A vital sign detection method and device with a light reflector

Abstract

The present invention relates to a method and device for detecting vital signs using a light reflector, belonging to the technical field of vital sign parameter monitoring. The method addresses the issues of shortening the sensing fiber length of existing microbend fiber (BCG) sensors and reducing measurement errors caused by fluctuations in their light source output power. The method comprises: generating light using a light source; allowing the light to enter an optical circuit circulator via a first port and then enter a fiber optic sensor via a second port; applying a BCG signal to the fiber optic sensor, causing the light entering the fiber optic sensor to reach a light reflector; reflecting the light reaching the light reflector back to the fiber optic sensor and then back to the light circuit circulator; receiving the first light signal returning to the optical circuit circulator via a third port of the optical circuit circulator and converting the first light signal into a first electrical signal; and obtaining vital sign information based on the first electrical signal. The light reflector is used to cause the light wave to pass through the sensing fiber twice, thereby halving the sensing fiber length while maintaining the same sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of vital sign parameter monitoring, and in particular to a vital sign detection method and device with a light reflector. Background Art

[0002] In medicine, vital signs refer to indicators used to determine the severity and criticality of a patient's condition. The four major vital signs include respiration, pulse, body temperature, and blood pressure. Currently, the main vital sign sensing technologies include photoplethysmography (PPG), electrocardiogram (ECG), and ballistocardiogram (BCG). Monitoring of PPG and ECG signals generally requires direct contact with the skin, and electrodes are attached to the body. Patient compliance is poor, making it difficult to conduct long-term monitoring of patients' vital sign parameters. Monitoring of BCG signals generally does not require direct contact with the skin. Sensors are embedded in mattresses and cushions, and patients can obtain vital sign information such as heart rate, respiratory rate, and sleep quality while lying or sitting. This does not impose a physiological burden on patients and has received widespread attention in recent years.

[0003] The main methods for detecting BCG signals are piezoelectric sensing method and fiber optic sensing method. The piezoelectric sensing method is to sense BCG signals through piezoelectric film, which is easily disturbed by the external environment and can only detect dynamic forces; the fiber optic sensing method is to sense BCG signals through optical fiber, which has the advantages of anti-electromagnetic interference, good safety, and the ability to detect tiny static forces and dynamic forces. According to the different modulation methods of the optical signal, the fiber optic BCG sensor can be divided into BCG sensor based on micro-bend optical fiber, BCG sensor based on fiber grating and BCG sensor based on fiber interferometer. Among them, the BCG sensor based on micro-bend optical fiber has the advantages of simple structure and low cost. The structure of the traditional vital signs monitoring device based on micro-bend optical fiber is as follows: Figure 1 As shown in Figure 1, when a BCG signal acts on a microbend fiber sensor composed of a sensing fiber and a grid structure, the sensing fiber undergoes a microbend, causing some of the energy to enter the fiber cladding, resulting in light intensity loss. The BCG signal can be detected by measuring the output light intensity of the microbend fiber sensor. However, traditional microbend fiber-based vital sign monitoring devices require long sensing fibers and serpentine routing to achieve high system sensitivity. Furthermore, fluctuations in the light source output power can lead to measurement errors. Summary of the Invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a method and device for detecting vital signs with a light reflector, so as to shorten the sensing optical fiber length of the existing micro-bend optical fiber BCG sensor and reduce the measurement error caused by the output power fluctuation of the light source of the existing micro-bend optical fiber BCG sensor.

[0005] On the one hand, an embodiment of the present invention provides a vital sign detection method with a light reflector, comprising: generating light through a light source; a first beam of the light enters an optical path circulator via a first port, and then enters an optical fiber sensor via a second port; when a BCG signal acts on the optical fiber sensor, the light passes through the optical fiber sensor and reaches the light reflector; the light reaching the light reflector is reflected back to the optical fiber sensor and returns to the optical path circulator; the first optical signal returned to the optical path circulator is received via a third port of the optical path circulator and the first optical signal is converted into a first electrical signal; and BCG information is obtained based on the first electrical signal, thereby obtaining vital sign information.

[0006] The beneficial effects of the above technical solution are as follows: the present invention uses a light reflector to allow light waves to pass through the sensing optical fiber twice in succession. Compared with the traditional vital sign micro-bend optical fiber sensing system, under the condition of the same sensitivity, the length of the sensing optical fiber can be shortened by half, thereby optimizing the performance of the vital sign detection device.

[0007] Based on a further improvement of the above method, light is passed through the sensing optical fiber twice in succession through the light reflector to shorten the length of the sensing optical fiber in the optical fiber sensor under the same sensitivity, wherein the light reflector includes a fiber-coated total reflector or a fiber ring reflector.

[0008] Based on a further improvement of the above method, a feedback control loop is connected between the light source and the optical path circulation device to stabilize the output power of the light source, wherein stabilizing the output power of the light source includes: dividing the light into the first beam of light and the second beam of light; receiving the second beam of light through a first photodetector and converting the second beam of light into a second electrical signal; and adjusting the voltage or current loaded on the light source in real time according to the second electrical signal to keep the optical power output by the light source stable.

[0009] On the other hand, an embodiment of the present invention provides a vital sign detection device with a light reflector, including: a light source for generating light; an optical path circulatory device, for allowing a first beam of light to enter the optical path circulatory device via a first port and then enter an optical fiber sensor via a second port; the optical fiber sensor, when a BCG signal acts on the optical fiber sensor, the light passes through the optical fiber sensor and reaches the light reflector; the light reflector is used to reflect the light reaching the light reflector back to the optical fiber sensor and return to the optical path circulatory device; a second photodetector is used to receive the first optical signal returned to the optical path circulatory device via a third port and convert the first optical signal into a first electrical signal; and a signal demodulation and detection module is used to obtain vital sign information based on the first electrical signal.

[0010] Based on further improvement of the above device, the light reflector allows light to pass through the sensing optical fiber twice in succession, so as to shorten the length of the sensing optical fiber in the optical fiber sensor under the same sensitivity, wherein the light reflector is a fiber-coated total reflector or a fiber ring reflector.

[0011] Based on a further improvement of the above device, the vital sign detection device with a light reflector further includes a feedback control loop connected between the light source and the light path circulation device for stabilizing the output power of the light source.

[0012] Based on a further improvement of the above device, the feedback control loop includes a fiber optic coupler, a first photodetector and a light source driving module, wherein the fiber optic coupler is used to split the light into a first beam of light and a second beam of light; the first photodetector is used to receive the second beam of light and convert the second beam of light into a second electrical signal; and the light source driving module is used to adjust the voltage or current loaded on the light source in real time according to the second electrical signal to keep the optical power output by the light source stable.

[0013] Based on the further improvement of the above device, the optical circuit device is a fiber circulator or a MEMS spatial optical beam splitter.

[0014] Based on further improvements of the above device, the sensing optical fiber in the optical fiber sensor includes a multimode optical fiber, a polarization-maintaining optical fiber or a single-mode optical fiber.

[0015] Based on further improvements of the above-mentioned device, the optical fiber sensor includes: the sensing optical fiber, a grid structure, an upper flexible cover and a lower flexible cover, wherein the grid structure is laid below the sensing optical fiber; the upper flexible cover is arranged above the sensing optical fiber and in contact with the upper surface of the sensing optical fiber; and the lower flexible cover is arranged below the grid structure and in contact with the lower surface of the grid structure.

[0016] Based on further improvements to the above device, the vital signs detection device can be built into daily necessities, wherein the daily necessities include mattresses, cushions or pillows.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0018] 1. The embodiment of the present invention utilizes a light reflector to allow light waves to pass through the sensing optical fiber twice. Compared with the traditional micro-bend optical fiber sensing system for vital signs, the length of the sensing optical fiber in the vital signs detection device can be shortened by half under the condition of the same sensitivity, thereby optimizing the performance of the vital signs detection device.

[0019] 2. Compared with traditional micro-bend optical fiber sensing systems for vital signs, the embodiments of the present invention introduce closed-loop feedback control to stabilize the output power of the light source, which can effectively suppress measurement errors caused by fluctuations in the light source output power, thereby optimizing the performance of the vital signs detection device.

[0020] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0022] Figure 1 Schematic diagram of the structure of the traditional vital sign micro-bend optical fiber sensing system.

[0023] Figure 2 Flowchart of a method for detecting vital signs using a light reflector according to an embodiment of the present invention.

[0024] Figure 3 4 is a block diagram of the working principle of a vital sign detection device with a light reflector according to an embodiment of the present invention.

[0025] Figure 4 2 is a schematic structural diagram of a vital sign detection device with a light reflector according to a first embodiment of the present invention.

[0026] Figure 5 FIG. 4 is a schematic structural diagram of a vital sign detection device with a light reflector according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0028] A specific embodiment of the present invention discloses a method for detecting vital signs using a light reflector. Figure 2As shown, the vital sign detection method with a light reflector includes: in step S202, light is generated by a light source (the light source in this article is a width light source) and the light is divided into a first beam of light and a second beam of light; in step S204, the first beam of light enters the optical path circulator through the first port, and then enters the optical fiber sensor (the optical fiber sensor in this article is a slightly bent optical fiber sensor) through the second port; in step S206, when the BCG signal acts on the optical fiber sensor, the light reaches the light reflector after passing through the optical fiber sensor; in step S208, the light reaching the light reflector is reflected back to the optical fiber sensor and returns to the optical path circulator; in step S210, the first optical signal returned to the optical path circulator is received through the third port of the optical path circulator and the first optical signal is converted into a first electrical signal; and in step S212, BCG information is obtained according to the first electrical signal, thereby obtaining vital sign information, specifically, the vital sign information includes heart rate, respiratory rate, etc.

[0029] Compared with the existing technology, the embodiment of the present invention uses a light reflector to make the light wave pass through the sensing optical fiber twice in succession. Compared with the traditional vital sign micro-bend optical fiber sensing system, under the same sensitivity, the length of the sensing optical fiber in the vital sign detection device can be shortened by half.

[0030] In the following, reference Figure 2 A method for detecting vital signs using a light reflector according to an embodiment of the present invention is described in detail.

[0031] In step S202, light is generated by a broadband light source and split into a first beam and a second beam. In step S204, the first beam enters an optical circuit circulator via a first port and then enters a fiber optic sensor (herein, a slightly bent fiber optic sensor) via a second port. Specifically, the optical circuit circulator includes a first port, a second port, and a third port. In step S206, when a BCG signal is applied to the fiber optic sensor, the light passes through the sensor and reaches a light reflector. In step S208, the light that reaches the light reflector is reflected back to the fiber optic sensor and returns to the optical circuit circulator. The light passes through the optical circuit circulator twice through the light reflector, thereby shortening the sensing fiber length in the fiber optic sensor while maintaining the same sensitivity. Specifically, the light reflector includes a fiber-coated total reflection mirror or a fiber loop reflector. In step S210, the first optical signal returning to the optical circuit circulator is received via the third port of the optical circuit circulator and converted into a first electrical signal. In step S212, BCG information is obtained based on the first electrical signal, thereby obtaining vital sign information. Specifically, vital sign information includes heart rate, respiratory rate, etc.

[0032] A feedback control loop is connected between the light source and the optical circuit device to stabilize the light source's output power. Specifically, stabilizing the light source's output power includes: splitting the light into a first beam and a second beam; receiving the second beam via a first photodetector and converting it into a second electrical signal; and adjusting the voltage or current applied to the light source in real time based on the second electrical signal to maintain a stable optical power output from the light source.

[0033] A specific embodiment of the present invention discloses a vital sign detection device with a light reflector. Figures 3 to 5 The vital signs detection device with a light reflector includes: a light source 2, an optical path loop device 5, an optical fiber sensor 6, a light reflector 7, a second photodetector 8, a signal demodulation detection module 9 and a feedback control loop. Figures 3 to 5 , the various components of the vital sign detection device with a light reflector according to an embodiment of the present invention are described in detail.

[0034] The light source 2 is used to generate light and is a light emitting diode or other low-cost light sources.

[0035] A feedback control loop is connected between the light source and the optical path loop device and is used to stabilize the output power of the light source. The feedback control loop also includes a fiber coupler 3, a first photodetector 4, and a light source driver module 1. The fiber coupler 3 is used to split the light into a first beam and a second beam. The first photodetector 4 is used to receive the second beam and convert it into a second electrical signal; and the light source driver module 1 is used to adjust the voltage or current applied to the light source 2 in real time based on the second electrical signal to maintain the optical power output by the light source stable. Specifically, when the detected light intensity is greater than the set value, the voltage or current applied to the light source is reduced, and when the detected light intensity is less than the set value, the voltage or current applied to the light source is increased.

[0036] The optical circuit 5 includes a first port, a second port, and a third port. The first beam of light enters the optical circuit 5 through the first port and then enters the optical fiber sensor 6 through the second port. The optical circuit 5 is a fiber circulator or a MEMS spatial optical beam splitter.

[0037] When the BCG signal 10 acts on the optical fiber sensor 6, the light entering the optical fiber sensor 6 propagates in the forward direction and reaches the light reflector 7. The types of sensing optical fibers in the optical fiber sensor 6 include multimode optical fibers, polarization-maintaining optical fibers, or single-mode optical fibers. The optical fiber sensor 6 is built into everyday items, wherein the everyday items include mattresses, seat cushions, or pillows. The optical fiber sensor 6 includes a sensing optical fiber, a grid structure, an upper flexible cover, and a lower flexible cover. Specifically, the grid structure is laid below the sensing optical fiber, and when the BCG signal 10 acts on the optical fiber sensor 6, the sensing optical fiber is slightly bent. The upper flexible cover is arranged above the sensing optical fiber and contacts the upper surface of the sensing optical fiber. The lower flexible cover is arranged below the grid structure and contacts the lower surface of the grid structure.

[0038] The light reflector 7 is used to reflect the light reaching the light reflector 7 back to the optical fiber sensor 6 and return to the optical path circulation device 5. The light reflector 7 allows the light to pass through the optical fiber sensor 6 twice in succession, thereby shortening the sensing optical fiber length in the optical fiber sensor 6 under the same sensitivity. Figure 4 and Figure 5 The optical reflector 7 is a fiber-coated total reflector or a fiber ring reflector. Specifically, a fiber-coated total reflector is a fiber device that is coated at the fiber cut surface to cause total reflection of light. The fiber ring reflector consists of a 2×2 or 2×1 fiber coupler with a 50:50 splitting ratio.

[0039] The second photodetector 8 is configured to receive the first optical signal returned to the optical circuit circulator 5 via the second output port and convert the first optical signal into a first electrical signal.

[0040] The signal demodulation and detection module 9 is used to obtain BCG information and thus vital sign information based on the first electrical signal. Specifically, the vital sign information includes heart rate, respiratory rate, etc. The BCG signal is obtained based on the electrical signal, and then vital sign information such as heart rate and respiratory rate are extracted from the BCG signal. The method for extracting heart rate and respiratory rate from the BCG signal is as follows: the heart rate of an adult is between 0.50Hz and 3.00Hz, and the respiratory rate is between 0.16Hz and 0.50Hz. A bandpass filter is used to suppress other noise to obtain heart rate or respiratory rate information. The first electrical signal is a voltage, and the magnitude of the voltage represents the magnitude of the BCG signal. The respiratory rate and heart rate are extracted from the BCG signal.

[0041] In the following, reference will be made to Figures 3 to 5 , a vital sign detection device with a light reflector according to an embodiment of the present invention is described in detail by way of a specific example.

[0042] Reference Figure 3The present invention provides a vital sign detection device with a light reflector, including a light source driving module 1, a light source 2, a fiber optic coupler 3, a first photodetector 4, an optical path circulation device 5, a slightly bent fiber optic sensor 6, a light reflector 7, a second photodetector 8, a signal demodulation detection module 9, and a BCG signal 10; the slightly bent fiber optic sensor 6 is composed of a sensing fiber and a grid structure.

[0043] The light source driving module 1, the light source 2, the optical fiber coupler 3 and the first photodetector 4 are connected to form a closed loop; the light source driving module 1 is connected to the light source 2; the light source 2 is connected to the optical fiber coupler 3; the optical fiber coupler 3 is connected to the first photodetector 4; the first photodetector 4 is connected to the light source driving module 1; the optical path circulation device 5 has three ports, which are respectively connected to the optical fiber coupler 3, the second photodetector 8 and the slightly bent optical fiber sensor 6; the slightly bent optical fiber sensor 6 is connected to the optical reflector 7; the second photodetector 8 is connected to the signal demodulation detection module 9; and the BCG signal 10 acts on the slightly bent optical fiber sensor 6.

[0044] In the following, reference Figures 3 to 5 , the principle of the vital sign detection device with a light reflector according to an embodiment of the present invention is described in detail.

[0045] Reference Figure 3 The light emitted by light source 2 is split into two beams by fiber coupler 3 (with a ratio ranging from 1:99 to 50:50, with the signal at the closed-loop feedback end being smaller). One beam is received by first detector 4 and converted into an electrical signal. Light source driver module 1 adjusts the voltage or current applied to light source 2 in real time based on this electrical signal to maintain a stable optical power output by light source 2 (when the detected light intensity is greater than the set value, the voltage or current applied to the light source is reduced; when the detected light intensity is less than the set value, the voltage or current applied to the light source is increased). The other beam of light separated from fiber coupler 3 enters optical path circulator 5, exits optical path circulator 5, enters slightly bent optical fiber sensor 6, exits slightly bent optical fiber sensor 6, reaches optical reflector 7, is reflected by optical reflector 7 back to slightly bent optical fiber sensor 6, returns to optical path circulator 5, and finally reaches second photodetector 8, which converts the optical signal into an electrical signal. This electrical signal is then passed through signal demodulation detection module 9 to obtain vital sign information such as heart rate and respiratory rate. In the above working principle process, the light wave passes through the sensing optical fiber twice. Compared with the traditional vital signs micro-bend optical fiber sensing system, under the same sensitivity, the length of the sensing optical fiber in the vital signs detection device can be shortened by half.

[0046] In an exemplary embodiment of the present invention, two structures of vital sign detection devices with optical reflectors are proposed, namely, a vital sign detection device with an optical fiber coated total reflector and a vital sign detection device with an optical fiber ring reflector.

[0047] The first embodiment of the present invention provides a vital sign detection device with a light reflector. Figure 4 The vital sign detection device with a light reflector includes: a light source, a light source driver module, a fiber coupler, a first photodetector, a fiber circulator, a second photodetector, a sensing fiber, a grid structure, a fiber-coated total reflector, and a signal demodulation detection module. The device parameters in the vital sign detection device with a light reflector can be set as follows:

[0048] Light source: light emitting diodes with a wavelength of 1550nm, 1310nm or 850nm, or other low-power, low-cost light sources.

[0049] Fiber optic coupler: can use 1 × 2 fiber couplers or 2 × 2, wherein the coupling output intensity at one end is between 1% and 50%.

[0050] Sensing optical fiber: uses multimode optical fiber, single-mode optical fiber or polarization-maintaining optical fiber; a grid structure is laid underneath, the grid is composed of interwoven fibers, and the sensing optical fiber and the grid structure form a micro-bend optical fiber sensor; the sensing optical fiber and the grid structure are flanked by flexible outer covers made of silicone.

[0051] Fiber-coated total reflector: operating wavelength is 1550nm, 1310nm or 850nm, low insertion loss.

[0052] Signal demodulation and detection module: can be used to extract vital signs information such as heart rate and respiratory rate.

[0053] The second embodiment of the present invention provides a vital sign detection device with a light reflector. Figure 5 The vital signs monitoring device with a light reflector includes: a light source, a light source driver module, a fiber coupler, a first photodetector, a fiber circulator, a second photodetector, a sensing fiber, a grid structure, a fiber ring reflector, and a signal demodulation detection module. In a specific implementation, the parameters of the components in the vital signs monitoring device can be set to:

[0054] Light source: light emitting diodes with a wavelength of 1550nm, 1310nm or 850nm, or other low-power, low-cost light sources.

[0055] Fiber optic coupler: can use 1 × 2 fiber couplers or 2 × 2, wherein the coupling output intensity at one end is between 1% and 50%.

[0056] Sensing optical fiber: uses multimode optical fiber, single-mode optical fiber or polarization-maintaining optical fiber; a grid structure is laid underneath, the grid is composed of interwoven fibers, and the sensing optical fiber and the grid structure form a micro-bend optical fiber sensor; the sensing optical fiber and the grid structure are flanked by flexible outer covers made of silicone.

[0057] Fiber ring reflector: The fiber type used is multimode fiber, single mode fiber or polarization maintaining fiber, which is composed of a 1 × 2 or 2 × 2 fiber coupler.

[0058] Signal demodulation and detection module: can be used to extract vital signs information such as heart rate and respiratory rate.

[0059] In summary, the present invention provides a vital sign detection device with a light reflector. Compared to traditional microbend fiber optic sensing systems for vital signs, this device utilizes a light reflector to force light waves to pass through the sensing fiber twice. This reduces the sensing fiber length by half while maintaining the same sensitivity. Furthermore, this device incorporates closed-loop feedback control to stabilize the light source's output power, effectively suppressing measurement errors caused by fluctuations in the light source's output power.

[0060] Those skilled in the art will appreciate that all or part of the process steps of the above-described embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0061] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for detecting vital signs using a light reflector, characterized in that: include: generating light by means of a light source; The first beam of light enters the optical circuit device through the first port and then enters the optical fiber sensor through the second port; When the BCG signal acts on the optical fiber sensor, the light passes through the optical fiber sensor and reaches the light reflector; The light reaching the optical reflector is reflected back to the optical fiber sensor and returns to the optical path circulation device; receiving a first optical signal returned to the optical circuit circulator via a third port of the optical circuit circulator and converting the first optical signal into a first electrical signal; as well as Vital sign information is obtained according to the first electrical signal.

2. The method for detecting vital signs using a light reflector according to claim 1, wherein: The light is made to pass through the optical fiber sensor twice in succession through the light reflector, so as to shorten the sensing optical fiber length in the optical fiber sensor under the same sensitivity. The light reflector includes an optical fiber coated total reflector or an optical fiber ring reflector.

3. The method for detecting vital signs using a light reflector according to claim 1, wherein: Connecting a feedback control loop between the light source and the optical circuit device to stabilize the output power of the light source, wherein stabilizing the output power of the light source comprises: Splitting the light into the first beam of light and a second beam of light; receiving the second beam of light through a first photodetector and converting the second beam of light into a second electrical signal; and The voltage or current applied to the light source is adjusted in real time according to the second electrical signal, so that the optical power output by the light source remains stable.

4. A vital sign detection device with a light reflector, characterized in that: include: a light source for generating light; an optical circuit device, configured to allow a first beam of light to enter the optical circuit device through a first port and then enter the optical fiber sensor through a second port, wherein the optical circuit device is a fiber circulator or a MEMS spatial optical beam splitter; The optical fiber sensor, when the BCG signal acts on the optical fiber sensor, the light passes through the optical fiber sensor and reaches the light reflector; The light reflector is used to reflect the light reaching the light reflector back to the optical fiber sensor and return to the optical path circulation device. The light reflector allows the light to pass through the optical fiber sensor twice in succession, thereby shortening the length of the sensing optical fiber in the optical fiber sensor under the same sensitivity. The light reflector is a fiber-coated total reflection mirror or a fiber ring reflector; a second photodetector for receiving the first optical signal returned to the optical circuit loop device via a third port and converting the first optical signal into a first electrical signal; and a signal demodulation detection module for obtaining vital sign information according to the first electrical signal.

5. The vital sign detection device with a light reflector according to claim 4, characterized in that: It also includes a feedback control loop connected between the light source and the optical path circulation device, and is used to stabilize the output power of the light source.

6. The vital sign detection device with a light reflector according to claim 5, characterized in that: The feedback control loop includes a fiber coupler, a first photodetector and a light source driving module, wherein: The optical fiber coupler is used to split the light into a first beam of light and a second beam of light; The first photodetector is configured to receive the second light beam and convert the second light beam into a second electrical signal; and The light source driving module is used to adjust the voltage or current loaded on the light source in real time according to the second electrical signal, so that the optical power output by the light source remains stable.

7. The vital sign detection device with a light reflector according to claim 4, characterized in that: The sensing optical fiber in the optical fiber sensor includes a multimode optical fiber, a polarization-maintaining optical fiber or a single-mode optical fiber.

8. The vital sign detection device with a light reflector according to claim 7, characterized in that: The optical fiber sensor comprises: the sensing optical fiber, a grid structure, an upper flexible outer cover and a lower flexible outer cover, wherein: The grid structure is laid below the sensing optical fiber; The upper flexible cover is disposed above the sensing optical fiber and in contact with the upper surface of the sensing optical fiber; and The lower flexible outer cover is arranged below the grid structure and contacts the lower surface of the grid structure.

Images