CN115770019B - Pulse measurement sensing device and measurement system - Google Patents
Pulse measurement sensing device and measurement system Download PDFInfo
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Abstract
The invention relates to a pulse measurement sensing device and a measurement system, comprising a force-sensitive flexible mechanism and an optical fiber Bragg grating, wherein the force-sensitive flexible mechanism comprises a top plate, a base and two groups of four-bar amplifying mechanisms which are parallel and symmetrically distributed, the four-bar amplifying mechanisms comprise two flexible bar mechanisms which are symmetrically arranged, and the flexible bar mechanisms comprise a first rigid bar and a second rigid bar which are respectively connected with the top plate, the base and each other through flexible hinges; when the vertical distance between the top plate and the base is reduced, the four flexible link mechanisms can generate displacement motion in the X direction; the fiber Bragg grating is loaded on the two groups of four-bar amplifying mechanisms and is parallel to the X axis. The sensing device can output the amplified pulse impact force and act on the fiber Bragg grating, so that the fiber Bragg grating can generate more remarkable strain signals, and then outputs more accurate pulse waveforms with high definition and obvious characteristic peaks.
Description
Technical Field
The invention relates to the field of pulse measurement, in particular to a pulse measurement sensing device and a pulse measurement system based on an optical fiber Bragg grating and a force-sensitive flexible mechanism.
Background
Pulse is one of the most important vital sign signals of human body, and is an important index for human health condition assessment. In clinical diagnosis, indexes such as heart rate, pulse waveform parameters and the like obtained by analyzing pulse signals are diagnostic bases for judging illness states and etiology by doctors. Arterial pulse waveform analysis has long been an important method for clinical examination and disease diagnosis; moreover, the pulse feeling theory of traditional Chinese medicine still has important research value in the current medical field through long-time development and practical verification. In the clinical research process, a method for estimating the aortic center pressure by using a high-fidelity radial pulse waveform is widely researched and applied, and the radial pulse waveform is also proved to be a predictor of cardiovascular diseases; by analyzing the arterial pulse waveform, arterial compliance, which is an important index reflecting the elasticity of blood vessels and is one of important indexes for diagnosing cardiovascular diseases, can be obtained. In addition, central aortic pressure is more predictive of cardiovascular conditions than peripheral arterial pressure, while carotid arteries are closer to the central aorta, whose pulse is considered the best indicator for measuring aortic central pressure. Therefore, developing a simple, convenient, real-time, high-sensitivity pulse measurement technique to obtain a pulse waveform with high definition has a very important research value.
In order to realize accurate measurement of human pulse signals, researchers have developed various types of sensing measurement devices based on ultrasonic devices, photoplethysmography, capacitive sensing units and the like. Wherein: arterial detection based on ultrasonic equipment can measure the change of the diameter of a blood vessel under the non-invasive condition, so that the local pulse wave velocity, the blood pressure and the like in the systolic period and the diastolic period can be evaluated, and the parameters can reflect the characteristics of the wall of the blood vessel. However, the resolution of the method is limited, the required measurement system is complex and large, and the method is not suitable for long-term clinical monitoring or wearable monitoring. The photoplethysmograph sensor is widely applied to various intelligent hand rings for measuring pulse signals due to the advantages of simple structure, convenient use, low cost and the like. However, this method has limited measurement accuracy, and the measured pulse waveform generally does not have clear detail features, and is only suitable for pulse frequency monitoring. In addition, a sensing device based on optical imaging, hall element and the like is also developed for pulse measurement, however, the sensor has the problems of complex measurement process, low sensitivity, poor sensing precision, easiness in environmental interference and the like, and is difficult to be widely popularized and applied.
In order to solve the limitations and application difficulties of the sensing technology, the fiber bragg grating sensor is widely applied to the field of pulse measurement by virtue of good sensing performance. However, the mainstream sensing technology at present generally adopts a design method of packaging an optical fiber in a film structure, so that the optical fiber measuring sensor still has the defects of complex process, high processing difficulty, low measuring sensitivity, poor accuracy, unclear pulse waveform, limited working frequency, incapability of being applied to wearable measurement and the like.
Disclosure of Invention
In order to solve one or more of the problems existing in the application of the conventional fiber Bragg grating sensor to pulse measurement, the invention provides a pulse measurement sensing device and a pulse measurement system, which have the advantages of small volume, simple structure, easy processing and preparation, high measurement sensitivity and capability of acquiring pulse waveforms with high precision; the device outputs the pulse impact force after amplification and acts on the fiber Bragg grating loaded in the X direction of the mechanism by configuring the force-sensitive flexible mechanism with the force amplification function, so that the fiber Bragg grating can generate more remarkable wavelength offset signals, and then outputs more accurate and clear pulse waveforms.
The technical scheme adopted by the invention for solving the technical problems is as follows: a pulse measurement sensing device comprises an optical fiber Bragg grating as a sensing element and a force-sensitive flexible mechanism for outputting and amplifying pulse vertical acting force; wherein:
The force-sensitive flexible mechanism comprises a top plate and a base which can move relatively, wherein the top plate and the base are mutually parallel and are connected with each other, two groups of four-bar amplifying mechanisms are symmetrically distributed about a Z-X plane, each group of four-bar amplifying mechanisms respectively comprises two flexible bar mechanisms symmetrically arranged about a Z-Y plane, each flexible bar mechanism comprises a first rigid bar and a second rigid bar, and the first rigid bar is connected with the top plate, the second rigid bar is connected with the base and the first rigid bar and the second rigid bar through flexible hinges; when the vertical distance between the top plate and the base is reduced, the four flexible link mechanisms can cooperatively generate displacement motion in the X direction;
The fiber Bragg grating is loaded on two groups of four-bar amplifying mechanisms which are arranged in parallel, and the fiber Bragg grating is parallel to the X axis.
Preferably, two optical fiber fixing platforms which are symmetrical with respect to the Y direction are connected between two groups of four-bar amplifying mechanisms which are arranged in parallel, and the optical fiber Bragg gratings are respectively connected to the two optical fiber fixing platforms in a mode of fixing two ends and suspending in the middle; the fiber Bragg gratings arranged on the two fiber fixing platforms are positioned on the Z-X plane and are equal to the distance between the top plate and the base.
Preferably, the fiber bragg gratings are fixed on the two fiber fixing platforms in a tensioning state under the action of pretightening force.
Preferably, in the flexible link mechanism, the included angle between the first rigid rod and the top plate and the included angle between the second rigid rod and the base are the same, and the included angle is larger than 90 degrees and smaller than 180 degrees.
Preferably, the included angle between the first rigid rod and the top plate and the included angle between the second rigid rod and the base are 150-160 degrees.
Preferably, the pulse measuring and sensing device further comprises a contact boss which is used for being attached to the pulse position, the contact boss is cylindrical, and the central axis of the cylindrical contact boss is overlapped with the Z-axis direction.
Preferably, the contact boss is arranged on a top plate, the top plate is a movable platform, and the base is a fixed platform; the cross-sectional area of the base is greater than the cross-sectional area of the top plate.
Preferably, the force-sensitive flexible mechanism is an integrally formed flexible hinge mechanism obtained by adopting a rigid body displacement method; the force-sensitive flexible mechanism can be manufactured integrally by 3D printer technology.
Preferably, the pulse measurement sensing device is wearable.
The invention also provides a pulse measuring system, which comprises a signal processing unit and the pulse measuring sensing device, wherein the signal processing unit comprises a fiber bragg grating demodulator and a computer system, the fiber bragg grating demodulator is connected with the fiber bragg grating, and the computer system is connected with the fiber bragg grating demodulator and is used for converting a grating strain signal into a digital signal and outputting a pulse waveform obtained by measurement.
The invention mainly provides a carotid pulse measuring device, which comprises the pulse measuring system, wherein: two symmetrical mounting grooves in the Y direction are formed in the base of the sensing device, elastic belts are respectively connected and arranged in the mounting grooves, and the elastic belts are used for being worn and fixed on a human body
Compared with the prior art, the invention has the following advantages and effects:
1. In the pulse measuring and sensing device, the force-sensitive flexible mechanism comprises a top plate, a base and two groups of four-bar linkage amplifying mechanisms connected with the base and the top plate, wherein the two groups of four-bar linkage amplifying mechanisms are parallel and symmetrically distributed, and can be respectively enclosed with the top plate and the base to form a flexible six-bar linkage amplifying mechanism; meanwhile, in the application, the fiber Bragg gratings fixed on the two groups of four-bar amplifying mechanisms are arranged in parallel with the X axis, so that the fiber Bragg gratings are positioned in the direction of the tensile force applied to the optical fibers by the flexible hinge mechanism; the optical fiber is always in a regular horizontal tension state under the action of a larger output force, and correspondingly generates a sensitive, obvious, good-uniformity and higher-linearity strain signal; compared with the traditional pulse measuring device, the device has the characteristics of high measuring sensitivity, good accuracy, convenience and quickness.
2. In the pulse measuring and sensing device, the fiber Bragg grating is tensioned and arranged on the horizontal center position of the Z-X plane of the force-sensitive flexible mechanism in a mode that two ends are fixed and the middle is suspended under the action of pretightening force; when the force-sensitive flexible structure deforms or expands to two sides under the action of pulse impact force, the fiber Bragg grating arranged in the hollow structure is tensioned, so that higher sensitivity, higher resolution and larger measurement range can be obtained; compared with the traditional mode of directly pasting the whole optical fiber or pasting the optical fiber part or arranging the optical fiber in the sleeve, the two-point fixed arrangement mode can effectively avoid the chirp phenomenon caused by uneven grating strain.
3. In the pulse measurement sensing device, the included angle between the first rigid rod and the second rigid rod in the force-sensitive flexible mechanism is the same and is larger than 90 degrees; wherein: when the included angle between the first rigid rod and the top plate and the included angle between the second rigid rod and the base are larger, the amplification factor of the force-sensitive flexible mechanism on pulse impact force can be improved more favorably, but the corresponding sensor has lower structural strength; therefore, in order to comprehensively consider the structural strength and the amplification factor of the sensor, the included angles between the first rigid rod and the top plate and between the second rigid rod and the base are limited to 150-160 degrees, and the structural strength of the force-sensitive flexible mechanism can be ensured when 150 degrees are preferred, and the pulse impact force with the maximum amplification factor can be output.
4. In the pulse measuring and sensing device, the force-sensitive flexible mechanism not only has the function of amplifying pulse impact force, but also improves the measuring sensitivity of the device; the two groups of four-bar amplifying mechanisms are arranged in parallel, so that the high sensitivity is ensured, and meanwhile, the sensing device has stronger anti-radial crosstalk capability, and further has stronger anti-interference capability.
5. In the pulse measuring and sensing device, the four flexible link mechanisms realize micro-displacement movement by means of elastic deformation and elastic restoring force of the structurally weak parts (namely the flexible hinges), and the pulse measuring and sensing device has the advantages of being simple in structure, sensitive in movement, free of lubrication, free of friction and the like.
6. The force sensitive flexible structure in the pulse measuring and sensing device is obtained by adopting a rigid body displacement method, so that a complex rigid hinge connection structure is avoided; meanwhile, the force-sensitive flexible structure can be integrally manufactured in a 3D printing mode, has the characteristics of simple structure and small volume, and is easy to design into a wearable mode, so that long-term monitoring of human pulse can be conveniently and rapidly realized during practical application.
7. In the pulse measuring and sensing device, the flexible connecting rod mechanism with the force amplifying capability is arranged, so that the force-sensitive flexible mechanism has compact structure and good dynamic characteristics.
8. The invention also provides a pulse measuring system, which can convert vertical displacement/force generated by carotid pulse impact into X-direction telescopic displacement of the force-sensitive flexible mechanism and amplify pulse impact force when being applied to carotid pulse measurement; meanwhile, the amplified pulse impact force acts on the fiber Bragg grating suspended in the center of the force-sensitive flexible mechanism, a reflection center wavelength offset signal which is more uniform, more sensitive and high in linearity can be output, the strain signal is processed through the signal processing unit, and a clearer and more accurate carotid pulse waveform can be output, so that the carotid pulse signal can be measured rapidly, conveniently and in real time, and a high-fidelity pulse signal with clear waveform and obvious characteristics is provided for human physiological health evaluation and disease diagnosis.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
Fig. 1 is a schematic perspective view of a pulse measurement sensor according to an embodiment of the invention.
Fig. 2 is a schematic perspective view of a force-sensitive flexible mechanism according to an embodiment of the present invention.
FIG. 3 is a schematic diagram showing the conversion of a force-sensitive flexible mechanism by a rigid body displacement method in an embodiment of the present invention.
Fig. 4 is a schematic diagram of a rigid prototype of a force-sensitive flexible mechanism according to an embodiment of the present invention and a principle of implementing force amplification.
Fig. 5 is a graph showing the relationship between strain and stress of an optical fiber in the pulse measuring sensor according to the embodiment of the present invention.
Fig. 6 is a schematic diagram of a carotid pulse measurement system according to an embodiment of the invention.
Fig. 7 is a waveform diagram of carotid pulse of a human body measured by the carotid pulse measurement system according to an embodiment of the invention.
Description of the reference numerals: 1. a force sensitive flexible mechanism; 11. a top plate; 12. a base; 121. a mounting groove; 13. a flexible linkage mechanism; 131. a first rigid rod; 132. a flexible hinge; 133. a second rigid rod; 14. an optical fiber fixing platform; 15. a contact boss; 2. a fiber bragg grating; 3. an elastic belt; 4. a fiber grating demodulator; 5. a computer system.
Detailed Description
The present invention will be described in further detail with reference to the following examples, which are illustrative of the present invention and are not intended to limit the present invention thereto.
Example 1: as shown in fig. 1 to 3, a pulse measurement sensing device includes a fiber bragg grating 2 as a sensing element and a force-sensitive flexible mechanism 1 for outputting and amplifying a pulse vertical force; wherein:
The force-sensitive flexible mechanism 1 comprises a top plate 11 and a base 12 which can relatively move, wherein the top plate 11 and the base 12 are mutually parallel and are connected with each other, two groups of four-bar amplifying mechanisms are arranged in parallel and are symmetrically distributed about a Z-X plane, each group of four-bar amplifying mechanisms respectively comprises two flexible bar mechanisms 13 symmetrically arranged about a Z-Y plane, each flexible bar mechanism 13 comprises a first rigid bar 131 and a second rigid bar 133, and the first rigid bar 131 is connected with the top plate 11, the second rigid bar 133 is connected with the base 12 and the first rigid bar 131 and the second rigid bar 133 through flexible hinges 132; when the vertical distance between the top plate 11 and the base 12 is reduced, the four flexible link mechanisms 13 can cooperatively generate displacement motion in the X direction;
The fiber Bragg grating 2 is loaded on two groups of four-bar amplifying mechanisms which are arranged in parallel, and the fiber Bragg grating 2 is parallel to the X axis.
Specifically, in the embodiment 1, the flexible hinge 132 may be a flexible hinge in the form of a circular arc incision, an elliptical incision or a right angle incision, and may be other types of flexible hinges; the flexible hinge in the form of the circular arc incision has the characteristics of high rigidity, convenient processing and high precision, so as shown in fig. 1 and 2, in the pulse measurement sensing device of the embodiment, the structural form of the flexible hinge is preferably a flexible hinge in the form of the circular arc incision.
Further, as shown in fig. 1, 2 and 3, in this embodiment, two sets of four-bar amplifying mechanisms, which are arranged in parallel and symmetrically, and the top plate 11 and the base 12 can be respectively enclosed to form a flexible six-bar amplifying mechanism, and the two sets of flexible six-bar amplifying mechanisms can amplify the vertical acting force of the input pulse and generate micro-displacement motion in the X direction and directly act on the fiber bragg grating 2 arranged in parallel with the X direction; specifically, in this embodiment, as a preferred embodiment, the fiber bragg grating 2 is connected and disposed on the force-sensitive flexible mechanism by:
As shown in fig. 2, two optical fiber fixing platforms 14 symmetrical with respect to the Y direction are connected between two groups of four-bar amplifying mechanisms arranged in parallel, and the optical fiber bragg grating 2 is loaded on the two optical fiber fixing platforms 14 in a manner of fixing two ends and suspending in the middle; further, the fiber Bragg gratings 2 disposed on the two fiber holding platforms 14 are located on the Z-X plane (i.e., on the symmetry plane of the two sets of four-bar linkages) and are equidistant from the top plate 11 and the base 12. The arrangement mode enables the fiber Bragg grating 2 to be directly arranged in the maximum displacement output direction of the X direction of the force-sensitive flexible mechanism, and can generate a grating strain signal with extremely obvious effect and higher sensitivity under the action of the pulse acting force with maximum output (namely maximum amplification factor); compared with the traditional mode of directly pasting the whole optical fiber or pasting the optical fiber part or arranging the optical fiber in the sleeve, the two-point fixed arrangement mode can effectively avoid the chirp phenomenon caused by uneven grating strain.
As a further preferred aspect, in the pulse measurement sensor device according to embodiment 1, the fiber bragg gratings 2 may be fixed on the two fiber fixing platforms 14 in a tensioned state under the action of a pre-tightening force; when the force-sensitive flexible structure deforms or is displaced to two sides under the action of pulse impact force, the fiber Bragg grating 2 which is arranged in the hollow structure in a tensioning manner can obtain higher sensitivity, higher resolution and larger measurement range.
The pulse measurement sensing device described in embodiment 1 has a symmetrical structure and high overall rigidity; when pulse impact force is applied to the top plate 11 along the Z-axis direction of the mechanism, the vertical distance between the top plate 11 and the base 12 is reduced, and two groups of flexible link mechanisms which are arranged left and right symmetrically and are positioned on two sides of the top plate 11 can respectively output amplified pulse impact force, so that the fiber Bragg grating loaded on the force-sensitive flexible mechanism generates a remarkable grating strain signal under the action of larger horizontal tension, and the precise and clear pulse waveform can be output after the grating strain signal is converted, wherein the specific working principle is as follows:
as shown in fig. 1,2 and 3, in the embodiment 1, the pulse measuring and sensing device has a symmetrical structure, the left side structure is identical to the right side structure, and two flexible link mechanisms 13 in the four-link mechanism can be enclosed with the top plate 11 and the base 12 to form a flexible six-link mechanism; when vertical displacement (pulse impact force F) is input along the Z direction of the force-sensitive flexible mechanism, the vertical distance between the top plate 11 and the base 12 is reduced, and the two parallel flexible six-bar mechanisms have displacement which is opened to two sides (namely, the X direction) under the elastic deformation of the flexible hinge, and correspondingly output amplified pulse impact force, and further directly act on the fiber Bragg grating which is parallel to the X direction in the arrangement direction, so that the fiber Bragg grating stretches regularly, and obvious, uniform and high-linearity strain signals are generated; further, the strain on the fiber bragg grating can change the grating pitch of the grating, so that the center wavelength of the reflected wave of the grating is shifted, and the relationship between the center wavelength shift and the strain of the fiber bragg grating is as follows:
Wherein lambda is the initial center wavelength of the fiber Bragg grating, delta lambda is the center wavelength drift amount of the grating, alpha f is the thermal expansion coefficient of the fiber, zeta is the thermal optical coefficient of the fiber material, and P e is the elasto-optical coefficient of the fiber; delta epsilon is the strain change generated by the fiber bragg grating;
The reflection center wavelength of the fiber Bragg grating generates regular periodic changes along with pulse impact and recovery of stretching and elastic deformation of the four-bar mechanism, so that a corresponding grating strain signal is obtained by detecting the reflection center wavelength, and a corresponding pulse waveform can be output.
Further, in this embodiment, the force-sensitive flexible mechanism is a force amplifying mechanism, and may output an amplified pulse impact force, and the specific principle is explained as follows:
As shown in fig. 4, since the force-sensitive flexible mechanism is a symmetrical structure, the left side structure is identical to the right side structure, and therefore, one set of flexible link mechanisms FE and ED is illustrated as follows:
Mechanical analysis was performed for points D and E:
FFBG＝2*FDE*cosα；
the mechanical force amplification ratio can be calculated by using the ratio of the tensile force F FBG and the pulse input F In received by the fiber Bragg grating; where α=30° when defining an angle of 150 ° between the rigid rod DE and the top plate, the result is as follows:
The invention discloses the force amplifying performance of the force-sensitive flexible mechanism, and the amplifying multiple is 3.46.
Example 2: as shown in fig. 1 to 3, a pulse measurement sensor device is different from embodiment 1 in that the present embodiment focuses on defining the flexible link mechanism 13 as follows:
In the flexible link mechanism 13, the first rigid rod 131 and the top plate 11 and the second rigid rod 132 and the base 12 have the same included angle, and the included angle is greater than 90 ° and smaller than 180 °. Wherein: when the included angle between the first rigid rod 131 and the top plate 11 and the included angle between the second rigid rod 132 and the base 12 are larger, the amplification factor of the force-sensitive flexible mechanism on the pulse impact force F is more beneficial to be improved, but the corresponding sensor is not beneficial to keep better structural strength; therefore, in order to comprehensively consider the structural strength and the magnification of the sensor, the included angle between the first rigid rod 131 and the top plate 11 and the included angle between the second rigid rod 132 and the base 12 are limited to 150 ° -160 °. Further, when the included angle is limited to 150 °, the structural strength of the force-sensitive flexible mechanism can be ensured, and the pulse impact force of the maximum amplification factor can be output.
Example 3: this embodiment is further defined on the basis of embodiments 1 and 2 as follows: as shown in fig. 1 to 3:
In this embodiment, the top plate 11 is defined as a moving platform, contacts with the pulse of the human body, and is used for inputting a vertical displacement or pulse vertical force (also "pulse impact force") F in the Z direction, and the base 12 is defined as a fixed platform, and is used for bearing radial load; further, in the present embodiment, the cross-sectional shapes of the top plate 11 and the base 12 are respectively set to be square, preferably rectangular; and defines the cross-sectional area of the base 12 to be larger than the cross-sectional area of the top plate 11; the arrangement mode enables the whole bottom of the force-sensitive flexible mechanism to be high in rigidity and stability and high in radial load bearing capacity.
Further, in this embodiment, in order to better achieve the input of the vertical displacement or the pulse vertical force F, a contact boss 15 for fitting with the pulse of the tester may be provided on the top plate 11; wherein: preferably, as shown in fig. 2, the contact boss 15 may be configured as a cylinder, and the central axis of the cylindrical contact boss is defined to overlap with the Z-axis direction, so as to ensure that the vertical displacement or the pulse vertical force F can be uniformly transferred to two sets of four-bar mechanisms which are parallel and symmetrically arranged along the Z-axis direction of the force-sensitive flexible mechanism, and then the displacement in the X-direction and the amplified pulse impact force are symmetrically output.
In addition, as a preferred embodiment, as shown in fig. 3, in examples 1 to 3 of the present invention, the force-sensitive flexible mechanism is an integrally molded flexible hinge mechanism, and the flexible hinge mechanism can be obtained by replacing the connection node in the six-bar mechanism by a rigid body replacement method. As a further preferred feature, the force sensitive flexible mechanism may be integrally manufactured by 3D printer technology. Therefore, the measuring and sensing device has the characteristics of simple structure, small volume and convenient preparation; when in actual use, the wearable measurement can be realized through the integrated elastic belt, so that the measurement is extremely convenient and quick.
In summary, the present invention provides a pulse measurement sensing device, in which: the force-sensitive flexible mechanism is designed by a rigid body displacement method; specifically, the force-sensitive flexible mechanism comprises a moving platform and a fixed platform which are arranged in parallel, two groups of four-bar linkage amplifying mechanisms which are arranged in parallel and symmetrically are connected between the moving platform and the fixed platform, each group of four-bar linkage amplifying mechanisms consists of two flexible bar linkage mechanisms which are arranged symmetrically, the left side structure and the right side structure of the force-sensitive flexible mechanism which are arranged in the structure are identical, and the input pulse impact force can be amplified, so that the measurement sensitivity of the sensing device is improved; further, the two groups of four-bar amplifying mechanisms are arranged in parallel, so that high sensitivity is guaranteed, and meanwhile, stronger radial crosstalk resistance is achieved, and the measuring device further has stronger anti-interference performance.
Verification analysis:
The pulse measuring and sensing device disclosed by the embodiment of the invention is verified and analyzed by ANSYS simulation software, and a relation curve chart of the strain and the stress of the fiber Bragg grating (optical fiber for short) is output, as shown in fig. 5.
As can be seen from FIG. 5, the relationship between the strain and the stress of the optical fiber in the pulse measuring and sensing device is linear, and the slope is 1541.5. Mu.. Epsilon./N. For the optical fiber with the center wavelength of 1550nm, the offset of the center wavelength is about 1.2 times of the strain of the optical fiber, so that the sensitivity of the measuring device is about 1849.8pm/N, which proves the advantages of high linearity and high sensitivity of the sensing device, so that an accurate pulse waveform can be obtained when the sensing device is used for pulse measurement, and high-fidelity pulse data can be provided for human health evaluation.
Example 4: as shown in fig. 6, a pulse measurement system includes a signal processing unit and a pulse measurement sensing device in the above embodiment; wherein:
the signal processing unit comprises a fiber grating demodulator 4 and a computer system 5; the fiber bragg grating demodulator 4 is connected with the fiber bragg grating 2; the computer system 5 is connected with the fiber grating demodulator 4 and is used for converting the grating strain signal into a digital signal and outputting the pulse waveform obtained by measurement.
Example 5: the pulse measuring system of embodiment 4 of the present invention may be applied to pulse sites including radial artery, temporal artery, carotid artery, brachial artery, dorsum of foot artery, posterior tibial artery, femoral artery, etc.; specifically, the present embodiment provides a wearable measurement system suitable for carotid pulse measurement, which is different from embodiment 4 in that:
As shown in fig. 1 and 2, two mounting grooves 121 symmetrical with respect to the Y direction are formed on the base 12 of the pulse sensing device in the embodiment 3, and the elastic bands 3 are respectively connected and disposed in the mounting grooves 121; during measurement, the sensing device is worn at the neck through the elastic belts 3 arranged on the two sides of the base of the sensing device, the contact boss 15 is attached to the carotid artery, and corresponding pulse waveforms can be output through the signal processing unit, so that the device has the characteristics of simplicity, convenience and rapidness.
Specifically, the measurement process of the measurement system according to this embodiment is as follows: before the measurement starts, ensuring that the fiber Bragg grating led out from the sensing device is connected to the fiber Bragg grating demodulator 4, and ensuring that the fiber Bragg grating demodulator 4 is communicated with the computer system 5 normally; the subject should avoid strenuous exercise and sit in a chair in a normal comfortable position to maintain a steady state to ensure minimal disturbance during pulse measurements. In the measuring process, the subject firstly props the measuring contact point of the sensing device contact boss against the obvious position of the cervical carotid artery pulsation, then the main body structure of the device is stably worn at a proper position by using the elastic belt with the help of auxiliary personnel, and the bonding position of the elastic belt is further adjusted to adjust the tightness degree of the belt so as to obtain a good measuring effect, and the wearing comfort of the subject in the measuring process is ensured. The measured pulse information is converted into a pulse waveform displayed in real time through a sensing device, a demodulator and a computer system. As shown in FIG. 7, the pulse waveform measured by the measuring system is clear, the amplitude is higher than 300pm, and the index is higher than that of a plurality of similar sensors, so that the good pulse waveform measuring capability of the measuring device is verified. The cardiovascular health of the subject can be further assessed by analyzing the waveform.
In addition, the specific embodiments described in the present specification may differ in terms of parts, shapes of components, names, and the like. All equivalent or simple changes of the structure, characteristics and principle according to the inventive concept are included in the protection scope of the present invention. Those skilled in the art may make various modifications or additions to the described embodiments or substitutions in a similar manner without departing from the scope of the invention as defined in the accompanying claims.
Claims (9)
1. A pulse measurement sensing device, which is characterized by comprising an optical fiber Bragg grating as a sensing element and a force-sensitive flexible mechanism for amplifying pulse vertical acting force; wherein:
The force-sensitive flexible mechanism comprises a top plate and a base which can move relatively, wherein the top plate and the base are mutually parallel and are connected with each other, two groups of four-bar amplifying mechanisms are arranged in parallel and are symmetrically distributed about a Z-X plane, each group of four-bar amplifying mechanisms respectively comprises two flexible bar mechanisms symmetrically arranged about a Z-Y plane, each flexible bar mechanism comprises a first rigid bar and a second rigid bar, and the first rigid bar is connected with the top plate, the second rigid bar is connected with the base and the first rigid bar and the second rigid bar through flexible hinges; when the vertical distance between the top plate and the base is reduced, the four flexible link mechanisms can generate displacement motion in the X direction;
The optical fiber Bragg grating is loaded on two groups of four-bar amplifying mechanisms which are arranged in parallel, and the optical fiber Bragg grating is parallel to the X axis;
In the flexible connecting rod mechanism, the included angles between the first rigid rod and the top plate and between the second rigid rod and the base are the same, and the included angles are larger than 90 degrees and smaller than 180 degrees.
2. The pulse measurement sensing device according to claim 1, wherein two optical fiber fixing platforms symmetrical to the Y direction are connected between two groups of four-bar amplifying mechanisms which are arranged in parallel, and the optical fiber Bragg gratings are respectively connected to the two optical fiber fixing platforms in a mode of fixing two ends and suspending in the middle; the fiber Bragg gratings arranged on the two fiber fixing platforms are positioned on the Z-X plane and are equal to the distance between the top plate and the base.
3. The pulse measurement sensing device of claim 2, wherein the fiber bragg grating is secured in tension to two fiber fixation platforms under a pre-tension force.
4. The pulse measurement sensing device of claim 1, wherein the first rigid rod is disposed at an angle ranging from 150 ° to 160 ° to the top plate and the second rigid rod is disposed at an angle ranging from the base.
5. The pulse measurement sensing device of claim 1, further comprising a contact boss for conforming to the pulse site, the contact boss being cylindrical, a central axis of the cylindrical contact boss overlapping the Z-axis direction.
6. The pulse measurement sensing device of claim 5, wherein the contact boss is disposed on a top plate, the top plate is a moving platform, and the base is a fixed platform; the cross-sectional area of the base is greater than the cross-sectional area of the top plate.
7. The pulse measurement sensing device according to claim 6, wherein the force sensitive flexible mechanism is an integrally formed flexible hinge mechanism obtained by a rigid body displacement method and is integrally manufactured by a 3D printer technology.
8. A pulse measurement system comprising a signal processing unit and the sensing device of any one of claims 1 to 7, the signal processing unit comprising a fiber grating demodulator and a computer system; the fiber bragg grating demodulator is connected with the fiber bragg grating; the computer system is connected with the fiber grating demodulator and is used for converting the grating strain signal into a digital signal and outputting the pulse waveform obtained by measurement.
9. The carotid pulse measurement system comprises the pulse measurement system as claimed in claim 8, and is characterized in that two mounting grooves symmetrically arranged in the Y direction are formed in the base of the sensing device, and elastic belts are respectively connected and arranged in the mounting grooves.
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