Disclosure of Invention
The invention aims to solve the technical problems that: in order to solve the problem that an electrical force sensor is difficult to be compatible with a magnetic resonance imaging technology in the prior art, the invention provides a guide wire tip three-dimensional force sensor based on a Fabry-Perot interference microcavity, which is used for measuring and feeding back a contact force based on an optical sensing technology and has the advantages of electromagnetic interference resistance and compatibility with the magnetic resonance imaging technology, and solves the problem that the electrical force sensor is difficult to be compatible with the magnetic resonance imaging technology in the prior art.
The technical scheme adopted for solving the technical problems is as follows:
a guide wire tip three-dimensional force sensor based on a Fabry-Perot interference microcavity comprises a chassis, an optical measurement structure and a microcolumn arranged between the chassis and the optical measurement structure;
the optical measurement structure is provided with a film and a Fabry-Perot interference microcavity, and the film is positioned between the microcolumn and the Fabry-Perot interference microcavity.
Optionally, the optical measurement structure comprises a bottom plate, the fabry-perot interference microcavity is arranged at the upper end of the bottom plate, and the microcolumn is connected to the lower end of the bottom plate; the film is formed between the Fabry-Perot interference microcavity and the micropillars.
Optionally, the optical measurement structure further comprises a sidewall connected to the base plate; the bottom plate and the side wall are enclosed to form an optical fiber accommodating cavity.
Alternatively, the number of micropillars, the thin film, and the Fabry-Perot interferometric microcavities is four.
Alternatively, the microcolumns have a diameter of 40-50. Mu.m.
Alternatively, the film has a thickness of 8-10 μm.
Alternatively, the Fabry-Perot interferometric microcavity has a length of 80-100 μm.
Optionally, a boss is arranged on the chassis, and the microcolumn is connected to the boss.
Alternatively, the guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity is prepared by adopting two-photon micronano printing integrated molding.
Alternatively, the three-dimensional force sensor based on the tip of the guide wire of the Fabry-Perot interference microcavity can be matched and integrated with an interventional guide wire of 0.035inch on a bed.
The invention has the beneficial effects that:
the guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity provided by the invention is based on an optical sensing technology, adopts the Fabry-Perot interference principle to realize detection feedback of the contact force, has the characteristics of high sensitivity and no electromagnetic margin, can resist electromagnetic interference, is compatible with a magnetic resonance imaging technology, and is beneficial to application in the medical field.
Detailed Description
The present invention will now be described in further detail. The embodiments described below are exemplary and intended to be illustrative of the invention and are not to be construed as limiting the invention, as all other embodiments, based on which a person of ordinary skill in the art would come within the scope of the invention without inventive faculty.
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
In order to solve the problem that an electrical force sensor is difficult to be compatible with a magnetic resonance imaging technology in the prior art, the invention provides a guide wire tip three-dimensional force sensor based on a Fabry-Perot interference microcavity, which is shown in figures 1-3 and comprises a chassis 1, an optical measurement structure 2 and a microcolumn 3 arranged between the chassis 1 and the optical measurement structure 2; in the using process, the lower end of the chassis 1 (the upper part and the lower part in the application are respectively shown by the direction marks in the figure 1) is connected with the semispherical yarn guiding spherical cap, and the application preferably uses medical light curing glue to connect the semispherical yarn guiding spherical cap with the lower end of the chassis 1 in a glue dispensing mode; the shape and the size of the chassis 1 are determined according to the hemispherical yarn guide spherical cap, the chassis 1 is preferably in a circular plate-shaped structure, and the diameter of the chassis 1 is further preferably 890 mu m; the optical measurement structure 2 is connected with the structures such as the mandrel of the guide wire, the optical fiber, the guide wire spring and the like so as to integrate the force sensor with the medical intervention device, and the contact force is measured through the optical measurement structure 2.
Specifically, the optical measurement structure 2 is provided with a thin film 21 and a fabry-perot interference microcavity 22, the thin film 21 is located between the microcolumn 3 and the fabry-perot interference microcavity 22, and an optical fiber is connected with the fabry-perot interference microcavity 22, so that incident light enters the fabry-perot interference microcavity 22 through the optical fiber, the incident light is reflected in the fabry-perot interference microcavity 22, and then the wavelength of the reflected light is detected, and the force is detected according to the detected wavelength of the reflected light.
Referring to fig. 4 a, when the hemispherical guide wire spherical cap is not in contact with the tissue, the reflecting surface of the hemispherical guide wire spherical cap, which is in contact with the air, of the incident light reaching the end surface of the optical fiber through the optical fiber is a first reflecting surface R1, then a part of the incident light is reflected, a part of the incident light is transmitted, the transmitted incident light is reflected for the second time by the air and the film layer, namely a second reflecting surface R2, and the fabry-perot interference occurs in the two reflections; in the using process, after the hemispherical guide wire spherical cap is in contact with tissues, the hemispherical guide wire spherical cap is extruded, the extrusion force is transmitted to the film 21 through the microcolumn 3, so that the film 21 deforms, the film 21 deflects into the Fabry-Perot interference microcavity 22, the interference cavity length of the Fabry-Perot interference microcavity 22 changes, the light path difference of two reflections changes, and finally the reflection wavelength deflects, and the received force magnitude is further related to the reflection wavelength deflection, so that the received force magnitude can be calculated according to the reflection light wavelength deflection, and the force detection is realized. The method and the element for detecting the wavelength of the reflected light, the method for calculating the offset of the wavelength of the reflected light based on the detection result, the method for calculating the contact force based on the offset, the element, and the like can be selected according to the prior art, and the present invention is not limited to this portion.
The guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity provided by the invention is based on an optical sensing technology, adopts the Fabry-Perot interference principle to realize detection feedback of the contact force, has the characteristics of high sensitivity and no electromagnetic margin, can resist electromagnetic interference, is compatible with a magnetic resonance imaging technology, and is beneficial to application in the medical field.
In order to facilitate the detection of the contact force and simplify the structure of the sensor, the optical measurement structure 2 of the invention preferably comprises a bottom plate 23, a Fabry-Perot interference microcavity 22 is arranged at the upper end of the bottom plate 23, and a microcolumn 3 is connected to the lower end of the bottom plate 23; a thin film 21 is formed between the fabry-perot interference microcavity 22 and the microcolumn 3.
In particular, the invention preferably has a circular plate-like structure as the bottom plate 23, and the bottom plate 23 is connected with the chassis 1 through the microcolumns 3; the fabry-perot interference microcavity 22 is a circular groove-shaped structure arranged on the bottom plate 23, and the position of the fabry-perot interference microcavity 22 corresponds to the microcolumn 3, so that a film 21 with the thickness smaller than the bottom plate 23 is formed between the fabry-perot interference microcavity 22 and the microcolumn 3; when the hemispherical guide wire spherical cap is in contact with tissues, the contact force is transmitted to the position of the film 21 through the microcolumn 3, the film 21 is extruded, the film 21 is shifted into the Fabry-Perot interference microcavity 22, the cavity length of the Fabry-Perot interference microcavity 22 is changed, and then the contact force is detected according to the method.
Further, to facilitate integration of the force sensor with interventional devices such as guidewires, the optical measurement structure 2 of the present invention preferably further comprises a sidewall 24 connected to the bottom plate 23; the bottom plate 23 and the side walls 24 enclose a fiber receiving chamber 25 so that an optical fiber can be connected to the fabry-perot interferometer microcavity 22 through the fiber receiving chamber 25.
In order to realize three-dimensional measurement of the contact force, the number of the microcolumns 3, the films 21 and the Fabry-Perot interference microcavities 22 is preferably four; correspondingly, the number of the optical fibers is four, and the four optical fibers are respectively connected with four Fabry-Perot interference microcavities 22; and further, four Fabry-Perot interference microcavities 22 and four optical fibers are symmetrically arranged at intervals of 90 degrees, the guide wire mandrel is arranged at the center position of the four optical fibers, and five devices are inserted into the reserved cavity of the four microcavity sensing structure together, namely the optical fiber accommodating cavity 25, and the end faces of the five devices are ensured to be in the same plane.
To improve the sensitivity of the measurement, the membrane 21 is preferably a circular membrane sheet structure, the stress situation of which is shown in fig. 6; the relationship between the deformation of the center point of the membrane 21 upon receiving a force and the pressure, the dimensional characteristics and the geometric characteristics of the membrane 21 is shown in the following formula:
where h is the thickness (μm) of the film 21; d is the cavity length (μm) of the Fabry-Perot interferometric microcavity 22; Δd is the amount of cavity length variation (nm) of the fabry-perot interferometric microcavity 22; v is the poisson's ratio of the film; p is the pressing force, i.e., the contact force (Pa), to which the film 21 is subjected; r is the radius (μm) of the Fabry-Perot interferometric microcavity 22, E is the elastic modulus (Pa) of the membrane, and h is the film thickness (μm). .
The relationship between the amount of change in the cavity length of the fabry-perot interferometer microcavity 22 and the amount of shift in the wavelength of the reflected wave is as follows:
wherein lambda ism Is the initial reflected center wavelength (nm); Δλ (delta lambda)m Is the peak center wavelength shift (nm).
For any complex force, we can break it down into forces in the x, y and z axes, see FIG. 7; wherein, the relation between the force and the resultant force of the three shaft decomposition is shown as a formula:
Fz ＝Fcsoβ
Fx ＝Fsinβcosα
Fy ＝Fsibβsinα
wherein F is the spatial force (N); f (F)x Decomposing the component force (N) in the x-axis direction for F; f (F)y Decomposing the component force (N) in the y-axis direction for F; f (F)z To decompose a component (N) in the z-axis direction; alpha is an included angle (°) between F and the X axis after being projected on the xoy plane; beta is the angle (°) between F and the z-axis.
For the whole device, focusing on the cavity of each optical fiber end face, the change of the cavity length is also contributed by the effect generated by the forces of three axes, so that an equation between the change of the cavity lengths of four cavities and the wavelength offset of the reflected light can be obtained, as shown in the following formula:
Δd＝Δdx+Δdy+Δdz
Δdi ＝d(F，α，β)
where i=1,2,3,4.
In summary, three-axis force decoupling equations are established to decouple the complex three-dimensional force information experienced by the guidewire tip through the symmetrical arrangement of four interferometric microcavities, namely the fabry-perot interferometric microcavities 22.
The invention provides a sensor which adopts four optical fibers to be symmetrically arranged, and utilizes force decomposition and synthesis to match complex force with the change of cavity lengths of four cavities by a multidimensional force decoupling method, so that the applied force information is demodulated from complex reflected wave signals.
For the guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity provided by the invention, the critical structural dimensions are the diameter of the microcolumn 3, the thickness of the film 21 and the length of the Fabry-Perot interference microcavity 22; the diameter of the microcolumn 3 and the thickness dimension of the membrane 21 are set such that, when the sensor is measuring a force in the force-measuring target range, the strength requirement is met under conditions sufficient to cause sufficient deformation of the membrane 21 such that a significant spectral shift is produced by the fabry-perot interference microcavity 22.
In particular, the diameter of the microcolumn 3 is preferably 40-50 μm; preferably, the film 21 has a thickness of 8-10 μm; the length of the fabry-perot interferometric microcavity 22 is preferably 80-100 μm.
Further, in the invention, a boss 11 is arranged on the chassis 1, and the microcolumn 3 is connected to the boss 11; preferably, the outer diameter of the boss 11 is matched with the inner diameter of the guide wire spring, so that the spring is pushed to the boss 11 directly in the assembly process, and then solidification connection is carried out through the photo-curing adhesive.
The invention is preferably prepared by adopting two-photon micro-nano printing integrated molding based on a guide wire tip three-dimensional force sensor of a Fabry-Perot interference microcavity; the material for carrying out the two-photon micro-nano printing can select a corresponding prior art according to actual requirements; by adopting the two-photon micro-nano printing sensor, the assembly difficulty is greatly reduced, the error in assembly is reduced, and the maximum cross-sectional area of the size of the whole sensor is smaller than 1mm2 The three-dimensional force sensing can be realized, the electromagnetism is free from edges, the force measuring range can reach Newton level, the measurement of the contact pressure can be monitored in real time when the guide wire is applied to a human body, and the potential of pressure monitoring can be realized in other extremely narrow spaces.
The prior interventional device tip integrated force sensor device has larger integrated size, generally more than 2mm, and mostly adopts an electrical working principle, such as resistance type, permittivity and the like, and has the defects of complex integration, low sensitivity, large error, electromagnetic incompatibility and the like. The three-dimensional force sensor of the guide wire tip based on the Fabry-Perot interference microcavity provided by the invention can integrate the cross section size smaller than 1mm2 The intervention apparatus is arranged below the device, and the effect of three-dimensional force sensing can be realized.
The three-dimensional force sensor based on the guide wire tip of the Fabry-Perot interference microcavity provided by the invention can be integrated with four optical fibers, a guide wire mandrel and a guide wire spring by the following methods:
s1: stripping the other ends of four single-mode optical fibers with connectors at the single ends to a cladding; cutting the end face of the optical fiber into a plane by using an optical fiber cutting machine;
s2: fixing the positions of the four optical fibers and the guide wire core shaft by using a preprinted fixing die, symmetrically arranging the four fixed optical fibers at 90-degree intervals, inserting the guide wire core shaft into the circular center position of the guide wire core shaft, and ensuring that the end faces of the five devices are positioned on the same plane;
s3: fixing the fixing die on a micro-operation table, inserting five devices into a reserved cavity of a printed four-microcavity sensing structure, namely a Fabry-Perot interference microcavity 22 of a guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity, and curing the joint by using light-cured glue;
s4: pushing the spring to a reserved boss 11 of the printed chassis 1, and curing the joint by using photo-curing glue;
s5: and dispensing glue on the other side of the printed chassis 1 by using photo-curing glue for medical use to form the tip of the hemispherical guide wire spherical cap.
In summary, the present invention provides a method of making a maximum cross-sectional area of less than 1mm2 The miniature three-dimensional force sensor (the subject integrates 0.035inch and 0.014inch medical guide wires) with the size below 1mm can be integrated, and a new solution is provided for the contact force feedback of the tip of the miniature interventional device; the three-dimensional force decoupling is realized by adopting the Fabry-Perot interference principle and combining a symmetrical flexible structure; the two-photon micro-nano printing is integrally formed, the processing is convenient, the cost is low, and the specific characteristics of the sensor can be used for finely adjusting the structure (film thickness and cavity length) of the two-photon printing device and the proportion of photoresist used for the two-photon printing; the force sensor is printed and then the optical fiber and the guide wire are integrated, so that the micro-nano structure is prevented from being directly printed at the tip of the optical fiber, the processing difficulty is reduced on the one hand, the integration difficulty is reduced on the other hand, and the stability of the structure is improved; compared with other types of sensors, the sensor has superior force measuring performance (high sensitivity and resolution, good biocompatibility, no electromagnetic margin and the like).
The guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity provided by the invention can be applied to various fields, and has wide application prospects, for example, in vascular interventional operations, doctors use guide wires to guide catheters into blood vessels so as to treat diseases such as vascular stenosis, thrombosis and the like. The force sensor provided by the invention is integrated at the tip of the guide wire and used as a pressure sensing force sensor, so that the contact pressure between the guide wire and a blood vessel can be measured when the guide wire is operated, and a doctor is helped to judge the position of the guide wire and the physiological state of the blood vessel, thereby guiding operation; in cardiac interventional operation, the pressure sensor provided by the invention can be integrated at the tip of the guide wire to measure the pressure in the heart, including coronary arterial pressure, ventricular pressure and the like, so as to assist a doctor in performing operation and evaluating operation effect; the pressure sensor provided by the invention can be integrated at the tip of the guide wire in the digestive tract interventional operation, so that the pressure in the digestive tract can be measured, and doctors can be helped to evaluate the pathological change position, pathological change property and tissue physiological state, thereby guiding the operation; the force sensor provided by the invention is integrated at the tip of the guide wire in urinary tract interventional operation, so that the pressure in the urinary tract can be measured, a doctor can know the physiological states of organs such as urethra, bladder, ureter and the like, and the operation is guided.
The guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity provided by the invention can obtain great economic and social benefits; regarding economic benefit, the sensor has wide application prospect and has a cross section of 1mm2 The environment has excellent performance in the environment of measuring force, has application potential in the environment of measuring force with larger size, and can integrate other structures more conveniently due to the annular structural design; the sensor is manufactured by adopting two-photon micro-nano printing, so that the structure has flexible adjustability, the processing cost is low, and the sensor can accurately sense the contact pressure of blood vessels and tissues in a human body in real time through being integrated with a guide wire (also can be integrated with a catheter), thereby having great economic benefit; regarding social benefits, the sensor can solve the following social problems:
1. clinical intervention:
1) Cardiac ablation
Insufficient force in catheter ablation therapy may result in incomplete treatment, while excessive force may result in heart chamber damage.
2) FFR monitoring
Through FFR measurement, a doctor can evaluate the stenosis from the aspect of function and accurately identify the stenosis which causes myocardial ischemia and has functional significance, so that the doctor can select the optimal treatment scheme for a patient.
2. Navigation of the interventional device:
traditional interventional procedures rely primarily on the physician's technique to sense pressure and friction between the guidewire tip and the vessel by the force transmitted by the guidewire tip to the hand to drive the catheter and guidewire, which presents a safety hazard.
3. Intervention operation robot manpower feedback module:
to date, many commercial interventional robotic systems, such as Corpath-R robots and the like, have been developed to assist in interventional procedures in hospitals; but these commercial robots do not achieve accurate tactile force feedback.
4. The method also has application prospects in the fields of earthquake monitoring, ultrasonic monitoring and the like.
The above-described preferred embodiments according to the present invention are intended to suggest that, from the above description, workers skilled in the art can make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of the claims.