Flexible electrode array method for non-contact vital sign monitoring
By using a non-contact flexible electrode array method, based on human body size and capacitive sensing principles, and adjusting the electrode array layout, the interference problem of traditional ECG monitoring devices during sleep is solved, achieving accurate ECG and sleep posture monitoring.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2026-04-10
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional ECG monitoring devices can easily disrupt sleep due to excessive wiring, and existing capacitively coupled ECG sensors cannot accurately measure ECG signals when the user turns over.
A non-contact flexible electrode array method is adopted, the electrode array layout is set based on human body size, the electrode array is adjusted using the principle of capacitance sensing, and the changes in sleeping posture are identified and the monitoring area is located through capacitance data, so as to achieve accurate acquisition of electrocardiogram signals.
It enables accurate monitoring of users' electrocardiogram (ECG) data and changes in sleeping posture without disturbing their sleep, providing long-term continuous ECG monitoring capabilities.
Smart Images
Figure CN122004873A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of biomedical engineering technology, specifically a non-contact flexible electrode array method for monitoring vital signs. Background Technology
[0002] Electrocardiography (ECG) is the gold standard tool for the clinical diagnosis and assessment of cardiovascular diseases. Abnormal signals indicate varying degrees of lesions in the human cardiovascular system. However, abnormal ECG signals caused by cardiovascular diseases are often sporadic, intermittent, and transient. Especially in the early stages of the disease, the frequency of abnormal signals is extremely low, making it difficult for short-term, intermittent ECG monitoring techniques to effectively capture these early abnormal signals. Therefore, achieving long-term continuous monitoring of human ECG signals has become a key technological support for the early diagnosis and prevention of cardiovascular diseases.
[0003] However, at present, when monitoring vital signs, traditional sensors are in direct contact with the skin, which can easily lead to too many connecting wires in the electrocardiogram monitoring device and interfere with the user's sleep. While existing capacitively coupled electrocardiogram sensing electrodes can accurately collect electrocardiogram signals through clothing and sheets without disturbing the user's normal sleep activities, the user may turn over and the body may be removed from the electrocardiogram measurement area, making it impossible to accurately measure the vital signs of the user being tested. Therefore, this invention proposes a flexible electrode array method for non-contact vital sign monitoring. Summary of the Invention
[0004] The purpose of this invention is to propose a non-contact flexible electrode array method for monitoring vital signs, so as to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: A non-contact method for monitoring vital signs using a flexible electrode array, the method comprising: Step S1: Set the layout of the flexible electrode array according to the human body size and the measurement range of the flexible electrodes, and construct the vital sign monitoring mattress based on the layout of the flexible electrode array. Step S2: Analyze the transmission process of ECG signals based on the principle of capacitive sensing, determine the qualification of the flexible electrode array, and adjust any unqualified flexible electrode arrays. Step S3: Measure the capacitance data of the flexible electrode array of the user under test during sleep, and identify the user's sleeping posture and changes in sleeping posture based on the capacitance data; Step S4: Based on the sleeping posture of the user to be tested, the flexible electrode array is located and activated for monitoring, and the sleeping posture data of the user to be tested and the measured electrocardiogram data are output.
[0006] Further, step S1 includes the following sub-steps: Step S11: Obtain the shoulder width range of an adult and read the upper limit value of the shoulder width range. Step S12: Set the abduction width and lateral turning allowance for adults during sleep; Step S13: The width of the electrode array is obtained by adding the upper limit of the shoulder width to the natural outward width and adding twice the unilateral turning allowance. Step S14: Obtain the range of torso length for an adult, and read the upper limit value of torso length within the range of torso length. Step S15: Set the sleep posture extension length. The electrode array length is obtained by adding the upper limit of the torso length to the sleep posture extension length.
[0007] Furthermore, step S1 also includes the following sub-steps: Step S16: Read the measurement range of the flexible electrode and identify the single-sided measurement length of the corresponding flexible electrode; obtain the number of flexible electrodes in the horizontal direction by dividing the electrode array width by the single-sided measurement length, and obtain the number of flexible electrodes in the vertical direction by dividing the electrode array length by the single-sided measurement length. The total number of electrodes in the flexible electrode array is obtained by multiplying the number of flexible electrodes in the horizontal direction by the number of flexible electrodes in the vertical direction. Step S17: Construct a flexible electrode array based on the number of flexible electrodes in the horizontal direction and the number of flexible electrodes in the vertical direction; load the flexible electrode array onto the mattress to obtain a vital sign monitoring mattress.
[0008] Further, step S2 includes the following sub-steps: Step S201: The user to be tested lies on the vital signs monitoring mattress, and the vital signs monitoring mattress is used to monitor the user's electrocardiogram signal. Step S202: Measure the actual electrocardiogram (ECG) signal of the user to be tested. Subtract the actual ECG signal from the measured ECG signal and take the absolute value to obtain the ECG signal deviation value. Divide the ECG signal deviation value by the actual ECG signal to obtain the ECG deviation rate of the measured ECG signal. Step S203: Compare the ECG deviation rate with the deviation rate threshold. If the ECG deviation rate is less than the deviation rate threshold, proceed to step S3. If the ECG deviation rate is greater than or equal to the deviation rate threshold, proceed to step S204.
[0009] Furthermore, step S2 also includes the following sub-steps: Step S204: The process of generating an electrocardiogram (ECG) signal from the heart until it reaches the flexible electrode is regarded as the equivalent circuit of capacitive coupling of the corresponding ECG signal. The ECG potential emitted by the heart, the dermal equivalent resistance of the dermal layer where the ECG potential is located, the epidermal equivalent capacitance and epidermal equivalent resistance of the epidermal layer are recorded. Step S205: The total impedance of the human body is calculated based on the electrocardiogram potential, dermal equivalent resistance, epidermal equivalent capacitance and epidermal equivalent resistance in the capacitive coupling equivalent circuit of the human body. Step S206: The electric field distribution corresponding to the weak electrocardiogram signal on the skin surface is equivalent to the surface charge density on the skin side. When the flexible electrode is close to the skin, the electric field lines between the flexible electrode and the skin pass through the coupling layer, forming electrostatic induction, and the equivalent parallel plate capacitor formed by the skin and the flexible electrode is obtained.
[0010] Furthermore, step S2 also includes the following sub-steps: Step S207: Record the value of the electrocardiogram potential when it reaches the skin after being reduced by the total impedance of the human body. The electrocardiogram potential will undergo a second reduction when it reaches the flexible electrode from the skin. The process of the second reduction is regarded as a parallel circuit of an equivalent parallel plate capacitor and a resistor, and thus the total coupling impedance is obtained. Step S208: Connect the flexible electrode array to the amplifier, and record the impedance at the input terminal as the input impedance; Step S209: Obtain the ECG signal output by the amplifier based on the total human body impedance, the total coupling impedance, and the input impedance.
[0011] Furthermore, step S2 also includes the following sub-steps: Step S210, as learned from step S207, if it is necessary to ensure that the output ECG signal is close to the actual generated ECG signal, then only the total coupling impedance can be adjusted. Step S211: Increase the area of the flexible electrode array by adjusting the total coupling impedance; Step S212: Gradually add flexible electrodes to the flexible electrode array to increase the area of the flexible electrode array, measure the ECG signal after the addition again, and calculate the corresponding ECG deviation rate until the ECG deviation rate is less than the deviation rate threshold. Save the corresponding flexible electrode array and execute step S3. Step S213: Record the detected ECG signal as the ECG data of the user to be tested.
[0012] Further, step S3 includes the following sub-steps: Step S301: When no one is on the vital signs monitoring mattress, measure the reference capacitance value of each flexible electrode in the flexible electrode array, mark the reference capacitance value on the graph according to the location of the flexible electrode, construct a reference arrangement graph of the flexible electrodes, construct a plane rectangular coordinate system on the reference arrangement graph, and identify the coordinates of each flexible electrode. Step S302: The user to be tested lies supine on the vital signs monitoring mattress. The real-time capacitance value of each flexible electrode in the flexible electrode array is collected in real time. The time of the first collection of real-time capacitance value is marked as the first moment, the time of the second collection of real-time capacitance value is marked as the second moment, and so on, until the Nth moment is obtained. Step S303: Mark the real-time capacitance value on the graph according to the location of the flexible electrode to construct a real-time arrangement graph of the flexible electrode at the corresponding time.
[0013] Furthermore, step S3 also includes the following sub-steps: Step S304: Perform a difference operation between the real-time arrangement diagram at the first moment and the reference arrangement diagram to obtain the flexible electrode capacitance difference diagram at the first moment. The vertical axis of each flexible electrode in the flexible electrode capacitance difference diagram is the capacitance difference value. Step S305: Count the flexible electrodes whose capacitance difference value is greater than a preset value in the capacitance difference graph of the flexible electrode at the first moment and record them as contact electrodes; count the number of contact electrodes. Step S306: Sum the coordinates of all contact electrodes and take the average to obtain the centroid coordinates. Draw a vertical line upwards and downwards based on the centroid coordinates to divide the contact electrodes into left and right sides, and calculate the symmetry of the left and right sides. Step S307: Matching is performed in a preset template based on the number of contact electrodes, centroid coordinates, and symmetry to identify the initial sleeping posture of the user to be tested; Step S308: Following the process in step S304, construct the flexible electrode capacitance difference map from the second time to the Nth time; record the moment when the real-time capacitance value of k flexible electrodes in the flexible electrode capacitance difference map changes abruptly as the start time of the sleeping posture change, and record the moment when the capacitance difference value of k flexible electrodes in the flexible electrode capacitance difference map becomes zero as the end time of the sleeping posture change.
[0014] Furthermore, step S3 also includes the following sub-steps: Step S309: Perform steps S305-S306 using the differential capacitance map of the flexible electrodes at the end of the sleeping posture change to obtain the centroid coordinates, the number of contact electrodes, and the symmetry at the end of the sleeping posture change. Step S310: Based on the centroid coordinates, the number of contact electrodes, and the symmetry at the end of the sleeping posture change, the sleeping posture of the user at the end of the sleeping posture change is obtained, and the turning direction of the user is obtained based on the movement of the centroid coordinates. Step S311: Record the changes in sleeping posture of the user under test as sleeping posture data and output them.
[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention sets the layout of the flexible electrode array based on human body size and the measurement range of the flexible electrode, and constructs a vital sign monitoring mattress based on the layout of the flexible electrode array; it analyzes the transmission process of electrocardiogram signals based on the principle of capacitive sensing, judges the qualification of the flexible electrode array, adjusts unqualified flexible electrode arrays, and realizes the layout control of the flexible electrode array by using the measurement results of human electrocardiogram signals from the flexible electrode array. 2. This invention measures the capacitance data of a flexible electrode array on a user during sleep, identifies the user's sleeping posture and changes in sleeping posture based on the capacitance data, and finally uses the user's sleeping posture as a basis to specifically locate and activate the flexible electrode array for monitoring. The user's sleeping posture data and the measured electrocardiogram data are output. By treating the human body and the flexible electrode array as equivalent circuits, the user's electrocardiogram data and changes in sleeping posture are measured, thereby achieving non-contact, non-interference and accurate monitoring of the user's vital signs. Attached Figure Description
[0016] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.
[0017] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram illustrating the principle of capacitive sensing. Figure 3 This is a reference arrangement diagram of the flexible electrode array; Figure 4 This is a schematic diagram of the capacitance differential of the flexible electrode. Figure 5 This is a schematic diagram of the electronic device in this invention. Detailed Implementation
[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] A flexible electrode is an electronic device made of flexible, bendable, and stretchable materials, used for electrical interaction with biological tissues. A flexible electrode array is a system that integrates multiple flexible electrode contacts and corresponding wires on a flexible substrate, which can simultaneously record signals collected from multiple points, thereby recording the spatial distribution of neural electrical activity or electrocardiographic conduction. In this invention, the flexible electrode array is mounted on a vital sign monitoring mattress, which monitors the vital signs of the user under test during sleep.
[0020] Example 1: Please refer to Figures 1-4 As shown, the technical solution provided by the present invention is: a non-contact flexible electrode array method for monitoring vital signs, which sets the layout of the flexible electrode array based on human body size and the measurement range of the flexible electrode, analyzes and optimizes the set flexible electrode array, and uses the optimized flexible electrode array to measure the electrocardiogram data and sleeping posture data of the user under test using the principle of capacitance sensing. In this invention, the method of the flexible electrode array for non-contact vital sign monitoring is as follows: Step S1: Set the layout of the flexible electrode array according to the human body size and the measurement range of the flexible electrodes, and construct the vital sign monitoring mattress based on the layout of the flexible electrode array. In this invention, step S1 includes the following sub-steps: Step S11: Obtain the shoulder width range of an adult and read the upper limit of the shoulder width range; where the average shoulder width range of an adult is generally between 40cm and 50cm, so the upper limit of the shoulder width is taken as 50cm. Step S12: Set the abduction width and lateral turning allowance for adults during sleep; It should be noted that the abduction width is the extra width occupied by the natural abduction of the shoulders during sleep, and the unilateral turning allowance is the allowance for turning to one side during sleep; both the abduction width and the unilateral turning allowance are in centimeters. Step S13: The electrode array width is obtained by adding the upper limit of shoulder width, the natural abduction width, and twice the unilateral rollover allowance; in fact, the electrode array width can be 82.5cm. Step S14: Obtain the range of trunk length for an adult and read the upper limit of trunk length within the range; trunk length refers to the length from the neck (7th cervical vertebra) to the buttocks (iliac crest), which is generally 50cm-70cm. Step S15: Set the sleep posture extension length. The electrode array length is obtained by adding the upper limit of the torso length to the sleep posture extension length. It should be noted that the sleep posture extension length is the length of the torso that shifts upward or downward when a human is sleeping due to curling up or stretching. It is generally 10cm-20cm. Therefore, the electrode array length is preferably 90cm. Step S16: Read the measurement range of the flexible electrode and identify the single-sided measurement length of the corresponding flexible electrode; obtain the number of flexible electrodes in the horizontal direction by dividing the electrode array width by the single-sided measurement length, and obtain the number of flexible electrodes in the vertical direction by dividing the electrode array length by the single-sided measurement length. The total number of electrodes in the flexible electrode array is obtained by multiplying the number of flexible electrodes in the horizontal direction by the number of flexible electrodes in the vertical direction. It should be noted that in this invention, the measurement range of the flexible electrode is considered as a square, where the side length in the positive direction is the measurement length of a single side. Step S17: Construct a flexible electrode array based on the number of flexible electrodes in the horizontal direction and the number of flexible electrodes in the vertical direction; load the flexible electrode array into the mattress to obtain the vital sign monitoring mattress.
[0021] Step S2: Analyze the transmission process of ECG signals based on the principle of capacitive sensing, determine the qualification of the flexible electrode array, and adjust any unqualified flexible electrode arrays. In this invention, step S2 includes the following sub-steps: Step S201: The user to be tested lies on the vital signs monitoring mattress, and the vital signs monitoring mattress is used to monitor the user's electrocardiogram (ECG) signal. It should be noted that the ECG signal of the user to be tested is transmitted from the dermis layer where the heart is located through the epidermis and coupling layer to the corresponding flexible electrode of the vital signs monitoring mattress. The epidermis layer is the keratinous tissue of the human body, and the coupling layer is the clothing medium between the human body and the vital signs monitoring mattress. Step S202: The actual electrocardiogram (ECG) signal of the user to be tested is measured using a medical ECG machine. The ECG signal deviation value is obtained by subtracting the actual ECG signal from the measured ECG signal and taking the absolute value. The ECG signal deviation value is then divided by the actual ECG signal to obtain the ECG deviation rate of the measured ECG signal. Both the measured ECG signal and the actual ECG signal are electromotive forces (i.e., voltages). In the specific calculation, the measured ECG signal and the actual ECG signal at the same time are used for calculation. Step S203: Compare the ECG deviation rate with the deviation rate threshold. If the ECG deviation rate is less than the deviation rate threshold, proceed to step S3. If the ECG deviation rate is greater than or equal to the deviation rate threshold, proceed to step S204. For step S204, please refer to... Figure 2 As shown, the process of the electrocardiogram (ECG) signal being generated from the heart until it reaches the flexible electrode is regarded as the equivalent circuit of the corresponding ECG signal with capacitive coupling. The ECG potential emitted by the heart is denoted as Vheart. The dermis where the ECG potential is located is regarded as the dermal equivalent resistance Rd. The epidermis is regarded as the parallel circuit of the epidermal equivalent capacitance Ce and the epidermal equivalent resistance Re. The total impedance of the human body is denoted as Zb. Step S205: Based on the data in the human body equivalent circuit, derive the formula for the total impedance of the human body. The specific derivation formula is as follows: In the formula, || represents parallel operation, 1 / sCe is the impedance expression of capacitor Ce, where s is the complex frequency, which is a variable on the complex plane; For step S206, please refer to... Figure 3As shown, since there is a weak electrocardiogram (ECG) signal on the skin surface, the electric field distribution corresponding to the ECG signal is equivalent to the surface charge density on the skin side. When the flexible electrode approaches the skin, the electric field lines between the flexible electrode and the skin pass through the coupling layer, forming an electrostatic induction. Therefore, an equivalent parallel-plate capacitor formed by the skin and the flexible electrode is obtained; the capacitance Cp of the equivalent parallel-plate capacitor is expressed as: Cp = ε0 × εr × M ÷ d; where ε0 is the vacuum dielectric constant, εr is the dielectric constant of the coupling layer, M is the area of the flexible electrode array, and d is the distance between human skin and the flexible electrode array. It needs to be explained that a parallel plate capacitor consists of two parallel plates separated by a dielectric material. When there is a certain potential difference between the two plates, an electrostatic field will be distributed between the plates. In contrast, one of the plates of an equivalent parallel plate capacitor is a flexible electrode, and the other plate is skin. Step S207: The value of the ECG potential reaching the skin after being reduced by the total impedance of the human body is denoted as VECG. Due to the capacitive reactance of the coupling layer, the ECG potential will undergo a second reduction from the skin to the flexible electrode. The process of the second reduction is regarded as a parallel circuit of an equivalent parallel plate capacitor and a resistor Rc. The total coupling impedance is denoted as Zc, and the derivation formula of the total coupling impedance Zc is obtained as follows: 1 / sCp is the impedance expression for capacitor Cp; Step S208: Connect the flexible electrode array to the amplifier. Denote the input impedance as input impedance Zin. The input terminal can also be considered as a parallel circuit of resistor Rin and capacitor Cin. Therefore, based on step S25, the derivation formula for the input impedance is as follows: 1 / sCin is the impedance expression for capacitor Cin; Step S209: The ECG signal output by the amplifier is denoted as Vout. According to Kirchhoff's voltage law, in any closed loop, the algebraic sum of the voltage drops across each component is equal to the algebraic sum of the electromotive forces. That is, when starting from a point, looping around the point, and returning to that point, the algebraic sum of the voltages across each segment is always equal to zero. Therefore, we can obtain: Vout=Vheart×Zin / (Zb+Zc+Zin); An amplifier is an electronic device specifically designed to amplify the weak bioelectrical signals generated by cardiac electrical activity. Since electrocardiogram (ECG) signals are extremely weak and easily interfered with, an amplifier is needed to process these weak ECG signals into stable electrical signals. Specifically, the amplifier is externally connected to a flexible electrode array to amplify the ECG signals measured by the flexible electrodes. Step S210: As can be seen from the formula in step S207, if the output ECG signal is similar to the actual generated ECG signal, then it is necessary to increase the input impedance Zin, decrease the total coupling impedance Zc, and decrease the total human body impedance Zb. Since each person's body has certain differences, its impedance is also different. Zb is determined by the characteristics of the human body itself, so Zb cannot be effectively controlled. The input impedance Zin is an inherent property of the amplifier, so it is also inconvenient to make adjustments. In step S211, since Rc is an inherent property of the coupling layer and is considered a constant, it can be seen from the derivation formula of the total coupling impedance that if the value of the total coupling impedance Zc is to be reduced, the value of the capacitance Cp of the equivalent parallel plate capacitor should be increased. From the expression of Cp, it can be seen that ε0 and εr are constants, and the distance d between the human skin and the flexible electrode array cannot be further reduced, so the only way to achieve this is to increase the area of the flexible electrode array. Step S212: Gradually add flexible electrodes to the flexible electrode array to increase the area of the flexible electrode array, measure the ECG signal after the addition again, and calculate the corresponding ECG deviation rate until the ECG deviation rate is less than the deviation rate threshold. Save the corresponding flexible electrode array and execute step S3. Step S213: Record the detected ECG signal as the ECG data of the user to be tested.
[0022] Step S3: Measure the capacitance data of the flexible electrode array of the user under test during sleep, and identify the user's sleeping posture and changes in sleeping posture based on the capacitance data; In this invention, step S3 includes the following sub-steps: It should be noted that, in order to facilitate the explanation of the sleep posture monitoring process, this step takes the process of the user rolling from supine to right lateral position as an example for analysis; Step S301: When the vital signs monitoring mattress is unoccupied, measure the reference capacitance value of each flexible electrode in the flexible electrode array, such as... Figure 4 As shown, the reference capacitance value is marked on the graph according to the location of the flexible electrode to construct a reference arrangement diagram of the flexible electrode. A Cartesian coordinate system is constructed on the reference arrangement diagram to identify the coordinates of each flexible electrode. Step S302: The user to be tested lies supine on the vital signs monitoring mattress, and the real-time capacitance value of each flexible electrode in the flexible electrode array is collected in real time. The time of the first collection of real-time capacitance value is marked as the first moment, the time of the second collection of real-time capacitance value is marked as the second moment, and so on, until the Nth moment is obtained; where N is a positive integer, preferably N is 10. Step S303: Mark the real-time capacitance value on the graph according to the location of the flexible electrode to construct a real-time arrangement graph of the flexible electrode at the corresponding time. For step S304, please refer to... Figure 5 As shown, the real-time arrangement diagram at the first moment is compared with the reference arrangement diagram to obtain the flexible electrode capacitance difference diagram at the first moment. The vertical axis of each flexible electrode in the flexible electrode capacitance difference diagram is the capacitance difference value. Specifically, the difference operation is as follows: the difference obtained by subtracting the reference capacitance value at the same coordinate in the reference arrangement diagram from the real-time capacitance value in the real-time arrangement diagram at the first moment is used as the capacitance difference value of the flexible electrode at the corresponding coordinate in the flexible electrode capacitance difference diagram. Step S305: Count the flexible electrodes whose capacitance difference value is greater than a preset value in the capacitance difference graph of the flexible electrode at the first moment and record them as contact electrodes; count the number of contact electrodes. Step S306: Sum the coordinates of all contact electrodes and take the average to obtain the centroid coordinates. Draw a vertical line upwards and downwards based on the execution coordinates to divide the contact electrodes into left and right sides, and calculate the symmetry of the left and right sides. Specifically, to calculate the symmetry, the flexible electrodes on the left and right sides can be connected in sequence to obtain the left and right figures respectively, and the Euclidean distance between the left and right figures can be calculated as the similarity. Step S307: Match the user's initial sleeping posture in a preset template based on the number of contact electrodes, centroid coordinates, and symmetry. For example, with an 8×8 flexible electrode array, the supine template is: the number of contact electrodes is ≥30 and the abscissa of the centroid coordinate is between 3 and 5 and the symmetry is ≥0.8. Step S308: Following the process in step S304, construct the flexible electrode capacitance difference map from the second time to the Nth time; record the moment when the real-time capacitance values of k flexible electrodes in the flexible electrode capacitance difference map suddenly change as the start time of the sleeping posture change, and record the moment when the capacitance difference value of the corresponding k flexible electrodes in the flexible electrode capacitance difference map becomes zero as the end time of the sleeping posture change; where k is a constant; a sudden change in real-time capacitance value means that the absolute value of the capacitance difference value is greater than a preset capacitance threshold; It should be noted that if the subject turns over during sleep, the real-time capacitance value of the flexible electrode on the side away from the vital signs monitoring mattress will decrease (the distance d between the skin and the flexible electrode is the biggest influencing factor when calculating the real-time capacitance value), and the real-time capacitance value of the flexible electrode on the side closer to the vital signs monitoring mattress will increase. (Therefore, the capacitance difference value is calculated by subtracting the real-time capacitance value of the previous moment from the real-time capacitance value of the flexible electrode at the same position in the flexible electrode array at the next moment, and then the starting and ending moments of the subject's sleeping posture change can be determined based on the capacitance difference value.) Step S309: Perform steps S305-S306 using the differential capacitance map of the flexible electrodes at the end of the sleeping posture change to obtain the centroid coordinates, the number of contact electrodes, and the symmetry at the end of the sleeping posture change. Step S310: Based on the centroid coordinates, the number of contact electrodes, and the symmetry at the end of the sleeping posture change, the sleeping posture of the user at the end of the sleeping posture change is obtained, and the turning direction of the user is obtained based on the movement of the centroid coordinates. Step S311: Record the changes in sleeping posture of the user under test as sleeping posture data and output them.
[0023] Step S4: Based on the sleeping posture of the user to be tested, the flexible electrode array is located and activated for monitoring, and the sleeping posture data of the user to be tested and the measured electrocardiogram data are output.
[0024] Example 2: This embodiment of the invention also provides an electronic device for operating the aforementioned non-contact vital sign monitoring flexible electrode array method; see [link to previous example]. Figure 5 The schematic diagram of an electronic device provided by an embodiment of the present invention is shown. The electronic device includes a memory and a processor. The memory is used to store one or more computer instructions, which are executed by the processor to realize the above-mentioned non-contact vital sign monitoring flexible electrode array method. Furthermore, Figure 5 The electronic device shown also includes a communication bus and a communication interface, with the processor, communication interface and memory connected via the communication bus; The memory may include high-speed random access memory (RAM) and may also include non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface (which can be wired or wireless), such as the Internet, wide area network, local area network, metropolitan area network, etc. The communication bus can be an ISA bus, PCI bus, or EISA bus, etc. The communication bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 5 The symbol is represented by only one double-headed arrow, but this does not mean that there is only one communication bus or one type of communication bus. The processor may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above methods can be completed by integrated logic circuits in the processor's hardware or by software instructions. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the method described in the foregoing embodiments.
[0025] Example 3: This embodiment of the invention also provides a computer storage medium storing computer-executable instructions. When these computer-executable instructions are called and executed by a processor, they cause the processor to implement the above-described non-contact vital sign monitoring flexible electrode array method. For specific implementation details, please refer to the method embodiment, which will not be repeated here. The computer program product of the non-contact vital sign monitoring flexible electrode array method provided in the embodiments of the present invention includes a computer storage medium storing program code. The instructions included in the program code can be used to execute the methods in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.
[0026] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system or device described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.
[0027] Furthermore, in the description of the embodiments of the present invention, 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 the present invention based on the specific circumstances.
[0028] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A flexible electrode array method for non-contact vital sign monitoring, characterized in that, The methods include: Step S1: Set the layout of the flexible electrode array according to the human body size and the measurement range of the flexible electrodes, and construct the vital sign monitoring mattress based on the layout of the flexible electrode array. Step S2: Analyze the transmission process of ECG signals based on the principle of capacitive sensing, determine the qualification of the flexible electrode array, and adjust any unqualified flexible electrode arrays. Step S3: Measure the capacitance data of the flexible electrode array of the user under test during sleep, and identify the user's sleeping posture and changes in sleeping posture based on the capacitance data; Step S4: Based on the sleeping posture of the user to be tested, the flexible electrode array is located and activated for monitoring, and the sleeping posture data of the user to be tested and the measured electrocardiogram data are output.
2. The flexible electrode array method for non-contact vital sign monitoring according to claim 1, characterized in that, Step S1 includes the following sub-steps: Step S11: Obtain the shoulder width range of an adult and read the upper limit value of the shoulder width range. Step S12: Set the abduction width and lateral turning allowance for adults during sleep; Step S13: The width of the electrode array is obtained by adding the upper limit of the shoulder width to the natural outward width and adding twice the unilateral turning allowance. Step S14: Obtain the range of torso length for an adult, and read the upper limit value of torso length within the range of torso length. Step S15: Set the sleep posture extension length. The electrode array length is obtained by adding the upper limit of the torso length to the sleep posture extension length.
3. The flexible electrode array method for non-contact vital sign monitoring according to claim 2, characterized in that, Step S1 further includes the following sub-steps: Step S16: Read the measurement range of the flexible electrode and identify the single-sided measurement length of the corresponding flexible electrode; obtain the number of flexible electrodes in the horizontal direction by dividing the electrode array width by the single-sided measurement length, and obtain the number of flexible electrodes in the vertical direction by dividing the electrode array length by the single-sided measurement length. The total number of electrodes in the flexible electrode array is obtained by multiplying the number of flexible electrodes in the horizontal direction by the number of flexible electrodes in the vertical direction. Step S17: Construct a flexible electrode array based on the number of flexible electrodes in the horizontal direction and the number of flexible electrodes in the vertical direction. A flexible electrode array is mounted on a mattress to create a vital signs monitoring mattress.
4. The flexible electrode array method for non-contact vital sign monitoring according to claim 1, characterized in that, Step S2 includes the following sub-steps: Step S201: The user to be tested lies on the vital signs monitoring mattress, and the vital signs monitoring mattress is used to monitor the user's electrocardiogram signal. Step S202: Measure the actual electrocardiogram (ECG) signal of the user to be tested. Subtract the actual ECG signal from the measured ECG signal and take the absolute value to obtain the ECG signal deviation value. Divide the ECG signal deviation value by the actual ECG signal to obtain the ECG deviation rate of the measured ECG signal. Step S203: Compare the ECG deviation rate with the deviation rate threshold. If the ECG deviation rate is less than the deviation rate threshold, proceed to step S3. If the ECG deviation rate is greater than or equal to the deviation rate threshold, proceed to step S204.
5. The flexible electrode array method for non-contact vital sign monitoring according to claim 4, characterized in that, Step S2 further includes the following sub-steps: Step S204: The process of generating an electrocardiogram (ECG) signal from the heart until it reaches the flexible electrode is regarded as the equivalent circuit of capacitive coupling of the corresponding ECG signal. The ECG potential emitted by the heart, the dermal equivalent resistance of the dermal layer where the ECG potential is located, the epidermal equivalent capacitance and epidermal equivalent resistance of the epidermal layer are recorded. Step S205: The total impedance of the human body is calculated based on the electrocardiogram potential, dermal equivalent resistance, epidermal equivalent capacitance and epidermal equivalent resistance in the capacitive coupling equivalent circuit of the human body. Step S206: The electric field distribution corresponding to the weak electrocardiogram signal on the skin surface is equivalent to the surface charge density on the skin side. When the flexible electrode is close to the skin, the electric field lines between the flexible electrode and the skin pass through the coupling layer, forming electrostatic induction, and the equivalent parallel plate capacitor formed by the skin and the flexible electrode is obtained.
6. The flexible electrode array method for non-contact vital sign monitoring according to claim 5, characterized in that, Step S2 further includes the following sub-steps: Step S207: Record the value of the electrocardiogram potential when it reaches the skin after being reduced by the total impedance of the human body. The electrocardiogram potential will undergo a second reduction when it reaches the flexible electrode from the skin. The process of the second reduction is regarded as a parallel circuit of an equivalent parallel plate capacitor and a resistor, and thus the total coupling impedance is obtained. Step S208: Connect the flexible electrode array to the amplifier, and record the impedance at the input terminal as the input impedance; Step S209: Obtain the ECG signal output by the amplifier based on the total human body impedance, the total coupling impedance, and the input impedance.
7. The flexible electrode array method for non-contact vital sign monitoring according to claim 6, characterized in that, Step S2 further includes the following sub-steps: Step S210, as learned from step S207, if it is necessary to ensure that the output ECG signal is close to the actual generated ECG signal, then only the total coupling impedance can be adjusted. Step S211: Increase the area of the flexible electrode array by adjusting the total coupling impedance; Step S212: Gradually add flexible electrodes to the flexible electrode array to increase the area of the flexible electrode array, measure the ECG signal after the addition again, and calculate the corresponding ECG deviation rate until the ECG deviation rate is less than the deviation rate threshold. Save the corresponding flexible electrode array and execute step S3. Step S213: Record the detected ECG signal as the ECG data of the user to be tested.
8. The flexible electrode array method for non-contact vital sign monitoring according to claim 1, characterized in that, Step S3 includes the following sub-steps: Step S301: When no one is on the vital signs monitoring mattress, measure the reference capacitance value of each flexible electrode in the flexible electrode array, mark the reference capacitance value on the graph according to the location of the flexible electrode, construct a reference arrangement graph of the flexible electrodes, construct a plane rectangular coordinate system on the reference arrangement graph, and identify the coordinates of each flexible electrode. Step S302: The user to be tested lies supine on the vital signs monitoring mattress. The real-time capacitance value of each flexible electrode in the flexible electrode array is collected in real time. The time of the first collection of real-time capacitance value is marked as the first moment, the time of the second collection of real-time capacitance value is marked as the second moment, and so on, until the Nth moment is obtained. Step S303: Mark the real-time capacitance value on the graph according to the location of the flexible electrode to construct a real-time arrangement graph of the flexible electrode at the corresponding time.
9. The flexible electrode array method for non-contact vital sign monitoring according to claim 7, characterized in that, Step S3 further includes the following sub-steps: Step S304: Perform a difference operation between the real-time arrangement diagram at the first moment and the reference arrangement diagram to obtain the flexible electrode capacitance difference diagram at the first moment. The vertical axis of each flexible electrode in the flexible electrode capacitance difference diagram is the capacitance difference value. Step S305: Count the flexible electrodes whose capacitance difference value is greater than a preset value in the capacitance difference graph of the flexible electrode at the first moment and record them as contact electrodes; count the number of contact electrodes. Step S306: Sum the coordinates of all contact electrodes and take the average to obtain the centroid coordinates. Draw a vertical line upwards and downwards based on the centroid coordinates to divide the contact electrodes into left and right sides, and calculate the symmetry of the left and right sides. Step S307: Matching is performed in a preset template based on the number of contact electrodes, centroid coordinates, and symmetry to identify the initial sleeping posture of the user to be tested; Step S308: Following the process of step S304, construct the flexible electrode capacitance differential map from the second time point to the Nth time point. The moment when the real-time capacitance value of k flexible electrodes in the flexible electrode capacitance difference graph suddenly changes is recorded as the start time of the sleeping posture change, and the moment when the capacitance difference value of k flexible electrodes in the flexible electrode capacitance difference graph becomes zero is recorded as the end time of the sleeping posture change.
10. The flexible electrode array method for non-contact vital sign monitoring according to claim 9, characterized in that, Step S3 further includes the following sub-steps: Step S309: Perform steps S305-S306 using the differential capacitance map of the flexible electrodes at the end of the sleeping posture change to obtain the centroid coordinates, the number of contact electrodes, and the symmetry at the end of the sleeping posture change. Step S310: Based on the centroid coordinates, the number of contact electrodes, and the symmetry at the end of the sleeping posture change, the sleeping posture of the user at the end of the sleeping posture change is obtained, and the turning direction of the user is obtained based on the movement of the centroid coordinates. Step S311: Record the changes in sleeping posture of the user under test as sleeping posture data and output them.