Temperature self-compensating invasive fiber optic pressure guidewire and FFR wireless monitor

Abstract

The present invention proposes a temperature self-compensating invasive optical fiber pressure guidewire and FFR wireless monitor, which belongs to the field of optical fiber sensing technology; including: a first guidewire segment, a second guidewire segment, a third guidewire segment, and a FBG-FP cascade optical fiber sensor which are arranged in sequence and are hollow; the first guidewire segment is used to guide the second guidewire segment and the third guidewire segment in a blood vessel; the second guidewire segment and the third guidewire segment are hollow inside and are connected to each other; the FBG-FP cascade optical fiber sensor is arranged inside the second guidewire segment and extends toward the inside of the third guidewire segment; the FBG-FP cascade optical fiber sensor includes a multimode optical fiber, a hollow optical fiber and a single-mode optical fiber which are arranged in sequence, and a fiber grating FBG is arranged on the single-mode optical fiber; the FBG-FP cascade optical fiber sensor is used to simultaneously measure the temperature and strain signals in the blood vessel. The present invention is particularly suitable for parameter measurement of the front and rear areas of intravascular stenosis lesions.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to an interventional optical fiber pressure guide wire with temperature self-compensation and an FFR wireless monitor. Background Art

[0002] In percutaneous coronary intervention, coronary angiography, intravascular ultrasound and CT have always been the commonly used diagnostic techniques for coronary artery stenosis in clinical practice. However, their ability to obtain functional information of vascular stenosis is very limited and cannot evaluate the physiological function of the stenotic lesion. In most cases, the degree of coronary artery stenosis must be evaluated based on the doctor's diagnostic experience. There is a large subjective factor, which is prone to underestimate or overestimate the degree of stenosis, thereby delaying or amplifying the condition and causing major medical accidents.

[0003] Fractional Flow Reserve (FFR) is a physiological and functional index used to evaluate the effect of coronary artery stenosis on blood flow. It determines whether the stenosis caused by intravascular plaque is severe enough to require interventional treatment by measuring the pressure at different locations in the coronary artery, that is, the ratio of the mean pressure in the distal coronary artery (Pd) to the mean pressure in the proximal aorta (Pa) of the coronary artery under the state of maximum myocardial hyperemia. In clinical practice, it is often used to evaluate whether there is functional ischemia in critical lesions and to guide revascularization in coronary intervention. The use of pressure guidewires to measure the blood flow pressure difference before and after the stenotic lesion is the gold standard for clinical measurement of FFR. At present, electrical pressure guidewires are commonly used for measurement in clinical practice. Due to the presence of a large number of electromagnetic medical equipment in modern hospitals, electrical pressure guidewires are subject to electromagnetic interference, resulting in drift, disconnection and calibration problems, and electrical components are also easily corroded by blood, which seriously affects their sensitivity and accuracy. In recent years, fiber optic sensors have attracted widespread attention due to their advantages such as small size, strong electromagnetic compatibility, good biocompatibility and high accuracy. The research on optical fiber pressure sensors at home and abroad has been relatively mature, but the application in the medical field is not deep enough. In addition, the demodulation frequency of the existing optical fiber demodulation system cannot meet the real-time monitoring needs of high-frequency signals, most of them use wired data transmission, resulting in complex wiring, and FBG and FP cannot be mixed and demodulated at the same time.

[0004] Therefore, based on the above situation, it is very necessary to provide a temperature self-compensating interventional fiber optic pressure guidewire and FFR wireless monitor to assist doctors in real-time monitoring of patients' physiological parameters, timely understand the patients' condition, and provide reference data support for treatment plans. Summary of the invention

[0005] In view of this, the present invention proposes an FP cavity and fiber Bragg grating cascade structure, which realizes synchronous monitoring of temperature and pressure by decoupling the FP cavity length and FBG wavelength, and is an invasive fiber optic pressure guidewire and FFR wireless monitor that is easy to implant into blood vessels for temperature self-compensation.

[0006] On the one hand, the present invention provides a temperature self-compensating interventional optical fiber pressure guidewire, comprising: a first hollow guidewire segment, a second guidewire segment, a third guidewire segment, and a FBG-FP cascade optical fiber sensor arranged in sequence;

[0007] The first guide wire segment is used to guide the second guide wire segment and the third guide wire segment in the blood vessel;

[0008] The second guide wire segment and the third guide wire segment are hollow inside and are connected to each other;

[0009] The FBG-FP cascade optical fiber sensor is arranged inside the second guide wire segment and extends toward the inside of the third guide wire segment; the FBG-FP cascade optical fiber sensor includes a multi-mode optical fiber, a hollow optical fiber and a single-mode optical fiber arranged in sequence, and a fiber grating FBG is arranged on the single-mode optical fiber; the FBG-FP cascade optical fiber sensor is used to simultaneously measure the temperature and strain signals in the blood vessel.

[0010] On the basis of the above technical solution, preferably, the preparation method of the FBG-FP cascade optical fiber sensor comprises the following steps:

[0011] S1: Strip the coating of the single-mode optical fiber and the hollow-core optical fiber with the fiber grating FBG and cut them. After cutting, the end face of the single-mode optical fiber is 2-5mm away from the FBG; put the single-mode optical fiber and the hollow-core optical fiber into the fusion splicer for fusion splicing;

[0012] S2: Keep a certain length of the hollow-core fiber, and cut one end of the single-mode fiber away from the fiber grating FBG flat;

[0013] S3: Put the cut end of the hollow-core optical fiber and the multimode optical fiber into a fusion splicer for fusion splicing; an FP cavity is formed inside the hollow-core optical fiber;

[0014] S4: Cut off the end of the multimode optical fiber away from the hollow-core optical fiber, and keep a certain length of the multimode optical fiber;

[0015] S5: grinding the end of the multimode optical fiber away from the hollow-core optical fiber to grind the multimode optical fiber to 3-4 μm;

[0016] S6: Soak the ground multimode optical fiber in hydrofluoric acid, so that the hydrofluoric acid corrodes the multimode optical fiber for multiple times until the multimode optical fiber is corroded to 1-2 μm, thereby obtaining a FBG-FP cascade optical fiber sensor.

[0017] Preferably, the first guide wire segment, the second guide wire segment, and the third guide wire segment have the same outer diameters but not completely equal inner diameters.

[0018] On the other hand, the present invention provides a FFR wireless monitor, comprising the above-mentioned temperature self-compensating interventional optical fiber pressure guidewire, and also comprising a power module, an optical path module, a circuit module, a signal processing module, a wireless communication module, and a touch display module;

[0019] The power module is electrically connected to the optical path module, the circuit module, the signal processing module, the wireless communication module, and the touch display module respectively, and is used to provide working power;

[0020] The optical path module provides a frequency sweeping optical signal for the temperature self-compensating interventional optical fiber pressure guide wire, and receives an optical signal output by the temperature self-compensating interventional optical fiber pressure guide wire;

[0021] The circuit module is electrically connected to the optical path module, and the circuit module is also connected to the temperature self-compensating interventional optical fiber pressure guidewire optical path, on the one hand, driving the optical path module to work, and on the other hand, receiving the optical signal output by the temperature self-compensating interventional optical fiber pressure guidewire, and performing photoelectric conversion and signal preprocessing on the optical signal;

[0022] The signal processing module is electrically connected to the output end of the circuit module, and performs data smoothing, adaptive threshold segmentation of FBG / FP spectrum, peak search algorithm to obtain the central wavelength of FBG spectrum, and cavity length demodulation algorithm to calculate the cavity length of FP cavity on the pre-processed signal output by the circuit module;

[0023] The wireless communication module is respectively connected to the output end of the signal processing module and the touch display module, and the central wavelength of the FBG spectrum and the FP cavity length of the FBG-FP cascade optical fiber sensor obtained by the signal processing module are sent to the touch display module through wireless transmission;

[0024] The touch display module receives the data sent by the wireless communication module, displays the central wavelength of the FBG spectrum and the FP cavity length demodulated by the FBG-FP cascade fiber optic sensor output in real time, and further calculates the intravascular temperature and pressure according to the sensitivity of the FBG-FP cascade fiber optic sensor and displays the output.

[0025] On the basis of the above technical solution, preferably, the optical path module includes a SLED laser, an optical isolator, a tunable FP filter, an optical splitter and at least one optical circulator;

[0026] The output end of the SLED laser is optically connected to the input end of the optical isolator for outputting a wide-spectrum laser;

[0027] The output end of the optical isolator is optically connected to the input end of the tunable FP filter;

[0028] The output end of the tunable FP filter is connected to the input end of the optical splitter, and is used to tune the input wide-spectrum laser into a periodic narrow-band swept-frequency pulse light source and then input it into the optical splitter;

[0029] The output end of the optical splitter is connected to the first end of at least one optical circulator, and is used to divide the swept frequency pulse light source output by the tunable FP filter into multiple outputs;

[0030] At least one optical circulator comprises a first end, a second end and a third end, the first end is unidirectionally connected to the second end, and the second end is unidirectionally connected to the third end; the second end of at least one optical circulator is optically connected to an FBG-FP cascade optical fiber sensor in a temperature self-compensating interventional optical fiber pressure guidewire in a one-to-one correspondence; the third end of at least one optical circulator is optically connected to a third end of a circuit module; the second end of at least one optical circulator outputs a swept frequency pulse light source to the FBG-FP cascade optical fiber sensor, and outputs a reflected light signal of the FBG-FP cascade optical fiber sensor to the circuit module through the third end of at least one optical circulator.

[0031] Preferably, the circuit module includes a photodetector, a signal conditioning circuit, a signal acquisition circuit, and a constant current drive and constant temperature control circuit;

[0032] A photoelectric detector is connected to the third end optical path of at least one optical circulator, and is used to convert the reflected light signal of the FBG-FP cascade optical fiber sensor into an electrical signal; the output end of the photoelectric detector is electrically connected to the input end of the signal conditioning circuit;

[0033] A signal conditioning circuit is used to amplify and filter the electrical signal output by the photodetector, and the output end of the signal conditioning circuit is electrically connected to the input end of the signal acquisition circuit;

[0034] The signal acquisition circuit performs analog-to-digital conversion on the amplified and filtered electrical signal. The output end of the signal acquisition unit is electrically connected to the input end of the signal processing module. The signal conditioning circuit and the signal acquisition circuit jointly perform signal preprocessing on the electrical signal.

[0035] The constant current driving and constant temperature control circuit is connected to the SLED laser to perform constant current driving and constant temperature control on the laser so that the SLED laser can output stably. The constant current driving and constant temperature control circuit is also connected to the signal processing module for communication.

[0036] Further preferably, the signal processing module includes a main control chip, and the working content of the main control chip is:

[0037] A) Data smoothing: Select the sliding average filter method for data smoothing. The calculation formula is as follows: , Corresponding to the inclusion The signal sequence of data, , n The moving average filter is used to smooth the data by sliding a fixed length of The window is formed and the average value of the data in the window is calculated to filter and eliminate the noise of the pre-processed electrical signal;

[0038] B) Adaptive threshold segmentation of FBG / FP spectrum: In order to separate the FBG spectrum from the FP spectrum in the reflection spectrum of the FBG-FP cascade optical fiber sensor, the Hilbert transform is used to segment the peak area of ​​the FBG spectrum data to obtain the FBG spectrum and FP spectrum respectively;

[0039] C) Peak-finding algorithm to obtain the central wavelength of the FBG spectrum: Gaussian polynomial fitting method is used to find the peak of the FBG spectrum corresponding to the reflected light signal in the FBG-FP cascade optical fiber sensor;

[0040] D) Cavity length demodulation algorithm to calculate the FP cavity length: Select a demodulation algorithm that combines fast Fourier transform with full phase information to calculate the fiber FP cavity length.

[0041] Further preferably, a Gaussian polynomial fitting method is used to find the peak of the FBG spectrum corresponding to the reflected light signal in the FBG-FP cascade optical fiber sensor, and the Gaussian polynomial of the FBG spectrum peak is: ,in is the intensity of the reflected light from the FBG-FP cascade optical fiber sensor, is the wavelength of light emitted by the optical path module, is the wavelength of the reflected light signal, is the 3dB bandwidth of the reflected optical signal. Taking the logarithm of both sides of the Gaussian polynomial, we get , can be written as a general polynomial: , , , , when the first-order derivative of the polynomial is zero through the least squares method, use Get the peak position of the FBG spectrum.

[0042] More preferably, the specific content of selecting a demodulation algorithm combining fast Fourier transform and full phase information to calculate the cavity length of the optical fiber FP cavity is:

[0043] The FP spectrum is obtained by removing the FBG spectrum from the reflection spectrum in the FBG-FP cascade optical fiber sensor. The interference light signal of the FP cavity is: , using optical frequency , rewrite the above formula as ,in is the reflectivity at both ends of the FP cavity, is the speed of light, L is the cavity length of the FP cavity, is the refractive index of the FP cavity weight medium, is the initial phase of the FP spectrum, and the formula of the interference light signal is transformed by Fourier transform to obtain: , is the frequency domain independent variable, and the center point of the function is between zero and , let the angular frequency ; Discretizing the spectrum in the frequency domain further yields: , Indicates the wave number corresponding to the starting wavelength of the FP spectrum, and the wave number range , Represents the FP spectrum termination wave number, and performs discrete Fourier transform on the discretization formula: , , find Equal to the horizontal coordinate corresponding to the extreme point , , get the frequency , the cavity length calculation formula is obtained , wavelength interval , is the frequency parameter, represents the central wavelength of the light emitted by the optical path module, and the cavity length calculation formula is rewritten as .

[0044] Preferably, the wireless communication module includes an ESP32 main controller, and the ESP32 main controller wirelessly sends the central wavelength of the FBG spectrum and the FP cavity length obtained by the signal processing module to the touch display module through the MQTT protocol.

[0045] The temperature self-compensating invasive optical fiber pressure guidewire and FFR wireless monitor provided by the present invention have the following beneficial effects compared with the prior art:

[0046] (1) The present invention adopts a cascade structure of FP cavity and fiber Bragg grating, and realizes synchronous monitoring of temperature and pressure by decoupling the FP cavity length and FBG wavelength, effectively eliminating the influence of temperature on the change of FP cavity length. In addition, the present invention can realize rapid demodulation of the reflected light signal of the FBG / FP composite sensor, improve the demodulation frequency of the demodulation system, realize FBG / FP hybrid demodulation, and realize multi-parameter monitoring, which is particularly suitable for the acquisition of lesion parameters in the narrow area of ​​the blood vessel;

[0047] (2) The present invention uses optical fiber grinding and etching technology to combine single-mode optical fiber, hollow optical fiber and multi-mode optical fiber into a FBG-FP cascade optical fiber sensor, measures temperature through FBG, and performs temperature compensation on the FP cavity; the FBG is subjected to temperature and strain at the same time, and the sensor can effectively improve the pressure sensitivity of the optical fiber FP cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 It is a system schematic diagram of the temperature self-compensating interventional optical fiber pressure guidewire and FFR wireless monitor of the present invention;

[0050] Figure 2 It is a structural diagram of the temperature self-compensating interventional optical fiber pressure guidewire and the guidewire of the FFR wireless monitor of the present invention;

[0051] Figure 3 The present invention is a flow chart for preparing the temperature self-compensating interventional optical fiber pressure guidewire and the FBG-FP cascade optical fiber sensor of the FFR wireless monitor;

[0052] Figure 4 A schematic diagram of the system structure of the temperature self-compensating interventional optical fiber pressure guidewire and the FFR wireless monitor of the present invention;

[0053] Figure 5 The present invention is a flow chart of the sensor spectrum signal processing of the temperature self-compensating interventional optical fiber pressure guidewire and FFR wireless monitor.

[0054] Figure numerals: 1. Temperature self-compensating interventional optical fiber pressure guidewire; 2. Quick-connect plug; 3. Wireless demodulator; 101. First guidewire segment; 102. Second guidewire segment; 103. Third guidewire segment; 104. FBG-FP cascade optical fiber sensor; 201. Single-mode optical fiber; 202. Hollow optical fiber; 203. Multi-mode optical fiber; 31. Power module; 32. Optical path module; 33. Circuit module; 34. Signal processing module; 35. Wireless communication module; 36. Touch display module; 321. SLED laser; 322. Optical isolator; 323. Tunable FP filter; 324. Optical splitter; 325. Optical circulator; 331. Photodetector; 332. Signal conditioning circuit; 333. Signal acquisition circuit; 334. Constant current drive and constant temperature control circuit. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0056] Existing electrical pressure guidewires usually have problems such as poor anti-electromagnetic interference, drift, disconnection calibration, etc. Existing demodulation systems have problems such as low frequency, short wired data transmission distance, and FBG or FP separate demodulation. Figure 2 As shown, the present invention provides a temperature self-compensating interventional optical fiber pressure guidewire, comprising: a first hollow guidewire segment 101, a second guidewire segment 102, a third guidewire segment 103, and a FBG-FP cascade optical fiber sensor 104 arranged in sequence;

[0057] The first guide wire segment 101 is used to guide the second guide wire segment 102 and the third guide wire segment 103 in the blood vessel;

[0058] The second guide wire segment 102 and the third guide wire segment 103 are hollow inside and are connected to each other;

[0059] The FBG-FP cascade optical fiber sensor 104 is arranged inside the second guide wire segment 102 and extends toward the inside of the third guide wire segment 103; the FBG-FP cascade optical fiber sensor 104 includes a multi-mode optical fiber 203, a hollow optical fiber and a single-mode optical fiber 201 arranged in sequence, and a fiber grating FBG is arranged on the single-mode optical fiber 201; the FBG-FP cascade optical fiber sensor 104 is used to simultaneously measure the temperature and strain signals in the blood vessel.

[0060] The diameters of the first guide wire segment 101, the second guide wire segment 102, and the third guide wire segment 103 are very small, and can guide the FBG-FP cascade optical fiber sensor 104 to advance or withdraw in the blood vessel. The diameter of the FBG-FP cascade optical fiber sensor 104 is smaller than the inner diameter of the first guide wire segment 101, the second guide wire segment 102, or the third guide wire segment 103.

[0061] As a preferred embodiment, the outer diameters of the first guide wire segment 101, the second guide wire segment 102, and the third guide wire segment 103 are the same, but the inner diameters are not completely equal. Specifically, the first guide wire segment 101 has a diameter of 0.36 mm and a length of 30 mm; the second guide wire segment 102 has an inner diameter of 0.3 mm, an outer diameter of 0.36 mm, and a length of 300-500 mm; the third guide wire segment 103 has an inner diameter of 0.18 mm, an outer diameter of 0.36 mm, and a length of 1000-1500 mm.

[0062] like Figure 3 As shown, the preparation method of the above-mentioned FBG-FP cascade optical fiber sensor 104 mainly includes four operations of welding, cutting, grinding and etching, including the following steps:

[0063] S1: Strip the coating of the single-mode optical fiber 201 and the hollow-core optical fiber 202 with the fiber grating FBG and cut them. After cutting, the end face of the single-mode optical fiber 201 is 2-5mm away from the FBG; the length of the hollow-core optical fiber without coating is about 10mm; put the single-mode optical fiber 201 and the hollow-core optical fiber 202 into a fusion splicer for fusion splicing; see Figure 3 The I in the upper left corner.

[0064] S2: Keep a certain length of the hollow-core fiber, and cut one end of the single-mode fiber 201 away from the fiber grating FBG flat; see Figure 3 II in the upper middle part.

[0065] S3: Put the cut end of the hollow core optical fiber and the multimode optical fiber 203 into a fusion splicer for fusion splicing; an FP cavity is formed inside the hollow core optical fiber; see Figure 3 III in the upper right.

[0066] S4: Cutting off the end of the multimode optical fiber 203 away from the hollow-core optical fiber, and retaining a certain length of the multimode optical fiber 203; Figure 3 IV in the lower left corner.

[0067] S5: grinding the end of the multimode optical fiber 203 away from the hollow core optical fiber to grind the multimode optical fiber 203 to 3-4 μm;

[0068] S6: Soak the ground multimode optical fiber 203 in hydrofluoric acid, so that the hydrofluoric acid corrodes the multimode optical fiber 203 for multiple times, and corrodes the multimode optical fiber 203 to 1-2 μm, thus obtaining a FBG-FP cascade optical fiber sensor. Figure 3 V at the bottom and VI at the bottom right.

[0069] The temperature self-compensating invasive optical fiber pressure guide measures the temperature through the FBG and performs temperature compensation on the FP cavity. When the FBG is subjected to temperature and strain at the same time, the change in the central wavelength drift is ;in: is the FBG center wavelength drift, is the effective elastic-optical coefficient, is the strain change of FBG, is the thermal expansion coefficient of FBG, is the thermo-optic coefficient of FBG, is the temperature change. Since the FBG in the temperature self-compensating interventional optical fiber pressure guide wire is loosely arranged, the FBG is not affected by strain, that is, the center wavelength drift of the FBG is only related to the temperature, which is ;in is the temperature sensitivity of FBG. The optical fiber pressure guide wire measures the pressure through the FP cavity, which is affected by both temperature and pressure. Its expression is: ;in: is the change in FP cavity length, is the pressure sensitivity of the FP cavity, is the temperature sensitivity of the FP cavity, is the pressure change, Combining the above formula, we can get the relationship between temperature, pressure, FBG wavelength drift and FP cavity length change: .

[0070] When the sensitivity is determined, the center wavelength drift of the FBG and the change in the cavity length of the FP cavity are obtained, and the temperature and pressure in the blood vessel can be obtained through the above matrix decoupling.

[0071] On the other hand, the present invention provides a FFR wireless monitoring instrument, which mainly includes three parts, such as Figure 1 As shown, the mark 1 in the figure is a temperature self-compensating interventional optical fiber pressure guide wire, the mark 2 is a quick-connect plug, and the mark 3 is a wireless demodulator external to the human body. The wireless demodulator 3 includes a power module 31, an optical path module 32, a circuit module 33, a signal processing module 34, a wireless communication module 35, and a touch display module 36.

[0072] The power module 31 is electrically connected to the optical path module 32, the circuit module 33, the signal processing module 34, the wireless communication module 35, and the touch display module 36 respectively, and is used to provide working power;

[0073] The optical path module 32 provides a frequency sweep optical signal for the temperature self-compensating interventional optical fiber pressure guide wire, and receives an optical signal output by the temperature self-compensating interventional optical fiber pressure guide wire;

[0074] The circuit module 33 is electrically connected to the optical path module 32, and is also connected to the temperature self-compensating interventional optical fiber pressure guidewire optical path. On the one hand, the circuit module 33 drives the optical path module 32 to work, and on the other hand, receives the optical signal output by the temperature self-compensating interventional optical fiber pressure guidewire, and performs photoelectric conversion and signal preprocessing on the optical signal.

[0075] The signal processing module 34 is electrically connected to the output end of the circuit module 33, and performs data smoothing, adaptive threshold segmentation of FBG / FP spectrum, peak search algorithm to obtain the central wavelength of FBG spectrum, and cavity length demodulation algorithm to calculate the cavity length of FP cavity on the pre-processed signal output by the circuit module 33;

[0076] The wireless communication module 35 is respectively connected to the output end of the signal processing module 34 and the touch display module 36 for communication, and sends the central wavelength of the FBG spectrum and the FP cavity length of the FBG-FP cascade optical fiber sensor obtained by the signal processing module 34 to the touch display module 36 via wireless transmission; the wireless communication module 35 includes an ESP32 main controller, and the ESP32 main controller wirelessly sends the central wavelength of the FBG spectrum and the FP cavity length obtained by the signal processing module 34 to the touch display module 36 via the MQTT protocol.

[0077] The touch display module 36 receives the data sent by the wireless communication module 35, and displays the center wavelength of the FBG spectrum and the length of the FP cavity demodulated by the FBG-FP cascade optical fiber sensor in real time, and further calculates the temperature and pressure in the blood vessel according to the sensitivity of the FBG-FP cascade optical fiber sensor and displays the output. After the temperature self-compensated invasive optical fiber pressure guidewire is packaged, the FBG temperature sensitivity, FP temperature and pressure sensitivity and other parameters of the FBG-FP cascade optical fiber sensor are measured, and a two-dimensional code is generated with these parameters. When the pressure guidewire is used to measure FFR, the sensitivity parameter is obtained by scanning the two-dimensional code corresponding to the pressure guidewire, and the temperature and pressure of the blood vessel can be calculated by inputting it into the touch display module 36.

[0078] The optical path module 32 includes a SLED laser 321, an optical isolator 322, a tunable FP filter 323, an optical splitter 324 and at least one optical circulator 325;

[0079] The output end of the SLED laser 321 is optically connected to the input end of the optical isolator 322 for outputting wide-spectrum laser.

[0080] The output end of the optical isolator 322 is optically connected to the input end of the tunable FP filter 323 .

[0081] The output end of the tunable FP filter 323 is connected to the input end of the optical splitter 324 , and is used to tune the input wide-spectrum laser into a periodic narrow-band swept-frequency pulse light source and then input it into the optical splitter 324 .

[0082] The output end of the optical splitter 324 is connected to the first end of at least one optical circulator 325, and is used to divide the swept frequency pulse light source output by the tunable FP filter 323 into multiple outputs; the optical splitter 324 can divide the light source into multiple simultaneous outputs as needed to achieve simultaneous demodulation of multiple channels.

[0083] At least one optical circulator 325 includes a first end, a second end and a third end, the first end is unidirectionally connected to the second end, and the second end is unidirectionally connected to the third end; the second end of at least one optical circulator 325 is optically connected to the FBG-FP cascade optical fiber sensor 104 in the temperature self-compensating interventional optical fiber pressure guidewire in a one-to-one correspondence; the third end of at least one optical circulator 325 is optically connected to the third end of the circuit module 33; the second end of at least one optical circulator 325 outputs a swept frequency pulse light source to the FBG-FP cascade optical fiber sensor 104, and outputs the reflected light signal of the FBG-FP cascade optical fiber sensor 104 to the circuit module 33 through the third end of at least one optical circulator 325. It is common knowledge in the art that adjacent ports of the optical circulator have the characteristic of unidirectional passage.

[0084] The circuit module 33 includes a photodetector 331, a signal conditioning circuit 332, a signal acquisition circuit 333, and a constant current drive and constant temperature control circuit 334;

[0085] The photodetector 331 is optically connected to the third end of at least one optical circulator 325, and is used to convert the reflected light signal of the FBG-FP cascade optical fiber sensor 104 into an electrical signal; the output end of the photodetector 331 is electrically connected to the input end of the signal conditioning circuit 332; the photodetector 331 can be implemented using a common photoelectric converter.

[0086] The signal conditioning circuit 332 is used to amplify and filter the electrical signal output by the photodetector 331 , and the output end of the signal conditioning circuit 332 is electrically connected to the input end of the signal acquisition circuit 333 ; the signal conditioning circuit 332 can be implemented by a peripheral filtering circuit composed of a power amplifier and circuit components.

[0087] The signal acquisition circuit 333 performs analog-to-digital conversion on the amplified and filtered electrical signal, and the output end of the signal acquisition unit is electrically connected to the input end of the signal processing module 34; the signal conditioning circuit 332 and the signal acquisition circuit 333 jointly perform signal preprocessing on the electrical signal; the signal acquisition circuit 333 can be implemented using an AD conversion chip.

[0088] The constant current drive and constant temperature control circuit 334 is connected to the SLED laser 321 to perform constant current drive and constant temperature control on the laser so that the SLED laser 321 outputs stably; the constant current drive and constant temperature control circuit 334 is also connected to the signal processing module 34. The constant current drive and constant temperature control circuit 334 can be implemented by a constant current power supply and a heat exchanger.

[0089] The signal processing module 34 includes a main control chip, which can be an FPGA. Its working contents are:

[0090] A) Data smoothing: Select the sliding average filter method for data smoothing. The calculation formula is as follows: , Corresponding to the inclusion The signal sequence of data, , n The moving average filter is used to smooth the data by sliding a fixed length of The window is formed and the average value of the data in the window is calculated to filter and eliminate the noise of the pre-processed electrical signal;

[0091] Data smoothing is the first step in processing the original signal, and its purpose is to eliminate the noise of the output original signal, smooth the original signal, and reduce the accuracy error of peak finding. In this embodiment, a sliding average filter method is selected for data smoothing filtering, which is a data smoothing processing method in the time domain.

[0092] B) Adaptive threshold segmentation of FBG / FP spectrum: In order to separate the FBG spectrum from the FP spectrum in the reflection spectrum of the FBG-FP cascade optical fiber sensor 104, the Hilbert transform is selected to segment the peak area of ​​the FBG spectrum data to obtain the FBG spectrum and the FP spectrum respectively; the adaptive threshold segmentation can reduce the subsequent data processing amount and improve the data processing speed. Each peak of the smoothed spectrum graph is located between the two extreme points after the Hilbert transform, and the phase has a 90° phase shift, and the left and right segmentation points of each peak of the smoothed spectrum graph correspond to the two extreme points after the Hilbert transform, which can realize the peak area segmentation of the adaptive spectrum signal.

[0093] C) Peak-finding algorithm to obtain the central wavelength of the FBG spectrum: For the FBG reflection spectrum, the light intensity distribution around the central wavelength is Gaussian symmetric, so the Gaussian polynomial fitting method is used to find the peak of the FBG spectrum corresponding to the reflected light signal in the FBG-FP cascade optical fiber sensor 104;

[0094] Specifically, the Gaussian polynomial of the FBG spectrum peak is: ,in is the intensity of the reflected light of the FBG-FP cascade optical fiber sensor 104, is the wavelength of the light emitted by the optical path module 32, is the wavelength of the reflected light signal, is the 3dB bandwidth of the reflected optical signal. Taking the logarithm of both sides of the Gaussian polynomial, we get , can be written as a general polynomial: , , , , when the first-order derivative of the polynomial is zero through the least squares method, use Get the peak position of the FBG spectrum.

[0095] D) Cavity length demodulation algorithm to calculate the FP cavity length: Select a demodulation algorithm that combines fast Fourier transform with full phase information to calculate the fiber FP cavity length.

[0096] The specific content is: the FP spectrum is obtained by removing the FBG spectrum from the reflection spectrum in the FBG-FP cascade optical fiber sensor 104, and the interference light signal of the FP cavity is: , using optical frequency , rewrite the above formula as ,in is the reflectivity at both ends of the FP cavity, is the speed of light, L is the cavity length of the FP cavity, is the refractive index of the FP cavity weight medium, is the initial phase of the FP spectrum, and the formula of the interference light signal is transformed by Fourier transform to obtain: , is the frequency domain independent variable, and the center point of the function is between zero and , let the angular frequency ; Discretizing the spectrum in the frequency domain further yields: , Indicates the wave number corresponding to the starting wavelength of the FP spectrum, and the wave number range , Represents the FP spectrum termination wave number, and performs discrete Fourier transform on the discretization formula: , , find Equal to the horizontal coordinate corresponding to the extreme point , , get the frequency , the cavity length calculation formula is obtained , wavelength interval , is the frequency parameter, represents the central wavelength of the light emitted by the optical path module 32, and the cavity length calculation formula is rewritten as , .

[0097] Due to the low resolution of discrete Fourier transform, the inverse tangent function is usually used in the phase calculation process. The phase result is limited to between -π and π in the computer, while the actual phase is an integer multiple of 2π of the inverse tangent function result. This is phase winding. Due to the phase winding of Fourier transform phase spectrum, the phase difference is an integer multiple of 2π calculated by the above formula. The actual phase is , the phase after discrete Fourier transform is , is a positive real number. The value of a obtained in the actual calculation process is not an integer. ,Will Rounding, we get , The cavity length is obtained by substituting m1 into the cavity length calculation formula. L .

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A temperature self-compensating interventional optical fiber pressure guidewire, characterized in that: include: A first hollow guide wire segment (101), a second guide wire segment (102), a third guide wire segment (103), and a FBG-FP cascade optical fiber sensor (104) are arranged in sequence; The first guide wire segment (101) is used to guide the second guide wire segment (102) and the third guide wire segment (103) in a blood vessel; The second guide wire segment (102) and the third guide wire segment (103) are hollow inside and are interconnected; An FBG-FP cascade optical fiber sensor (104) is arranged inside the second guide wire segment (102) and extends toward the inside of the third guide wire segment (103); the FBG-FP cascade optical fiber sensor (104) comprises a multimode optical fiber (203), a hollow optical fiber and a single-mode optical fiber (201) arranged in sequence, and a fiber grating (FBG) is arranged on the single-mode optical fiber (201); the FBG-FP cascade optical fiber sensor (104) is used to simultaneously measure temperature and strain signals in a blood vessel; A method for preparing a FBG-FP cascade optical fiber sensor (104) comprises the following steps: S1: stripping the coating of a single-mode optical fiber (201) and a hollow-core optical fiber (202) with a fiber grating FBG and cutting them, wherein the end face of the single-mode optical fiber (201) is 2-5 mm away from the FBG after cutting; placing the single-mode optical fiber (201) and the hollow-core optical fiber (202) in a fusion splicer for fusion splicing; S2: a certain length of the hollow-core optical fiber is retained, and one end of the single-mode optical fiber (201) of the hollow-core optical fiber away from the fiber grating FBG is cut flat; S3: placing the cut end of the hollow-core optical fiber and the multimode optical fiber (203) into a fusion splicer for fusion splicing; forming an FP cavity inside the hollow-core optical fiber; S4: cutting off the end of the multimode optical fiber (203) away from the hollow optical fiber, and retaining a certain length of the multimode optical fiber (203); S5: grinding the end of the multimode optical fiber (203) away from the hollow optical fiber, so that the multimode optical fiber (203) is ground to 3-4 μm; S6: soaking the ground multimode optical fiber (203) in hydrofluoric acid, allowing the hydrofluoric acid to corrode the multimode optical fiber (203) multiple times until the multimode optical fiber (203) is corroded to 1-2 μm, thereby obtaining a FBG-FP cascade optical fiber sensor; The first guide wire segment (101), the second guide wire segment (102), and the third guide wire segment (103) have the same outer diameter, but the inner diameters are not completely equal; the first guide wire segment (101) has a diameter of 0.36 mm and a length of 30 mm; the second guide wire segment (101) has an inner diameter of 0.3 mm, an outer diameter of 0.36 mm, and a length of 300-500 mm; the third guide wire segment (103) has an inner diameter of 0.18 mm, an outer diameter of 0.36 mm, and a length of 1000-1500 mm.

2. An FFR wireless monitoring instrument, characterized in that: The temperature self-compensating interventional optical fiber pressure guidewire according to claim 1 further comprises a power module (31), an optical path module (32), a circuit module (33), a signal processing module (34), a wireless communication module (35), and a touch display module (36); The power module (31) is electrically connected to the optical path module (32), the circuit module (33), the signal processing module (34), the wireless communication module (35), and the touch display module (36) respectively, and is used to provide working power; The optical path module (32) provides a frequency sweeping optical signal for the temperature self-compensating interventional optical fiber pressure guide wire, and receives an optical signal output by the temperature self-compensating interventional optical fiber pressure guide wire; The circuit module (33) is electrically connected to the optical path module (32), and the circuit module (33) is also connected to the temperature self-compensating interventional optical fiber pressure guidewire optical path, and on the one hand, drives the optical path module (32) to work, and on the other hand, receives the optical signal output by the temperature self-compensating interventional optical fiber pressure guidewire, and performs photoelectric conversion and signal preprocessing on the optical signal; The signal processing module (34) is electrically connected to the output end of the circuit module (33), and performs data smoothing, adaptive threshold segmentation of the FBG / FP spectrum, peak search algorithm to obtain the central wavelength of the FBG spectrum, and cavity length demodulation algorithm to calculate the cavity length of the FP cavity on the pre-processed signal output by the circuit module (33); The wireless communication module (35) is respectively connected to the output end of the signal processing module (34) and the touch display module (36) for communication, and sends the central wavelength of the FBG spectrum and the FP cavity length of the FBG-FP cascade optical fiber sensor obtained by the signal processing module (34) to the touch display module (36) via wireless transmission; The touch display module (36) receives data sent by the wireless communication module (35), displays in real time the central wavelength of the FBG spectrum and the length of the FP cavity demodulated by the FBG-FP cascade optical fiber sensor output, and further calculates the intravascular temperature and pressure according to the sensitivity of the FBG-FP cascade optical fiber sensor and displays the output.

3. The FFR wireless monitoring device according to claim 2, characterized in that: The optical path module (32) comprises a SLED laser (321), an optical isolator (322), a tunable FP filter (323), an optical splitter (324), and at least one optical circulator (325); The output end of the SLED laser (321) is optically connected to the input end of the optical isolator (322) for outputting wide-spectrum laser light; The output end of the optical isolator (322) is optically connected to the input end of the tunable FP filter (323); The output end of the tunable FP filter (323) is connected to the input end of the optical splitter (324) and is used to tune the input wide-spectrum laser into a periodic narrow-band frequency-sweeping pulse light source and then input it into the optical splitter (324); The output end of the optical splitter (324) is connected to the first end of at least one optical circulator (325) and is used to divide the swept frequency pulse light source output by the tunable FP filter (323) into multiple outputs; At least one optical circulator (325) comprises a first end, a second end and a third end, the first end is unidirectionally connected to the second end, and the second end is unidirectionally connected to the third end; the second end of the at least one optical circulator (325) is optically connected in a one-to-one correspondence with an FBG-FP cascade optical fiber sensor (104) in a temperature self-compensating interventional optical fiber pressure guidewire; the third end of the at least one optical circulator (325) is optically connected to a third end of a circuit module (33); the second end of the at least one optical circulator (325) outputs a swept frequency pulse light source to the FBG-FP cascade optical fiber sensor (104), and outputs a reflected light signal of the FBG-FP cascade optical fiber sensor (104) to the circuit module (33) through the third end of the at least one optical circulator (325).

4. The FFR wireless monitoring device according to claim 3, characterized in that: The circuit module (33) comprises a photodetector (331), a signal conditioning circuit (332), a signal acquisition circuit (333), and a constant current drive and constant temperature control circuit (334); A photoelectric detector (331) is optically connected to the third end of at least one optical circulator (325) and is used to convert a reflected light signal of the FBG-FP cascade optical fiber sensor (104) into an electrical signal; an output end of the photoelectric detector (331) is electrically connected to an input end of a signal conditioning circuit (332); A signal conditioning circuit (332) is used to amplify and filter the electrical signal output by the photodetector (331), wherein the output end of the signal conditioning circuit (332) is electrically connected to the input end of the signal acquisition circuit (333); The signal acquisition circuit (333) performs analog-to-digital conversion on the amplified and filtered electrical signal, and the output end of the signal acquisition unit is electrically connected to the input end of the signal processing module (34); the signal conditioning circuit (332) and the signal acquisition circuit (333) jointly perform signal preprocessing on the electrical signal; The constant current drive and constant temperature control circuit (334) is connected to the SLED laser (321) to perform constant current drive and constant temperature control on the laser, so that the SLED laser (321) outputs stably; the constant current drive and constant temperature control circuit (334) is also communicatively connected to the signal processing module (34).

5. The FFR wireless monitoring device according to claim 4, characterized in that: The signal processing module (34) comprises a main control chip, and the working content of the main control chip is: A) Data smoothing: Select the sliding average filter method for data smoothing. The calculation formula is as follows: , Corresponding to the inclusion The signal sequence of data, , n The moving average filter is used to smooth the data by sliding a fixed length of The window is formed and the average value of the data in the window is calculated to filter and eliminate the noise of the pre-processed electrical signal; B) Adaptive threshold segmentation of FBG / FP spectrum: In order to separate the FBG spectrum from the FP spectrum in the reflection spectrum of the FBG-FP cascade optical fiber sensor (104), Hilbert transform is selected to segment the peak area of ​​the FBG spectrum data to obtain the FBG spectrum and the FP spectrum respectively; C) obtaining the central wavelength of the FBG spectrum using a peak-finding algorithm: using a Gaussian polynomial fitting method to find the peak of the FBG spectrum corresponding to the reflected light signal in the FBG-FP cascade optical fiber sensor (104); D) Cavity length demodulation algorithm to calculate the FP cavity length: Select a demodulation algorithm that combines fast Fourier transform with full phase information to calculate the fiber FP cavity length.

6. The FFR wireless monitoring device according to claim 5, characterized in that: The Gaussian polynomial fitting method is used to find the peak value of the FBG spectrum corresponding to the reflected light signal in the FBG-FP cascade optical fiber sensor (104). The Gaussian polynomial of the FBG spectrum peak value is: ,in is the intensity of the reflected light from the FBG-FP cascade optical fiber sensor (104), is the wavelength of light emitted by the optical path module (32), is the wavelength of the reflected light signal, is the 3dB bandwidth of the reflected light signal. Taking the logarithm of both sides of the Gaussian polynomial, we get , can be written as a general polynomial: , , , , when the first-order derivative of the polynomial is zero through the least squares method, use Get the peak position of the FBG spectrum.

7. The FFR wireless monitoring device according to claim 6, characterized in that: The specific content of selecting the demodulation algorithm combining fast Fourier transform and full phase information to calculate the cavity length of the optical fiber FP cavity is: The FP spectrum is obtained by removing the FBG spectrum from the reflection spectrum in the FBG-FP cascade optical fiber sensor (104). The interference light signal of the FP cavity is: , using optical frequency , rewrite the above formula as ,in is the reflectivity at both ends of the FP cavity, is the speed of light, L is the cavity length of the FP cavity, is the refractive index of the FP cavity weight medium, is the initial phase of the FP spectrum, and the formula of the interference light signal is transformed by Fourier transform to obtain: , is the frequency domain independent variable, and the center point of the function is between zero and , let the angular frequency ; Discretizing the spectrum in the frequency domain further yields: , Indicates the wave number corresponding to the starting wavelength of the FP spectrum, and the wave number range , Represents the FP spectrum termination wave number, and performs discrete Fourier transform on the discretization formula: , , find Equal to the horizontal coordinate corresponding to the extreme point , , get the frequency , the cavity length calculation formula is obtained , wavelength interval , is the frequency parameter, represents the central wavelength of the light emitted by the optical path module (32), and the cavity length calculation formula is rewritten as .

8. The FFR wireless monitoring device according to claim 2, characterized in that: The wireless communication module (35) comprises an ESP32 main controller, and the ESP32 main controller wirelessly sends the central wavelength of the FBG spectrum and the FP cavity length obtained by the signal processing module (34) to the touch display module (36) via the MQTT protocol.

Images