CN115444406A - Intensity modulation type optical fiber vital sign monitoring device - Google Patents
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- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/024—Detecting, measuring or recording pulse rate or heart rate
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- A—HUMAN NECESSITIES
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- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
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Abstract
The invention discloses an intensity modulation type optical fiber vital sign monitoring device which comprises a light source, an optical fiber coupler, a first photoelectric detector, an optical fiber sensing probe, an air cushion, a second photoelectric detector and a signal processing unit, wherein the light source generates an optical signal; the optical fiber coupler divides the optical signal into a first optical signal and a second optical signal; the first photoelectric detector converts the first optical signal into a first electric signal; the air cushion acquires a vibration signal of a user and converts the vibration signal into a sound wave signal; the optical fiber sensing probe modulates the optical power of the second optical signal by using the acoustic wave signal; the second photoelectric detector converts a second optical signal from the optical fiber sensing probe into a second electric signal; the signal processing unit obtains the ratio information of the second electric signal and the first electric signal and extracts the vital sign information of the user. The sensing optical fiber part can be arranged at the corner of the air cushion or the extended air duct of the air cushion, other air cushion areas can be bent, the optical fiber does not need to be coiled inside the sensing cushion, and the manufacturing difficulty is reduced.
Description
Technical Field
The invention belongs to the technical field of vital sign monitoring, and particularly relates to an intensity modulation type optical fiber vital sign monitoring device.
Background
The ballistocardiogram signal is a weak change of the external pressure on the surface of a human body caused by the heart beating and the arterial blood flow, and is a weak human body vibration signal which can be acquired in a non-contact mode. In the process of transmitting the ballistocardiogram signal to the body surface of the human body, the volume of the chest cavity is changed due to the respiration effect, so that the respiration signal is superposed on the ballistocardiogram signal, and the weak vibration signal of the human body comprises the ballistocardiogram signal and the respiration signal.
At present, the detection method of human body weak vibration signals mainly adopts a piezoelectric sensing method and an optical fiber sensing method. Compared with a piezoelectric sensing method, the optical fiber sensing method has the advantages of electromagnetic interference resistance, good safety, capability of detecting micro static force and dynamic force and the like, and is concerned. Depending on the type of fiber optic sensor, existing fiber optic vital sign sensors can be classified into microbend fiber optic vital sign sensors based on intensity modulation, fiber grating vital sign sensors based on wavelength modulation, and fiber optic interferometer vital sign sensors based on phase modulation.
In prior art, the form that optic fibre sensing mat was all made to above three kinds of optic fibre vital sign sensors, and the human top that is located optic fibre sensing mat, optic fibre are located the inside (the human below) of optic fibre sensing mat, and the human response characteristic influence to optic fibre vital sign sensor for the position of optic fibre is great, and when the below of human position was not laid optic fibre, optic fibre vital sign sensor can't effectively perceive human weak vibration signal to influence the accuracy that vital sign detected. In addition, the microbend optical fiber vital sign sensor has the problems that the labor cost is high when the optical fiber is coiled in the sensing mat, the measurement performance is influenced by the light power fluctuation of a light source, and the like; the fiber grating vital sign sensor has the problems that the cost is difficult to reduce and the like under the condition that the precision is ensured by wavelength demodulation equipment.
Disclosure of Invention
In order to ensure that the measurement performance of the optical fiber vital sign sensor is not influenced by the position of a human body, the invention provides the intensity modulation type optical fiber vital sign monitoring device, which transmits a weak vibration signal of the human body to the intensity modulation type optical fiber microphone through the air cushion, and realizes the monitoring of vital signs such as heart rate, respiratory rate and the like under the non-inductive state of a user. The technical problem to be solved by the invention is realized by the following technical scheme:
the invention provides an intensity modulation type optical fiber vital sign monitoring device, which comprises a light source, an optical fiber coupler, a first photoelectric detector, an optical fiber sensing probe, an air cushion, a second photoelectric detector and a signal processing unit, wherein,
the light source is used for generating a light signal and transmitting the light signal to the optical fiber coupler; the optical fiber coupler is used for dividing the optical signal into a first optical signal and a second optical signal; the first photodetector is used for receiving the first optical signal and converting the first optical signal into a first electric signal;
the air cushion is used for acquiring a vibration signal of a user positioned on the air cushion and converting the vibration signal into a sound wave signal inside the air cushion; the optical fiber sensing probe is arranged in the air cushion and connected with the optical fiber coupler, and is used for receiving the second optical signal and modulating the optical power of the second optical signal by using the acoustic wave signal from the inside of the air cushion, so that the optical power of the second optical signal output to the second photoelectric detector changes along with the change of the acoustic wave signal; the second photoelectric detector is used for converting a second optical signal from the optical fiber sensing probe into a second electric signal;
the signal processing unit is respectively connected with the first photoelectric detector 3 and the second photoelectric detector, and is used for obtaining the ratio information of the second electric signal and the first electric signal in real time, and extracting the ballistocardiogram signal, the respiration signal and the vital sign information of the user from the ratio information.
In one embodiment of the invention, the fiber optic sensing probe includes an elastomeric diaphragm, a fiber optic assembly, and a sensing probe housing, wherein,
the optical fiber assembly is connected between the optical fiber coupler and the second photoelectric detector and used for transmitting a second optical signal output by the optical fiber coupler to the elastic diaphragm, and the elastic diaphragm can reflect the second optical signal and transmit the second optical signal to the second photoelectric detector through the optical fiber assembly; the elastic diaphragm is vertically fixed at one end of the shell of the sensing probe and can deform under the action of sound pressure, so that the optical power of the optical signal output by the optical fiber sensing probe changes.
In one embodiment of the invention, the fiber assembly includes an optical path circulator, a first measurement fiber, and a single fiber collimator, wherein,
the optical path circulator comprises at least three ports, wherein a first port is connected with the optical fiber coupler, a second port is connected with the single fiber collimator through the first measuring optical fiber, and a third port is connected with the second photoelectric detector; the single-fiber collimator penetrates through the first side wall of the sensing probe shell, so that the end face of the single-fiber collimator is located in the hollow interior of the sensing probe shell and is parallel to and spaced from the surface of the elastic diaphragm.
In one embodiment of the present invention, the optical circuit looping device is a fiber coupler or a fiber circulator.
In one embodiment of the invention, the single-fiber collimator is fixed to an end of the sensing probe housing opposite the elastic diaphragm by an adhesive.
In one embodiment of the invention, the fiber assembly comprises a second measurement fiber, a third measurement fiber, and a dual fiber collimator, wherein,
the first end of the second measuring optical fiber is connected with the optical fiber coupler, and the second end of the second measuring optical fiber is connected with the double-fiber collimator;
the first end of the third measuring optical fiber is connected with the second photoelectric detector, and the second end of the third measuring optical fiber is connected with the double-fiber collimator;
the double-fiber collimator penetrates through the first side wall of the sensing probe shell, so that the end face of the double-fiber collimator is located in the hollow interior of the sensing probe shell, is parallel to the surface of the elastic membrane and keeps a space with the elastic membrane.
In one embodiment of the invention, the second measuring fiber and the third measuring fiber are of the type single mode fiber, multimode fiber or polarization maintaining fiber.
In one embodiment of the invention, the light source is an incoherent light source, and the first photodetector and the second photodetector are photodiodes.
In one embodiment of the present invention, the signal processing unit comprises a power supply module, a first amplification module, a second amplification module, a first AD module, a second AD module, and a digital signal processing module, wherein,
the power supply module is used for supplying power to the light source, the first photoelectric detector, the second photoelectric detector and the signal processing unit;
the first amplifying module is used for amplifying a first electric signal output by the first photodetector to obtain a first analog electric signal, and the first AD module is used for converting the first analog electric signal into a first digital electric signal;
the second amplifying module is used for amplifying a second electric signal output by the second photodetector to obtain a second analog electric signal, and the second AD module is used for converting the second analog electric signal into a second digital electric signal;
the digital signal processing module is used for acquiring ratio information of the second digital electric signal and the first digital electric signal in real time, and extracting a ballistocardiogram signal, a breathing signal and vital sign information of a user from the ratio information.
Compared with the prior art, the invention has the beneficial effects that:
1. the intensity modulation type optical fiber vital sign monitoring device can arrange the optical fiber sensing head at one corner of the air cushion or the extended air duct thereof, and the other air cushion area can be bent to ensure that the intensity modulation type optical fiber vital sign monitoring device can still effectively sense heartbeat signals and respiration signals when a human body part contacts the air cushion.
2. Compared with an electrical sensor for detecting a weak human body vibration signal, the intensity modulation type optical fiber vital sign monitoring device provided by the invention has the advantages that the optical fiber sensor is adopted for detecting the weak human body vibration signal, the air cushion part runs without electricity, the output and the output of the optical signal in the air cushion can be remotely transmitted through optical fibers, the optical fiber vital sign monitoring device has the advantages of electromagnetic interference resistance, corrosion resistance, remote signal transmission and the like, and is suitable for being used in scenes such as nuclear magnetic resonance imaging examination and the like.
3. According to the intensity modulation type optical fiber vital sign monitoring device, the weak vibration signal of a user is represented by the ratio information of the second digital electric signal and the first digital electric signal, and the measurement error caused by the fluctuation of the light power of the light source can be effectively inhibited.
4. Compared with the microbend optical fiber vital sign detection device, the intensity modulation type optical fiber vital sign monitoring device provided by the invention does not need to coil optical fibers in the sensing mat, so that the manufacturing difficulty is greatly reduced.
5. Compared with the fiber grating vital sign detection device, the intensity modulation type fiber vital sign monitoring device obtains the weak vibration signal of the user by demodulating the light intensity information, does not need expensive wavelength demodulation equipment, and greatly reduces the cost.
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Drawings
Fig. 1 is a schematic structural diagram of an intensity-modulated optical fiber vital sign monitoring apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an optical fiber sensing probe according to an embodiment of the present invention;
fig. 3 is a block diagram of a signal processing unit according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another optical fiber sensing probe provided in the embodiment of the present invention.
Description of the reference numerals:
1-a light source; 2-a fiber optic coupler; 3-a first photodetector; 4-optical fiber sensing probe; 41-elastic membrane; 42-sensing probe housing; 43-optical path circulator; 44-a first measuring fiber; 45-single fiber collimator; 46-a binder; 47-a second measuring fiber; 48-a third measuring fiber; 49-double fiber collimator; 5, air cushion; 6-a second photodetector; 7-a signal processing unit; 71-a power supply module; 72-a first amplification module; 73-a second amplification module; 74-a first AD module; 75-a second AD module; 76-a digital signal processing module; 77-output module.
Detailed Description
To further explain the technical means and effects of the present invention adopted to achieve the predetermined objects, an intensity-modulated optical fiber vital sign monitoring device according to the present invention is described in detail below with reference to the accompanying drawings and the detailed description.
The foregoing and other technical matters, features and effects of the present invention will be apparent from the following detailed description of the embodiments, which is to be read in connection with the accompanying drawings. While the present invention has been described in connection with the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or device that comprises a list of elements does not include only those elements but may include other elements not expressly listed. Without further limitation, an element defined by the phrases "comprising one of \8230;" does not exclude the presence of additional like elements in an article or device comprising the element.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an intensity modulation type optical fiber vital sign monitoring device according to an embodiment of the present invention. The monitoring device comprises a light source 1, an optical fiber coupler 2, a first photoelectric detector 3, an optical fiber sensing probe 4, an air cushion 5, a second photoelectric detector 6 and a signal processing unit 7.
The light source 1 is used for generating an optical signal and is incident to the optical fiber coupler 2; the optical fiber coupler 2 is configured to receive an optical signal from the optical source 1 and split the optical signal into a first optical signal and a second optical signal, where the first optical signal and the second optical signal are output from a first port and a second port of the optical fiber coupler 2, respectively; the first photoelectric detector 3 is connected to the first port of the optical fiber coupler 2, and is configured to receive the first optical signal and convert the first optical signal into a first electrical signal; the air cushion 5 is used for acquiring weak vibration signals of a user positioned on the air cushion 5 and converting the weak vibration signals of the user into sound wave signals inside the air cushion 5; the first port of the optical fiber sensing probe 4 is connected with the second port of the optical fiber coupler 2 and is used for receiving the second optical signal; the optical fiber sensing probe 4 is arranged in the air cushion 5 and used for sensing the sound wave signal and modulating the optical power of the second optical signal by using the sound wave signal, so that the optical power of the second optical signal output by the optical fiber sensing probe 4 changes along with the change of the weak vibration signal; the second photodetector 6 is connected to the second port of the optical fiber sensing probe 4, and is configured to receive the modulated second optical signal output from the optical fiber sensing probe 4 and convert the modulated second optical signal into a second electrical signal; the signal processing unit 7 is connected with the first photoelectric detector 3 and the second photoelectric detector 6, and is used for obtaining ratio information of the second electric signal and the first electric signal in real time, wherein the ratio information can represent the strength of weak vibration signals of a user positioned on the air cushion; the signal processing unit 7 is used for extracting the ballistocardiogram signal and the respiration signal of the user from the ratio information, and extracting the vital sign information such as the heart rate and the respiration rate from the ballistocardiogram signal and the respiration signal.
During use, the air cushion 5 can be arranged on a chair, or in a pillow, or under a mattress, or built-in a mattress, or placed on a mattress, and a user lies on the bed or sits on the air cushion 5.
The light source 1 of the present embodiment is a light emitting diode, and the emitted light signal is incoherent light to suppress coherent noise in the light path. The first photodetector 3 and the second photodetector 6 of the present embodiment are both photodiodes; the air cushion 5 is filled with foam plastics and is used for supporting the shape of the air cushion; the optical fiber coupler 2 of the present embodiment is a 2 × 2 optical fiber coupler or a 1 × 2 optical fiber coupler, and the type of the optical fiber for manufacturing the optical fiber coupler is a single mode optical fiber, a multimode optical fiber or a polarization maintaining optical fiber; the splitting ratio of the optical fiber coupler 2 of the present embodiment is about 50.
Referring to fig. 2, fig. 2 is a schematic structural diagram of an optical fiber sensing probe according to an embodiment of the present invention. The optical fiber sensing probe 4 of the present embodiment includes an elastic diaphragm 41, an optical fiber assembly and a sensing probe housing 42, wherein the optical fiber assembly is connected between the optical fiber coupler 2 and the second photodetector 6, and is configured to transmit a second optical signal output by the optical fiber coupler 2 to the elastic diaphragm 41, and the elastic diaphragm 41 can reflect the second optical signal and transmit the second optical signal to the second photodetector 6 through the optical fiber assembly; the elastic diaphragm 41 is vertically fixed at one end of the sensing probe shell 42 and can deform under the action of sound pressure, so that the optical power of the optical signal output by the optical fiber sensing probe 4 changes.
Further, the optical fiber assembly of the present embodiment includes an optical path circulator 43, a first measurement optical fiber 44, and a single-fiber collimator 45, where the optical path circulator 43 includes at least three ports, a first port is connected to the optical fiber coupler 2, a second port is connected to the single-fiber collimator 45 through the first measurement optical fiber 44, and a third port is connected to the second photodetector 6; the single fiber collimator 44 passes through a first side wall of the sensing probe housing 42 such that an end face of the single fiber collimator 44 is located within the hollow interior of the sensing probe housing 42 and is parallel to and spaced apart from a surface of the elastic diaphragm 41.
In the present embodiment, the sensing probe housing 42 is a rectangular or cylindrical hollow structure made of a capillary glass tube or a metal tube, the sensing probe housing 42 has an open structure at the left and right sides, and one side is fixed by the elastic diaphragm 41 during the assembly process, in other words, the elastic diaphragm 41 is used as one side wall of the sensing probe housing 42. On the other hand, one end of the single fiber collimator 44 is fixed on the other side of the sensing probe housing 42 opposite to the elastic diaphragm 41 by an adhesive 46; the optical fiber sensing probe 4 is positioned in the air cushion 5 or at the position of an air duct extending out of the air cushion. It should be noted that the single collimator 44 is spaced apart from the elastic diaphragm 41 so that the elastic diaphragm 41 does not contact with the single collimator 44 even if the elastic diaphragm is bent to be close to the single collimator 44.
When a user's weak vibration signal on the air cushion acts on the elastic membrane 41 through the air cushion 5, the elastic membrane 41 deforms under the action of the weak vibration and changes the distance from the single-fiber collimator 44, so that the optical power reflected into the single-fiber collimator 44 changes. Under the condition that other parameters are not changed, the optical power entering the single fiber collimator 44 depends on the distance between the input/output end face thereof and the elastic membrane 41, and the distance between the input/output end face of the single fiber collimator 44 and the elastic membrane 41 can be obtained by detecting the change of the optical power, so as to obtain a weak vibration signal of a user.
The elastic diaphragm 41 of the present embodiment is made of a polyester film having a circular arc shape or a flat shape, which is plated for the purpose of increasing the light reflectance, and is preferably a metal plated film. The single fiber collimator 44 in this embodiment is formed by aligning and packaging a single fiber pigtail and a lens, wherein the lens can be replaced by a multimode fiber; the light incident/exiting end surface of the single fiber collimator 44 is parallel to the plane of the elastic diaphragm 41, and is kept at a certain distance.
Further, referring to fig. 3, fig. 3 is a block diagram of a signal processing unit 7 according to an embodiment of the present invention. The signal processing unit 7 of the present embodiment includes a power module 71, a first amplifying module 72, a second amplifying module 73, a first AD module 74, a second AD module 75, a digital signal processing module 76, and an output module 77. The power module 71 is configured to supply power to the light source 1, the first photodetector 3, the second photodetector 6, and the signal processing unit 7, the first amplifying module 72 is configured to amplify a first electrical signal output by the first photodetector 3 to obtain a first analog electrical signal, the first AD module 74 is configured to convert the first analog electrical signal output by the first amplifying module 72 into a first digital electrical signal, the second amplifying module 73 is configured to amplify a second electrical signal output by the second photodetector 6 to obtain a second analog electrical signal, the second AD module 75 is configured to convert the second analog electrical signal output by the second amplifying module 73 into a second digital electrical signal, the digital signal processing module 76 is configured to obtain ratio information between the second digital electrical signal and the first digital electrical signal in real time, the ratio information represents the strength of a weak vibration signal of a user on the air cushion, and the digital signal processing module 76 extracts a ballistocardiogram signal and a respiration signal of the user from the ratio information, and extracts vital sign information such as a heart rate and a respiration rate from the ballistocardiogram signal and the respiration signal. The core chip of the digital signal processing module 76 of this embodiment is a single chip, DSP or FPGA.
According to the embodiment, the strength of the weak vibration signal of the user is represented by the ratio information of the second digital electric signal and the first digital electric signal, but not by the second digital electric signal, so that the measurement error caused by the output light power fluctuation of the light source can be effectively inhibited.
The working process of the intensity modulation type optical fiber vital sign monitoring device of the embodiment is as follows:
the air cushion 5 is arranged on a bed or a chair, a person lies or sits on the air cushion 5, and an optical signal emitted by the light source 1 is divided into two beams of light, namely a first optical signal and a second optical signal, through the optical fiber coupler 2; the first optical signal enters the first photodetector 3 and is converted into a first electrical signal by the first optical signal; the second optical signal enters the first port of the optical path circulator 43 to reach the second port, and enters the single-fiber collimator 44; the second optical signal is collimated and expanded by the single-fiber collimator 44 and reaches the elastic membrane 41; when a weak vibration signal of a user on the air cushion acts on the elastic diaphragm 41 through the air cushion 5, the distance between the elastic diaphragm 41 and the single-fiber collimator 44 changes, so that the optical power of the second optical signal reflected and coupled into the single-fiber collimator 44 changes; the second optical signal enters the second photoelectric detector 6 from the third port of the optical path circulator 43 through the single-fiber collimator 44, and is converted into a second electrical signal by the second optical signal, and then the first electrical signal and the second electrical signal are processed by the signal processing unit 7, so that ratio information of the second digital electrical signal and the first digital electrical signal is obtained in real time, the ratio information represents the strength of a weak vibration signal of a user on the air cushion, a ballistocardiogram signal and a respiration signal of the user are extracted from the ratio information, vital sign information such as heart rate and respiration rate is extracted from the ballistocardiogram signal and the respiration signal, and the measurement error caused by optical power fluctuation of the light source can be effectively inhibited by obtaining the weak vibration signal of the user through the ratio information.
The intensity modulation type optical fiber vital sign monitoring device of this embodiment can be located the air duct department that certain edge of air cushion or its extension were located with optical fiber sensing probe part, and other air cushion regions can buckle, need not to coil optic fibre in sensing pad inside, have reduced the preparation degree of difficulty. And the optical fiber sensor is adopted to detect a weak vibration signal of a human body, the air cushion part runs without electricity, the output and output of an optical signal in the air cushion can realize remote transmission through optical fibers, and the optical fiber sensor has the advantages of electromagnetic interference resistance, corrosion resistance, remote signal transmission and the like, and is suitable for scenes such as nuclear magnetic resonance imaging examination and the like.
Example two
On the basis of the first embodiment, the present embodiment provides another optical fiber sensing probe, please refer to fig. 4, where the optical fiber sensing probe 4 includes an elastic diaphragm 41, an optical fiber assembly and a sensing probe housing 42, where the optical fiber assembly is connected between the optical fiber coupler 2 and the second photodetector 6, and is used for transmitting the second optical signal output by the optical fiber coupler 2 to the elastic diaphragm 41, and the elastic diaphragm 41 can reflect the second optical signal and transmit the second optical signal to the second photodetector 6 through the optical fiber assembly; the elastic diaphragm 41 is vertically fixed at one end of the sensing probe shell 42 and can deform under the action of sound pressure, so that the optical power of the optical signal output by the optical fiber sensing probe changes.
The optical fiber assembly of the present embodiment comprises a second measuring optical fiber 47, a third measuring optical fiber 48 and a dual-fiber collimator 49, wherein the first end of the second measuring optical fiber 47 is connected to the optical fiber coupler 2, and the second end is connected to the dual-fiber collimator 49; the first end of the third measuring optical fiber 48 is connected with the second photoelectric detector 6, and the second end is connected with the double-fiber collimator 49; a dual fiber collimator 49 passes through a first side wall of the sensing probe housing 42 such that an end face of the dual fiber collimator 49 is located in the hollow interior of the sensing probe housing 42 and is parallel to the surface of the flexible diaphragm 41 and spaced from the flexible diaphragm 41.
In the present embodiment, the sensing probe housing 42 is a rectangular or cylindrical hollow structure made of a capillary glass tube or a metal tube, the sensing probe housing 42 has an open structure at the left and right sides, and one side is fixed by the elastic diaphragm 41 during the assembly process, in other words, the elastic diaphragm 41 is used as one side wall of the sensing probe housing 42. On the other hand, a two-fiber collimator 49 is fixed on the other side of the sensing probe housing 42 opposite to the elastic diaphragm 41 by an adhesive 46; the fiber sensing probe 4 is located inside the air cushion 5. It should be noted that the dual-fiber collimator 49 is spaced from the elastic diaphragm 41 so that the elastic diaphragm 41 does not contact the dual-fiber collimator 49 even if it is bent to approach the dual-fiber collimator 49.
When a weak vibration signal of a user on the air cushion acts on the elastic diaphragm 41 through the air cushion 5, the elastic diaphragm 41 deforms under the action of the weak vibration signal and slightly changes the distance between the elastic diaphragm and the dual-fiber collimator 49, so that the optical power reflected into the dual-fiber collimator 49 correspondingly changes. Under the condition that other parameters are not changed, the optical power entering the dual-fiber collimator 49 depends on the distance between the input/output end face and the elastic membrane 41, and the distance between the input/output end face of the dual-fiber collimator 49 and the elastic membrane 41 can be obtained by detecting the change of the optical power, so that a weak vibration signal of a user can be obtained.
The dual-fiber collimator 49 of the present embodiment is formed by aligning and packaging a dual-fiber pigtail and a lens, wherein the lens can be replaced by a multi-mode fiber, and the light incident/emergent end surface of the lens is parallel to the plane of the elastic membrane 41, and a certain distance is kept between the two.
The working process of the vital sign monitoring device based on the strength type optical fiber microphone is as follows:
the air cushion 5 is arranged on a bed or a chair, a person lies or sits on the air cushion 5, and an optical signal emitted by the light source 1 is divided into two beams of light, namely a first optical signal and a second optical signal, by the optical fiber coupler 2; the first optical signal enters the first photodetector 3 and is converted into a first electrical signal by the first optical signal; the second optical signal enters the dual-fiber collimator 49 through the first port of the dual-fiber collimator 49, is collimated and expanded by the dual-fiber collimator 49, and reaches the elastic membrane 41; when a weak vibration signal of a user on the air cushion acts on the elastic diaphragm 41 through the air cushion 5, the distance between the elastic diaphragm 41 and the dual-fiber collimator 49 changes, so that the optical power of the second optical signal reflected and coupled into the dual-fiber collimator 49 changes; the second optical signal reaches the second photodetector 6 through the second port of the dual-fiber collimator 49; the second photodetector 6 converts the second optical signal into a second electrical signal. Subsequently, the signal processing unit 7 is used for processing the first electric signal and the second electric signal, the analog signal is converted into a digital signal, ratio information of the second digital electric signal and the first digital electric signal is obtained in real time, the ratio information represents the strength of a weak vibration signal of a user on the air cushion, a ballistocardiogram signal and a respiration signal of the user are extracted from the ratio information, vital sign information such as a heart rate and a respiration rate is extracted from the ballistocardiogram signal and the respiration signal, the weak vibration signal of the user is obtained through the ratio information, and a measurement error caused by light power fluctuation of the light source can be effectively inhibited. According to the intensity modulation type optical fiber vital sign monitoring device, the weak vibration signal of a user is represented by the ratio information of the second digital electric signal and the first digital electric signal, so that the measurement error caused by the fluctuation of the light power of the light source can be effectively inhibited; the weak vibration signal of the user is obtained by demodulating the light intensity information, expensive wavelength demodulation equipment is not needed, and the cost is greatly reduced.
The foregoing is a further detailed description of the invention in connection with specific preferred embodiments and it is not intended to limit the invention to the specific embodiments described. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (9)
1. An intensity modulation type optical fiber vital sign monitoring device is characterized by comprising a light source (1), an optical fiber coupler (2), a first photoelectric detector (3), an optical fiber sensing probe (4), an air cushion (5), a second photoelectric detector (6) and a signal processing unit (7), wherein,
the light source (1) is used for generating an optical signal and is incident to the optical fiber coupler (2); the optical fiber coupler (2) is used for dividing the optical signal into a first optical signal and a second optical signal; the first photodetector (3) is used for receiving the first optical signal and converting the first optical signal into a first electric signal;
the air cushion (5) is used for acquiring a vibration signal of a user positioned on the air cushion (5) and converting the vibration signal into a sound wave signal inside the air cushion (5); the optical fiber sensing probe (4) is arranged inside the air cushion (5) and connected with the optical fiber coupler (2) and is used for receiving the second optical signal and modulating the optical power of the second optical signal by using an acoustic wave signal from the inside of the air cushion (5), so that the optical power of the second optical signal output to the second photoelectric detector (6) is changed along with the change of the acoustic wave signal; the second photoelectric detector (6) is used for converting a second optical signal from the optical fiber sensing probe (4) into a second electric signal;
the signal processing unit (7) is respectively connected with the first photoelectric detector (3) and the second photoelectric detector (6) and is used for acquiring ratio information of the second electric signal and the first electric signal in real time and extracting ballistocardiogram signals, respiration signals and vital sign information of a user from the ratio information.
2. Intensity modulated fiber optic vital signs monitoring device according to claim 1, wherein the fiber optic sensing probe (4) comprises an elastic membrane (41), a fiber optic assembly and a sensing probe housing (42), wherein,
the optical fiber assembly is connected between the optical fiber coupler (2) and the second photodetector (6) and is used for transmitting a second optical signal output by the optical fiber coupler (2) to the elastic diaphragm (41), and the elastic diaphragm (41) can reflect the second optical signal and transmit the second optical signal to the second photodetector (6) through the optical fiber assembly; the elastic diaphragm (41) is vertically fixed at one end of the sensing probe shell (42) and can deform under the action of sound pressure, so that the optical power of the optical signal output by the optical fiber sensing probe (4) changes.
3. Intensity modulated fiber optic vital signs monitoring device according to claim 2, wherein the fiber assembly comprises an optical path circulator (43), a first measurement fiber (44) and a single fiber collimator (45), wherein,
the optical path circulator (43) comprises at least three ports, a first port is connected with the optical fiber coupler (2), a second port is connected with the single-fiber collimator (45) through the first measuring optical fiber (44), and a third port is connected with the second photoelectric detector (6); the single-fiber collimator (44) penetrates through the first side wall of the sensing probe shell (42) so that the end face of the single-fiber collimator (44) is located in the hollow interior of the sensing probe shell (42) and is parallel to and spaced from the surface of the elastic diaphragm (41).
4. Intensity modulated fiber optical vital signs monitoring device according to claim 3, wherein the optical path circulator device (43) is a fiber coupler or a fiber circulator.
5. The intensity modulated fiber optic vital signs monitoring device of claim 3, wherein the single fiber collimator (44) is secured to an end of the sensing probe housing (42) opposite the flexible diaphragm (41) by an adhesive (46).
6. Intensity modulated fiber optic vital signs monitoring device according to claim 2, wherein the fiber assembly comprises a second measuring fiber (47), a third measuring fiber (48) and a two-fiber collimator (49), wherein,
the first end of the second measuring optical fiber (47) is connected with the optical fiber coupler (2), and the second end of the second measuring optical fiber is connected with the double-fiber collimator (49);
the first end of the third measuring optical fiber (48) is connected with the second photoelectric detector (6), and the second end of the third measuring optical fiber is connected with the double-fiber collimator (49);
the dual-fiber collimator (49) penetrates through the first side wall of the sensing probe shell (42) so that the end face of the dual-fiber collimator (49) is located in the hollow interior of the sensing probe shell (42) and is parallel to the surface of the elastic diaphragm (41) and is spaced from the elastic diaphragm (41).
7. Intensity modulated fiber vital signs monitoring device according to claim 6, wherein the second measuring fiber (47) and the third measuring fiber (48) are of the type single mode fiber, multimode fiber or polarization maintaining fiber.
8. The intensity modulated fiber optic vital signs monitoring device according to claim 1, wherein the light source (1) is an incoherent light source and the first (3) and second (6) photodetectors are photodiodes.
9. Intensity modulated fiber optic vital signs monitoring device according to any one of claims 1 to 8, wherein the signal processing unit (7) comprises a power supply module (71), a first amplification module (72), a second amplification module (73), a first AD module (74), a second AD module (75) and a digital signal processing module (76), wherein,
the power supply module (71) is used for supplying power to the light source (1), the first photodetector (3), the second photodetector (6) and the signal processing unit (7);
the first amplifying module (72) is used for amplifying the first electric signal output by the first photodetector (3) to obtain a first analog electric signal, and the first AD module (74) is used for converting the first analog electric signal into a first digital electric signal;
the second amplifying module (73) is configured to amplify the second electrical signal output by the second photodetector (6) to obtain a second analog electrical signal, and the second AD module (75) is configured to convert the second analog electrical signal into a second digital electrical signal;
the digital signal processing module (76) is used for obtaining the ratio information of the second digital electric signal and the first digital electric signal in real time, and extracting the ballistocardiogram signal, the respiration signal and the vital sign information of the user from the ratio information.
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