Detection antenna and detection system for senile sarcopenia

Abstract

The invention provides a senile sarcopenia detection antenna and detection system. The system comprises a pair of detection antennas, a feed connector and a vector network analyzer, the pair of detection antennas are oppositely arranged and respectively serve as a signal receiving end and a signal transmitting end, and an area for accommodating an arm of a to-be-detected object is formed between the detection antennas; and the detection antenna is connected with the vector network analyzer through the feed connector. The detection antenna comprises a dielectric substrate, an antenna patch, a feeder line and a grounding end which jointly form a coplanar waveguide feed microstrip antenna structure; the antenna patch, the feeder line and the grounding ends are installed on the dielectric substrate, the antenna patch is rectangular, the center of the bottom of the antenna patch is connected with the feeder line, the antenna patch is loaded with branches and is slotted, the grounding ends are symmetrically arranged on the left side and the right side of the feeder line, and gaps exist between the grounding ends and the feeder line. Miniaturization and large working bandwidth of the antenna are realized, a current path is increased by adding branches and slots, and broadband and low return loss of the antenna are further realized.

Description

Technical Field

[0001] The present invention belongs to the field of antenna and microwave engineering as well as medical engineering integration, and specifically relates to an antenna and a detection system for sarcopenia in the elderly. Background Art

[0002] Sarcopenia is a geriatric syndrome characterized by age-related loss of muscle mass, decreased muscle strength, and decreased physical function. Sarcopenia can cause falls, mobility disorders, fractures, disability, etc. in the elderly, increasing the risk of disability and loss of self-care ability. Epidemiological research data show that the prevalence of sarcopenia in China is 8.9%-38.8%, with a higher prevalence in men than in women. The prevalence of sarcopenia increases significantly with age, and the prevalence of sarcopenia in the elderly aged 80 and above can be as high as 67.1%. In 2016, sarcopenia was assigned an International Classification of Diseases code as an independent disease. European and Asian scholars in the field of geriatrics have reached the latest consensus on the definition and diagnosis of sarcopenia: early identification of high-risk groups and early intervention in sarcopenia in the elderly are of great significance to reducing complications and improving the quality of life of the elderly.

[0003] There is still considerable controversy about how to define sarcopenia and the best way to diagnose it. Sarcopenia is usually identified by a combination of muscle strength, muscle function, muscle quality, and muscle quantity. The first two require mechanical or observational tests to measure, while the latter requires traditional imaging and sensing. Muscle strength in sarcopenia is usually tested using handgrip strength or self-reported SARCF questionnaires. Patients who score low on the tests undergo imaging and sensory examinations to assess muscle mass, and then a definitive diagnosis of sarcopenia is made. Quantification of muscle thickness or muscle area can be achieved using conventional imaging (CT, MRI, or US), and whole-body muscle mass can also be measured using dual-energy X-ray absorptiometry (DXA) or bioelectrical impedance analysis (BIA). Muscle mass includes the degree of intramuscular fat (myoplasia) or fibrosis. Finally, muscle function tests usually reflect the severity of sarcopenia by examining other aspects such as gait speed and muscle coordination.

[0004] From the consensus mentioned above, it is not difficult to find that the early detection and judgment of sarcopenia is crucial, and developing a detection method that is easy to promote and use has become a top priority. Only when sarcopenia is detected in time in the early stage can measures be taken to intervene. There is currently no simple method for detecting sarcopenia, so it is urgent to design a small, easy-to-use, low-cost antenna system that can be used for sarcopenia detection, and realize sarcopenia detection based on this system. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides an antenna and a system for detecting sarcopenia in the elderly.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides an antenna for detecting sarcopenia in the elderly, characterized in that it includes a dielectric substrate, an antenna patch, a feed line and a ground terminal, which together form a coplanar waveguide-fed microstrip antenna structure; the antenna patch, the feed line and the ground terminal are installed on the dielectric substrate, the antenna patch is rectangular, and the center of its bottom is connected to the feed line, the ground terminals are symmetrically arranged on the left and right sides of the feed line, and there is a gap between the ground terminal and the feed line.

[0008] Optionally, two pairs of rectangular branches are symmetrically loaded on the left and right sides of the antenna patch, wherein the first pair of branches are located on both sides of the top of the antenna patch, and the upper edges of the first pair of branches are flush with the upper edge of the antenna patch, and the second pair of branches are located on both sides of the middle of the antenna patch, and the horizontal axis of the second pair of branches is located below the horizontal axis of the antenna patch.

[0009] Optionally, the length of the second pair of branches is smaller than that of the first pair of branches.

[0010] Optionally, a rectangular first slot is opened at the top center of the antenna patch, upper and lower edges of the first slot are flush with upper and lower edges of the first pair of branches respectively, and a vertical axis of the first slot coincides with a vertical axis of the feed line.

[0011] Optionally, a pair of rectangular second grooves are symmetrically opened on the left and right sides of the antenna patch, the second grooves are located inside the second pair of branches, and the horizontal axis of the second grooves coincides with the horizontal axis of the second pair of branches.

[0012] Optionally, a left edge of the second groove on the left side is flush with a left edge of the antenna patch, and a right edge of the second groove on the right side is flush with a right edge of the antenna patch.

[0013] Optionally, the horizontal width W of the antenna patch is:

[0014]

[0015] In the formula, c represents the speed of light, f represents the center frequency of the antenna, and ε r Represents the dielectric constant of the dielectric substrate;

[0016] The vertical length L of the antenna patch is:

[0017] L=λ e / 2;

[0018] In the formula, λ e represents the waveguide wavelength in the dielectric substrate and is calculated as follows:

[0019]

[0020] Where h represents the thickness of the dielectric substrate.

[0021] In a second aspect, the present invention provides a system for detecting sarcopenia in the elderly, comprising: a pair of detection antennas, a feeding connector and a vector network analyzer as described in any one of claims 1 to 7; the pair of detection antennas are arranged relative to each other, serving as a receiving end and a transmitting end of the signal respectively, and forming an area in the middle to accommodate the arm of the object to be tested; the detection antenna is connected to the vector network analyzer through the feeding connector.

[0022] Optionally, the distance between a pair of detection antennas is not less than 10 cm.

[0023] Optionally, the detection antenna is fixed by a foam board.

[0024] The beneficial effects of the present invention are:

[0025] (1) The present invention is based on a quasi-coplanar waveguide feeding structure and takes a relatively simple rectangular patch antenna as the design basis. By slotting and loading branches on the rectangular patch, the current path is increased, thereby achieving a larger bandwidth and higher gain.

[0026] (2) The present invention takes into account that loading branches, opening slots, and changing the shape of the radiation patch on the antenna patch will affect the performance indicators such as the return loss and working bandwidth of the ultra-wideband antenna. Therefore, the loaded branches and the opened slots are specially designed to increase the working bandwidth to achieve optimal performance.

[0027] (3) The present invention selects the coplanar waveguide feeding method. Compared with the general simple feeding, the coplanar waveguide feeding has the advantages of simple and compact structure and easy impedance matching, which can realize the miniaturization of the antenna.

[0028] (4) The present invention aims to address the shortcomings of current sarcopenia detection, such as complex equipment, inconvenient use, difficult promotion, and high prices. The design of the sarcopenia detection system is to achieve miniaturization, portability, and low cost. The sarcopenia detection system of the present invention is composed of two coplanar waveguide ultra-wideband antennas, and a portable network analyzer is used to achieve low cost and portability of the entire detection system. During the use of the detection system, by observing the transmission characteristics of the antenna in the corresponding frequency band, the amount of muscle content can be roughly determined, thereby achieving the detection of sarcopenia. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is an application diagram of a system for detecting sarcopenia in the elderly;

[0030] Figure 2 It is a front view of an antenna for detecting sarcopenia in the elderly (antenna C);

[0031] Figure 3 is a bottom view of antenna C;

[0032] Figure 4 is a top view of the initial antenna A;

[0033] Figure 5 is a top view of the initial antenna B;

[0034] Figure 6 S11 parameter diagrams without upper arm tissue loading for antennas A, B, and C;

[0035] Figure 7 S21 parameter diagrams without upper arm tissue loading for antennas A, B, and C;

[0036] Figure 8 S11 parameter map for loading upper arm tissue and varying muscle thickness for antenna C;

[0037] Fig. 9 S21 parameter map for antenna C with upper arm tissue loaded and varying muscle thickness;

[0038] Fig.10 Schematic diagram of function fitting for the relationship between S21 and muscle thickness.

[0039] The figure numbers are as follows: 1. dielectric substrate; 2. antenna patch; 3. feed line; 4. ground terminal; 5-8. branches; 9. first slot; 10. second slot; 12. feed connector; 13. upper limb multi-layer model; 14. skin model; 15. fat model; 16. muscle model; 17. bone model. DETAILED DESCRIPTION

[0040] The present invention will now be described in further detail with reference to the accompanying drawings.

[0041] Since different tissues (such as muscle, fat, etc.) have different dielectric constants, different muscle contents will lead to different signal transmission characteristics. The muscle content of patients with sarcopenia is lower than that of ordinary people. Therefore, in this embodiment, the main observation object is the change of S21 within a certain range, that is, the change of the proportion of muscle in the entire observed tissue can be observed. This requires the designed antenna to have a wide frequency band range. The wider the frequency band covered, the easier it is to observe S21 in the corresponding frequency. The ultra-wideband antenna system can meet the above requirements.

[0042] Common feeding methods for antennas include microstrip line feeding, coaxial feeding, electromagnetic coupling feeding, etc. Coplanar waveguide feeding is a common feeding method for ultra-wideband antennas. The coplanar waveguide feeding method has the advantages of simple and compact structure, easy impedance matching, and easy integration with circuit systems. Therefore, in order to suppress back radiation, this embodiment adopts a coplanar waveguide structure, develops an antenna transceiver system, and proposes a system that can be used for the detection of sarcopenia in the elderly.

[0043] This embodiment proposes a system for detecting sarcopenia in the elderly. Figure 1 As shown, it includes a pair of detection antennas 11, a feeding connector 12 and a vector network analyzer; the pair of detection antennas 11 are arranged opposite to each other, serving as the receiving end and the transmitting end of the signal respectively, and forming an area for accommodating the arm of the object to be tested in the middle; the detection antenna 11 is connected to the vector network analyzer through the feeding connector 12. The detection antenna 11 is antenna C, and its structure is as follows Figure 2 As shown. Antenna C is placed opposite to each other, and the arm is placed between them; Figure 1 An upper limb multilayer model 13 is placed in the middle, and from the outside to the inside, there are a skin model 14, a fat model 15, a muscle model 16 and a bone model 17. In actual use, an external portable vector network analyzer can be used to observe S21 of the corresponding frequency band, and the muscle content can be determined by S21, thereby realizing the detection of sarcopenia.

[0044] The circumference of the upper arm of a normal adult male is about 25-35 cm, and that of a normal adult female is about 23-33 cm, so the space with a diameter of 10 cm is sufficient to accommodate the upper arms of most people. Therefore, the distance between the antennas C in this embodiment can be set to be no less than 10 cm.

[0045] Since foam does not affect the transmission characteristics of electromagnetic waves, foam board is selected as the material for fixing the antenna in this embodiment. A cylinder with a diameter of 10 cm is cut out of the foam, and two antennas C are placed opposite to each other in the foam on both sides of the hollowed-out cylinder, that is, the relative distance between the two antennas C is about 12 cm. Then they are connected to the vector network analyzer LiteVNA, which can meet the measurement requirements of 50kHz-6.3GHz.

[0046] This embodiment also proposes an antenna for detecting sarcopenia in the elderly, that is, the antenna C used in the sarcopenia detection system in the elderly. Figure 2 This is a patch diagram of antenna C. Figure 3 FIG. 1 is a bottom view of the antenna C, that is, viewed from the bottom up. Since the present embodiment adopts the coplanar waveguide feeding which is easy to process, Figure 3 It is also a schematic diagram of coplanar waveguide feeding. Figure 3 The middle of the antenna C is a feeder line 3, and both sides are ground terminals 4. The specific dimensions of the antenna C in this embodiment are shown in Table 1.

[0047] Table 1 Specific dimensions of antenna C in this embodiment (unit: mm)

[0048]

[0049]

[0050] for Figure 4 The rectangular antenna patch 2 is located on the upper surface of the dielectric substrate 1 and is fed by a microstrip line. The dielectric substrate 1 is in the middle and has a complete ground plane at the bottom. Assume that the vertical length of the antenna patch 2 is L, the horizontal width is W, and the length is approximately half the working wavelength. The thickness of the dielectric substrate 1 is h, and the working wavelength is λ.

[0051] Since the thickness h of the dielectric substrate is much smaller than the working wavelength, the electric field along the dielectric substrate 1 does not change much and can be approximately ignored. From an ideal state analysis, the electric field in the width W direction does not change. Therefore, the radiation of the antenna patch 2 is only generated by the open edge, which contains two components, vertical and horizontal. Since the length L of the antenna patch is half the working wavelength, the electric field at both ends of it will produce opposite vertical components and the same horizontal components, which cancel and superimpose each other in the far field area, thereby forming radiation characteristics.

[0052] The first step in the design is to determine the center frequency of the antenna as f, select a suitable dielectric substrate, and set the dielectric constant of the dielectric substrate as ε r , calculate the width W of the radiation patch according to the following formula:

[0053]

[0054] The dielectric substrate 1 in this embodiment is made of FR4 with a thickness of 1.6 mm and a dielectric constant ε r is 4.4, c is the speed of light, and the portable vector network analyzer can measure the frequency band below 6.3 GHz, so the center frequency is selected as 4.2 GHz, and W is calculated to be approximately 22 mm.

[0055] The length of antenna patch 2 is generally selected as λ e / 2,λ e is the waveguide wavelength in the medium, and λ is calculated e It is about 36mm, half of which is 18mm. e The calculation formula is as follows:

[0056]

[0057] Considering the need for small design volume and the optimization of subsequent loading branches, the W in the initial stage is designed to be 15 mm, that is, 2*W3+W2=15 mm in the design. The unsatisfactory return loss S11 caused by this can be solved in the subsequent optimization. L is L-L2=18.75 mm in the design.

[0058] exist Figure 4 On the basis of the antenna A, branches 5, 6, 7, and 8 are loaded at the top and slightly below the middle of the antenna patch 2 (offset from the central axis) to form Figure 5 Antenna B in the figure achieves the purpose of optimizing the return loss S11. S11 is significantly reduced, and has good return loss. The location of the branch is mainly selected for subsequent trenching. If the branch is too low, it is too close to the ground. The closer it is to the feeder, the stronger the radiation. The lower pair of branches 7 and 8 are shorter than the upper pair of branches 5 and 6, so that the radiation can be better pushed upward.

[0059] Next in Figure 5 The groove is dug on the basis of Figure 2 Antenna C in the embodiment. In this embodiment, the slots include a rectangular first slot 9 and a rectangular second slot 10, which are respectively opened at the top center and left and right sides of the antenna patch 2. Two slots (i.e., the second slot 10) are located on both sides of the area where the branch part was originally loaded, avoiding the main radiation area corresponding to the feeder 3, i.e., the middle area of ​​the antenna patch 2. This can ensure that the antenna return loss will not be deteriorated. Only by digging slots in this part can the main radiation area be avoided as much as possible to protect the return loss from being affected. Another slot (i.e., the first slot 9) is located in the middle of the top of the antenna B. Although it is located on the midline and is in line with the feeder 3, compared with the feeder position, this is the end of the antenna patch 2, and digging slots here will hardly affect the return loss. The slots dug in this embodiment are relatively small in area. If the slot area is too large or too many slots are dug, it will affect the antenna patch area, and then affect the return loss of the antenna. Therefore, antenna C has three slots dug without affecting the antenna bandwidth and return loss, optimizing the transmission characteristic S21.

[0060] Figure 6 This is the return loss diagram of the detection antenna of this embodiment evolving from the initial antenna A to the final antenna C. It can be seen from the diagram that after the initial antenna A is added with branches and grooves, the antenna matching is the best and the return loss is significantly reduced. At this time, the bandwidth is 3.2 GHz-4.5 GHz. Although the working bandwidth is slightly reduced, it still has a working bandwidth of 1.3 GHz.

[0061] Figure 7The transmission loss diagram of the detection antenna of this embodiment is that the initial antenna A evolves to the final antenna C without loading the upper arm tissue. It can be seen from the diagram that the final antenna C has the best transmission performance and obtains a stable passband, that is, a stable in-band gain. It has good antenna performance while having a large working bandwidth.

[0062] observe Figure 6 From S11 in the figure, we can see that the frequency when the return loss of antenna A is the lowest is 4.17 GHz, and the center frequency of antennas B and C is 4.17 GHz. Figure 7 In the figure, the S21 of antenna A at 4.17GHz is significantly lower than that of antenna B and antenna C, that is, the transmission characteristics of antenna B and antenna C are better than those of antenna A. The reason for the optimization of transmission characteristics is that the increase in the antenna patch area caused by the addition of branches allows the signal between the two patch antennas to be better received. Antenna C is a further grooved antenna based on antenna B, with three small rectangles dug out. The area is smaller and is inside patch antenna B. Therefore, it has almost no effect on the antenna's return loss and working bandwidth. The specific design reasons have been explained above. Figure 6 The images of antennas B and C in the figure almost overlap; Figure 7 In the figure, the image of antenna C is slightly flatter than that of antenna B. This is due to the gaps created by the grooves on antenna patch 2. However, the more grooves there are, the better. If the area of ​​the grooves is too large, the area of ​​the patch will be reduced, resulting in a deterioration of the return loss. Antenna C slightly optimizes the transmission characteristics while ensuring that the return loss is not affected. In addition, as an antenna used on the upper limbs of the human body, the grooves also make antenna C more breathable than antenna B. In summary, antenna C has a certain degree of comfort while ensuring good performance.

[0063] Figure 8 This is the return loss graph of the antenna C in this embodiment when the upper arm tissue is loaded and the muscle thickness is changed. It can be seen from the graph that when the upper arm tissue is loaded and the muscle thickness changes, the return loss is below -10dB between 3.2GHz and 4.5GHz, indicating that the antenna C can still maintain good performance after loading the upper arm tissue with different muscle thicknesses. The working bandwidth can reach 1.3GHz, which has great application value.

[0064] Fig. 9 : This is the transmission loss diagram of the antenna C of this embodiment when the upper arm tissue is loaded and the muscle thickness is changed. It can be seen from the figure that the transmission characteristics of the antenna C change with the change of muscle thickness, and it is regular, which verifies the feasibility of the antenna of this embodiment being applied to the detection of sarcopenia.

[0065] In actual application, it is necessary to process the data after completing the collection of muscle content data of a certain number of elderly people. The baseline value and correction value are determined based on the collected data, and the differences caused by individuals are eliminated. After the function is fitted, the entire detection system can detect sarcopenia.

[0066] It can be found from the simulation that the value of S21 changes regularly with the muscle thickness. Therefore, this embodiment uses software to fit the function of the relationship between S21 and muscle thickness. The fitted function graph is as follows: Fig.10 As shown. The fitted function is a linear function with a slope of about -1.15 and an intercept of about -34.4. The function is approximately y = -1.15x-34.4, where x is muscle thickness in mm and y is S21 in dB. In later testing, the muscle content can be found by corresponding points based on the function curve.

[0067] In summary, the present invention studies the influence of key parameters on return loss for sarcopenia detection antennas. Studies have shown that the antenna works in the range of 3.2GHz to 4.5GHz, and can achieve a level of -10dB within the bandwidth, with an absolute bandwidth greater than 1.3GHz, which meets the frequency band requirements required for sarcopenia detection. It can be seen from the simulation results that the S21 parameter in the frequency band increases with the reduction of muscle content, and the corresponding relationship between muscle content and S21 parameters can be found based on this, so that sarcopenia can be detected, so the antenna designed by the present invention is a potential candidate method for sarcopenia detection at present. The antenna of the present invention maintains good performance in the application frequency band of the portable network analyzer, so that the sarcopenia detection system built by the antenna unit in the design and the portable network analyzer has the advantages of low cost, small size, portability and easy promotion compared to traditional detection equipment (CT, MRI, DXA, BIA, etc.).

[0068] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. An antenna for detecting sarcopenia in the elderly, characterized by: The invention comprises a dielectric substrate (1), an antenna patch (2), a feed line (3) and a grounding terminal (4), which together form a coplanar waveguide-fed microstrip antenna structure; the antenna patch (2), the feed line (3) and the grounding terminal (4) are mounted on the dielectric substrate (1); the antenna patch (2) is rectangular, and the center of its bottom is connected to the feed line (3); the grounding terminals (4) are symmetrically arranged on the left and right sides of the feed line (3); and there is a gap between the grounding terminal (4) and the feed line (3).

2. The antenna for detecting sarcopenia in the elderly as claimed in claim 1, characterized in that: Two pairs of rectangular branches (5, 6, 7, 8) are symmetrically loaded on the left and right sides of the antenna patch (2), wherein the first pair of branches (5, 6) are located on both sides of the top of the antenna patch (2), and the upper edges of the first pair of branches (5, 6) are flush with the upper edge of the antenna patch (2), and the second pair of branches (7, 8) are located on both sides of the middle of the antenna patch (2), and the horizontal axis of the second pair of branches (7, 8) is located below the horizontal axis of the antenna patch (2).

3. The antenna for detecting sarcopenia in the elderly as claimed in claim 2, characterized in that: The length of the second pair of branches (7, 8) is shorter than that of the first pair of branches (5, 6).

4. The antenna for detecting sarcopenia in the elderly as claimed in claim 2, characterized in that: A rectangular first groove (9) is provided at the center of the top of the antenna patch (2); the upper and lower edges of the first groove (9) are respectively flush with the upper and lower edges of the first pair of branches (5, 6); and the vertical axis of the first groove (9) coincides with the vertical axis of the feed line (3).

5. The antenna for detecting sarcopenia in the elderly as claimed in claim 2, characterized in that: A pair of rectangular second grooves (10) are symmetrically provided on the left and right sides of the antenna patch (2); the second grooves (10) are located inside the second pair of branches (7, 8); and the horizontal axis of the second grooves (10) coincides with the horizontal axis of the second pair of branches (7, 8).

6. The antenna for detecting sarcopenia in the elderly as claimed in claim 5, characterized in that: The left edge of the second groove (10) located on the left side is flush with the left edge of the antenna patch (2), and the right edge of the second groove (10) located on the right side is flush with the right edge of the antenna patch (2).

7. The antenna for detecting sarcopenia in the elderly as claimed in claim 1, characterized in that: The horizontal width W of the antenna patch (2) is: In the formula, c represents the speed of light, f represents the center frequency of the antenna, and ε r Represents the dielectric constant of the dielectric substrate; The vertical length L of the antenna patch (2) is: L=λ e / 2; In the formula, λ e represents the waveguide wavelength in the dielectric substrate and is calculated as follows: Where h represents the thickness of the dielectric substrate.

8. A system for detecting sarcopenia in the elderly, characterized in that: include: A pair of detection antennas (11), a feeding connector (12) and a vector network analyzer as described in any one of claims 1 to 7; the pair of detection antennas (11) are arranged opposite to each other, respectively serving as a receiving end and a transmitting end of a signal, and forming an area in the middle for accommodating the arm of the object to be measured; the detection antenna (11) is connected to the vector network analyzer via the feeding connector (12).

9. The elderly sarcopenia detection system according to claim 8, characterized in that: The distance between the pair of detection antennas (11) is not less than 10 cm.

10. The elderly sarcopenia detection system according to claim 8, characterized in that: The detection antenna (11) is fixed by a foam board.

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