Temperature-pressure integrated fiber Bragg grating sensor and human sleep multi-sign monitoring system

Abstract

The present invention discloses a temperature-pressure integrated fiber grating sensor and a human sleep multi-vital sign monitoring system. The system comprises a mattress, a plurality of temperature-pressure integrated fiber grating sensors, a demodulator, and a host computer. The plurality of vital sign fiber grating sensors are fixedly arranged in a gap between a mattress and a bed net, and their depths are kept at the same horizontal plane. The plurality of vital sign fiber grating sensors are connected to the demodulator to transmit data to the host computer. The present invention identifies the pressure exerted on the sensor by detecting the wavelength of a fiber grating spectrum signal peak splitting point, identifies the ambient temperature of the sensor by detecting the center wavelength drift of the fiber grating spectrum signal, monitors the multi-vital sign information of the user in bed, including the respiratory rate, heart rate, and the state of falling out of bed, etc. The system has the advantages of simple structure, small size, anti-electromagnetic interference, low cost, etc.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, and in particular to a temperature-pressure integrated fiber grating sensor and a human sleep multi-vital sign monitoring system. Background Art

[0002] Respiration, heart rate, body temperature and other parameters are the main parameters for health assessment of the elderly. They are usually completed by large-scale instruments for manual and regular monitoring. It is impossible to achieve real-time dynamic monitoring at all times and it requires a lot of human resources. Especially at night when there is no one to accompany the elderly, the health status of the elderly is extremely difficult to monitor, and medical resources are tight. If a major sudden illness occurs, it is very easy to miss the best golden time for treatment.

[0003] Existing instruments often measure multiple vital signs through one-to-one sensor measurement. This method requires a large number of sensors, high integration density and difficulty, complex circuits, and a large monitoring system, which causes great inconvenience to the elderly. In response to the above problems, a solution is proposed below. Summary of the invention

[0004] The purpose of the present invention is to provide a temperature-pressure integrated fiber grating sensor and a human sleep multi-vital sign monitoring system, which has the advantages of real-time monitoring of human multi-vital sign signals and simplifying the circuit complexity of the application environment.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A temperature-pressure integrated fiber grating sensor and a human sleep multi-vital sign monitoring system, including a mattress, a vital sign fiber grating sensing device, a demodulator and a host computer, wherein the mattress includes a bed net, a fabric and a filling material, wherein the filling material is located between the bed net and the fabric material, and the vital sign fiber grating sensing device includes a plurality of distributed temperature-pressure integrated fiber grating sensors, wherein the plurality of distributed temperature-pressure integrated fiber grating sensors are buried in the filling material, and the burial depths of the plurality of distributed temperature-pressure integrated fiber grating sensors are maintained at the same horizontal plane, wherein the plurality of distributed temperature-pressure integrated fiber grating sensors are all connected to a demodulator, wherein the demodulator is connected to the host computer via a network, and wherein the demodulator receives and analyzes signals transmitted by the plurality of distributed temperature-pressure integrated fiber grating sensors, and transmits the processed signals to the host computer, so as to monitor the health status of the user during sleep.

[0007] Preferably, a plurality of the distributed temperature-pressure integrated fiber Bragg grating sensors are evenly distributed in the mattress, and the distributed temperature-pressure integrated fiber Bragg grating sensors are used to measure the distribution of temperature field and pressure field, monitor human body temperature, respiratory vital signs parameters, and analyze the situation of falling out of bed.

[0008] Preferably, the distributed temperature-pressure integrated fiber Bragg grating sensor comprises an optical fiber, an I-shaped flexible beam housing, a substrate and an adhesive, the optical fiber is fixed on the substrate, the two ends of the light are fixedly connected to the substrate by the adhesive, the I-shaped flexible beam housing is fixedly connected to the substrate, and the connection between the I-shaped flexible beam housing and the substrate is sealed by the adhesive, a fiber Bragg grating is provided on the optical fiber, the fiber Bragg grating is located in the middle of the contact part between the substrate and the optical fiber, and the part of the optical fiber on the substrate is in a fully stretched state.

[0009] Preferably, the monitoring method includes a temperature monitoring method and a pressure monitoring method. The temperature monitoring method is as follows: when the measured ambient temperature changes, the central wavelength of the fiber Bragg grating drifts, and the temperature change is obtained through the drift value, thereby achieving temperature monitoring.

[0010] Preferably, the pressure monitoring method is as follows: when the upper part of the I-shaped flexible beam structure is subjected to force and produces a downward displacement, the lower part of the I-shaped flexible beam structure acts on the optical fiber, causing the fiber grating to be locally stressed, thereby causing the reflection spectrum peak to split, and the pressure change is measured by the wavelength value of the splitting point.

[0011] Preferably, the calculation of the temperature sensitivity of the distributed temperature-pressure integrated fiber Bragg grating sensor comprises the following steps:

[0012] Step 1: Relationship between the change in period and temperature of a fiber Bragg grating under thermal expansion effect:

[0013] ΔΛ=α·Λ·ΔT (1.15)

[0014] Where ΔΛ is the change in grating period and α is the thermal expansion coefficient.

[0015] Step 2: Relationship between the change in effective refractive index of optical fiber and the change in temperature under the thermo-optical effect:

[0016] Δn eff =ξ·n eff ΔT (1.16)

[0017] In the formula, Δn eff is the effective refractive index of the fiber core, and ζ is the thermo-optical coefficient of the fiber material.

[0018] Step 3: Solve for the temperature sensitivity coefficient K t :

[0019] The sensing characteristics of fiber Bragg grating are:

[0020]

[0021] Substituting equations (1.15) and (1.16) into (1.17), we obtain

[0022]

[0023] In the formula, λ B is the center wavelength of the fiber Bragg grating in the initial state, Δλ B is the optical fiber center wavelength drift, α is the optical fiber thermal expansion coefficient, ζ is the optical fiber thermo-optic coefficient, K t is the fiber Bragg grating sensitivity coefficient to temperature, and ΔT is the temperature change.

[0024] Preferably, the calculation of the pressure sensitivity of the distributed temperature-pressure integrated fiber Bragg grating sensor comprises the following steps:

[0025] Step 1: Solve the displacement Δ1 caused by the bending deformation of the I-beam:

[0026]

[0027]

[0028] Combining formulas (1.1) and (1.2), we get the following expression for Moore's law:

[0029]

[0030] Where M(x) is the internal force caused by the original load, is the internal force caused by unit force, E is the Young's modulus of the material, I is the moment of inertia of the rod, and x is the distance between any section on the rod and the end receiving the force;

[0031] The I-beam structure is symmetrical on the left and right. Since the stress and deformation of the left and right beams are the same, the left beam is taken for specific stress analysis:

[0032] (4) Calculate the bending moment equation under the original load

[0033] The flexible hinge part of the I-beam is initially in a horizontal state, and the moving end H is subjected to a downward load F. At this time, the AB, CD, QM, PN, and IG sections of the rod will all receive downward forces and upward bending moments. From the symmetry of the I-beam structure, it is known that the AB section is subjected to the same forces as the CD section, and the QM section is subjected to the same forces as the PN section. The bending moments at any cross section on the rod are:

[0034]

[0035] Among them, a is the distance from the force point to the AC segment, x1, x2, and x3 are the horizontal distances between any cross section on the rod AB, IG, and PN segments and the AC segment, respectively.

[0036] (5) Calculate the bending moment equation under unit load

[0037] Replace the load F with a unit downward load. The bending moment of any section of the rod AB, IG, and PN segments is:

[0038]

[0039] (6) Solve the displacement Δ1 caused by the bending deformation of the I-beam based on the unit load method;

[0040]

[0041]

[0042] Among them, l1, l2, l3 are the deformation lengths of segments AB, IG, and PN, respectively, b is the rod width, and d is the rod thickness.

[0043] Step 2: Solve the displacement Δ2 caused by torsional deformation;

[0044] The torsion angle σ generated by the rod BD is calculated based on material mechanics:

[0045]

[0046]

[0047]

[0048] Where, m is the length of the BD segment, G is the shear modulus, ν is the Poisson's ratio, and I P is the polar moment of inertia of the rod;

[0049] Therefore, the deformation Δ2 caused by torsion is:

[0050]

[0051] Where b is the rod width, c is the distance between rods AC and BD;

[0052] Step 3: Calculate the total displacement Δ of the moving end H under the action of load F;

[0053] Based on formula (1.6) and formula (1.11), the total displacement Δ of the moving end H under the action of load F is:

[0054]

[0055] Step 4: Calculate the pressure sensitivity s of the I-beam;

[0056] The pressure sensitivity calculation of the temperature-pressure integrated fiber Bragg grating sensor requires converting the load F' into pressure P:

[0057]

[0058] Where F' is the load acting on the force-bearing part of the sensor, and S is the area of ​​the force-bearing part of the sensor;

[0059] When the load F' acts vertically on the force-bearing part of the sensor, the load F' on a set of I-beams is 2F, so the pressure sensitivity s of the sensor is:

[0060]

[0061] The beneficial effects of the present invention are:

[0062] 1. Based on the symmetrical I-shaped flat plate folding structure, a load-bearing spring with compact structure and easy processing is designed, which solves the problems of ordinary springs on the market that they occupy a large space, have circumferential motion and friction loss.

[0063] 2. Sensors designed based on fiber grating (FBG) can realize the coordinated decoupling detection of multiple vital signs of the human body (such as body temperature, respiration, etc.). In addition, they also have the advantages of small size, anti-electromagnetic interference, and distributed sensing.

[0064] 3. The designed fiber Bragg grating (FBG) sensor integrates temperature and pressure measurement, which can optimize the configuration method of sensor measurement points, simplify sensor wiring rules, and save mattress space; the single-fiber multi-parameter measurement method can automatically compensate for temperature errors;

[0065] 4. The designed temperature-pressure integrated fiber Bragg grating sensor has a simple structure, and all components can be directly formed through 3D printing technology, which greatly reduces the assembly difficulty and production cost and is easy to realize mass production.

[0066] 5. The designed temperature-pressure integrated fiber Bragg grating sensor can identify the pressure of the sensor by demodulating the wavelength change of the peak splitting point of the spectral signal. The demodulation circuit is simple and the cost is low.

[0067] 6. By adjusting the size parameters of the I-shaped flat plate folding structure, the beam stiffness can be changed, thereby adjusting the sensitivity of the distributed temperature-pressure fiber Bragg grating sensor;

[0068] 7. The designed human sleep multi-sign sleep monitoring system can realize non-invasive all-weather sleep monitoring, better ensuring monitoring reliability and user comfort.

[0069] 8. The designed human sleep multi-sign sleep monitoring system is simple to manufacture, low in cost, and easy to use. It is especially suitable for one-to-one or one-to-two monitoring in a small family environment. It has high accuracy, is easy to realize productization, and has a broad market. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 is a schematic diagram of a monitoring system according to an embodiment of the present invention;

[0071] FIG2 is a schematic diagram of a distributed temperature-pressure integrated fiber Bragg grating sensor according to an embodiment of the present invention, including FIG2(a), FIG2(b), and FIG2(c);

[0072] FIG3 is a working principle diagram of a distributed temperature-pressure integrated fiber Bragg grating sensor according to an embodiment of the present invention, wherein FIG3(a) is a working principle diagram of a local force of the sensor, and FIG3(b) is a principle diagram of equivalent stiffness of a force-bearing component of the sensor;

[0073] Figure 4 This is a working principle diagram of a distributed temperature-pressure integrated fiber Bragg grating sensor for monitoring respiratory rate according to an embodiment of the present invention;

[0074] Figure 5 This is a working principle diagram of a distributed temperature-pressure integrated fiber Bragg grating sensor for monitoring human body temperature according to an embodiment of the present invention;

[0075] Figure 6 This is a flow chart of the packaging of a distributed temperature-pressure integrated fiber Bragg grating sensor according to an embodiment of the present invention;

[0076] Figure 7 This is a structural diagram of an I-beam of a distributed temperature-pressure integrated fiber Bragg grating sensor according to an embodiment of the present invention;

[0077] Figure 8 This is a force analysis diagram of a flexible hinge segment of an I-beam according to an embodiment of the present invention;

[0078] Fig. 9 is a schematic diagram of the distribution of measuring points of a multi-sign fiber Bragg grating sensor according to an embodiment of the present invention;

[0079] Fig.10 Schematic diagram of a single mattress monitoring system according to an embodiment of the present invention.

[0080] Reference numerals:

[0081] 101. Single-mode quartz optical fiber; 102. Fiber Bragg grating (FBG); 103. Sensor packaging structure; 104. Substrate; 105. Adhesive; 1.3.1. I-shaped flexible hinge structure; 1.3.2. Force-bearing platform; 1.3.2. Fixed end. DETAILED DESCRIPTION

[0082] The following is only a preferred embodiment of the present invention, and the protection scope is not limited to this embodiment. All technical solutions under the concept of the present invention should belong to the protection scope of the present invention. The same parts are represented by the same figure marks. It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings, and the words "bottom" and "top", "inside" and "outside" refer to the directions toward or away from the geometric center of a specific component, respectively.

[0083] like Figure 1 As shown, the temperature-pressure integrated fiber Bragg grating sensor and human sleep multi-vital sign monitoring system provided by the present invention include a mattress, a plurality of vital sign fiber Bragg grating sensors, a demodulator, and a host computer;

[0084] Several vital sign fiber Bragg grating sensors include several distributed temperature-pressure fiber Bragg grating sensors;

[0085] Several vital sign fiber grating sensors are fixedly set in the gap between the mattress and the bed net, and the depth is kept at the same level;

[0086] Several vital sign fiber Bragg grating sensors are connected to a demodulator, and the demodulator output signal is transmitted to a host computer through a network to monitor the user's health status during sleep.

[0087] As shown in FIG2 , it is a schematic diagram of a distributed temperature-pressure fiber Bragg grating sensor according to an embodiment of the present invention. The distributed temperature-pressure fiber Bragg grating sensor provided in this embodiment can realize the measurement of temperature and pressure at the same time. When a human body lies on the mattress integrated with the sensor provided in this embodiment, the surface of the human body is in close contact with the upper side of the sensor integrated mattress. The temperature change of the human body is transmitted to the grating through the medium such as the mattress, causing the drift of the optical fiber center wavelength to change. The higher the temperature within the measurement range, the greater the drift. The temperature change of the human body can be identified by the measured drift change of the optical fiber center wavelength. When the human body breathes, it will be accompanied by the rise and fall of the chest cavity, which will generate pressure on the sensor provided in this embodiment. The force unit of the sensor provided in this embodiment acts on the local 10mm grating area, causing the peak of the optical fiber Bragg grating reflection spectrum to split. In one cycle, the greater the force on the sensor provided in this example, the greater the wavelength value of the split point. The wavelength value of the split point of the reflection spectrum peak can be used to identify the human breathing rate. The distributed temperature-pressure fiber Bragg grating sensor of the embodiment of the present invention is composed of an optical fiber, a fiber Bragg grating, an I-shaped flexible beam structure, a substrate, and an adhesive; the optical fiber is fixed on the substrate in a straightened state, and the two ends are fixed together by an adhesive; the I-shaped flexible beam structure is fixed together with the substrate, and the connection between the I-shaped flexible beam structure and the substrate is sealed by an adhesive. The fiber Bragg grating is arranged on the optical fiber, and is located in the middle of the contact part between the substrate and the optical fiber. The optical fiber is in a straightened and taut state at the above position, so as to sensitively sense the pressure on the sensor, and at the same time sensitively sense the drift of the central wavelength of the fiber Bragg grating caused by temperature changes, reduce errors, and thus realize the measurement of human body temperature and pressure.

[0088] The distributed temperature-pressure fiber Bragg grating sensor of this embodiment places the optical fiber containing the fiber Bragg grating on the substrate, fixes the optical fiber at one end of the substrate with an adhesive, stretches the optical fiber to make it taut, and then fixes the optical fiber on the other side to the edge of the other side of the substrate. The substrate is bonded under the I-shaped flexible beam structure to protect the optical fiber and sense pressure. When the measured ambient temperature changes, the central wavelength of the fiber Bragg grating drifts, and the temperature change is obtained through the drift value, thereby realizing temperature monitoring.

[0089] According to the fiber grating sensing principle, the relationship between wavelength drift and temperature change is as follows:

[0090]

[0091] Among them, λ B is the center wavelength of the fiber Bragg grating in the initial state, K T is the temperature sensitivity coefficient of the fiber Bragg grating, ΔT is the change in ambient temperature, Δλ B is the center wavelength offset value of the fiber grating FBG, ζ represents the thermo-optical coefficient of the fiber, and α represents the thermal expansion coefficient of the fiber.

[0092] When the upper raised part of the I-shaped flexible beam structure is subjected to force and produces a downward displacement, the lower raised part of the I-shaped flexible beam structure acts on the optical fiber, causing the fiber Bragg grating to be locally stressed, thereby splitting the peak of its reflection spectrum, and measuring the pressure change through the wavelength value of the split point. Multiple temperature-pressure sensors are distributed in the system to form a temperature-pressure field, and then the measurement values ​​of different sensors in the temperature-pressure field are analyzed to obtain the body temperature and the situation of falling out of bed.

[0093] According to the fiber Bragg grating local force model, when the distributed temperature-pressure fiber Bragg grating sensor is subjected to force F, it is assumed that the total stiffness of the I-shaped compliant beam is K eq , the force transmitted to the fiber Bragg grating is F f , then based on the combined stiffness method, the total stiffness calculation formula of the compliant beam mechanism is as follows:

[0094]

[0095] Among them, K eq is the total stiffness of the compliant mechanism, k1 and k3 are the bending stiffness of rod 1 and rod 3 respectively, and k2 is the torsional stiffness of rod 2.

[0096] For each torsion spring, its stiffness can be calculated:

[0097]

[0098] Where L i is the length of the torsion section and G is the stiffness modulus. is a parameter related to the cross-sectional geometry, t is the beam thickness, and w is the beam width.

[0099] For each bending spring, its stiffness can be calculated based on the pseudo-rigid body model:

[0100]

[0101] Where E is the elastic modulus, I B is the moment of inertia of the beam, L B is the length of the curved segment.

[0102] From the material mechanics and FBG transverse force model, we know that when a certain section of the fiber Bragg grating with a length of L is subjected to a uniform transverse pressure, it can be regarded as three small continuous fiber Bragg gratings with lengths of L1, L2, and L3, respectively. The force-bearing section L2<<L. We can assume that the transverse force of this section of the fiber Bragg grating belongs to the plane strain condition, that is, ε x =0, so the stresses in all directions of the fiber grating cross section are as follows: Where D is the fiber diameter and v is the Poisson's ratio.

[0103] It can be known that the strain of the fiber Bragg grating in the reverse direction of the force is

[0104]

[0105] Therefore, the displacement of the fiber Bragg grating in the direction of force is

[0106]

[0107] Fiber Optic f The stiffness against deformation under the action of

[0108]

[0109] Under the action of external load F, the fiber Bragg grating and I-shaped compliant beam structure are equivalent to parallel springs, and the force finally distributed to the fiber Bragg grating is:

[0110]

[0111] According to the principle of photoelastic effect, the refractive index of the fiber grating in the x and y polarization directions of the stressed section changes:

[0112]

[0113]

[0114] Where p 11 、p 12 is the elastic-optical coefficient of the optical fiber (101), v is the Poisson's ratio, and E is the elastic modulus.

[0115] The transmission matrix method is used to solve the reflectivity of the spectrum:

[0116] Set input The output after the first grating is:

[0117]

[0118] By analogy, the relationship between the input and output of the entire optical fiber is:

[0119]

[0120] By boundary characteristics:

[0121]

[0122] In the formula

[0123]

[0124] K is the coupling coefficient.

[0125] The fiber Bragg grating reflectivity value is obtained as follows:

[0126]

[0127]

[0128] In the formula,

[0129] Let Δφ=2Δβ2L2

[0130] calculate:

[0131]

[0132] Simplify:

[0133]

[0134] From the above formula, we can know that the term e in the transmission matrix of the fiber Bragg grating segment under pressure is -jΔφ It has periodicity, that is, when Δφ=Δφ0+2kπ, the spectrum completes one cycle of change.

[0135] Simplified by Δφ=2Δβ2L2, we can get

[0136]

[0137] make

[0138] Then formula (2.1) can be simplified to

[0139]

[0140] when When , the force period can be obtained from formula (2.3) as

[0141] At this time, the reflectivity expression is

[0142]

[0143] Where φ=φ A1 +φ A3 -φ B1 +φ B3

[0144] where φ A1 ,φ A3 is the phase angle of A1 and A3, φ B1 ,φ B3 is the phase angle of B1 and B3.

[0145] Due to φ B1 =φ B3 Therefore, φ=φA1 +φ A3 .

[0146] When the fiber Bragg grating is compressed at the middle position, the reflectivity expression is simplified to:

[0147]

[0148] The approximate linear expression of φ is as follows:

[0149]

[0150] The split point in the spectrum is the minimum reflectivity. Considering only one period, when R takes the minimum value, Δφ-φ=π

[0151] Available

[0152]

[0153] Therefore, a linear model from the wavelength of the splitting point of the fiber Bragg grating reflection spectrum to the force F on the sensor can be established:

[0154]

[0155] Where Δλ is the bandwidth of the grating, λ0 is the initial value of the bandwidth, and F T is the value of one force cycle for spectrum splitting.

[0156] Compared with traditional electrical sensors, fiber grating sensors have the advantages of small size, anti-electromagnetic interference, corrosion resistance, easy to realize dynamic distributed detection and long-distance signal transmission, etc. In view of this, the present invention proposes a temperature-pressure integrated fiber grating sensor that can be integrated on a mattress, and uses fiber grating wavelength division multiplexing technology to propose a human sleep multi-sign monitoring system based on this sensor, which can realize real-time monitoring of multiple signs during sleep, such as body temperature, breathing, heart rate, etc.

[0157] In actual implementation, the selection of materials and size design of the multi-sign fiber Bragg grating sensor in the present invention can improve the performance of the multi-sign fiber Bragg grating sensor; the integration density of the multi-sign fiber Bragg grating sensor on the mattress can also affect the distribution of the temperature field-pressure field; the sensor monitoring principle of the present invention is not limited to the fiber Bragg grating principle. If inspired by the present invention, other personnel can also make designs similar to the present invention or make modifications to the present invention. It is particularly important to point out that as long as they do not deviate from the design purpose of the present invention and the fiber Bragg grating monitoring method under this configuration, all obvious changes and similar designs with equivalent replacements are included in the protection scope of the present invention.

[0158] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0159] It should be understood that the above description of the preferred embodiment is relatively detailed and cannot be regarded as limiting the scope of protection of the patent of the present invention. Under the guidance of the present invention, ordinary technicians in this field can also make substitutions or modifications without departing from the scope of protection of the claims of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A non-invasive distributed optical fiber monitoring system for multiple signs of human sleep, characterized in that: The invention comprises a mattress, a vital sign fiber Bragg grating sensor device, a demodulator and a host computer. The mattress comprises a bed net, a fabric and a filler. The filler is located between the bed net and the fabric. The vital sign fiber Bragg grating sensor device comprises a plurality of distributed temperature-pressure integrated fiber Bragg grating sensors. The plurality of distributed temperature-pressure integrated fiber Bragg grating sensors are buried in the filler, and the buried depths of the plurality of distributed temperature-pressure integrated fiber Bragg grating sensors are kept on the same horizontal plane. The plurality of distributed temperature-pressure integrated fiber Bragg grating sensors are connected to the demodulator, and the demodulator is connected to the host computer through a network. The demodulator receives and analyzes the signals transmitted by the plurality of distributed temperature-pressure integrated fiber Bragg grating sensors, and transmits the processed signals to the host computer to monitor the health status of the user during sleep. The calculation of the pressure sensitivity of the distributed temperature-pressure integrated fiber Bragg grating sensor comprises the following steps: Step 1: Solve the displacement Δ1 caused by the bending deformation of the I-beam: Combining formulas (1.1) and (1.2), we get the following expression for Moore's law: Where M(x) is the internal force caused by the original load, is the internal force caused by unit force, E is the Young's modulus of the material, I is the moment of inertia of the rod, and x is the distance between any cross section on the rod and the end receiving the force; The I-beam structure is symmetrical on the left and right. Since the stress and deformation of the left and right beams are the same, the left beam is taken for specific stress analysis: (1) Calculate the bending moment equation under the original load The flexible hinge part of the I-beam is initially in a horizontal state, and the moving end H is subjected to a downward load F. At this time, the AB, CD, QM, PN, and IG segments of the rod are all subjected to downward forces and upward bending moments. According to the symmetry of the I-beam structure, the AB segment is subjected to the same force as the CD segment, and the QM segment is subjected to the same force as the PN segment. The bending moments at any cross section on the rod are: Among them, a is the distance from the force point to the AC segment, x1, x2, and x3 are the horizontal distances between any cross section on the rod AB, IG, and PN segments and the AC segment respectively; (2) Calculate the bending moment equation under unit load Replace the load F with a unit downward load. The bending moment of any section of the rod AB, IG, and PN segments is: (3) Solve the displacement Δ1 caused by the bending deformation of the I-beam based on the unit load method; Among them, l1, l2, l3 are the deformation lengths of the AB, IG, and PN segments, b is the rod width, and d is the rod thickness; Step 2: Solve the displacement Δ2 caused by torsional deformation; The torsion angle σ generated by the rod BD is calculated based on material mechanics: Where, m is the length of the BD segment, G is the shear modulus, ν is the Poisson's ratio, and I P is the polar moment of inertia of the rod; Therefore, the deformation Δ2 caused by torsion is: Where b is the rod width, c is the distance between rods AC and BD; Step 3: Calculate the total displacement Δ of the moving end H under the action of load F; Based on formula (1.6) and formula (1.11), the total displacement Δ of the moving end H under the action of load F is: Step 4: Calculate the pressure sensitivity s of the I-beam; The pressure sensitivity calculation of the temperature-pressure integrated fiber Bragg grating sensor requires converting the load F' into pressure P: Where F' is the load acting on the force-bearing part of the sensor, and S is the area of ​​the force-bearing part of the sensor; When the load F' acts vertically on the force-bearing part of the sensor, the load F' on a set of I-beams is 2F, so the pressure sensitivity s of the sensor is:

2. A non-invasive distributed optical fiber monitoring system for multiple signs of human sleep according to claim 1, characterized in that: A plurality of the distributed temperature-pressure integrated fiber Bragg grating sensors are evenly distributed in the mattress, and the distributed temperature-pressure integrated fiber Bragg grating sensors are used to measure the distribution of temperature field and pressure field, monitor human body temperature, respiratory vital signs parameters, and analyze the situation of falling out of bed.

3. A non-invasive distributed optical fiber monitoring system for multiple signs of human sleep according to claim 2, characterized in that: The distributed temperature-pressure integrated fiber Bragg grating sensor comprises an optical fiber, an I-shaped flexible beam housing, a substrate and an adhesive. The optical fiber is fixed on the substrate, and both ends of the optical fiber are fixedly connected to the substrate by an adhesive. The I-shaped flexible beam housing is fixedly connected to the substrate, and the connection between the I-shaped flexible beam housing and the substrate is sealed by an adhesive. A fiber Bragg grating is provided on the optical fiber, and the fiber Bragg grating is located in the middle of the contact part between the substrate and the optical fiber, and the part of the optical fiber on the substrate is in a fully stretched state.

4. The monitoring method of a non-invasive distributed optical fiber monitoring system for multiple signs of human sleep according to any one of claims 1 to 3, characterized in that: The monitoring method includes a temperature monitoring method and a pressure monitoring method. The temperature monitoring method is as follows: when the measured ambient temperature changes, the central wavelength of the fiber grating drifts, and the temperature change is obtained through the drift value, thereby realizing temperature monitoring.

5. The monitoring method of a non-invasive distributed optical fiber monitoring system for multiple signs of human sleep according to claim 4, characterized in that: The pressure monitoring method is as follows: when the upper part of the I-shaped flexible beam structure is subjected to force and produces a downward displacement, the lower part of the I-shaped flexible beam structure acts on the optical fiber, causing the fiber grating to be locally stressed, thereby causing the reflection spectrum peak to split, and the pressure change is measured by the wavelength value of the splitting point.

6. The monitoring method of a non-invasive distributed optical fiber monitoring system for multiple signs of human sleep according to claim 4, characterized in that: The calculation of the temperature sensitivity of the distributed temperature-pressure integrated fiber Bragg grating sensor includes the following steps: Step 1: Relationship between the change in period and temperature of a fiber Bragg grating under thermal expansion effect: ΔΛ=α·Λ·ΔT(0.15) Where ΔΛ is the change in the grating period, and α is the thermal expansion coefficient; Step 2: Relationship between the change in effective refractive index of optical fiber and the change in temperature under the thermo-optical effect: Δn eff =ξ·n eff ·ΔT(0.16) In the formula, Δn eff is the effective refractive index of the fiber core, ζ is the thermo-optical coefficient of the fiber material; Step 3: Solve for the temperature sensitivity coefficient K t : The sensing characteristics of fiber Bragg grating are: Substituting equations (1.15) and (1.16) into (1.17), we obtain In the formula, λ B is the center wavelength of the fiber Bragg grating in the initial state, Δλ B is the optical fiber center wavelength drift, -α is the optical fiber thermal expansion coefficient, -ζ is the optical fiber thermo-optic coefficient, K t is the fiber Bragg grating sensitivity coefficient to temperature, and ΔT is the temperature change.

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