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, and the sensor is used for measuring and feeding back contact force based on an optical sensing technology, 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; and the film is formed between the Fabry-Perot interference microcavity and the microcolumn.
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.
Optionally, the number of the microcolumns, the thin film and the fabry-perot interference microcavity is four.
Alternatively, the diameter of the microcolumn is 40-50 μm.
Alternatively, the film has a thickness of 8-10 μm.
Optionally, the length of the fabry-perot interference microcavity is 80-100 μm.
Optionally, a boss is arranged on the chassis, and the microcolumn is connected to the boss.
Optionally, the guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity is prepared by adopting two-photon micro-nano printing integrated molding.
Alternatively, the Fabry-Perot interference microcavity-based guide wire tip three-dimensional force sensor can be matched and integrated with a clinically 0.035inch interventional guide wire.
The beneficial effects of the invention are as follows:
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 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 illustrate the invention and should not be construed as limiting the invention, as all other embodiments, based on which a person of ordinary skill in the art would obtain without inventive faculty, are within the scope of the invention.
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 application provides a guide wire tip three-dimensional force sensor based on a Fabry-Perot interference microcavity, which is shown in fig. 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 use 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 a hemispherical guide wire spherical cap, and the hemispherical guide wire spherical cap is preferably connected with the lower end of the chassis 1 by using medical photo-curing glue in a dispensing mode; the shape and the size of the chassis 1 are determined according to the hemispherical guide wire 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. 4a, when the hemispherical guide wire spherical cap is not in contact with the tissue, the reflecting surface of the incident light, which reaches the end surface of the optical fiber through the optical fiber and is in contact with the air, 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 thin film layer, namely a second reflecting surface R2, and fabry-perot interference occurs in the two reflections; in the use process, after the hemispherical guide wire spherical cap is contacted 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 optical path difference of two reflections is changed, and finally the deflection of the reflection wavelength is caused, as shown in fig. 5, the received force is further related to the deflection of the reflection wavelength, and the received force can be calculated according to the deflection of the reflection wavelength, so that the detection of the force 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 according to the detection result, the method for calculating the contact force according to 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 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 at 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 bottom plate 23 is preferably a circular plate-shaped structure, 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 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, so that the film 21 deflects into the Fabry-Perot interference microcavity 22, the cavity length of the Fabry-Perot interference microcavity 22 is changed, and the contact force is detected according to the method.
Further, to facilitate integration of the force sensor with interventional devices such as guide wires, 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 cavity 25 for facilitating the connection of an optical fiber to the fabry-perot interference microcavity 22 through the fiber receiving cavity 25.
In order to realize three-dimensional measurement of contact force, the number of the microcolumn 3, the thin film 21 and the Fabry-Perot interference microcavity 22 is four; correspondingly, the number of the optical fibers is four, and the four optical fibers are respectively connected with the four Fabry-Perot interference microcavities 22; and further preferably, the four fabry-perot interference microcavities 22 and the 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 diaphragm-like structure, the stress 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 of the membrane 21 and the geometric characteristics 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 interference microcavity 22; Δd is the amount of change in cavity length (nm) of the fabry-perot interference 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 interference 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 interference microcavity 22 and the amount of shift in the wavelength of the reflected wave is as follows:
Wherein lambdam is the initial reflection center wavelength (nm); Δλm is the peak center wavelength shift (nm).
For any one 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 three shaft decomposition is shown as a formula:
Fz＝Fcsoβ
Fx＝Fsinβcosα
Fy＝Fsibβsinα
Wherein F is the spatial force (N); fx is the component force (N) of F decomposition in the x-axis direction; fy is the component force (N) of F decomposition in the y-axis direction; fz is a component force (N) decomposed 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.
Looking at the cavity of each fiber end face for the whole device, the change of the cavity length is also contributed by the effect generated by the forces of the three axes, so that the equation between the change of the cavity length of the 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 axial force decoupling equations are established, and the complex three-dimensional force information suffered by the guide wire tip is decoupled by the symmetrical arrangement of four interference microcavities, namely the Fabry-Perot interference 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 the cavity length 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, 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 to 50. Mu.m; preferably, the film 21 has a thickness of 8-10 μm; preferably, the length of the Fabry-Perot interferometric microcavity 22 is from 80 to 100 μm.
Furthermore, in the invention, the chassis 1 is preferably provided with a boss 11, 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 directly pushed to the boss 11 in the assembling process, and then the springs are solidified and connected 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, the maximum cross-sectional area of the size of the whole sensor is smaller than 1mm2, three-dimensional force sensing can be realized, electromagnetism is free from edges, the force measuring range can reach Newton level, the measurement of the contact pressure of the guide wire in real time during human body application can be realized, and the potential of realizing pressure monitoring in other extremely narrow spaces is realized.
The existing device for integrating the force sensor at the tip of the interventional device has the defects of large total size, more than 2mm, adoption of electric working principles, such as resistance type, capacitance type and the like, complex integration, low sensitivity, large error, electromagnetic incompatibility and the like. The guide wire tip three-dimensional force sensor based on the Fabry-Perot interference microcavity provided by the invention can integrate interventional instruments with cross section dimensions smaller than 1mm2 and can realize the effect of three-dimensional force sensing.
The three-dimensional force sensor at the tip of the guide wire based on the Fabry-Perot interference microcavity can be integrated with four optical fibers, a guide wire mandrel and a guide wire spring by the following method:
s1: stripping the other ends of the four single-mode fibers with the joints at the single ends to a cladding; cutting the end face of the optical fiber into a plane by using an optical fiber cutter;
S2: fixing the four optical fibers and the guide wire core shaft at the fixed positions by using a preprinted fixing die, wherein the four optical fibers are symmetrically arranged at 90-degree intervals after being fixed, the guide wire core shaft is inserted into the circular center position of the guide wire core shaft, and the end faces of the five devices are ensured to be positioned on the same plane;
S3: fixing a fixed 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 photo-curing 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 the medical photo-curing adhesive on the other side of the printed chassis 1 to form a hemispherical guide wire spherical cap tip.
In summary, the invention provides a miniature three-dimensional force sensor with the largest cross-sectional area smaller than 1mm2 and capable of integrating instruments with the size smaller than 1mm (the subject integrates medical guide wires of 0.035inch and 0.014 inch), and provides a new solution for the contact force feedback of the tip of a miniature interventional device; the three-dimensional force decoupling is realized by adopting the Fabry-Perot interference principle and combining a symmetrically arranged flexible structure; the two-photon micro-nano printing integrated molding is adopted, the processing is convenient, the cost is low, and the specific characteristics of the sensor can be used for fine adjustment of the structure (film thickness and cavity length) of the two-photon printing device and the proportion of photoresist used for the two-photon printing for modulation; 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 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 edge 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 a wide application prospect, for example, in vascular intervention operation, a doctor uses a guide wire to guide a catheter into a blood vessel 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 induction 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, so that the operation is guided; 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 artery 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 is 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; in urinary tract 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 urinary tract, help doctors know the physiological states of organs such as the urinary tract, the bladder, the ureter and the like, and guide operation.
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 benefits, the sensor has wide application prospect, has excellent performance in a force measuring environment with the cross section of less than 1mm2, has application potential in a force measuring environment with a larger scale, and can integrate other structures more conveniently due to the annular structure 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 functionality, accurately identify the stenosis which causes myocardial ischemia and has functional significance, and therefore select the optimal treatment scheme for a patient for the doctor.
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, a process that 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 the interventional procedure of hospitals; but these commercial robots do not achieve accurate tactile force feedback.
4. The method also has application prospect in the fields of earthquake monitoring, ultrasonic monitoring and the like.
With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to 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 claims.