions of the present invention is to provide a wearable dynamic and static blood circulation monitoring device, which includes a front-end testing module and a back-end processing module. The front-end testing module is connected to the back-end processing module through a front-end and back-end connection cable, and the front-end testing module covers the patient's skin.

[0016] The front-end testing module includes a pressure layer and a light transceiver layer. A pressure sensor is arranged on the pressure layer, and a light-emitting diode and a photodetector are arranged on the light transceiver layer. The pressure layer is connected to the light transceiver layer via internal front-end connection lines. Both the pressure layer and the light transceiver layer are encapsulated on both sides.

[0017] The back-end processing module includes a signal acquisition, processing and transmission layer, on which signal acquisition, processing and transmission components are arranged, and both sides of the signal acquisition, processing and transmission layer are encapsulated.

[0018] Furthermore, the pressure layer includes a pressure circuit substrate on which a piezoelectric thin film sensor is disposed.

[0019] Furthermore, the light transceiver layer includes a light circuit substrate on which short-wavelength and long-wavelength light-emitting diodes are arranged in parallel, and short-wavelength and long-wavelength photodetectors are arranged in two layers surrounding the light-emitting diodes. The short-wavelength and long-wavelength light-emitting diodes emit two different wavelengths of light, with the short-wavelength light-emitting diodes emitting short-wavelength red light and the long-wavelength light-emitting diodes emitting long-wavelength near-infrared light. The short-wavelength and long-wavelength photodetectors absorb the two different wavelengths of light emitted by the light-emitting diodes, with the short-wavelength photodetectors absorbing short-wavelength red light and the long-wavelength photodetectors absorbing long-wavelength near-infrared light. Since oxyhemoglobin and deoxyhemoglobin in the blood absorb red light and near-infrared light, respectively, two sets of devices, one for long-wavelength and one for short-wavelength light, are used to comprehensively calculate the blood oxygen saturation of the tissue.

[0020] As a preferred technical solution, the same type of photodetector and light-emitting diode are spaced at the same distance, and a fixed distance is maintained between adjacent photodetectors.

[0021] As a preferred technical solution, the center of the pressure sensor is concentric with the center of the parallel-arranged light-emitting diodes.

[0022] Furthermore, pressure sensors are arranged in a single row or in an array on the pressure layer.

[0023] Furthermore, the light transceiver layer is provided with a single set or multiple arrays of light-emitting diodes and photodetectors, with the photodetectors arranged in a group around the light-emitting diodes.

[0024] As a preferred technical solution, the pressure layer and the light transceiver layer have a circular or rectangular sheet structure, and a circular or rectangular piezoelectric thin film sensor is arranged on the pressure circuit substrate.

[0025] As a preferred technical solution, a protrusion is provided at the edge of the pressure layer and the optical transceiver layer, and the protrusion realizes the electrical connection between the pressure layer and the optical transceiver layer by connecting the internal connecting line at the front end.

[0026] As a preferred technical solution, the internal connecting line of the front end extends vertically from the plane where the pressure layer and the light transceiver layer are located.

[0027] As a preferred technical solution, the shape of the protrusion includes a circle or a rectangle.

[0028] As a preferred technical solution, the signal acquisition, processing and transmission layer has a circular or rectangular sheet structure.

[0029] As a preferred technical solution, an interface is extended from the protrusion of the optical transceiver layer and the edge of the signal acquisition, processing and transmission layer. This interface enables the electrical connection between the front-end test module and the back-end processing module by plugging in the front-end and back-end connection cables.

[0030] As a preferred technical solution, the front-end and back-end connection lines extend parallel to the plane where the optical transceiver layer and the signal acquisition, processing and transmission layer are located.

[0031] As a preferred technical solution, the shape of the interface includes a circle or a rectangle.

[0032] Furthermore, the signal acquisition, processing, and transmission layer includes a signal circuit substrate on which an antenna module, a microprocessor chip (MCU), a signal conditioning circuit, and a battery are arranged. The signal conditioning circuit includes an analog-to-digital converter (ADC), an operational amplifier (AMP), and a low-pass filter (LPF). The pressure layer is connected to the optical transceiver layer via an internal front-end connection line, and then connected to the low-pass filter of the signal acquisition, processing, and transmission layer via a front-end and rear-end connection line. While powering the light-emitting diode, it also acquires the voltage signals of the photodetector and pressure sensor. The low-pass filter, operational amplifier, ADC, microprocessor chip, and antenna module are connected in sequence. The battery powers the front-end test module and the signal acquisition, processing, and transmission components. The raw oxygen saturation signal is divided into short-wave and long-wave signals, which, together with the pressure signal, are distributed into three paths. The low-pass filter and operational amplifier are responsible for signal processing, the ADC is responsible for signal acquisition and conversion, the microprocessor chip processes the oxygen saturation and pressure data to obtain the data, and then the antenna module is responsible for transmitting the information to the mobile terminal.

[0033] As a preferred technical solution, the circuit substrate is a flexible printed circuit board (PCB), the circuit is engraved using a laser engraving machine, and the components are fixed to the circuit substrate by low-temperature solder paste hot air welding.

[0034] Furthermore, the front-end test module includes a front-end top package, a pressure layer, a front-end middle partition package, a light transceiver layer, and a front-end bottom package. The pressure layer is disposed between the front-end top package and the front-end middle partition package, and the light transceiver layer is disposed between the front-end middle partition package and the front-end bottom package.

[0035] The back-end processing module includes a top back-end package, a signal acquisition, processing and transmission layer, and a bottom back-end package, with the signal acquisition, processing and transmission layer disposed between the top back-end package and the bottom back-end package.

[0036] As a preferred technical solution, the pressure layer and the optical transceiver layer are isolated by encapsulation, and all parts except the protrusions are covered to achieve external insulation.

[0037] Furthermore, the shape and size of the encapsulation match the pressure layer, the light transceiver layer, and the signal acquisition, processing, and transmission layer. All materials used are the flexible polymer material Ecoflex, which has good tensile properties, waterproof properties, and biocompatibility. It can also be made into any shape as needed. Therefore, Ecoflex was chosen as the encapsulation material for the device.

[0038] Furthermore, the device is placed on the surface of the patient's transplanted skin flap. The front-end testing module and the back-end processing module are laid out in a flat manner, connected but not overlapping, with the front-end testing module attached above the transplanted skin flap.

[0039] As a preferred technical solution, the device is placed on the transplanted skin flaps of the patient's limbs or trunk.

[0040] As a preferred technical solution, the front-end testing module is bonded to the skin via an adhesive method.

[0041] As a preferred technical solution, the back-end processing module can be placed flat on the skin of other parts of the body, or connected to a table or chair via a long front-end and back-end connection cable.

[0042] One of the technical solutions of the present invention is to provide a wearable dynamic and static blood circulation monitoring method. This method uses the aforementioned device to perform non-invasive real-time monitoring of the static and dynamic blood circulation status of a patient's skin. The method includes the following steps:

[0043] In static monitoring mode, the light emitted by the LED is transmitted through the epidermis to the dermis. The dermis is rich in capillary networks, and the oxyhemoglobin and deoxyhemoglobin in the blood of these capillary networks absorb light. After partial absorption, the light is reflected and received by the photodetector. Upon receiving the light, the photodetector causes a change in the current in the circuit, converting the optical signal into an electrical signal. This electrical signal is then processed by the back-end processing module to obtain the tissue's blood oxygen saturation. StO 2 The oxygen saturation of tissues reflects the blood supply to the skin. When blood supply to the skin is good, the oxygen saturation in the tissues is the initial value. When blood supply to the skin is impaired due to blockage of arteries or veins, the oxygen content in the tissues will decrease relative to the initial value. By comparing the initial values, we can obtain an approximate state of blood supply to the skin.

[0044] In dynamic pressure mode, when pressure is applied to the front-end testing module, the resistance of the pressure sensor changes, and the electrical signal is collected and processed by the back-end processing module to obtain the pressure value. Subcutaneous blood vessels experience temporary ischemia due to pressure, and when the pressure is released, blood refills the blood vessels. During the formation of the ischemic environment and the restoration of refill, the tissue blood oxygen value changes dynamically. Since arterial and venous blood vessels have different blood flow conditions, different recovery curves are used to determine the location and severity of the blockage.

[0045] As a preferred technical solution, the red and near-infrared light emitted by the short-wavelength light-emitting diode and the long-wavelength light-emitting diode are transmitted through the epidermis to the dermis. The dermis is rich in capillary networks. The oxyhemoglobin and deoxyhemoglobin in the blood of the capillary network have an absorption effect on red and near-infrared light of different wavelengths. After being partially absorbed, the red and near-infrared light are reflected and received by the short-wavelength photodetector and the long-wavelength photodetector.

[0046] As a preferred technical solution, the photodetector will cause a change in the current in the circuit after receiving light, and the light signal will be converted into an electrical signal. The electrical signal will obtain the corresponding light absorption value through the back-end processing module. By calculating the proportion of absorbed light, the content of oxyhemoglobin and deoxyhemoglobin in the blood can be obtained, and then the blood oxygen saturation of the tissue can be calculated.

[0047] As a preferred technical solution, the initial value of tissue blood oxygen is uploaded to the communication device via Bluetooth or WiFi wireless transmission function, and the real-time blood oxygen value in the tissue is also wirelessly transmitted to the communication device in real time, so that patients or medical staff can read the relevant information through application software.

[0048] As a preferred technical solution, when a finger applies pressure to the front-end testing module, the resistance of the piezoelectric film sensor will change. The electrical signal is collected and processed by the back-end processing module and then wirelessly transmitted to the communication device. The pressure value can be viewed through application software.

[0049] As a preferred technical solution, based on a preset ischemic pressure range, after maintaining effective pressure for a certain period of time, subcutaneous blood vessels experience transient ischemia due to pressure.

[0050] As a preferred technical solution, the pressure value range that can achieve the ischemic effect is calculated in advance through simulation and uploaded to the server. The mobile terminal obtains the effective pressure value range from the server and provides real-time prompts on the effectiveness of the pressure application.

[0051] As a preferred technical solution, tissue blood oxygen saturation information is wirelessly transmitted to a communication device. The communication device obtains from the server the mapping relationship between the restored blood flow value of arteries and veins and the tissue blood oxygen saturation value obtained in advance through computational fluid dynamics (CFD) simulation, and uses the mapping relationship to determine the blockage end. Patients or medical staff can read the corresponding information through application software.

[0052] As a preferred technical solution, when the patient's blood supply is normal, pressing creates a brief ischemia, and the tissue's blood oxygen value will gradually decrease. After releasing the pressure, the blood oxygen value will gradually rise. However, due to the rapid influx of arterial blood, an overshoot process will occur, and the blood oxygen level will gradually return to its original level.

[0053] When a patient presents with venous occlusion, pressing mainly causes arterial blood to be blocked, and the blood oxygen level will drop faster than the normal rate of decline. At the same time, after releasing the pressure, due to the influx of arterial blood and the effect of venous occlusion, blood cannot flow out of the vein in time, and the blood oxygen level rises rapidly, making the overshoot phenomenon more significant, and then gradually returns to normal.

[0054] When a patient's artery is blocked, pressing mainly causes venous blood to be blocked, and the rate at which blood oxygen levels decrease will be slower than the normal rate of decrease. At the same time, after releasing the pressure, due to the arterial blockage, the rate of arterial blood flow is limited, the overshoot phenomenon will not occur, and the blood oxygen level will gradually return to normal.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) The present invention adopts a flexible wearable design and uses a combination of tissue oxygen saturation monitoring and pressure monitoring to achieve non-invasive real-time monitoring of the static and dynamic blood supply status of the skin, such as the postoperative skin flap in patients undergoing free flap transplantation. It can promptly grasp the blood supply status of the transplanted skin flap. When arterial and venous thrombosis causes the skin flap to be ischemic or congested, it can promptly determine the type of thrombosis and warn medical staff and patients, so as to take measures such as drugs or surgery as soon as possible to intervene and ensure the survival of the transplanted skin flap and the health of the patient.

[0057] (2) This invention, based on tissue oxygen saturation monitoring and combined with pressure monitoring, can achieve two different monitoring modes; the first monitoring mode is static use based on tissue oxygen saturation monitoring, where the light transceiver unit can measure the content of oxyhemoglobin and deoxyhemoglobin in the tissue, and then calculate the tissue oxygen saturation. StO 2When the skin's blood supply is good, the tissue's oxygen saturation should be maintained at a high level. By comparing it with normal blood oxygen values, it can be roughly determined whether the patient's skin blood supply is normal. The second monitoring method is a dynamic use based on the combination of tissue oxygen saturation monitoring and pressure monitoring. Since both venous and arterial blockages in the skin can cause tissue hypoxia, an ischemic state can be artificially created by gently pressing the skin with a finger, and the skin's blood return status can be monitored to determine the blockage. The pressure component can display the local pressure value. When the required pressure is reached, it is maintained for a fixed time and then released. The tissue oxygen recovery status measured by the light transceiver component during the recovery process is observed. Since there are differences between venous blood and arterial blood, the location and severity of the blockage can be determined by the recovery speed.

[0058] (3) In this invention, the light photodetector for measuring oxygen saturation is arranged in multiple groups and in an array around the light photodiode, which can improve the light absorption efficiency, improve the measurement accuracy of oxyhemoglobin and deoxyhemoglobin content in tissue, and improve the calculation accuracy of tissue oxygen saturation.

[0059] (4) The present invention has both wearing comfort in terms of packaging. The packaging design uses Ecoflex, a flexible polymer material, which has excellent tensile properties, waterproof properties and biocompatibility. Using this material to encapsulate the device can make the device more skin-friendly and comfortable to wear.

[0060] (5) The present invention adopts a non-invasive patch-on wearing method, which is convenient to wear and has a wide range of applications. It can monitor various parts such as the limbs and trunk, and can meet the needs of most flap transplant patients and patients with skin blood circulation disorders.

[0061] (6) The device proposed in this invention is small and portable, and easy to use. It only needs to be attached to the skin to be tested and the status can be viewed through a mobile terminal. Therefore, it can achieve accurate postoperative monitoring for each patient. This invention delivers skin blood circulation status information to patients and medical staff wirelessly. Medical staff can remotely monitor the vital signs of multiple patients at the same time. When abnormalities are found, the patient's condition can be simply assessed. This can greatly reduce the workload of medical staff and enable patients to receive timely treatment, thereby reducing the postoperative risk of patients. Attached Figure Description

[0062] Figure 1 This is a three-dimensional structural diagram of the wearable dynamic and static blood circulation monitoring device in Embodiment 1 of the present invention;

[0063] Figure 2 This is a schematic diagram of the exploded structure of the wearable dynamic and static blood circulation monitoring device in Embodiment 1 of the present invention;

[0064] Figure 3This is a schematic diagram of the pressure layer structure in Embodiment 1 of the present invention;

[0065] Figure 4 This is a schematic diagram of the structure of the light transceiver layer in Embodiment 1 of the present invention;

[0066] Figure 5 This is a schematic diagram of the composition of the backend processing module in Embodiment 1 of the present invention;

[0067] Figure 6 This is a schematic diagram of the installation of the wearable dynamic and static blood supply monitoring device attached to the patient's arm transplant flap in Embodiment 1 of the present invention;

[0068] Figure 7 This is a schematic diagram of the installation of the wearable dynamic and static blood supply monitoring device attached to the transplanted skin flap on the patient's leg in Embodiment 1 of the present invention;

[0069] Figure 8 This is a schematic diagram showing the state of the front-end testing module attached to the transplanted flap under the static long-term monitoring mode in Embodiment 1 of the present invention;

[0070] Figure 9 The oxygen saturation after static free flap transplantation in Example 1 of this invention ( StO 2 A schematic diagram illustrating the monitoring results;

[0071] Figure 10 This is a schematic diagram showing the state of the front-end testing module attached to the transplant flap in the dynamic pressing mode of Embodiment 1 of the present invention;

[0072] Figure 11 This is a schematic diagram illustrating the monitoring effect of blood oxygen saturation after dynamic free flap transplantation in Embodiment 1 of the present invention;

[0073] Figure 12 This is an exploded structural diagram of the wearable dynamic and static blood circulation monitoring device in Embodiment 2 of the present invention;

[0074] Figure 13 This is a schematic diagram of the pressure layer structure in Embodiment 2 of the present invention;

[0075] Figure 14 This is a schematic diagram of the structure of the light transceiver layer in Embodiment 2 of the present invention.

[0076] Explanation of markings in the diagram:

[0077] 1—Top front-end package, 2—Pressure layer, 3—Middle front-end partition package, 4—Optical transceiver layer, 5—Bottom front-end package;

[0078] 21—Piezoelectric thin film sensor; 22—Pressure circuit substrate;

[0079] 23—Internal connection cable at the front end;

[0080] 41—Fiber optic circuit substrate; 42—Short-wavelength photodetector; 43—Long-wavelength photodetector; 44—Short-wavelength light-emitting diode; 45—Long-wavelength light-emitting diode;

[0081] 6—Front-end and back-end connection cables;

[0082] 7—Top rear package; 8—Signal acquisition, processing and transmission layer; 9—Bottom rear package;

[0083] 81—Signal circuit substrate, 82—Antenna module, 83—Microprocessor chip, 84—Signal conditioning circuit, 85—Battery. Detailed Implementation

[0084] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0085] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for 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. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," "third," etc., used to describe a common object only indicate different instances of the same object, and do not imply that the objects described in this way must be in a given order, whether temporally, spatially, sequentially, or in any other way.

[0086] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 this invention based on the specific circumstances.

[0087] Example 1:

[0088] A wearable dynamic and static blood circulation monitoring device, such as Figure 1 and Figure 2 As shown, it includes a front-end testing module and a back-end processing module. The front-end testing module is connected to the back-end processing module via a front-end / back-end connection cable 6. The front-end testing module is placed on the patient's skin.

[0089] The front-end test module includes a pressure layer 2 and a light transceiver layer 4. A single pressure sensor is arranged on the pressure layer 2, and a single set of light-emitting diodes and photodetectors is arranged on the light transceiver layer 4. The pressure layer 2 is connected to the light transceiver layer 4 via an internal front-end connection line 23. Both the pressure layer 2 and the light transceiver layer 4 are encapsulated on both sides.

[0090] The back-end processing module includes a signal acquisition, processing and transmission layer 8, on which signal acquisition, processing and transmission components are arranged, and both sides of the signal acquisition, processing and transmission layer 8 are encapsulated.

[0091] The pressure layer 2 and the light transceiver layer 4 have a circular sheet structure. A pair of protrusions are provided at the edge of the pressure layer 2 and the light transceiver layer 4. The two protrusions are rectangular in shape. The two protrusions are electrically connected to the pressure layer 2 and the light transceiver layer 4 by connecting the front internal connection line 23. The front internal connection line 23 extends vertically from the plane where the pressure layer 2 and the light transceiver layer 4 are located.

[0092] The signal acquisition, processing and transmission layer 8 has a rectangular sheet structure. A pair of interfaces extend from the protrusion of the optical transceiver layer 4 and the edge of the signal acquisition, processing and transmission layer 8. The two interfaces are rectangular in shape. The two interfaces are connected to the front-end test module and the back-end processing module through the front-end and back-end connection line 6. The front-end and back-end connection line 6 extends parallel from the plane where the optical transceiver layer 4 and the signal acquisition, processing and transmission layer 8 are located.

[0093] The front-end test module includes a front-end top package 1, a pressure layer 2, a front-end middle partition package 3, a light transceiver layer 4, and a front-end bottom package 5. The pressure layer 2 is disposed between the front-end top package 1 and the front-end middle partition package 3, and the light transceiver layer 4 is disposed between the front-end middle partition package 3 and the front-end bottom package 5. The pressure layer 2 and the light transceiver layer 4 are isolated by the package, and all parts except the protrusions are covered to achieve external insulation.

[0094] The back-end processing module includes a back-end top package 7, a signal acquisition, processing and transmission layer 8, and a back-end bottom package 9, with the signal acquisition, processing and transmission layer 8 disposed between the back-end top package 7 and the back-end bottom package 9.

[0095] The shape and size of the encapsulation match the pressure layer 2, the light transceiver layer 4, and the signal acquisition, processing and transmission layer 8. The materials used are all flexible polymer materials, such as Ecoflex. Ecoflex has good tensile properties, waterproof properties and biocompatibility. At the same time, it can be made into any shape as needed. Therefore, Ecoflex was chosen as the encapsulation material for the device.

[0096] like Figure 3As shown, the pressure layer 2 includes a pressure circuit substrate 22, and a circular one-piece piezoelectric thin film sensor 21 is arranged at the center of the pressure circuit substrate 22. The pressure circuit substrate 22 is a flexible printed circuit board (PCB), and the circuit is engraved using a laser engraving machine. The piezoelectric thin film sensor 21 is fixed to the pressure circuit substrate 22 by low-temperature solder paste hot air soldering.

[0097] For sensitivity and integrated design considerations, the piezoelectric thin film sensor 21 uses the FER402 thin film pressure sensor from Interlink Electronics, which has a sensitivity range of 0.2-20 N and high sensitivity.

[0098] like Figure 4 As shown, the light transceiver layer 4 includes a light circuit substrate 41. At the center of the light circuit substrate 41 are two short-wavelength light-emitting diodes (LEDs) 44 and long-wavelength light-emitting diodes (LEDs) 45 arranged side-by-side. At the edge of the substrate 41 are eight short-wavelength photodetectors 42 and long-wavelength photodetectors 43 arranged in two layers, inner and outer, surrounding the LEDs. The short-wavelength LEDs 44 and 45 emit two different wavelengths of light, with the short-wavelength LEDs 44 emitting short-wavelength red light and the long-wavelength LEDs 45 emitting long-wavelength near-infrared light. The short-wavelength photodetectors 42 and 43 respectively absorb the two wavelengths of light emitted by the LEDs. Different wavelengths of light are used. Four inner-layer short-wave photodetectors 42 absorb short-wave red light, and four outer-layer long-wave photodetectors 43 absorb long-wave near-infrared light. Since oxyhemoglobin and deoxyhemoglobin in the blood absorb red light and near-infrared light respectively, two sets of devices, one for long-wave and one for short-wave, are set up to comprehensively calculate the blood oxygen saturation of the tissue. The light circuit substrate 41 is a flexible printed circuit board, and the circuit is engraved using a laser engraving machine. The short-wave light-emitting diode 44, the long-wave light-emitting diode 45, the short-wave photodetector 42, and the long-wave photodetector 43 are fixed to the light circuit substrate 41 by low-temperature solder paste hot air soldering.

[0099] The same type of photodetector and light-emitting diode are spaced at the same distance, and a fixed distance is maintained between two adjacent photodetectors;

[0100] For miniaturization and integration design considerations, the short-wavelength light-emitting diode 44 and the long-wavelength light-emitting diode 45 are respectively selected from III-V Materials' TCSD14-660 and TCSD14-850, and the short-wavelength photodetector 42 and the long-wavelength photodetector 43 are both selected from Vishay Semiconductors' T1197P6. The size of the light-emitting diodes and photodetectors is at the micrometer level, which is smaller than the millimeter size, and multi-point arrangement of the devices can be realized.

[0101] The center of the piezoelectric thin film sensor 21 is concentric with the centers of the short-wavelength light-emitting diode 44 and the long-wavelength light-emitting diode 45;

[0102] like Figure 5 As shown, the signal acquisition, processing, and transmission layer 8 includes a signal circuit substrate 81. An antenna module 82, a microprocessor chip (MCU) 83, a signal conditioning circuit 84, and a battery 85 are arranged on the signal circuit substrate 81. The signal conditioning circuit 84 includes an analog-to-digital converter (ADC), an operational amplifier (AMP), and a low-pass filter (LPF). The pressure layer 2 is connected to the optical transceiver layer 4 via an internal front-end connection line 23, and then connected to the low-pass filter of the signal acquisition, processing, and transmission layer 8 via a front-end / back-end connection line 6. This power supply provides power to the light-emitting diodes while simultaneously acquiring voltage signals from the photodetector and pressure sensor. The low-pass filter, operational amplifier, ADC, microprocessor chip 83, and antenna module 82 are sequentially connected. The battery 85 powers the front-end test module and the signal acquisition, processing, and transmission components. The tissue oxygen saturation raw signal is divided into short-wave and long-wave signals, which are compared with the pressure signal. The signal is divided into three paths: a low-pass filter and an operational amplifier are responsible for signal processing, an analog-to-digital converter is responsible for signal acquisition and conversion, and the microprocessor chip 83 processes the oxygen saturation and pressure data to obtain the data. Then, the antenna module 82 is responsible for transmitting the information to the mobile terminal. The signal circuit substrate 81 is a flexible printed circuit board, and the circuit is engraved using a laser engraving machine. The antenna module 82, microprocessor chip 83, signal conditioning circuit 84 and battery 85 are fixed on the optical circuit substrate 41 by low-temperature solder paste hot air welding.

[0103] The analog-to-digital converter (ADC) is Texas Instruments' ADS1120 12-bit ADC, the operational amplifier is the precision operational amplifier OPA2333, the low-pass filter is a resistor-capacitor network, the antenna module 82 is Johnson's Mini 2.45 GHz Antenna, which can improve the reception and transmission range of Bluetooth or WiFi wireless transmission signals, the microprocessor chip 83 is Espressif Systems' ESP32-C3 chip, which is inexpensive and has low-power Bluetooth and WiFi functions, enabling wireless data transmission, and the battery 85 is a 3V button battery.

[0104] like Figure 6 and Figure 7 As shown, when using the device, it is placed on the patient's skin flap, such as the lower arm or calf flap. The front-end testing module and the back-end processing module are laid out in a flat manner, connected but not overlapping. The front-end testing module is attached to the top of the transplanted skin flap and bonded to the skin. The back-end processing module is naturally placed on the skin of other parts of the body. It can also be connected and placed on a table or chair through a long front-end and back-end connecting line 6.

[0105] A wearable dynamic and static blood supply monitoring method is provided, which uses the aforementioned device to perform non-invasive real-time monitoring of the static and dynamic blood supply status of the skin flap in patients undergoing free flap transplantation. The specific steps are as follows:

[0106] like Figure 8 and Figure 9 As shown, in the static long-term monitoring mode, the red and near-infrared light emitted by the short-wavelength LED 44 and long-wavelength LED 45 located at the center of the light transceiver layer 4 is conducted through the epidermis to the dermis. The dermis is rich in capillary networks, and the oxyhemoglobin and deoxyhemoglobin in the blood of the capillary network absorb red and near-infrared light of different wavelengths. After partial absorption, the red and near-infrared light are reflected and received by the short-wavelength photodetector 42 and the long-wavelength photodetector 43. After receiving the light, the photodetector will cause a change in the current in the circuit, and the light signal will be converted into an electrical signal. The electrical signal is collected and processed by the back-end processing module to obtain the corresponding light absorption value. By calculating the proportion of absorbed light, the content of oxyhemoglobin and deoxyhemoglobin in the blood can be obtained, and then the tissue oxygen saturation can be calculated. StO 2 The blood oxygen saturation of the tissue reflects the blood supply effect of the transplanted flap. Immediately after the flap transplantation surgery, the blood supply in the flap tissue is good, and the blood oxygen saturation in the tissue is the initial value. When the flap experiences blood supply obstruction due to arterial or venous blockage, the blood oxygen content in the tissue will decrease relative to the initial value. The initial value of tissue blood oxygen can be uploaded to a mobile device via Bluetooth or WiFi wireless transmission. The real-time blood oxygen value in the tissue can also be wirelessly transmitted to the mobile device in real time. By comparing the initial value, the approximate status of the flap's blood supply can be obtained. Patients or medical staff can read the relevant information through the application software.

[0107] like Figure 10 and Figure 11As shown, in dynamic pressure mode, when a finger applies pressure to the front-end testing module, the resistance of the piezoelectric film sensor 21 changes. The electrical signal is collected and processed by the back-end processing module and then wirelessly transmitted to the mobile device. The pressure value can be viewed through the application software. The pressure value range that can achieve the ischemic effect is calculated in advance through simulation and uploaded to the server. The mobile device obtains the effective pressure value range from the server and provides real-time prompts on the effectiveness of the pressure. After maintaining effective pressure for a certain period of time, the subcutaneous blood vessels experience temporary ischemia due to pressure. When the pressure is released, blood refills the blood vessels. During the formation of the ischemic environment and the recovery of congestion, the tissue blood oxygen value changes dynamically. Since arterial and venous blood vessels have different blood flow conditions, the location and severity of the blockage can be determined by different recovery curves. The tissue blood oxygen saturation information is wirelessly transmitted to the mobile device. The mobile device obtains the mapping relationship between the arterial and venous blood flow values ​​and the tissue blood oxygen saturation values ​​obtained in advance through computational fluid dynamics (CFD) simulation from the server, and uses the mapping relationship to determine the blockage. Patients or medical staff can read the relevant information through the application software.

[0108] When the patient's blood supply is normal, applying pressure to the skin flap creates a brief period of ischemia, and the tissue's blood oxygen level will gradually decrease. After the pressure is released, the blood oxygen level will gradually rise. However, due to the rapid influx of arterial blood, an overshoot process will occur, and the blood oxygen level will gradually return to its original level.

[0109] When a patient presents with venous occlusion, pressing mainly causes arterial blood to be blocked, and the blood oxygen level will drop faster than the normal rate of decline. At the same time, after releasing the pressure, due to the influx of arterial blood and the effect of venous occlusion, blood cannot flow out of the vein in time, and the blood oxygen level rises rapidly, making the overshoot phenomenon more significant, and then gradually returns to normal.

[0110] When a patient's artery is blocked, pressing mainly causes venous blood to be blocked, and the rate at which blood oxygen levels decrease will be slower than the normal rate of decrease. At the same time, after releasing the pressure, due to the arterial blockage, the rate of arterial blood flow is limited, the overshoot phenomenon will not occur, and the blood oxygen level will gradually return to normal.

[0111] Example 2:

[0112] A wearable dynamic and static blood supply monitoring device, more suitable for monitoring large-area flap transplantation, is basically the same as Example 1, except that, as Figures 12 to 14As shown, multiple pressure sensors arranged in a square array and interconnected are arranged on the pressure layer 2, and multiple sets of light-emitting diodes and photodetectors arranged in a square array and interconnected are arranged on the light transceiver layer 4. The inner and outer layers of the photodetectors are arranged around the light-emitting diodes as a group, which can collect tissue blood oxygen saturation information at different positions of the skin flap. The finger can also apply pressure at any position on the device. The pressure layer 2 and the light transceiver layer 4 have a rectangular sheet structure. The pressure circuit substrate 22 is equipped with a square multi-sheet piezoelectric thin film sensor 21, a short-wave photodetector 42 arranged on the outer layer, and a long-wave photodetector 43 arranged on the inner layer.

[0113] For sensitivity and integrated design considerations, the piezoelectric thin film sensor 21 uses the FER406 thin film pressure sensor from Interlink Electronics, which has a sensitivity range of 0.2-20 N and high sensitivity.

[0114] A wearable method for monitoring dynamic and static blood flow is the same as in Example 1.

[0115] This embodiment enables precise monitoring of multiple locations on large-area transplanted flaps. It can obtain an overall blood supply effect map of large-area flaps by drawing tissue oxygen saturation location cloud maps. At the same time, it can also make a more accurate judgment on the location of arteriovenous thrombosis by pressing feedback at different locations.

[0116] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A wearable dynamic and static blood circulation monitoring device, characterized in that, This device enables non-invasive real-time monitoring of skin blood circulation and timely determination of thrombus type. The device includes a front-end testing module and a back-end processing module. The front-end testing module is connected to the back-end processing module via a front-end / back-end connection cable (6). The front-end testing module covers the patient's skin. The front-end testing module includes a pressure layer (2) and a light transceiver layer (4). A pressure sensor is arranged on the pressure layer (2), and a light-emitting diode and a photodetector are arranged on the light transceiver layer (4). The pressure layer (2) is connected to the light transceiver layer (4) through an internal front-end connection line (23). Both sides of the pressure layer (2) and the light transceiver layer (4) are provided with encapsulation. The back-end processing module includes a signal acquisition, processing and transmission layer (8), on which signal acquisition, processing and transmission components are arranged, and both sides of the signal acquisition, processing and transmission layer (8) are encapsulated. The light transceiver layer (4) is provided with short-wave light-emitting diodes (44) and long-wave light-emitting diodes (45) arranged in parallel, as well as short-wave photodetectors (42) and long-wave photodetectors (43) arranged in two layers around the light-emitting diodes. The center of the pressure sensor is concentric with the center of the LEDs arranged side by side; Using the aforementioned device for non-invasive real-time monitoring of the static and dynamic blood circulation status of a patient's skin includes the following steps: In static monitoring mode, the light emitted by the LED is transmitted through the epidermis to the dermis. The dermis is rich in capillary networks, and the oxyhemoglobin and deoxyhemoglobin in the blood of these capillary networks absorb light. After partial absorption, the light is reflected and received by the photodetector. Upon receiving the light, the photodetector causes a change in the current in the circuit, converting the optical signal into an electrical signal. This electrical signal is then processed by the back-end processing module to obtain the tissue's blood oxygen saturation. The tissue's blood oxygen saturation reflects the skin's blood circulation. When blood circulation in the skin is good, the tissue's blood oxygen saturation is at its initial value. When the skin experiences blood circulation impairment due to arterial or venous blockage, the tissue's blood oxygen content will decrease relative to the initial value. The skin's blood supply status is obtained by comparing it with initial values; In dynamic pressure mode, when pressure is applied to the front-end testing module, the resistance of the pressure sensor changes, and the electrical signal is collected and processed by the back-end processing module to obtain the pressure value. Subcutaneous blood vessels experience temporary ischemia due to pressure, and when the pressure is released, blood refills the blood vessels. During the formation of the ischemic environment and the restoration of refill, the tissue blood oxygen value changes dynamically. Since arterial and venous blood vessels have different blood flow conditions, the location of the blockage is determined by different recovery curves. Its dynamic monitoring recovery curve obtains the mapping relationship between arterial and venous blood flow values ​​and tissue oxygen saturation values ​​through computational fluid dynamics simulation, and uses this mapping relationship to determine the blockage. Patients or medical staff can read the relevant information through application software. When a patient presents with venous blockage, pressing mainly causes arterial blood blockage, and the rate of decrease in blood oxygen value will be greater than the normal decrease level. At the same time, after releasing the pressure, due to the influx of arterial blood and the influence of venous blockage, blood cannot flow out of the vein in time, and the blood oxygen value rises rapidly, with the overshoot phenomenon becoming more significant, before gradually returning to normal. When a patient has arterial blockage, pressing mainly causes venous blood blockage, and the rate of decrease in blood oxygen value will be less than the normal decrease level. At the same time, after releasing the pressure, due to arterial blockage, the inflow rate of arterial blood is limited, the overshoot phenomenon will not occur, and the blood oxygen value gradually returns to normal.

2. The wearable dynamic and static blood circulation monitoring device according to claim 1, characterized in that, The pressure layer (2) includes a pressure circuit substrate (22) on which a piezoelectric thin film sensor (21) is arranged.

3. The wearable dynamic and static blood circulation monitoring device according to claim 1, characterized in that, The light transceiver layer (4) includes a light circuit substrate (41), on which short-wavelength light-emitting diodes (44) and long-wavelength light-emitting diodes (45) are arranged in parallel, and short-wavelength photodetectors (42) and long-wavelength photodetectors (43) are arranged in two layers surrounding the light-emitting diodes.

4. The wearable dynamic and static blood circulation monitoring device according to claim 1, characterized in that, Pressure sensors are arranged in a single row or in an array on the pressure layer (2).

5. A wearable dynamic and static blood circulation monitoring device according to claim 1, characterized in that, The light transceiver layer (4) is provided with a single set of light-emitting diodes and photodetectors arranged in an array or in multiple sets. The photodetectors are arranged in a group around the light-emitting diodes.

6. The wearable dynamic and static blood circulation monitoring device according to claim 1, characterized in that, The signal acquisition, processing and transmission layer (8) includes a signal circuit substrate (81), on which an antenna module (82), a microprocessor chip (83), a signal conditioning circuit (84) and a battery (85) are arranged. The signal conditioning circuit (84) includes an analog-to-digital converter, an operational amplifier and a low-pass filter. The low-pass filter, operational amplifier, analog-to-digital converter, microprocessor chip (83) and antenna module (82) are connected in sequence.

7. A wearable dynamic and static blood circulation monitoring device according to claim 1, characterized in that, The front-end test module includes a front-end top package (1), a pressure layer (2), a front-end middle partition package (3), a light transceiver layer (4), and a front-end bottom package (5). The pressure layer (2) is disposed between the front-end top package (1) and the front-end middle partition package (3), and the light transceiver layer (4) is disposed between the front-end middle partition package (3) and the front-end bottom package (5). The back-end processing module includes a back-end top package (7), a signal acquisition, processing and transmission layer (8), and a back-end bottom package (9), wherein the signal acquisition, processing and transmission layer (8) is disposed between the back-end top package (7) and the back-end bottom package (9).

8. A wearable dynamic and static blood circulation monitoring device according to claim 1, characterized in that, The shape and size of the package match the pressure layer (2), the light transceiver layer (4), and the signal acquisition, processing and transmission layer (8), and the material used is the flexible polymer material Ecoflex.

9. A wearable dynamic and static blood circulation monitoring device according to claim 1, characterized in that, The device is placed on the surface of the patient's transplanted skin flap. The front-end testing module and the back-end processing module are laid out in a flat manner, connected but not overlapping. The front-end testing module is attached to the top of the transplanted skin flap.

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