A wearable metasurface device for magnetic resonance imaging

Abstract

The application provides a wearable metasurface device for magnetic resonance imaging, comprising: a plurality of first electrode plates; a plurality of second electrode plates, the plurality of first electrode plates and the plurality of second electrode plates are arranged one by one; the first electrode plate and the second electrode plate are attached and can slide relative to each other to form a variable structure capacitor; at least one annular connecting part, the plurality of first electrode plates and the plurality of second electrode plates are arranged in a circumferential array on the annular connecting part. The wearable metasurface device for magnetic resonance imaging provided in the embodiment of the application perfectly solves the problem of frequency shift caused by strain of the wearable metasurface, and helps to improve the signal-to-noise ratio of magnetic resonance imaging.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear magnetic resonance imaging, in particular to a wearable metasurface device for magnetic resonance imaging. BACKGROUND

[0002] Magnetic resonance imaging (MRI) is one of the modern medical high-end imaging diagnostic techniques, and the image quality mainly depends on the signal-to-noise ratio (SNR) of the image. High-quality image signal-to-noise ratio can make the magnetic resonance image clearer, provide higher quality detection for clinical diagnosis, and also can be used to shorten the scanning time to improve the detection efficiency. In the prior art, the image signal-to-noise ratio is mainly improved by increasing the static magnetic field strength B0 or using a multi-channel phased array line receiving coil. However, increasing B0 means a significant increase in cost. And the multi-channel phased array coil also encounters a bottleneck. The increase in the number of channels will bring the problems of cost increase, volume and weight exceeding the limit, decoupling complexity, etc.

[0003] Although the wearable metasurface has a higher theoretical SNR, due to the flexible wearable design of the metasurface, the configuration of the wearable metasurface is not fixed, and when worn on different human bodies, the wearable metasurface may be in different stretched states, which will cause the resonance frequency of the metasurface to shift. When the resonance frequency of the metasurface shifts to the working frequency of the MRI system, the signal-to-noise ratio enhancement performance will rapidly decrease. SUMMARY

[0004] The present application provides a wearable metasurface device for magnetic resonance imaging to solve the problem that the resonance frequency of the wearable metasurface shifts when it is stretched, which in turn causes the signal-to-noise ratio enhancement performance of the magnetic resonance to decrease.

[0005] In order to solve at least one of the above problems in the prior art, the present application provides a wearable metasurface device for magnetic resonance imaging.

[0006] According to the present application, a wearable metasurface device for magnetic resonance imaging is provided, which comprises:

[0007] a plurality of first electrode plates;

[0008] a plurality of second electrode plates, the plurality of first electrode plates and the plurality of second electrode plates are arranged in a one-to-one correspondence; the first electrode plate and the second electrode plate are bonded and can slide relative to each other to form a variable structure capacitor;

[0009] at least one annular connecting part, the plurality of first electrode plates and the plurality of second electrode plates are arranged in a circumferential array on the annular connecting part.

[0010] In some embodiments of the present application, the first electrode plate corresponding to any second electrode plate is electrically connected to one of the two second electrode plates adjacent to the any second electrode plate;

[0011] The first electrode plate corresponding to the any second electrode plate is electrically connected to the other of the two second electrode plates adjacent to the any second electrode plate.

[0012] In some embodiments of the present application, the first electrode plate comprises a first substrate and a first conductive layer;

[0013] The second electrode plate comprises a second substrate and a second conductive layer; wherein the first conductive layer is attached to the second substrate; or

[0014] The second conductive layer is attached to the first substrate.

[0015] In some embodiments of the present application, the first electrode plate and the second electrode plate are flexible circuit boards.

[0016] In some embodiments of the present application, the annular connecting part is composed of a plurality of elastic connecting members, and the first electrode plate and the second electrode plate corresponding thereto are arranged on an elastic connecting member.

[0017] In some embodiments of the present application, the number of annular connecting parts is two, and the plurality of first electrode plates and the plurality of second electrode plates are arranged in a circumferential array between the two annular connecting parts.

[0018] The annular connecting part comprises a plurality of sliding groove fixing seats corresponding to the number of first electrode plates;

[0019] At least one of the first electrode plate and the second electrode plate slides inside the sliding groove fixing seat.

[0020] In some embodiments of the present application, the sliding groove fixing seat comprises an elastic reset component for resetting at least one of the first electrode plate and the second electrode plate after sliding.

[0021] In some embodiments of the present application, the second electrode plate and the first electrode plate are not the same in length, and the second electrode plate is arranged inside the sliding groove fixing seat.

[0022] In some embodiments of the present application, there are gaps between the plurality of first electrode plates, and there are gaps between the first electrode plate and the second electrode plate adjacent thereto.

[0023] In some embodiments of the present application, the number of first electrode plates is even.

[0024] From the above description, the embodiment of the application provides a wearable metasurface device for magnetic resonance imaging, which comprises: a plurality of first polar plates; a plurality of second polar plates, the plurality of first polar plates and the plurality of second polar plates are arranged one by one; the first polar plate and the second polar plate are attached and can slide relative to each other to form a variable structure capacitor; at least one annular connecting part, the plurality of first polar plates and the plurality of second polar plates are arranged in a circumferential array on the annular connecting part.

[0025] The wearable metasurface device for magnetic resonance imaging provided by the embodiment of the application perfectly solves the problem of frequency shift caused by strain of the wearable metasurface, and helps to improve the signal-to-noise ratio of magnetic resonance imaging. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings. In the drawings:

[0027] Figure 1 It is the overall structure schematic diagram of the wearable metasurface device for magnetic resonance imaging of the embodiment of the application.

[0028] Figure 2 It is the schematic diagram of the metasurface resonance frequency compensation method principle of the wearable metasurface device for magnetic resonance imaging of the embodiment of the application.

[0029] Figure 3 It is the schematic diagram of the series formation mode of the variable structure capacitor of the embodiment of the application.

[0030] Figure 4 It is the structure schematic diagram of the first polar plate 1 and the second polar plate 2 of the embodiment of the application.

[0031] Figure 5 It is the schematic diagram of the initial state and the stretched state of the wearable metasurface device for magnetic resonance imaging of the embodiment of the application.

[0032] Figure 6 It is the application scene schematic diagram of the wearable metasurface device for magnetic resonance imaging of the specific application example of the application.

[0033] Figure 7 It is the overall structure schematic diagram of the wearable metasurface device for magnetic resonance imaging of the specific application example of the application.

[0034] Reference signs:

[0035] 1: first pole plate;

[0036] 2: second pole plate;

[0037] 3: annular connection portion;

[0038] 4: sliding groove fixing seat;

[0039] 5: wearable metasurface device for magnetic resonance imaging;

[0040] 6: mobile sickbed;

[0041] 7: radio frequency transmitting coil (body coil);

[0042] 8: gradient coil;

[0043] 9: main magnet coil;

[0044] 10: elastic cloth;

[0045] 24: elastic reset component;

[0046] 111: first base;

[0047] 221: second base; DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0049] It should be noted that the terms “include” and “have” and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover the inclusion not the exclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices. The embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0050] Metasurface provides a new way for further enhancement of SNR of MRI. Metasurface resonates at the working frequency of MRI, greatly enhances the RF magnetic field in the region of interest, amplifies the nuclear magnetic resonance signal, and further enhances the SNR of the magnetic resonance image. The traditional fixed configuration of metasurface has been verified to be feasible in improving the SNR of MRI. Wearable metasurface can be as close as possible to the surface of the measured target, adapt to the irregular structure of human body parts, and theoretically further improve the SNR compared with the fixed configuration of metasurface.

[0051] The existing multi-channel phased array magnetic resonance RF receiving coil receives MR signals through multiple single-loop RF coils simultaneously, and each coil covers a different anatomical region. These coils can work at different phases to simultaneously collect nuclear magnetic signals, and then combine the data of each channel to generate a magnetic resonance image.

[0052] This method needs to be connected to the magnetic resonance system through a cable. The multi-channel phased array coil technology has encountered bottlenecks. The increase in the number of channels will bring problems such as cost increase, size and weight exceeding the limit, and decoupling complexity. Moreover, as the number of channels increases, the SNR is basically no longer enhanced.

[0053] The prior art also uses a fixed configuration of metasurface, which uses a metal wire array to form a metasurface that can resonate at the working frequency of MRI, amplify the RF magnetic field in the region, and enhance the image SNR. However, due to the fixed configuration, it cannot be close to the surface of the measured target, so it cannot maximize the image SNR and cannot fully utilize the SNR enhancement performance of the metasurface. The flexible attachment feature of wearable metasurface can maximize the image SNR.

[0054] In order to solve at least one of the above problems in the prior art, the embodiments of the present application provide a wearable metasurface device for magnetic resonance imaging. Figure 1 A schematic diagram of the wearable metasurface device for magnetic resonance imaging of the embodiments of the present application is shown in FIG. 1. As shown in FIG. 1, the wearable metasurface device for magnetic resonance imaging comprises: Figure 1

[0055] a plurality of first electrode plates 1;

[0056] a plurality of second electrode plates 2, the plurality of first electrode plates 1 and the plurality of second electrode plates 2 are arranged one by one; the first electrode plate 1 and the second electrode plate 2 are attached and can slide relative to each other to form a variable structure capacitor;

[0057] at least one annular connecting part 3, the plurality of first electrode plates 1 and the plurality of second electrode plates 2 are arranged in a circumferential array on the annular connecting part 3.

[0058] In Figure 1 ​In the embodiment, the positions of the first electrode plate 1 and the second electrode plate 2 at least partially overlap in the vertical direction, that is, the first electrode plate 1 can be partially located in the upper portion of the second electrode plate 2 (both need to be arranged in close contact) or can be located in the lower portion of the second electrode plate 2 to form the upper electrode plate and the lower electrode plate of the variable structure capacitor. It can be understood that the variable structure capacitor in the above embodiment is a sliding variable capacitor, which changes the facing area between the upper and lower electrode plates by sliding the upper and lower electrode plates (the first electrode plate and the second electrode plate) to change the capacitance.

[0059] The inventor found that due to the size difference of the measured target, when the wearable metasurface is worn on the surface of different measured targets, the size of the metasurface structure changes, the equivalent inductance of the whole structure changes, the resonant frequency shifts, the radio frequency magnetic field enhancement performance of the metasurface decreases, and the image signal-to-noise ratio of the magnetic resonance imaging is affected.

[0060] Specifically, as shown in Figure 2 When the metasurface is worn on a larger target surface, the size of the metasurface is stretched, resulting in an increase in the equivalent inductance. According to the resonant frequency calculation formula of the metasurface (see the formula below), when the equivalent inductance increases, the resonant frequency of the metasurface will decrease, resulting in a decrease in the radio frequency magnetic field enhancement performance of the metasurface at the magnetic resonance resonance point.

[0061]

[0062] wherein, is the resonant frequency of the metasurface, L is the equivalent inductance of the metasurface, and C is the equivalent capacitance of the metasurface.

[0063] And the wearable metasurface device for magnetic resonance imaging described in the above embodiments of the present application has the beneficial effect of realizing the stretchability of the wearable metasurface, and at the same time compensates for the resonant frequency of the stretched wearable metasurface device.

[0064] Specifically, when the wearable metasurface device is stretched, the first electrode plate and the second electrode plate slide relative to each other, resulting in a decrease in the equivalent capacitance of the whole structure. By pre-setting the relationship between the area change of the relative sliding between the first electrode plate and the second electrode plate and the change in the equivalent inductance of the whole structure before and after stretching, the product of the equivalent capacitance and the equivalent inductance of the wearable metasurface device before and after stretching can be kept unchanged, and the resonant frequency of the wearable metasurface device can be kept unchanged, thereby ensuring the image signal-to-noise ratio of the magnetic resonance imaging.

[0065] In some embodiments of the present application, when the number of annular connecting parts 3 is 1, it is located at the middle position of the first electrode plate 1 and the second electrode plate 2 to better relatively fix the first electrode plate 1 and the second electrode plate 2.

[0066] Further, referring to Figure 1 When the number of the annular connecting portions 3 is two, the plurality of first electrode plates 1 and the plurality of second electrode plates 2 are arranged in a circumferential array between the two annular connecting portions 3, i.e. the two annular connecting portions 3 are located at the two ends of the first electrode plates 1 and the second electrode plates 2 (at this time, the annular connecting portion can also be referred to as an end ring).

[0067] In some embodiments of the present application, referring to Figure 3 , any second electrode plate 2 (here, the middle second electrode plate 2 is taken as an example, which is the upper electrode plate in the figure, and can also be the lower electrode plate, which is not limited in the present application) is electrically connected to the first electrode plate 1 corresponding to one of the two second electrode plates 2 adjacent to the any second electrode plate 2 (here, the first electrode plate 1 on the left side of the middle second electrode plate 2 is taken as an example, which is not limited in the present application). Figure 3

[0068] The first electrode plate 1 corresponding to the any second electrode plate 2 is electrically connected to the other second electrode plate 2 (i.e. the second electrode plate 2 on the right side of the middle second electrode plate 2) of the two second electrode plates 2 adjacent to the any second electrode plate 2. At this time, the plurality of first electrode plates 1 and the plurality of second electrode plates 2 are connected in series into a variable structure capacitor.

[0069] In some embodiments of the present application, referring to Figure 4 , the first electrode plate 1 comprises a first substrate 111 and a first conductive layer 112, and the second electrode plate 2 comprises a second substrate 221 and a second conductive layer 222; wherein the second conductive layer 222 is attached to the first substrate 111 (as shown in Figure 4 , i.e. the first electrode plate 1 as the lower electrode plate and the second electrode plate 2 as the upper electrode plate); or

[0070] the first conductive layer 112 is attached to the second substrate 221 (not shown in Figure 4 , in this embodiment, the first electrode plate 1 as the upper electrode plate and the second electrode plate 2 as the lower electrode plate).

[0071] Further, the first substrate 111 and the second substrate 221 are radio frequency loss substrates, i.e. material substrates with relatively low radio frequency loss, preferably at least one of FR4, 400C, Rogers substrate and polytetrafluoroethylene plastic in the PCB process.

[0072] In some embodiments of the present application, the first electrode plate 1 and the second electrode plate 2 are flexible circuit boards.

[0073] ​In some embodiments of the present application, the ring-shaped connecting part is composed of a plurality of elastic connecting members, and the first electrode plate and the second electrode plate corresponding thereto are arranged on an elastic connecting member. It can be understood that for the same ring-shaped connecting part, the elastic connecting member and the first electrode plate and the second electrode plate connected thereto are one-to-one corresponding.

[0074] In some embodiments of the present application, referring to Figure 1 When the number of ring-shaped connecting parts 3 is two, a plurality of first electrode plates 1 and a plurality of second electrode plates 2 are arranged in a circumferential array between the two ring-shaped connecting parts 3, i.e., the two ring-shaped connecting parts 3 are located at the two ends of the first electrode plates 1 and the second electrode plates 2 (at this time, the ring-shaped connecting part can also be referred to as an end ring).

[0075] Referring to Figure 1 , the ring-shaped connecting part 3 includes a plurality of sliding groove fixing seats 4 (shown by the red dashed line frame in the figure) corresponding to the number of first electrode plates 1;

[0076] At least one of the first electrode plate 1 and the second electrode plate 2 slides inside the sliding groove fixing seat 4.

[0077] In some embodiments of the present application, referring to Figure 4 and Figure 5 , the sliding groove fixing seat 4 includes an elastic reset component 24 for resetting at least one of the first electrode plate 1 and the second electrode plate 2 after sliding. Preferably, referring to Figure 4 and Figure 5 , the elastic reset component 24 is a spring rope or a tension spring.

[0078] In some embodiments of the present application, the second electrode plate 2 and the first electrode plate 1 are not the same in length, and the second electrode plate 2 is arranged inside the sliding groove fixing seat 4. Preferably, the length of the second electrode plate 2 is less than the length of the sliding groove fixing seat, i.e., the second electrode plate 2 is only arranged in the corresponding part of the ring-shaped connecting part 3, and further, the width of the second electrode plate 2 and the width of the first electrode plate 1 can also not be equal. It can be understood that this arrangement can further increase the extensibility of the wearable metasurface device. In this embodiment (the second electrode plate 2 is only arranged inside the sliding groove fixing seat 4, the first electrode plate 1 is the upper electrode, the second electrode plate 2 is the lower electrode, and the two ring-shaped connecting parts 3 are end rings), assuming that the length of the first electrode plate 1 is L1, the effective length of L 11 , the length of the second electrode plate 2 is L2, then L 11 is equal to the difference between the length of the first electrode plate 1 and the length of the two second electrode plates 2, i.e.: L 11 =L1-2L 2， For a single first electrode plate 1, the resonant frequency and the effective length L 11 , the capacitance C of the parallel plate capacitor have the following relationship:

[0079]

[0080]

[0081]

[0082] for the resonant frequency for the dielectric constant of the intermediate dielectric layer, S for the area of the upper and lower plates, k for the electrostatic force constant, and d for the distance between the upper and lower plates, for the electromagnetic wave wavelength at resonance, W for the wave impedance of the first plate, and X for the capacitive reactance of the parallel plate capacitor. During stretching and contraction of the wearable metasurface, S changes passively, thereby changing the value of the structure capacitance and achieving passive self-adaptive compensation of the resonant frequency of the metasurface.

[0083] In some embodiments of the present application, referring to Figure 1 , there are gaps between the plurality of first plates 1, and there are gaps between the first plates 1 and their adjacent second plates 2. It should be noted that the above-mentioned "there are gaps between the plurality of first plates 1" means that in the initial state of the wearable metasurface device, there are gaps between the plurality of first plates 1, and there are gaps between the first plates 1 and their adjacent second plates 2; and after stretching, there are still gaps between the plurality of first plates 1, and there are still gaps between the first plates 1 and their adjacent second plates 2.

[0084] In some embodiments of the present application, the number of first plates is even.

[0085] It should be noted that the concept of the wearable metasurface device for magnetic resonance imaging proposed in the present application is not limited to the stretching of the wearable metasurface device. In particular, when the person (or part) to be detected is relatively slender, the wearable metasurface device for magnetic resonance imaging proposed in the present application can also be tightened, for example, a tightening and stretching is provided on a certain sliding groove fixing seat to pull at least one of the first plate and the second plate, so that the circumference of the annular connecting part becomes smaller, or at least one first plate and the corresponding second plate and the sliding groove fixing seat are removed (similar to the way of shortening the watch chain), so as to also achieve the purpose of making the circumference of the annular connecting part smaller, and thus the wearable metasurface can be as close as possible to the surface of the measured target.

[0086] From the above description, the embodiment of the application provides a wearable metasurface device for magnetic resonance imaging, which comprises: a plurality of first polar plates; a plurality of second polar plates, the plurality of first polar plates and the plurality of second polar plates are arranged one by one; the first polar plate and the second polar plate are attached and can slide relative to each other to form a variable structure capacitor; at least one annular connecting part, the plurality of first polar plates and the plurality of second polar plates are arranged in a circumferential array on the annular connecting part.

[0087] The embodiment of the application provides a wearable metasurface device for magnetic resonance imaging, which aims to solve the problem that when the wearable metasurface is stretched, the resonance frequency is offset, and the signal-to-noise ratio of magnetic resonance imaging is enhanced, thereby realizing efficient signal transmission and enhancement in magnetic resonance imaging (MRI).

[0088] In order to further illustrate the scheme, the embodiment of the application takes the specific application scene of the wearable metasurface device for magnetic resonance imaging as an example, and provides a specific application example of the wearable metasurface device for magnetic resonance imaging.

[0089] Firstly, referring to Figure 6 , the position shown in Fig. 5 is the position of the wearable metasurface device for magnetic resonance imaging, which surrounds the measured target and is as close as possible to the surface of the measured target (only need to wear the wearable metasurface device on the part to be measured (wrist, knee, etc.), and use a suitable receiving coil (including but not limited to a spine coil, a body coil, an abdominal coil, etc.) to receive. Figure 6 In the figure, 6 is a mobile bed (which can move the human body to the best position according to detection requirements), 7 is a radio frequency transmitting coil (a body coil), 8 is a gradient coil, and 9 is a main magnet coil.

[0090] In order to solve the related technical problems in the prior art, the application adds a structure capacitor responding to deformation in the end ring of the metasurface. The structure capacitor is composed of upper and lower polar plates and a medium therebetween, and the upper and lower polar plates can slide relative to each other, and the facing area between the upper and lower polar plates determines the equivalent capacitance size.

[0091] It can be understood that after introducing the structure into the metasurface, when the size of the metasurface increases, the size of the end ring also increases, and the upper and lower polar plates of the structure capacitor will slide relative to each other under the action of force, resulting in a decrease in the facing area and a decrease in the structure capacitor. According to the resonance frequency calculation formula of the aforementioned metasurface, the resonance frequency of the metasurface will increase at this time, thereby correcting the decrease in the resonance frequency caused by the increase in the equivalent inductance.

[0092] Ideally, when the product of the equivalent inductance and the equivalent capacitance is The resonance frequency of the metasurface will remain constant when the constant is maintained. In practice, the signal-to-noise ratio enhancement performance is acceptable when the frequency is corrected to within 1% of the frequency of the magnetic resonance imaging system.

[0093] Specifically, the metasurface is as shown in the figure, and the structure is formed by a plurality of first plates 1 and corresponding second plates 2 arranged in a circular array, and all the first plates 1 and the corresponding second plates 2 are connected by a ring-shaped connecting part 3 (end ring) to form a resonant metasurface. The first plate 1 is composed of a first substrate 111 (low-loss substrate) and a first conductive layer 112. The first plate 1 extends along the length direction to the end ring, is fixedly connected with the sliding groove fixing seat 4 on the end ring, and intersects with the end ring, and the overlapping part with the end ring serves as the upper plate of the structural capacitor. Figure 1 The upper plate of the structural capacitor (the second plate 2) is composed of a second substrate 221 (low-loss substrate) and a second conductive layer 222, and can slide relative to the first plate 1 along the circumference of the end ring in the sliding groove fixing seat 4, together with the first plate 1 to form a variable structural capacitor.

[0094] On the other hand, the elastic reset component (elastic rope or tension spring) 24 elastically limits the second plate 2 on the sliding groove fixing seat 4 to limit the position of the second plate 2 relative to the sliding groove fixing seat 4, and the first plate 1 is fixedly arranged in the groove of the sliding groove fixing seat 4; so that the variable structural capacitor is formed in a circular array, and in this process, any second plate 2 (the first plate 1 corresponding to one of the two second plates 2 adjacent to the any second plate 2 is electrically connected; the first plate 1 corresponding to the any second plate 2 is electrically connected with the other second plate of the two second plates 2 adjacent to the any second plate 2. At this time, a plurality of first plates 1 and a plurality of second plates 2 are connected in series to form a variable structural capacitor.

[0095] Next, according to the variable structural capacitor calculation formula C

[0096] , the initial capacitance value of the variable structural capacitor can be determined by the dielectric constant of the first substrate 111, the thickness of the first conductive layer 112, and the relative area . Changing the relative area can linearly change the size of the structural capacitance value.

[0097] In the present application, when the metasurface is worn on the surface of different objects, the size change will be reflected in the change of the size of the end ring. The variable structural capacitor will be passively changed under the action of deformation, realizing the passive adaptive effect of the resonance frequency.

[0098] Further, the first and second electrode plates are made of PCB boards. PCB (Printed Circuit Board) is used to physically support and electrically connect electronic components. Electronic components are fixed on the board and connected by circuits to achieve electrical functions. PCB is composed of an insulating substrate (such as FR4) and a conductive layer (usually copper) covering it. The main components of the PCB are as follows:

[0099] Substrate: Provides physical support for the PCB, commonly FR4 (glass fiber reinforced epoxy), CEM1, CEM3, etc.

[0100] Conductive layer: usually copper, used to form conductive paths for circuits. It can be a single-sided board (only one side has a copper layer), a double-sided board (both sides have a copper layer), or a multi-layer board (multiple layers of copper and insulating layers are alternately stacked).

[0101] Copper layer: used to protect the copper circuit from oxidation and corrosion.

[0102] Solder pad: a point for soldering electronic components.

[0103] Via hole: a hole that provides electrical connection between different layers.

[0104] Silk screen layer: used for identifying component positions, markings, and other indication information.

[0105] The first and second substrates are made of materials with low radio frequency loss, and copper is coated on them to form conductive layers. The upper and lower electrode plates of the adjustable capacitor are made of two FPCs, and FR4 is added in the overlapping area to form a structural capacitor and a terminal ring. The upper electrode plate of the current structural capacitor is made of a metal wire in the terminal ring and extends along the circumferential direction, connected to the lower electrode plate of the previous structural capacitor, while the lower electrode plate of the current structural capacitor is extended and connected to the upper substrate of the next structural capacitor. The structural capacitors are arranged in a circular array to form the entire capacitor. To ensure that the upper and lower electrode plates can be attached to the middle dielectric layer and slide relative to each other, the lower electrode plate is fixed to the middle dielectric layer and fixed to a sliding groove fixed seat (capacitor seat), which is designed with a sliding groove for the upper electrode plate to slide. The capacitor seat can be made by 3D printing or machining.

[0106] Preferably, referring to Figure 7 , the surface of the wearable metasurface device for magnetic resonance imaging can be covered with a layer of elastic cloth 10 or other elastic material, which encapsulates the metasurface. The elastic material is in contact with the surface of the target to be measured and can be stretched.

[0107] As can be known from the above description, the specific application example of the present application provides a wearable metasurface device for magnetic resonance imaging, comprising: a plurality of first electrode plates; a plurality of second electrode plates, the plurality of first electrode plates and the plurality of second electrode plates are arranged one by one; the first electrode plate and the second electrode plate are bonded and can slide relative to each other to form a variable structure capacitor; at least one annular connecting part, the plurality of first electrode plates and the plurality of second electrode plates are arranged in a circumferential array on the annular connecting part.

[0108] The specific application example of the present application provides a wearable metasurface device for magnetic resonance imaging, which aims to solve the problem that when the wearable metasurface is stretched and deformed, the resonant frequency is offset, resulting in the decline of the magnetic resonance signal-to-noise ratio enhancement performance, so as to realize efficient signal transmission and enhancement in magnetic resonance imaging (MRI).

[0109] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation of the present application. In addition, the terms "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0110] The description of the terms "one embodiment", "one specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. The order of steps involved in each embodiment is used to illustrate the implementation of the present application, and the order of steps is not limited, and can be appropriately adjusted as needed.

[0111] In the description of the present application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0112] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other, and each embodiment focuses on the difference from other embodiments. In particular, for system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the description of the method embodiments. In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the specification. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0113] The above is only an embodiment of the embodiments of the present application, and is not intended to limit the embodiments of the present application. Those skilled in the art can make various changes and changes to the embodiments of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the embodiments of the present application shall be included in the scope of claims of the embodiments of the present application.

Claims

1. A wearable metasurface device for magnetic resonance imaging, characterized in that, The wearable metasurface device comprises: a plurality of first electrode plates; a plurality of second electrode plates, the plurality of first electrode plates and the plurality of second electrode plates are arranged one by one; the first electrode plate and the second electrode plate are bonded and can slide relative to each other to form a variable structure capacitor; at least one annular connecting part, the plurality of first electrode plates and the plurality of second electrode plates are arranged in a circumferential array on the annular connecting part; the annular connecting part is composed of a plurality of elastic connecting parts, the first electrode plate and the corresponding second electrode plate are arranged on an elastic connecting part; the number of annular connecting parts is two, and the plurality of first electrode plates and the plurality of second electrode plates are arranged in a circumferential array between the two annular connecting parts; the annular connecting part comprises a plurality of slide groove fixing seats which are the same as the number of the first electrode plates; at least one of the first electrode plate and the second electrode plate slides inside the slide groove fixing seat; the slide groove fixing seat comprises an elastic reset component for resetting at least one of the first electrode plate and the second electrode plate after sliding; 2. The wearable metasurface device of claim 1, wherein, During use, the wearable metasurface device is stretched and contracted, and during stretching and contraction, the facing area between the first electrode plate and the corresponding second electrode plate changes passively, thereby changing the capacitance value of the variable structure capacitor, and then realizing passive adaptive compensation of the metasurface resonance frequency. Any second electrode plate and the corresponding first electrode plate of one of the two second electrode plates adjacent to the any second electrode plate are electrically connected; the corresponding first electrode plate of the any second electrode plate and the other of the two second electrode plates adjacent to the any second electrode plate are electrically connected.

3. The wearable metasurface device according to claim 1, wherein: the first electrode plate comprises a first substrate and a first conductive layer; the second electrode plate comprises a second substrate and a second conductive layer; wherein the first conductive layer is bonded to the second substrate; or 4. The wearable metasurface device of claim 1, wherein, the second conductive layer is bonded to the first substrate.

5. The wearable metasurface device of claim 1, wherein, The first electrode plate and the second electrode plate are flexible circuit boards.

6. The wearable metasurface device of claim 1, wherein, The second electrode plate and the first electrode plate are not the same in length, and the second electrode plate is arranged inside the slide groove fixing seat.

7. The wearable metasurface device of any one of claims 1 to 6, wherein, There are gaps between the plurality of first electrode plates, and there are gaps between the first electrode plate and the second electrode plate adjacent to the first electrode plate. The number of first electrode plates is even.

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