CN116531150A - Bone implant crack detection system and implantable radio frequency identification sensor thereof - Google Patents
Bone implant crack detection system and implantable radio frequency identification sensor thereof Download PDFInfo
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- 239000007943 implant Substances 0.000 title claims abstract description 70
- 210000000988 bone and bone Anatomy 0.000 title claims abstract description 69
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- 230000005855 radiation Effects 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 15
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- 238000000338 in vitro Methods 0.000 claims description 8
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- 238000004458 analytical method Methods 0.000 claims description 6
- 230000000977 initiatory effect Effects 0.000 claims description 6
- 238000004088 simulation Methods 0.000 claims description 6
- 230000005540 biological transmission Effects 0.000 claims description 5
- 230000000877 morphologic effect Effects 0.000 claims description 5
- 238000002513 implantation Methods 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims description 3
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- 210000000056 organ Anatomy 0.000 claims description 3
- 230000008447 perception Effects 0.000 claims description 2
- 238000005516 engineering process Methods 0.000 abstract description 4
- 206010016256 fatigue Diseases 0.000 description 8
- 239000000470 constituent Substances 0.000 description 7
- 208000010392 Bone Fractures Diseases 0.000 description 6
- 206010017076 Fracture Diseases 0.000 description 6
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- 230000008901 benefit Effects 0.000 description 3
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/46—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/46—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor
- A61F2/4657—Measuring instruments used for implanting artificial joints
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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- Orthopedic Medicine & Surgery (AREA)
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Abstract
The invention discloses a bone implant crack detection system and an implantable radio frequency identification sensor thereof, wherein the sensor is arranged on the surface of a bone implant and is implanted into a living body together with the bone implant; the sensor includes a substrate and a radiator disposed on the substrate; a resonant cavity is formed between the radiator and the bone implant to sense the bone implant crack characteristics. The invention adopts the radio frequency identification sensing technology to realize the real-time and accurate detection of the shape, the position and the size of the crack of the bone implant.
Description
Technical Field
The invention belongs to the technical field of crack detection of bone implants, and particularly relates to a crack detection system of a bone implant and an implantable radio frequency identification sensor thereof.
Background
Bone implants are medical devices used clinically to replace, support, repair, supplement the original bone. The bone implant bears complex physiological environment and mechanical load during the human body, often generates failure behaviors such as cracks and the like, directly influences the fracture healing effect, causes clinical symptoms such as delayed healing, non-healing, bone tissue necrosis and the like, and has negative effects on the physiology and the psychology of patients. Therefore, there is a great need for systematic studies of the in vivo integrity of bone implants, prediction of fatigue risk points and fatigue life of the implants, and corresponding clinical measures.
The specific mechanism by which bone implants crack and fracture occurs is unclear due to the variety of individuals and fracture types. In addition, the failure analysis of the existing implant in the human body is based on simulation or after fracture, in-vitro test is carried out, the actual condition of the bone implant in the human body cannot be reflected in a simulation mode, the integrity of the bone implant cannot be accurately analyzed, and therefore accurate and reliable data support is provided for corresponding clinical measures; the in vitro test-based method requires surgery to perform an integrity analysis and cannot detect the integrity of the bone implant in the human body in time. There is therefore a need for a system that enables accurate in-vivo in-situ implant crack detection in real time.
Disclosure of Invention
In view of the foregoing problems with the prior art, the present invention provides an implantable radio frequency identification sensor. The invention adopts the radio frequency identification sensing technology to realize the real-time and accurate detection of the shape, the position and the size of the crack of the bone implant.
The invention is realized by the following technical scheme:
an implantable radio frequency identification sensor, the sensor being mounted on a surface of a bone implant, and being implanted in a living body together with the bone implant;
the sensor includes a substrate and a radiator disposed on the substrate;
a resonant cavity is formed between the radiator and the bone implant to sense the bone implant crack characteristics.
At present, a mode of simulation analysis is generally adopted to predict the crack of the bone implant, however, the mode is not consistent with the actual condition of crack initiation and propagation of the bone implant in a living body, and the fatigue dangerous point and the fatigue life of the bone implant cannot be accurately and reliably predicted; in the in vitro test, the bone implant is firstly required to be taken out by operation, and meanwhile, the fracture condition of the bone implant cannot be obtained in real time, so that timely response is realized. Based on the above, the radio frequency identification sensor provided by the embodiment can acquire the fracture condition of the bone implant in the body in real time by utilizing the radio frequency identification detection technology, and a response strategy is formulated in time, so that the risk is reduced.
Preferably, the radiator of the present invention comprises a rectangular sensing unit and a circular encoding unit.
Preferably, the rectangular sensing unit of the present invention comprises two basic radiation patterns: TM (TM) 10 And TM 01 The method comprises the steps of carrying out a first treatment on the surface of the The resonant frequencies corresponding to the two fundamental radiation modes are:
wherein f 10 Is TM 10 Resonant frequency f corresponding to radiation mode 01 Is TM 01 The resonant frequency corresponding to the radiation mode, c is the speed of light in vacuum, L is the length of the rectangular sensing unit, ΔL c The electric length of the rectangular sensing unit in the length direction caused by cracks is increased, W is the width of the rectangular sensing unit, and DeltaW c For increasing the electrical length of the rectangular sensing unit in the width direction caused by cracks re Is an effective dielectric constant.
Preferably, the resonance frequency of the circular coding unit of the present invention is:
wherein c is the speed of light in vacuum, R e Is the effective radius of the circular coding unit epsilon r Is the dielectric constant of the substrate.
In a second aspect, the present invention proposes a method for determining parameters of an implantable radio frequency identification sensor as described above, comprising:
selecting an operating frequency of the sensor and the substrate material having biocompatibility;
according to the radiation and absorption characteristics of biological tissues to electromagnetic fields, combining the sensor, the bone implant implantation position and the depth, establishing a sensor simulation calculation model, and optimizing the shape and the size of the radiator and the thickness of the substrate;
and calculating an energy coupling coefficient between the sensor and an external reader, and determining the final structural parameter of the sensor.
Preferably, the method for acquiring the radiation and absorption characteristics of the biological tissue to the electromagnetic field specifically comprises the following steps:
dividing the biological tissue anatomical structure into different layers or different areas by taking each organ as a unit, and establishing a morphological model;
corresponding electromagnetic parameters are assigned to each layer or each region in the morphological model, and an electromagnetic model is constructed;
and analyzing the radiation and absorption characteristics of the biological tissue to the electromagnetic field based on the electromagnetic model.
In a third aspect, the present invention provides a method for operating an implantable rfid sensor as described above, comprising:
by carrying out external electromagnetic excitation on the sensor in the organism, the sensor generates a reflection signal on the incident electromagnetic wave;
and receiving the reflected signal through an external reader and performing decoupling treatment to obtain the crack characteristics of the bone implant, so as to realize real-time perception of crack initiation and propagation conditions of the bone implant.
In a fourth aspect, the present invention provides a bone implant crack detection system comprising an implantable radio frequency identification sensor and an in vitro reader as described above;
the external reader is used for providing electromagnetic excitation for the identification sensor, receiving and processing the reflected signals transmitted by the sensor, and obtaining the crack characteristics of the bone implant.
Preferably, the extracorporeal reader of the present invention comprises a signal source, a signal separation device, a receiving unit, a signal processing unit and an antenna;
the signal source provides continuous wave excitation signals for the sensor through the antenna and outputs power;
the signal separation device is used for separating the reflected signal of the sensor and the continuous wave excitation signal received by the antenna and is responsible for distributing the output power of the signal source to the receiving unit according to a reference signal;
the receiving unit is used for carrying out test analysis on the amplitude-phase parameters of the reflected signal, the reference signal and the transmission signal;
the signal processing unit is used for completing decoupling of crack information of the bone implant according to the information output by the receiving unit and extracting crack characteristics.
Preferably, the signal processing unit of the present invention can also display the result according to the actual need.
The invention has the following advantages and beneficial effects:
the invention adopts the radio frequency identification antenna sensing technology to realize the real-time detection of the bone implant cracks, and has the advantages of low cost, passivity, wireless and high integration level.
The crack sensor provided by the invention can be conformal with the surface of a bone implant, and has good biocompatibility.
The crack sensor provided by the invention is implanted into a patient together with a bone implant, and the crack initiation and expansion conditions of the bone implant can be mastered in real time through an external reader, so that accurate and reliable data support is provided for clinical measures, and the health of the implanted person is ensured to the greatest extent.
According to the invention, different crack sensors can be designed according to the implantation position of the sensor in the human body and combining the electromagnetic characteristics of human tissues; the position of the implanted person is not required to be fixed in the detection process, so that the flexibility and the adaptability of detection are improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention. In the drawings:
fig. 1 is a schematic diagram of an implantable rfid sensor according to an embodiment of the present invention.
FIG. 2 is a top view of an implantable RFID sensor according to an embodiment of the present invention.
FIG. 3 is a schematic diagram showing the influence of different crack directions on the resonant mode in an embodiment of the present invention. (a) the crack is parallel to the width direction of the sensing unit; (b) the crack is parallel to the length direction of the sensing unit.
Fig. 4 is a schematic block diagram of a crack detection system according to an embodiment of the present invention.
In the drawings, the reference numerals and corresponding part names:
1-substrate, 2-radiator, 21-sensing unit, 22-coding unit, 3-bone implant, 4-crack, 5-current path.
Detailed Description
Hereinafter, the terms "comprises" or "comprising" as may be used in various embodiments of the present invention indicate the presence of inventive functions, operations or elements, and are not limiting of the addition of one or more functions, operations or elements. Furthermore, as used in various embodiments of the invention, the terms "comprises," "comprising," and their cognate terms are intended to refer to a particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be interpreted as first excluding the existence of or increasing likelihood of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.
In various embodiments of the invention, the expression "or" at least one of a or/and B "includes any or all combinations of the words listed simultaneously. For example, the expression "a or B" or "at least one of a or/and B" may include a, may include B or may include both a and B.
Expressions (such as "first", "second", etc.) used in the various embodiments of the invention may modify various constituent elements in the various embodiments, but the respective constituent elements may not be limited. For example, the above description does not limit the order and/or importance of the elements. The above description is only intended to distinguish one element from another element. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of various embodiments of the present invention.
It should be noted that: if it is described to "connect" one component element to another component element, a first component element may be directly connected to a second component element, and a third component element may be "connected" between the first and second component elements. Conversely, when one constituent element is "directly connected" to another constituent element, it is understood that there is no third constituent element between the first constituent element and the second constituent element.
The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the various embodiments of the invention. As used herein, the singular is intended to include the plural as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the invention belong. The terms (such as those defined in commonly used dictionaries) will be interpreted as having a meaning that is the same as the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in connection with the various embodiments of the invention.
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
Example 1
The present embodiment provides an implantable radio frequency identification sensor, as shown in fig. 1, which is composed of a substrate 1 and a radiator 2 disposed on the substrate 1, wherein the radiator 2 includes a sensing unit 21 and a coding unit 22. This example uses the characteristics of the backscatter signal of the in vitro reader crack pair sensor as a parameter for bone implant crack generation and quantification.
The sensor is mounted on the surface of a bone implant (bone plate) 3, the bone implant 3 is equivalent to the ground plane of the antenna sensor, and as known from microstrip antenna theory, a resonant cavity with a specific resonant frequency is formed between the radiator 2 and the ground plane.
The number of the coding units in the radio frequency identification sensor of the embodiment is set according to actual needs, the shapes of the coding units and the sensing units are set according to the sensitivity degree of the resonant frequency to crack information, and in the embodiment, the corresponding resonant frequency of the coding units is required to be insensitive to cracks and reading directions, so that the coding units are round, and the resonant frequency of the coding units is relatively fixed; the sensing unit is required to be sensitive to crack information and can distinguish crack directions, so that a rectangle is adopted, resonance frequencies in the length direction and the width direction of the rectangle have relatively large differences due to size differences, and the size and the direction information of the cracks can be obtained by reading in different directions. As shown in fig. 1, the radio frequency identification sensor of the present embodiment includes 4 circular encoding units 22 of different diameters, and the 4 encoding units 22 are arranged at the periphery of a rectangular sensing unit 21.
The working principle of the radio frequency identification sensor of the embodiment is as follows:
the rectangular sensor unit comprises two basic radiation patterns (TM) 10 And TM 01 ) The current distribution in different radiation modes is different, and the generation of cracks on the bone implant can change the path of the current distribution, so that the electrical path of the antenna sensor in the radiation mode is increased, and the resonant frequency of the radio frequency identification sensor in the corresponding radiation mode is changed. As shown in FIG. 3, when the crack is parallel to the width direction of the rectangular sensor unit, the electrical length in the length direction is increased, affecting the TM 10 Resonant frequency f corresponding to radiation mode 10 ，TM 01 Resonant frequency f corresponding to radiation mode 01 Is not affected. When the crack is parallel to the length direction of the rectangular sensing unit, the electrical length in the width direction is increased to affect TM 01 Resonant frequency f corresponding to radiation mode 01 ，TM 01 Resonant frequency f corresponding to radiation mode 01 Is not affected. When the crack direction and the edge of the rectangular sensing unit have a certain angle, the electrical length in the length direction and the width direction are increased to influence TM 10 And TM 01 Resonant frequency f corresponding to radiation mode 10 And f 01 . The resonant frequencies corresponding to the two fundamental radiation modes are calculated as follows:
wherein c is the speed of light in vacuum, L is the length of the rectangular sensing unit, ΔL c The electric length of the rectangular sensing unit in the length direction caused by cracks is increased, W is the width of the rectangular sensing unit, and DeltaW c For increasing the electrical length of the rectangular sensing unit in the width direction caused by cracks re For effective dielectric constant, the following is calculated:
wherein ε r The dielectric constant of the sensor substrate, h, is the thickness of the sensor substrate. The resonant frequency of the RFID sensor circular coding unit is calculated as follows:
wherein R is e The effective radius of the circular coding unit is determined by the following formula;
wherein R is the radius of the coding unit, and h is the thickness of the sensor substrate.
The working process of the radio frequency identification sensor of the embodiment is as follows:
mounting a radio frequency identification sensor on the surface of a bone implant and implanting the radio frequency identification sensor and the bone implant into a living body together;
the radio frequency identification sensor generates a back scattering signal to the incident electromagnetic wave by carrying out external electromagnetic excitation on the radio frequency identification sensor;
the back scattering signal is received by an external reader and is subjected to decoupling treatment to obtain crack characteristics of the bone implant, so that crack initiation and expansion conditions of the bone implant can be perceived in real time, and fatigue danger points and fatigue life of the bone implant are predicted.
The electromagnetic impedance characteristic of biological tissue is the basis of the interaction between electromagnetic field and organism, and the radio frequency identification sensor is used as an implantable medical device, so that not only is good biocompatibility realized, but also the transmission loss and biological effect of the biological tissue on electromagnetic wave energy absorption are considered. According to the biological tissue anatomical structure, the embodiment divides each organ into different layers or different areas to establish a morphological model; then, corresponding electromagnetic parameters are assigned to each layer or region, and an electromagnetic model is constructed; analyzing the radiation and absorption characteristics of biological tissue to the electromagnetic field, ensuring proper communication between the in vitro reader and the in vivo sensor and reducing the effect of the radio frequency field on the biological tissue.
The embodiment also provides a parameter determining method of the implantable radio frequency identification sensor, electromagnetic radiation and device size of the implantable radio frequency identification sensor can meet biomedical requirements, and the implantable radio frequency identification sensor is small in size and can perform high-efficiency energy transmission and wireless data communication. Therefore, the parameter determination method specifically comprises the following steps:
selecting a proper working frequency of the sensor and a substrate material with biocompatibility;
according to the radiation and absorption characteristics of biological tissues to electromagnetic fields, a sensor simulation calculation model is established by combining the sensor and the implantation position and depth of the bone implant, and the shape and size of the sensor radiator and the thickness of the substrate are optimized;
and calculating the energy coupling coefficient between the radio frequency identification sensor and the external reader, and determining the final structural parameter of the implantable radio frequency identification sensor.
Example 2
The present embodiment provides a bone implant crack detection system, which includes the radio frequency identification sensor and the external reader set forth in embodiment 1.
As shown in fig. 4, the extracorporeal reader of this embodiment is composed of a signal source, a signal separation device, a receiving unit, a signal processing unit, and an antenna.
The signal source is responsible for providing continuous wave excitation signals of the antenna and has the functions of wide-range frequency scanning and power scanning. The signal source of the embodiment adopts a synthesized sweep frequency signal source to provide an excitation signal, adopts two parts of automatic level gain control and an attenuator to complete power scanning control and adjustment, the automatic level gain control ensures the stability of the power of an input signal and the power scanning control (i.e. fine adjustment of the power), and the attenuator completes the large-range power scanning adjustment (i.e. coarse adjustment of the power).
The signal separation device separates the reflected signal of the radio frequency identification sensor and the continuous wave excitation signal collected by the antenna and is responsible for distributing the output power of the signal source to the receiving unit according to a fixed proportion (reference signal). In order to prevent interference of the transmitted signal to the received signal processing, the signal separation device of the present embodiment employs a power divider and a directional coupler to extract the excitation signal and the reflected signal, respectively. The directional coupler is used for separating signals in different directions and corresponds to separation of an excitation signal and a receiving signal. Because the intensity of the transmitting power is higher, the direct measurement of the power is difficult to realize, and therefore, the power divider is used for distributing a part of the signal transmitted by the signal source to the signal measuring device.
The receiving unit completes test analysis of parameters such as amplitude, phase and the like of a reference signal, a reflected signal and a transmission signal; and the frequency synchronous scanning of the receiving unit and the signal source is ensured in the frequency sweeping processing process. The receiving unit of the embodiment adopts a tuning receiver to restrain harmonic waves and parasitic signals so as to achieve good test sensitivity and dynamic range.
The signal processing unit performs inversion and decoupling on crack information of the bone implant (a series of cracks with different shapes, positions and sizes are preset, signal characteristics corresponding to the sensor are acquired, the relation between the signal characteristics and the crack information is established, in the actual detection process, after the signal characteristics are acquired, the crack information can be acquired according to the relation between the signal characteristics and the cracks), the crack characteristics are extracted, and the result is displayed according to a required mode. The signal processing unit of the embodiment is used for extracting features and separating interference by introducing a pattern recognition algorithm, so that the sensitivity and the robustness of crack detection are improved.
The detection system of this embodiment works as follows:
the external reader emits electromagnetic waves through frequency scanning and power scanning to excite the radio frequency identification sensor arranged on the bone implant in the body, the radiator of the radio frequency identification sensor and the bone implant form a resonant cavity, backscattering signals are generated on the incident electromagnetic waves, cracks with different shapes, positions and sizes can generate different responses, after the reader receives different scattering absorption, the received signals are decoupled, crack characteristics are extracted, crack initiation and propagation conditions of the bone implant can be sensed in real time, and fatigue dangerous points and fatigue life of the bone implant are predicted.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. An implantable radio frequency identification sensor, characterized in that the sensor is mounted on the surface of a bone implant (3), and is implanted in a living being together with the bone implant (3);
the sensor comprises a substrate (1) and a radiator (2) arranged on the substrate (1);
a resonant cavity is formed between the radiator (2) and the bone implant (3) to perceive crack characteristics of the bone implant (3).
2. An implantable radio frequency identification sensor according to claim 1, characterized in that the radiator (2) comprises a rectangular sensing unit (21) and a circular coding unit (22).
3. An implantable radio frequency identification sensor according to claim 2, characterized in that the rectangular sensing unit (21) comprises two basic radiation patterns: TM (TM) 10 And TM 01 ；
The resonant frequencies corresponding to the two fundamental radiation modes are:
wherein f 10 Is TM 10 Resonant frequency f corresponding to radiation mode 01 Is TM 01 The resonant frequency corresponding to the radiation mode, c is the speed of light in vacuum, L is the length of the rectangular sensing unit, ΔL c The electric length of the rectangular sensing unit in the length direction caused by cracks is increased, W is the width of the rectangular sensing unit, and DeltaW c For increasing the electrical length of the rectangular sensing unit in the width direction caused by cracks re Is an effective dielectric constant.
4. An implantable radio frequency identification sensor according to claim 2, wherein the resonance frequency of the circular encoding unit is:
wherein c is the speed of light in vacuum, R e Is the effective radius of the circular coding unit epsilon r Is the dielectric constant of the substrate.
5. A method of determining parameters of an implantable radio frequency identification sensor as claimed in any one of claims 1 to 4, comprising:
selecting an operating frequency of the sensor and the substrate material having biocompatibility;
according to the radiation and absorption characteristics of biological tissues to electromagnetic fields, combining the sensor, the bone implant implantation position and the depth, establishing a sensor simulation calculation model, and optimizing the shape and the size of the radiator and the thickness of the substrate;
and calculating an energy coupling coefficient between the sensor and an external reader, and determining the final structural parameter of the sensor.
6. The method according to claim 5, wherein the method for obtaining radiation and absorption characteristics of the biological tissue to the electromagnetic field is specifically as follows:
dividing the biological tissue anatomical structure into different layers or different areas by taking each organ as a unit, and establishing a morphological model;
corresponding electromagnetic parameters are assigned to each layer or each region in the morphological model, and an electromagnetic model is constructed;
and analyzing the radiation and absorption characteristics of the biological tissue to the electromagnetic field based on the electromagnetic model.
7. A method of operating an implantable radio frequency identification sensor as claimed in any one of claims 1 to 4, comprising:
by carrying out external electromagnetic excitation on the sensor in the organism, the sensor generates a reflection signal on the incident electromagnetic wave;
and receiving the reflected signal through an external reader and performing decoupling treatment to obtain the crack characteristics of the bone implant, so as to realize real-time perception of crack initiation and propagation conditions of the bone implant.
8. A bone implant crack detection system comprising the implantable radio frequency identification sensor of any one of claims 1-4 and an in vitro reader;
the external reader is used for providing electromagnetic excitation for the identification sensor, receiving and processing the reflected signals transmitted by the sensor, and obtaining the crack characteristics of the bone implant.
9. The bone implant crack detection system according to claim 8, wherein the in vitro reader comprises a signal source, a signal separation device, a receiving unit, a signal processing unit, and an antenna;
the signal source provides continuous wave excitation signals for the sensor through the antenna and outputs power;
the signal separation device is used for separating the reflected signal of the sensor and the continuous wave excitation signal received by the antenna and is responsible for distributing the output power of the signal source to the receiving unit according to a reference signal;
the receiving unit is used for carrying out test analysis on the amplitude-phase parameters of the reflected signal, the reference signal and the transmission signal;
the signal processing unit is used for completing decoupling of crack information of the bone implant according to the information output by the receiving unit and extracting crack characteristics.
10. The bone implant crack detection system according to claim 9, wherein the signal processing unit is further configured to display the results according to actual needs.
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