CN117179748A - Fiber bragg grating vital sign monitoring device and method - Google Patents
Fiber bragg grating vital sign monitoring device and method Download PDFInfo
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Abstract
The application relates to a fiber grating vital sign monitoring device and a fiber grating vital sign monitoring method, belongs to the technical field of vital sign monitoring, and solves the problems that a fiber grating packaging structure is complex, manufacturing difficulty is high and the like in the existing fiber grating vital sign monitoring device. The device comprises: a light source for generating a first optical signal; the first optical fiber circulator is used for receiving the first optical signal and transmitting the first optical signal to the sensing probe array; the sensing probe array is used for sensing weak vibration signals of a human body, the first optical signals are reflected at each sensing probe of the sensing probe array, and reflected light returns to the first optical fiber circulator; and the signal demodulation component is used for receiving the reflected light from the first optical fiber circulator and acquiring cardiopulmonary vibration signals at each sensing probe according to the spectrum information of the reflected light. The application provides a fiber grating sensor structure suitable for vital sign monitoring, which can improve the service life and performance of a fiber grating vital sign monitoring device.
Description
Technical Field
The application relates to the technical field of vital sign monitoring, in particular to a fiber bragg grating vital sign monitoring device and method.
Background
With the economic development and social progress, people's attention to health is gradually increased, and daily vital sign monitoring is helpful for early discovery and early intervention of diseases. The current common vital sign monitoring device is high in accuracy, needs to be in direct contact with skin, and is not suitable for daily health monitoring. The Ballistocardiogram (BCG) sensor based on optical fiber sensing can be used in carriers such as mattresses, seat cushions and the like, realizes noninvasive, continuous and non-skin direct contact type vital sign monitoring, is suitable for long-term use, and has the advantages of electromagnetic interference resistance, good safety, high sensitivity and the like.
The fiber bragg grating has mature application in the fields of construction, aviation and the like due to the advantages of wavelength coding of sensing signals, suitability for distributed measurement and the like. At present, the fiber bragg grating has less application in vital sign monitoring, the existing fiber bragg grating packaging structure for vital sign sensing is complex, and the manufacturing difficulty is high.
Disclosure of Invention
In view of the above analysis, the embodiments of the present application aim to provide a fiber bragg grating vital sign monitoring device and method, which are used for solving the problems of complex structure, high manufacturing difficulty, etc. of the existing fiber bragg grating packaging structure for vital sign sensing.
In one aspect, an embodiment of the present application provides a fiber bragg grating vital sign monitoring device, including: a light source for generating a first optical signal; the first optical fiber circulator is used for receiving the first optical signal and transmitting the first optical signal to the sensing probe array; the sensing probe array is used for sensing weak vibration signals of a human body, the first optical signals are reflected at each sensing probe of the sensing probe array, and reflected light returns to the first optical fiber circulator; and the signal demodulation component is used for receiving the reflected light from the first optical fiber circulator, processing the reflected light to obtain spectrum information of the reflected light, obtaining weak vibration signals of the human body at each sensing probe according to the spectrum information, and extracting vital signs according to the weak vibration signals of the human body.
The beneficial effects of the technical scheme are as follows: compared with a piezoelectric vital sign sensor, the sensor has the advantages of electromagnetic interference resistance, no electrified running of the sensor head and the like. Compared with a microbend optical fiber vital sign sensor, the measured information of the microbend optical fiber vital sign sensor is coded by light wavelength, the interference resistance is high, and the distributed sensing is realized by inscribing a plurality of gratings with different wavelengths on one optical fiber.
Based on the further improvement of the device, the sensing probe array comprises a sensing grating array and a reference grating array, wherein the sensing grating array comprises a plurality of sensing gratings which are sequentially connected, and the reference grating array comprises a plurality of reference gratings which are sequentially connected, wherein one sensing probe is internally packaged with one sensing grating and one reference grating.
Based on the further improvement of the device, the fiber bragg grating vital sign monitoring device further comprises an optical switch, wherein the optical switch is used for connecting the first fiber optic circulator and the sensing probe array, and the signal demodulation component receives the reflected light through the optical switch and the first fiber optic circulator, wherein before the optical switch is switched, the reflected light is reflected light by a sensing grating array in the sensing probe array; the reflected light is reflected light of a reference grating array in the sensing probe array through the switching of the optical switch; the wavelength of the reflected light of the sensing grating is corrected by referring to the wavelength of the reflected light of the grating, the measuring deviation of the sensing grating caused by the change of the ambient temperature is compensated, and the weak vibration signals of the human body at each position of the sensing probe array are obtained by the corrected wavelength of the reflected light of the sensing grating, and vital signs are extracted according to the weak vibration signals of the human body.
The beneficial effects of the technical scheme are as follows: the ambient temperature change is obtained through the reference grating and is used for correcting the output signal of the sensing grating, so that the sensing grating measurement deviation caused by the ambient temperature change is compensated, and the performance of the vital sign sensor can be effectively improved.
Based on a further improvement of the above device, the sensing probe comprises: the annular shell is fixedly connected with the outer wall of the annular base; a reference grating disposed at a bottom portion within the cavity of the annular base; the sensing grating is arranged at the top part in the cavity of the annular base and is adhered below the elastic membrane; the silica gel block is above the elastic membrane and is fixedly connected with the elastic membrane, wherein the top surface of the silica gel block is higher than the top surface of the annular shell, so that the human body part acts on the elastic membrane through the silica gel block; and the optical fiber tail fiber passes through the opposite side walls of the annular base and the annular shell and is used as an input end and an output end.
Based on the further improvement of the device, the optical fiber tail fiber comprises a first optical fiber tail fiber and a second optical fiber tail fiber, wherein one end of the first optical fiber tail fiber is connected with a sensing grating, and the other end of the first optical fiber tail fiber is connected with a sensing grating in another sensing probe or is connected with the first optical fiber circulator through an optical switch; and one end of the second optical fiber pigtail is connected with the reference grating, and the other end of the second optical fiber pigtail is connected with the reference grating in the other sensing probe or connected with the first optical fiber circulator through an optical switch.
The beneficial effects of the technical scheme are as follows: the fiber bragg grating for vital sign monitoring is structurally packaged, so that the precision and the service life of the fiber bragg grating sensor are improved, and the fiber bragg grating sensor is not easy to damage.
Based on the further improvement of the device, the weak vibration signals of the human body comprise heart-lung vibration signals, the human body acts on the elastic diaphragm through the silica gel block, the elastic diaphragm deforms along with the heart-lung vibration signals, the grid distance of the sensing grating adhered below the elastic diaphragm changes, the wavelength of reflected light of the sensing grating changes, and the signal demodulation component obtains the heart-lung vibration signals at the silica gel block according to the wavelength of reflected light.
Based on a further improvement of the above apparatus, the signal demodulation assembly includes: a monostable frequency light source for generating a second optical signal; the optical fiber coupler is used for combining the second optical signal with the reflection light from the first optical fiber circulator into one path and providing the combined path for the photoelectric detector through the F-P tunable filter; the photoelectric detector is used for converting the synthesized optical signals into first analog signals and transmitting the first analog signals to the digital signal processing unit; the digital signal processing unit is used for generating a triangular wave scanning signal to act on the F-P tunable filter, processing a first analog signal to obtain a spectrum of light reflected by the sensing grating array, and then switching through an optical switch to obtain a spectrum of light reflected by the reference grating array; and acquiring a heart-lung vibration signal based on the spectrum of the light reflected by the sensing grating array and the spectrum of the light reflected by the reference grating array.
Based on a further improvement of the above apparatus, the digital signal processing unit comprises: the AD module is used for converting the first analog signal into a first digital signal; a DA module for generating a triangular wave scanning signal to periodically adjust the cavity length of the F-P tunable filter 53; the digital signal processing chip is used for generating a second digital signal according to the first digital signal, transmitting the second digital signal to the DA module, processing the first digital signal, obtaining the spectrum of the reflected light of the sensing grating array and the spectrum of the reflected light of the reference grating array in a time-sharing mode according to the switching state of the optical switch, correcting the reflected light wavelength of the sensing grating in the same sensing probe through the reflected light wavelength of the reference grating in the sensing probe, compensating the sensing grating measurement deviation caused by the change of the ambient temperature, and obtaining the heart-lung vibration signals at the positions of the sensing probes according to the corrected wavelength of the reflected light of the sensing grating.
The beneficial effects of the technical scheme are as follows: in fiber grating wavelength demodulation, it is proposed to calibrate an F-P tunable filter by a monostable frequency laser to suppress wavelength demodulation errors caused by non-ideal characteristics such as hysteresis and creep of piezoelectric ceramics in the F-P tunable filter, environmental temperature changes, and the like.
In another aspect, an embodiment of the present application provides a method for monitoring vital signs of an optical fiber grating, including: the sensing probe array is arranged in a mattress or a seat cushion, arranged under the mattress or the seat cushion, or arranged on the mattress or the seat cushion, and a user lies on the mattress or sits on the seat cushion; the first optical signal generated by the light source is provided to the sensing probe array through the first optical fiber circulator and the optical switch; the sensing probe array senses a weak human body vibration signal, the weak human body vibration signal enables the spectrum of reflected light of the first optical signal at the sensing probe array to change, and the reflected light returns to the first optical fiber circulator; the reflected light reaches a signal demodulation assembly after passing through an optical switch and a first optical fiber circulator, the signal demodulation assembly obtains a spectrum of reflected light of a sensing grating array in a sensing probe array, and then the spectrum of reflected light of a reference grating array in the sensing probe array is obtained through switching of the optical switch; the method comprises the steps of correcting the wavelength of reflected light of a sensing grating in the same sensing probe through the wavelength of reflected light of a reference grating in the sensing probe, compensating the measurement deviation of the sensing grating caused by the change of the ambient temperature, obtaining weak vibration signals of human bodies at each position of a sensing probe array through the wavelength of the reflected light of the corrected sensing grating, and extracting vital signs according to the weak vibration signals of the human bodies.
Based on a further improvement of the above method, the human body weak vibration signal includes a cardiopulmonary vibration signal, the human body weak vibration signal changes a spectrum of light reflected by the first optical signal at the sensing probe array, and the returning of the reflected light to the first optical fiber circulator includes: the cardiopulmonary vibration signals of the user act on the silica gel blocks of each sensing probe in the sensing probe array; the heart-lung vibration signal acts on the elastic diaphragm through the silica gel block, and the elastic diaphragm deforms along with the heart-lung vibration signal, so that the grid distance of the sensing grating adhered below the elastic diaphragm changes, and the wavelength of the reflected light of the sensing grating changes; under the influence of ambient temperature, the reflected light wavelengths of the reference grating and the sensing grating change in the same trend along with the temperature, and the ambient temperature change is obtained through the reference grating and is used for correcting the output signal of the sensing grating and compensating the measurement deviation of the sensing grating caused by the ambient temperature change; and under the action of the cardiopulmonary vibration signal, the reflected light wavelength of the sensing grating deviates from the central wavelength, and the cardiopulmonary vibration signal is obtained according to the wavelength variation, wherein the central wavelength is the reflected light wavelength of the sensing grating when no stress acts.
Compared with the prior art, the application has at least one of the following beneficial effects:
1. compared with a piezoelectric vital sign sensor, the fiber bragg grating vital sign monitoring device provided by the embodiment of the application has the advantages of electromagnetic interference resistance, no electrified running of a sensor head and the like;
2. compared with a microbend optical fiber vital sign sensor, the measured information of the optical fiber grating vital sign monitoring device provided by the embodiment of the application is encoded by wavelength, has strong anti-interference capability, and realizes distributed sensing by inscribing a plurality of gratings with different wavelengths on one optical fiber;
3. according to the fiber bragg grating vital sign monitoring device provided by the embodiment of the application, the fiber bragg grating for vital sign monitoring is structurally packaged, so that the accuracy and the service life of the fiber bragg grating sensor are improved, and the fiber bragg grating sensor is not easy to damage;
4. according to the fiber bragg grating vital sign monitoring device provided by the embodiment of the application, the ambient temperature change is obtained through the reference grating, so that the fiber bragg grating vital sign monitoring device is used for correcting the output signal of the sensing grating and compensating the measurement deviation of the sensing grating caused by the ambient temperature change, and the performance of the vital sign sensor can be effectively improved;
5. according to the fiber bragg grating vital sign monitoring device provided by the embodiment of the application, in fiber bragg grating wavelength demodulation, the F-P tunable filter is calibrated by the monostable frequency laser, so that wavelength demodulation errors caused by non-ideal characteristics such as hysteresis and creep of piezoelectric ceramics in the F-P tunable filter, environmental temperature changes and the like are restrained.
In the application, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the application, like reference numerals being used to designate like parts throughout the drawings;
FIG. 1 is a block diagram of a fiber grating vital sign monitoring device according to an embodiment of the present application;
FIG. 2 is a cross-sectional view of a packaging structure of a sensing probe according to an embodiment of the application;
FIG. 3 is a timing diagram of a triangular wave scanning signal, an output electrical signal of a first photodetector, and an output signal of a second photodetector loaded on an F-P tunable filter according to an embodiment of the application;
fig. 4 is a flowchart of a fiber grating vital sign monitoring method according to an embodiment of the present application.
Detailed Description
The following detailed description of preferred embodiments of the application is made in connection with the accompanying drawings, which form a part hereof, and together with the description of the embodiments of the application, are used to explain the principles of the application and are not intended to limit the scope of the application.
Referring to fig. 1, in one embodiment of the present application, a fiber grating vital sign monitoring device is disclosed, comprising: a light source 1 for generating a first optical signal; a first optical fiber circulator 2 for receiving the first optical signal and transmitting the first optical signal to the sensing probe array 3; the sensing probe array 3 is used for sensing weak vibration signals of a human body, the first optical signals are reflected at each sensing probe of the sensing probe array, and reflected light returns to the first optical fiber circulator 2; and the signal demodulation component 5 is used for receiving the reflected light from the first optical fiber circulator 2, processing the reflected light to obtain spectrum information of the reflected light, obtaining weak vibration signals of the human body at each sensing probe according to the spectrum information, and extracting vital signs according to the weak vibration signals of the human body.
In vital sign monitoring, the sensing probe array 3 is built into, disposed under, or placed on a mattress or seat cushion.
Compared with the existing piezoelectric vital sign sensor, the fiber bragg grating vital sign monitoring device provided by the embodiment has the advantages of electromagnetic interference resistance, no electrified running of the sensor head and the like. Compared with a microbend optical fiber vital sign sensor, the measured information of the microbend optical fiber vital sign sensor is encoded by wavelength, has strong anti-interference capability, and realizes distributed sensing by inscribing a plurality of gratings with different wavelengths on one optical fiber.
Hereinafter, a fiber grating vital sign monitoring device according to an embodiment of the present application will be described in detail with reference to fig. 1 and 2.
Referring to fig. 1, a fiber grating vital sign monitoring device, comprising: the optical fiber sensor comprises a light source 1, a first optical fiber circulator 2, a sensing probe array 3, an optical switch 4 and a signal demodulation component 5.
The light source 1 is used for generating a first light signal.
The first optical fiber circulator 2 is configured to receive the first optical signal and transmit the first optical signal to the sensing probe array 3. The first optical fiber circulator 2 has one input end, one input and output end, and one output end. The first optical fiber circulator 2 receives the first optical signal via an input terminal and transmits the first optical signal to the sensing probe array 3 via an input terminal. The reflected light, which will be described below, returns to the first optical fiber circulator 2 via the input and output terminals, and is then transmitted to the signal demodulation element 5 via the output terminals.
The sensing probe array 3 is used for sensing weak vibration signals of a human body, the first optical signals are reflected at each sensing probe of the sensing probe array 3, and reflected light returns to the first optical fiber circulator 2. The sensing probe array 3 includes a sensing grating array and a reference grating array. The sensing grating array comprises a plurality of sensing gratings which are sequentially connected, and the reference grating array comprises a plurality of reference gratings which are sequentially connected, wherein one sensing probe is internally packaged with one sensing grating and one reference grating.
The optical switch 4 is used for being connected between the first optical fiber circulator 2 and the sensing probe array 3, and the sensing grating array and the reference grating array are switched through the optical switch 4. The signal demodulation component receives the reflected light via the optical switch and the first optical fiber circulator. Specifically, before the optical switch 4 is switched, the common terminal of the optical switch 4 is connected with the first terminal, the first terminal is connected with the sensing grating array, and the reflected light is reflected light by the sensing grating array in the sensing probe array; after the optical switch 4 is switched, the common terminal of the optical switch 4 is connected with the second terminal, and the second terminal is connected with the reference grating array, and the reflected light is reflected light of the reference grating array in the sensor probe array. The wavelength of the reflected light of the sensing grating is corrected by referring to the wavelength of the reflected light of the grating, the measuring deviation of the sensing grating caused by the change of the ambient temperature is compensated, and the weak vibration signals of the human body at each position of the sensing probe array 3 are obtained by the corrected wavelength of the reflected light of the sensing grating, and vital signs are extracted according to the weak vibration signals of the human body.
Referring to fig. 2, a sensing probe includes: the annular shell 34 is fixedly connected with the outer wall of the annular base 33; the reference grating 37 is arranged at the bottom inside the cavity of the annular base 33; the sensing grating 32 is arranged at the top in the cavity of the annular base 33, and the sensing grating 32 is fixedly connected with the elastic diaphragm 31. The silica gel block 35 is above the elastic membrane 31 and is fixedly connected with the elastic membrane 31, wherein the top surface of the silica gel block 35 is higher than the top surface of the annular shell 34, so that the human body part acts on the elastic membrane 31 through the silica gel block 35; and fiber pigtails 36 pass through opposite sidewalls of annular base 33 and annular housing 34 as input and output ends.
Specifically, the optical fiber tail fiber comprises a first optical fiber tail fiber and a second optical fiber tail fiber, wherein one end of the first optical fiber tail fiber is connected with a sensing grating, and the other end of the first optical fiber tail fiber is connected with a sensing grating in another sensing probe or connected with a first optical fiber circulator 2 through an optical switch 4; and one end of the second fiber pigtail is connected with the reference grating, and the other end of the second fiber pigtail is connected with the reference grating in the other sensing probe or connected with the first fiber circulator 2 through the optical switch 4.
The weak vibration signals of the human body comprise heart and lung vibration signals. The human body acts on the elastic diaphragm 31 through the silica gel block 35, the elastic diaphragm 31 deforms along with the elastic diaphragm, the grid distance of the sensing grating 32 adhered below the elastic diaphragm 31 changes, the wavelength of reflected light of the sensing grating 32 changes, and the signal demodulation component 5 obtains a heart-lung vibration signal acting on the silica gel block 35 according to the change of the wavelength of reflected light.
The signal demodulation component 5 is configured to receive the reflected light from the first optical fiber circulator 2, process the reflected light to obtain spectrum information of the reflected light, obtain weak vibration signals of the human body at each sensing probe according to the spectrum information, and then extract vital signs according to the weak vibration signals of the human body.
Specifically, the signal demodulating section 5 includes: the monostable frequency light source 51 is used for generating a second optical signal; the optical fiber coupler 52 is used for combining the reflected light from the first optical fiber circulator 2 and the second optical signal into one path, and providing the combined light and the second optical signal to the photodetector 54 through the F-P tunable filter 53; the photodetector 54 is configured to convert the synthesized optical signal into a first analog signal, and transmit the first analog signal to the digital signal processing unit 55; the digital signal processing unit 55 is configured to generate a triangular wave scanning signal, apply the triangular wave scanning signal to the F-P tunable filter 53, process the first analog signal to obtain a spectrum of light reflected by the sensing grating array, and then switch the spectrum of light reflected by the reference grating array through the optical switch 4; and acquiring a heart-lung vibration signal based on the spectrum of the light reflected by the sensing grating array and the spectrum of the light reflected by the reference grating array.
The digital signal processing unit 55 includes: an AD module 551 for converting the first analog signal into a first digital signal; a DA module 553 for generating a triangular wave scanning signal, in particular, converting a second digital signal (i.e., a digital triangular wave signal, in particular, a digital triangular wave signal represented by a series of numbers) received from the digital signal processing signal 552 into an analog signal (i.e., a triangular wave scanning signal, in particular, an analog triangular wave scanning signal that is a real physical signal) to periodically adjust the cavity length of the F-P tunable filter 53; a digital signal processing chip 552 for generating a second digital signal and delivering to the DA module 553 (specifically, a second digital signal obtained from the first digital signal); and processing the first digital signal, according to the switching state of the optical switch 4, obtaining the spectrum of the reflected light of the sensing grating array and the spectrum of the reflected light of the reference grating array in a time-sharing manner, correcting the reflected light wavelength of the sensing grating in the same sensing probe through the reflected light wavelength of the reference grating in the sensing probe, compensating the sensing grating measurement deviation caused by the environmental temperature change, and obtaining the heart-lung vibration signals of the sensing probe array 3 according to the corrected wavelength of the reflected light of the sensing grating. Specifically, under the action of the triangular wave scanning signal, the photodetector 54 outputs an electrical signal as shown in fig. 3, and the highest wavelength of resonance in fig. 3 is the wavelength of the monostable laser 51, which is a known quantity, as a reference wavelength: by acquiring the relative positions of the reflected light wavelength spectrum of the sensing grating 32 and the reference wavelength, the reflected light wavelength of each sensing grating 32 is demodulated, and the reflected light wavelength of each reference grating 37 is demodulated by switching the optical switch 4. The piezoelectric ceramics used for adjusting the cavity length in the F-P tunable filter 53 have non-ideal characteristics such as hysteresis and creep, and can cause wavelength demodulation errors, so the F-P tunable filter 53 is calibrated by a single frequency stabilized laser.
Referring to fig. 4, another embodiment of the present application discloses a fiber grating vital sign monitoring method, which includes: in step S401, the sensing probe array is built in, disposed under, or placed on the mattress or cushion, and the user lies on the mattress or sits on the cushion; in step S402, a first optical signal generated by the optical source is provided to the sensing probe array via the first optical fiber circulator and the optical switch; in step S403, the sensing probe array senses a weak vibration signal of the human body, the weak vibration signal of the human body changes a spectrum of light reflected by the first optical signal at the sensing probe array, and the reflected light returns to the first optical fiber circulator; in step S404, the reflected light reaches the signal demodulation component after passing through the optical switch and the first optical fiber circulator, the signal demodulation module obtains the spectrum of the reflected light of the sensing grating array in the sensing probe array, and then the spectrum of the reflected light of the reference grating array in the sensing probe array is obtained through switching of the optical switch; in step S405, the wavelength of the reflected light of the sensing grating in the same sensing probe is corrected by the wavelength of the reflected light of the reference grating in the sensing probe, the measurement deviation of the sensing grating caused by the change of the ambient temperature is compensated, and the weak vibration signal of the mattress or the seat cushion of each human body is obtained by the corrected wavelength of the reflected light of the sensing grating, and vital signs are extracted according to the weak vibration signal of the human body.
The weak vibration signals of the human body comprise heart and lung vibration signals. Specifically, the cardiopulmonary vibration signals of the user act on the silica gel blocks of each sensing probe in the sensing probe array; the heart-lung vibration signal acts on the elastic diaphragm through the silica gel block, and the elastic diaphragm deforms along with the heart-lung vibration signal, so that the grid distance of the sensing grating adhered below the elastic diaphragm changes, and the wavelength of reflected light of the sensing grating changes; under the influence of ambient temperature, the reflected light wavelengths of the reference grating and the sensing grating change with the same trend along with the temperature; acquiring ambient temperature change through the reference grating, and correcting an output signal of the sensing grating to compensate sensing grating measurement deviation caused by the ambient temperature change; under the action of the cardiopulmonary vibration signal, the reflected light wavelength of the sensing grating deviates from the central wavelength, and the cardiopulmonary vibration signal can be obtained according to the wavelength variation, wherein the central wavelength is the reflected light wavelength of the sensing grating when no stress acts.
Hereinafter, a fiber grating vital sign monitoring device according to an embodiment of the present application will be described in detail by way of specific example with reference to fig. 1 to 3.
Referring to fig. 1, the present application provides a fiber bragg grating vital sign monitoring device, which includes: the device comprises a broadband light source 1, a first optical fiber circulator 2, a sensing probe array 3, an optical switch 4 and a signal demodulation component 5.
A light source 1 for generating a first optical signal; a first optical fiber circulator 2 which receives a first optical signal from the broadband light source 1 and transmits the first optical signal to the optical switch 4; the sensing probe array 3 receives a first optical signal from the optical switch 4, the first optical signal is reflected and transmitted at the sensing probe array 3, and the reflected light is transmitted to the first optical fiber circulator 2 after passing through the optical switch 4; the signal demodulation component 5 receives the first optical signal from the first optical fiber circulator 2, and is used for acquiring the wavelength of reflected light of each optical fiber grating in the sensing probe array 3, and extracting vital sign information through signal processing.
Further, the first optical signal generated by the optical source 1 is a broadband optical source.
Further, the sensing probe array 3 comprises a sensing grating array and a reference grating array, the sensing grating array comprises a plurality of sensing gratings which are sequentially connected, the reference grating array comprises a plurality of reference gratings which are sequentially connected, one sensing probe is internally packaged with one sensing grating and one reference grating, and the reference grating signals are used for correcting the sensing grating signals so as to improve the performance of the vital sign sensor. Further, the sensor probe array 3 may be built into or disposed under or on a mattress or seat cushion.
Further, the sensor probe array 3 is used to acquire cardiopulmonary vibration signals of the user, including BCG signals and respiratory signals.
Further, when the user lies on or sits on the sensing probe array 3, the heart-lung vibration signal of the user's human body changes the grating pitch of the sensing gratings 32 at all positions in the sensing probe array 3, changes the wavelength of reflected light of the sensing gratings 32 at all positions, and can obtain the heart-lung vibration signal at all positions by detecting the wavelength change of reflected light of the sensing gratings 32 at all positions.
Further, an optical switch 4 is used for switching the sensing grating array and the reference grating array in the sensing probe array 3.
Further, the signal demodulation component 5 processes the reflected light to obtain spectrum information of the reflected light, obtains weak vibration signals of the human body at each sensing probe according to the spectrum information, and then extracts vital signs according to the weak vibration signals of the human body.
Further, the signal demodulation component 5 processes the heart-lung vibration signals of all places; and obtaining physiological information such as heart rate, respiratory rate, heart rate variability, human body pressure distribution and the like by utilizing the characteristics that the heart rate of an adult is 0.50 Hz-2.00 Hz, the respiratory rate is 0.16 Hz-0.50 Hz and the like.
Based on the further improvement of the device, the sensing probe array 3 comprises a plurality of sensing probes, as shown in fig. 2, and each sensing probe consists of an elastic diaphragm 31, a sensing grating 32, an annular base 33, an annular shell 34, a silica gel block 35, a grating tail fiber 36 and a reference grating 37.
Wherein the sensing grating 32 is fixedly connected with the elastic membrane 31 by glue; the annular base 33 is fixedly connected with the annular shell 34, and the elastic diaphragm 31 is fixed between the annular base 33 and the annular shell 34; the silica gel block 35 is positioned above the elastic membrane 31 and fixedly connected by using a gel; one end of the grating tail fiber 36 is connected with the sensing grating 32, and the other end is connected with the sensing grating in the first optical fiber circulator 2 or the previous sensing probe; the reference grating 37 is adhered to the upper portion of the annular base 33.
Further, the cardiopulmonary vibration signal acts on the elastic membrane 31 through the silica gel block 35, the elastic membrane 31 deforms accordingly, the grating pitch of the sensing grating 32 adhered below the elastic membrane 31 changes, the wavelength of reflected light of the sensing grating 32 changes, and the cardiopulmonary vibration signal acting on the silica gel block 35 can be obtained by detecting the wavelength change of reflected light.
Further, the height of the silicone block 35 is higher than the height of the annular housing 34, so that a human body can act on the elastic membrane 31 through the silicone block 35.
Based on the further improvement of the device, the signal demodulation component 5 comprises a monostable frequency light source 51, a fiber coupler 52, an F-P tunable filter 53, a photoelectric detector 54 and a digital signal processing unit 55; the monostable frequency light source 51 is used for generating a second optical signal; the optical fiber coupler 52 is used for combining the reflected light from the first optical fiber circulator 2 and the second optical signal into one path, and providing the combined light and the second optical signal to the photodetector 54 through the F-P tunable filter 53; the photodetector 54 is used for converting the synthesized optical signal into a first analog signal, and transmitting the first analog signal to the digital signal processing unit 55.
Meanwhile, the digital signal processing unit 55 outputs a triangular wave scanning signal to act on the F-P tunable filter 53 for periodically adjusting the cavity length of the F-P tunable filter 53; and the first analog signal is processed to obtain the change of the reflected light wavelength of each sensing grating 32, and the change of the reflected light wavelength of each reference grating 37 is obtained by switching the optical switch 4; the wavelength of reflected light of the sensing grating 32 in the same sensing probe is corrected by the wavelength of reflected light of the reference grating 37 in one sensing probe; the heart-lung vibration signals of all places can be obtained through the wavelength of the reflected light of the corrected sensing grating; processing heart and lung vibration signals at all positions to obtain physiological information such as heart rate, respiratory rate, heart rate variability, human body pressure distribution and the like.
Further, the monostable light source 51 is distinguished by good stability of the wavelength of light.
Based on the further improvement of the device, the digital signal processing circuit 55 comprises an AD module 551, a digital signal processing chip 552 and a DA module 553; the AD module 551 is configured to receive an analog electrical signal from the photodetector 54 and convert the analog electrical signal into a first digital signal; DA module 553 is used to convert the digital triangular wave signal generated by digital signal processing chip 552 into an analog signal and acts on F-P tunable filter 53.
Meanwhile, the digital signal processing chip 552 processes the digital signal from the AD module 551 to obtain the reflected light wavelengths of the sensing grating 32 and the reference grating 37 everywhere in the sensing array 3; the wavelength of reflected light of the sensing grating 32 in the same sensing probe is corrected by the wavelength of reflected light of the reference grating 37 in one sensing probe; the heart-lung vibration signals of all places can be obtained through the wavelength of the reflected light of the corrected sensing grating; processing heart and lung vibration signals at all positions to obtain physiological information such as heart rate, respiratory rate, heart rate variability, human body pressure distribution and the like.
Further, the digital signal processing chip 552 is an FPGA chip, an STM32 chip, or a DSP chip.
Further, the human cardiopulmonary vibration signal comprises a BCG signal and a respiratory signal; by utilizing the characteristics that the heart rate of an adult is 0.50 Hz-2.00 Hz, the respiration rate is 0.16 Hz-0.50 Hz and the like, the heart-lung vibration signal is inhibited from noise by using a band-pass filter, and further physiological information such as heart rate, respiration rate, heart rate variability, human body pressure distribution and the like is obtained.
The method for monitoring vital signs of the fiber bragg grating in the embodiment comprises the following steps:
step1: the sensing probe array 3 is arranged in the mattress or the seat cushion, or is arranged under the mattress or the seat cushion, or is arranged on the mattress or the seat cushion, and a user lies on the mattress or sits on the seat cushion; the first optical signal generated by the light source 1 reaches the sensing probe array 3 after passing through the first optical fiber circulator 2 and the optical switch 4;
step11: the sensing probe array 3 consists of a sensing grating array and a reference grating array, and the optical switch 4 is used for switching the sensing grating array and the reference grating array in the sensing probe array 3;
step2: the first optical signal is reflected and transmitted at the sensing probe array 3, and the reflected light returns to the first optical fiber circulator 2;
step21: the heart and lung vibration signals of the user act on the silica gel blocks 35 of each sensing probe in the sensing probe array 3;
step22: under the action of the cardiopulmonary vibration signal, the silica gel block 35 is elastically deformed and transmitted to the elastic diaphragm 31, and the elastic diaphragm 31 is deformed accordingly, so that the grating pitch of the sensing grating 32 adhered below the elastic diaphragm 31 is changed, and the wavelength of reflected light of the sensing grating 32 is changed; the reflected light wavelengths of the reference grating 37 and the sensing grating 32 will change with the same trend with temperature, which is affected by the ambient temperature and other factors;
step3: the reflected light of the first optical signal reaches the signal demodulation component 5 after passing through the first optical fiber circulator 2 and the optical switch 4, the signal demodulation component 5 obtains the wavelength of the reflected light of each sensing grating 32 of the sensing probe array 3, and the wavelength of the reflected light of each reference grating 37 is obtained by switching through the optical switch 4;
step31: in the signal demodulating component 5, the triangular wave scanning signal loaded on the F-P tunable filter 53 is shown in fig. 3, and is used for periodically controlling the cavity length thereof;
step32: after the first optical signal passes through the F-P tunable filter 53, a plurality of resonance peak signals appear in the electrical signal output by the first photodetector, as shown in fig. 3, and the relation between the transmittance T of the F-P tunable filter and the wavelength λ of incident light, and the cavity length L is:
；
in the above equation, R is the cavity mirror reflectivity, and each resonance peak signal in fig. 3 represents the wavelength spectrum of reflected light from each sensor grating 32.
Step33: the monostable frequency laser 51 generates a second optical signal for calibrating the F-P tunable filter 53, and under the action of the triangular wave scanning signal, the second photodetector outputs an electrical signal as shown in fig. 3, where the resonant wavelength in fig. 3 is the wavelength of the monostable frequency laser 51, and is a known quantity, and is used as a reference wavelength. The piezoelectric ceramics used for adjusting the cavity length in the F-P tunable filter 53 have non-ideal characteristics such as hysteresis and creep, and can cause wavelength demodulation errors, so the F-P tunable filter 53 is calibrated by a single frequency stabilized laser.
Step34: after the output electric signals of the first photoelectric detector and the second photoelectric detector are synchronously collected through two channels, the relative positions of the reflected light wavelength spectrum of the sensing grating 32 and the reference wavelength are obtained, the reflected light wavelength of each sensing grating 32 is demodulated, and the reflected light wavelength of each reference grating 37 is demodulated by switching the optical switch 4.
Step4: and correcting the reflected light wavelength of the sensing grating in the same sensing probe through the reflected light wavelength of the reference grating in the sensing probe, and obtaining the heart-lung vibration signals of all places through the corrected reflected light wavelength of the sensing grating.
Step5: and processing heart and lung vibration signals of all parts by utilizing the characteristics of the heart rate of an adult at 0.50 Hz-2.00 Hz, the breathing rate at 0.16 Hz-0.50 Hz and the like to obtain physiological information such as heart rate, breathing rate, heart rate variability, human body to bed pressure distribution and the like.
Those skilled in the art will appreciate that all or part of the flow of the methods of the embodiments described above may be accomplished by way of a computer program to instruct associated hardware, where the program may be stored on a computer readable storage medium. Wherein the computer readable storage medium is a magnetic disk, an optical disk, a read-only memory or a random access memory, etc.
The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application.
Claims (10)
1. A fiber grating vital sign monitoring device, comprising:
a light source for generating a first optical signal;
the first optical fiber circulator is used for receiving the first optical signal and transmitting the first optical signal to the sensing probe array;
the sensing probe array is used for sensing weak vibration signals of a human body, so that the first optical signals are reflected at each sensing probe of the sensing probe array, and reflected light returns to the first optical fiber circulator; and
the signal demodulation component is used for receiving the reflected light from the first optical fiber circulator, processing the reflected light to obtain spectrum information of the reflected light, obtaining weak vibration signals of the human body at each sensing probe according to the spectrum information, and extracting vital signs according to the weak vibration signals of the human body.
2. The fiber grating vital sign monitoring device of claim 1, wherein the sensing probe array comprises a sensing grating array and a reference grating array,
the sensing grating array comprises a plurality of sensing gratings which are sequentially connected, and the reference grating array comprises a plurality of reference gratings which are sequentially connected, wherein one sensing probe is internally packaged with one sensing grating and one reference grating.
3. The fiber grating vital sign monitoring device of claim 2, further comprising an optical switch for connection between the first fiber circulator and the sensing probe array, the signal demodulation component receiving the reflected light via the optical switch and the first fiber circulator, wherein the reflected light is reflected light by a sensing grating array of the sensing probe array prior to switching of the optical switch; the reflected light is reflected light of a reference grating array in the sensing probe array through the switching of the optical switch;
the wavelength of the reflected light of the sensing grating is corrected by referring to the wavelength of the reflected light of the grating, the measuring deviation of the sensing grating caused by the change of the ambient temperature is compensated, and the weak vibration signals of the human body at each position of the sensing probe array are obtained by the corrected wavelength of the reflected light of the sensing grating, and vital signs are extracted according to the weak vibration signals of the human body.
4. A fiber grating vital sign monitoring device according to claim 3, wherein the sensing probe comprises:
the annular shell is fixedly connected with the outer wall of the annular base;
a reference grating disposed at a bottom portion within the cavity of the annular base;
the sensing grating is arranged at the top part in the cavity of the annular base and is adhered below the elastic membrane;
the silica gel block is above the elastic membrane and is fixedly connected with the elastic membrane, wherein the top surface of the silica gel block is higher than the top surface of the annular shell, so that the human body part acts on the elastic membrane through the silica gel block; and
and the optical fiber tail fiber passes through the opposite side walls of the annular base and the annular shell and is used as an input and output end.
5. The fiber grating vital sign monitoring device of claim 4, wherein the fiber optic pigtail comprises a first fiber optic pigtail and a second fiber optic pigtail, wherein,
one end of the first optical fiber tail fiber is connected with the sensing grating, and the other end of the first optical fiber tail fiber is connected with the sensing grating in another sensing probe or connected with the first optical fiber circulator through an optical switch; and
one end of the second optical fiber pigtail is connected with the reference grating, and the other end of the second optical fiber pigtail is connected with the reference grating in the other sensing probe or connected with the first optical fiber circulator through an optical switch.
6. The fiber bragg grating vital sign monitoring device according to claim 4, wherein the weak vibration signal of the human body comprises a heart-lung vibration signal, the human body acts on the elastic membrane through the silica gel block, the elastic membrane deforms accordingly, the grating pitch of the sensing grating adhered below the elastic membrane changes, the wavelength of reflected light of the sensing grating changes, and the signal demodulation component obtains the heart-lung vibration signal at the silica gel block according to the wavelength of reflected light.
7. The fiber grating vital sign monitoring device of claim 4, wherein the signal demodulation assembly comprises:
a monostable frequency light source for generating a second optical signal;
the optical fiber coupler is used for combining the second optical signal and the reflection light from the first optical fiber circulator into one path and providing the combined path for the photoelectric detector through the F-P tunable filter;
the photoelectric detector is used for converting the synthesized optical signals into first analog signals and transmitting the first analog signals to the digital signal processing unit;
the digital signal processing unit is used for enabling the generated triangular wave scanning signal to act on the F-P tunable filter, processing the first analog signal to obtain a spectrum of the reflected light of the sensing grating array, and then obtaining a spectrum of the reflected light of the reference grating array through switching of the optical switch; and acquiring a heart-lung vibration signal based on the spectrum of the light reflected by the sensing grating array and the spectrum of the light reflected by the reference grating array.
8. The fiber grating vital sign monitoring device of claim 7, wherein the digital signal processing unit comprises:
the AD module is used for converting the first analog signal into a first digital signal;
the DA module is used for generating a triangular wave scanning signal so as to periodically adjust the cavity length of the F-P tunable filter;
the digital signal processing chip is used for generating a second digital signal according to the first digital signal, transmitting the second digital signal to the DA module, processing the first digital signal, obtaining the spectrum of the reflected light of the sensing grating array and the spectrum of the reflected light of the reference grating array in a time-sharing mode according to the switching state of the optical switch, correcting the reflected light wavelength of the sensing grating in the same sensing probe through the reflected light wavelength of the reference grating in one sensing probe, compensating the sensing grating measurement deviation caused by the change of the ambient temperature, and obtaining the heart-lung vibration signals at the positions of each sensing probe according to the corrected wavelength of the reflected light of the sensing grating.
9. The fiber bragg grating vital sign monitoring method is characterized by comprising the following steps of:
the sensing probe array is arranged in a mattress or a seat cushion, arranged under the mattress or the seat cushion, or arranged on the mattress or the seat cushion, and a user lies on the mattress or sits on the seat cushion;
the first optical signal generated by the light source is provided to the sensing probe array through the first optical fiber circulator and the optical switch;
the sensing probe array senses a weak human body vibration signal, the weak human body vibration signal enables the spectrum of the reflected light of the first optical signal at the sensing probe array to change, and the reflected light returns to the first optical fiber circulator;
the reflected light reaches a signal demodulation assembly after passing through an optical switch and the first optical fiber circulator, the signal demodulation module obtains a spectrum of reflected light of a sensing grating array in the sensing probe array, and then the spectrum of reflected light of a reference grating array in the sensing probe array is obtained through switching of the optical switch;
the method comprises the steps of correcting the wavelength of reflected light of a sensing grating in the same sensing probe through the wavelength of reflected light of a reference grating in the sensing probe, compensating the measurement deviation of the sensing grating caused by the change of the ambient temperature, obtaining weak vibration signals of human bodies at each position of a sensing probe array through the wavelength of the reflected light of the corrected sensing grating, and extracting vital signs according to the weak vibration signals of the human bodies.
10. The fiber grating vital sign monitoring method of claim 9, wherein the human weak vibration signal comprises a cardiopulmonary vibration signal that changes a spectrum of light reflected by the first optical signal at the sensing probe array, the returning of the reflected light to the first optical fiber circulator comprising:
the heart and lung vibration signals of the user act on the silica gel blocks of each sensing probe in the sensing probe array;
the cardiopulmonary vibration signal acts on the elastic diaphragm through the silica gel block, and the elastic diaphragm deforms along with the vibration signal, so that the grid distance of the sensing grating adhered below the elastic diaphragm changes, and the wavelength of the reflected light of the sensing grating changes;
under the influence of ambient temperature, the reflected light wavelengths of the reference grating and the sensing grating can change with the same trend along with the temperature; acquiring ambient temperature change through the reference grating, and correcting an output signal of the sensing grating to compensate sensing grating measurement deviation caused by the ambient temperature change;
the reflected light wavelength of the sensing grating deviates from the central wavelength under the action of the cardiopulmonary vibration signal so as to obtain the cardiopulmonary vibration signal according to the wavelength variation, wherein the central wavelength is the reflected light wavelength of the sensing grating when no stress acts.
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