Terahertz biological tissue imaging system and imaging method based on metasurface antenna

Abstract

The application discloses a terahertz biological tissue imaging system and method based on a metasurface antenna. The terahertz biological tissue imaging system comprises a terahertz signal generator, an intelligent system control device, a terahertz signal transmitter and a data acquisition module. The terahertz signal generator is used for generating an ultra-wideband terahertz wave signal. The intelligent system control device controls the terahertz signal generator to continuously generate the ultra-wideband terahertz wave signal. The terahertz signal transmitter is used for transmitting the ultra-wideband terahertz wave signal after programmable modulation to a biological tissue organ. The terahertz signal receiver is used for receiving terahertz biological signals scattered inside and around the biological tissue organ, and modulating the received terahertz biological signals. The data acquisition module is used for acquiring the terahertz biological signals. The intelligent sensing signal processing module is used for processing the terahertz biological signals to obtain a terahertz image of the biological tissue organ. The application solves the problems of narrow bandwidth and low gain in the corresponding technology.

Description

Technical Field

[0001] This invention relates to the field of terahertz biological imaging technology, and in particular to a terahertz biological tissue imaging system and imaging method based on a metasurface antenna. Background Technology

[0002] In recent years, terahertz wave (0.1–10 THz) imaging has attracted increasing attention, primarily due to its unique ability to penetrate a large number of optically opaque media, such as plastics and semiconductors. Compared to X-rays, terahertz waves have low energy, meaning that terahertz wave irradiation will not damage the human body or the object being measured. These unique properties make terahertz imaging technology a promising field for applications such as security inspection, biomedicine, and industry.

[0003] Existing terahertz imaging systems generally use focal plane array terahertz detectors or point-by-point mechanical scanning imaging. Focal plane array terahertz detectors have high requirements for manufacturing processes, are expensive, and have weak anti-interference capabilities. Point-by-point mechanical scanning imaging only requires a single-pixel detector, and the imaging target is scanned by sampling mechanical movement. It has advantages such as low cost, simple structure, and strong anti-interference capabilities. However, since each pixel of the image requires a complete time scan to obtain the final image, it greatly increases the acquisition time and the amount of data stored.

[0004] Terahertz detectors are the core component of terahertz imaging systems. Common terahertz detectors mainly include thermal detectors and Schottky diode detectors. Thermal detectors are already in practical use, but their response speed is slow and their sensitivity is low; Schottky diode detectors have a narrow bandwidth. Therefore, under the requirements of high-speed, high-sensitivity, and high-precision biomedical diagnostic applications, existing terahertz detectors and their imaging systems suffer from problems such as long processing time, complex driving, large size, and low sensitivity.

[0005] Metamaterials, as artificial composite structures, possess physical properties not found in natural materials. Their two-dimensional form, metasurfaces, not only enables the control of electromagnetic waves but also offers significant design flexibility and immense application value. With the rapid development of millimeter-wave technology, metamaterials and metasurface antennas have received widespread attention. However, currently, there are relatively few metasurface antennas suitable for terahertz imaging; most operate in the sub-6GHz band, exhibiting a narrow axial ratio bandwidth. Summary of the Invention

[0006] To address the technical problem of narrow bandwidth in existing metasurface antennas, this invention proposes a terahertz biological tissue imaging system and method based on metasurface antennas.

[0007] The terahertz biological tissue imaging system based on metasurface antennas proposed in this invention includes:

[0008] Terahertz signal generator, used to generate ultra-wideband terahertz wave signals;

[0009] The intelligent system control device controls the terahertz signal generator to continuously generate ultra-wideband terahertz wave signals;

[0010] A terahertz signal transmitter is used to programmatically modulate the ultra-wideband terahertz wave signal and transmit it to biological tissues and organs.

[0011] A terahertz signal receiver is used to receive terahertz biological signals scattered inside and around the biological tissues and organs, and to modulate the received terahertz biological signals.

[0012] The data acquisition module acquires the terahertz biosignals;

[0013] The intelligent sensing signal processing module processes the terahertz biological signal to obtain terahertz images of the biological tissues and organs.

[0014] Furthermore, the terahertz signal transmitter includes a first metasurface control unit, a first terahertz metasurface unit, and a terahertz transmitting antenna.

[0015] Furthermore, the terahertz signal receiver includes a second metasurface control unit, a second terahertz metasurface unit, and a terahertz receiving antenna.

[0016] Furthermore, the first terahertz metasurface unit and the second terahertz metasurface unit include an array of M*N metasurface cell units, where M≥2 and N≥2. Any metasurface cell unit of the first terahertz metasurface unit can be individually controlled by the first metasurface control unit to achieve programmable modulation of ultra-wideband terahertz wave signals. Any metasurface cell unit of the second terahertz metasurface unit can be individually controlled by the second metasurface control unit to achieve modulation of terahertz biological signals.

[0017] Furthermore, the first metasurface control unit and the second metasurface control unit include a semiconductor substrate and an epitaxial layer located on the surface of the semiconductor substrate, wherein an ohmic electrode and the metasurface cell unit array are disposed on the epitaxial layer.

[0018] Furthermore, the metasurface cell unit array includes: a first dielectric substrate, a first metal structure printed on the bottom of the first dielectric substrate, a second metal structure printed on the top of the first dielectric substrate, a second dielectric substrate, a third metal structure printed on the top of the second dielectric substrate, a third dielectric substrate, a first metal via distributed on the first dielectric substrate, and a second metal via distributed on the second dielectric substrate.

[0019] The first metal structure has a first slit groove etched on it, the second metal structure has a 1×4 second slit groove etched on it, the third metal structure has a 4×4 third slit groove etched on it, and the center of the third slit groove is aligned with the fourth metal structure. The fourth metal structure is composed of a 4×4 metasurface cell unit array, with a gap between adjacent metasurface cell units.

[0020] Furthermore, the intelligent sensing signal processing module includes a deep convolutional neural network unit and a signal processing unit.

[0021] Furthermore, it also includes an image display module for displaying the terahertz image.

[0022] Furthermore, the image display module includes a two-dimensional image display unit, a three-dimensional image display unit, an image reconstruction unit based on a deep convolutional network, and an image reconstruction unit based on holographic digital signals.

[0023] The imaging method of the terahertz biological tissue imaging system based on a metasurface antenna, proposed in this invention, includes:

[0024] The ultra-wideband terahertz wave signal generated by the terahertz signal generator is programmably modulated by the first terahertz metasurface unit in the terahertz signal transmitter, and the modulated ultra-wideband terahertz wave signal is transmitted to biological tissues and organs.

[0025] The scattered signals inside and around biological tissues and organs are remodulated by the second terahertz metasurface unit in the terahertz signal receiver;

[0026] The modulated terahertz bio-signal is detected by the terahertz receiving antenna of the terahertz signal receiver clock.

[0027] The detected terahertz biosignals were acquired by the data acquisition module;

[0028] The acquired terahertz biosignals are preprocessed and reconstructed by the intelligent sensing signal processing module and the image display module. Based on the preprocessed data, deep convolutional neural networks and holographic reconstruction algorithms are used to reconstruct the image of the imaging target.

[0029] The signal generating device of this invention can generate broadband signals, and the designed antenna can transmit ultra-wideband signals. Therefore, this invention can solve the problems of narrow bandwidth and low gain within the target frequency band. It can also further address the problems of slow speed and low resolution in existing terahertz imaging. Compared with traditional focal plane array terahertz detection imaging systems, the programmable spatial modulation metasurface module used in this invention is a two-dimensional planar structure with mature and easy-to-manufacture technology. Furthermore, because this invention uses deep learning and holographic imaging technology, compared with traditional point-by-point mechanical scanning imaging, this imaging system requires fewer data acquisitions, has a faster imaging speed, and requires less data storage. Compared with traditional point-to-point information acquisition methods, this invention utilizes sparse sampling of deep learning and holographic imaging technology to improve sampling efficiency and imaging speed. In addition, traditional terahertz imaging uses cameras to take pictures, which is expensive and difficult to perform deep tissue imaging. This invention uses a metasurface antenna to transmit signals to the target object, simultaneously acquiring scattered signals from the target area and reconstructing the image from the scattered signals. The imaging method and system differ. This imaging system does not require terahertz lenses and terahertz cameras, effectively improving imaging efficiency and reducing imaging costs. Attached Figure Description

[0030] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0031] Figure 1 This is a front view of the terahertz antenna based on a metasurface unit array according to the present invention;

[0032] Figure 2 This is a schematic diagram of the back of the terahertz antenna based on a metasurface element array according to the present invention.

[0033] Figures 3(a)-3(h) This is the location where the terahertz antenna and breast model of the present invention are set. Detailed Implementation

[0034] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0036] In one basic embodiment, the terahertz biological tissue imaging system based on metasurface antenna proposed in this invention includes: a terahertz signal generator, a terahertz signal transmitter, a terahertz signal receiver, a data acquisition module, an intelligent sensing signal processing module, and an intelligent system control device.

[0037] Terahertz signal generators are used to generate ultra-wideband terahertz wave signals.

[0038] The intelligent system control device controls the terahertz signal generator to continuously generate ultra-wideband terahertz wave signals.

[0039] Terahertz signal transmitters are used to programmatically modulate ultra-wideband terahertz wave signals and then transmit them to biological tissues and organs.

[0040] Terahertz signal receivers are used to receive terahertz biological signals scattered inside and around biological tissues and organs, and to modulate the received terahertz biological signals.

[0041] The data acquisition module collects terahertz biological signals.

[0042] In one embodiment, the terahertz signal generator may be a vector network analyzer.

[0043] The intelligent sensing signal processing module processes terahertz biological signals to obtain terahertz images of biological tissues and organs.

[0044] In one embodiment, the terahertz signal transmitter includes a first metasurface control unit, a first terahertz metasurface unit, and a terahertz transmitting antenna.

[0045] In one embodiment, the terahertz signal receiver includes a second metasurface control unit, a second terahertz metasurface unit, and a terahertz receiving antenna.

[0046] Specifically, the first terahertz metasurface unit comprises an array of M*N metasurface cell units, where M≥2 and N≥2. The second terahertz metasurface unit has the same structure as the first. The first metasurface control unit individually controls any metasurface cell unit of the first terahertz metasurface unit, enabling programmable modulation of ultra-wideband terahertz wave signals. The second metasurface control unit individually controls any metasurface cell unit of the second terahertz metasurface unit, enabling modulation of terahertz biological signals. The metasurface cell unit array is an array composed of multiple metasurface cell units. The two metasurface control units achieve spatial modulation of terahertz waves by changing the voltage of the two terahertz metasurface units. Specifically, any metasurface cell unit in the terahertz metasurface structure can be individually controlled, thereby achieving modulation of terahertz waves.

[0047] In one embodiment, the first metasurface control unit includes a semiconductor substrate and an epitaxial layer located on the surface of the semiconductor substrate. Ohmic electrodes and a metasurface cell unit array are disposed on the epitaxial layer. The second metasurface control unit has the same structure as the first metasurface control unit. Further, the metasurface cell unit array is composed of M×N metasurface cell units arranged in a row, where M (M≥2) is the number of vertically arranged periods and N (N≥2) is the number of horizontally arranged periods.

[0048] In one embodiment, the metasurface cell array includes: a first dielectric substrate, a first metal structure printed on the bottom of the first dielectric substrate, a second metal structure printed on the top of the first dielectric substrate, a second dielectric substrate, a third metal structure printed on the top of the second dielectric substrate, a third dielectric substrate, first metal vias distributed on the first dielectric substrate, and second metal vias distributed on the second dielectric substrate. The first, second, and third dielectric substrates are stacked and seamlessly connected.

[0049] A first slit groove is etched on the first metal structure, a 1×4 second slit groove is etched on the second metal structure, and a 4×4 third slit groove is etched on the third metal structure. The center of the third slit groove is aligned with the fourth metal structure. The fourth metal structure is composed of a 4×4 metasurface cell unit array, with spacing between adjacent metasurface cell units. Figure 1 The diagram shows a front view of the first and second metasurface unit arrays of the present invention, specifically including metasurface unit array 1, metasurface cell unit 2, and feed point 3. Figure 2 A schematic diagram of the back side of the first and second metasurface cell unit arrays of the present invention is shown.

[0050] The intelligent sensing signal processing module includes a deep convolutional neural network unit and a signal processing unit.

[0051] The intelligent system control device includes a target object imaging scanning control unit, a terahertz signal generator control unit, a terahertz signal transmitter control unit, a terahertz signal receiver control unit, a data acquisition module control unit, a signal processing control unit, and an image display control unit.

[0052] Figures 3(a)-3(h) The diagram shows the positional changes of the terahertz antenna 4 and the breast model. According to the simulation results, different simulation results will be obtained when the terahertz antenna is located in different positions of the breast model.

[0053] Based on the above embodiments, the terahertz biological tissue imaging system based on metasurface antenna of the present invention may further include an image display module for displaying the terahertz image.

[0054] In one embodiment, the image display module includes a two-dimensional image display unit, a three-dimensional image display unit, an image reconstruction unit based on a deep convolutional network, and an image reconstruction unit based on holographic digital signals. In other embodiments, the image display module may also include only any one of these listed units.

[0055] The working principle of this invention is as follows: An intelligent system control device controls a terahertz signal generator to produce a terahertz signal. The terahertz signal is transmitted to a metasurface control unit via a terahertz signal transmitter. The regulated terahertz signal is then transmitted to a terahertz signal transmitting antenna and emitted to the biological tissue or organ under test. The terahertz biological signals scattered inside and around the biological tissue or organ are spatially regulated by the metasurface cell unit array of the terahertz receiver. The regulated terahertz biological signal is detected by the terahertz receiving antenna. The detected terahertz biological signal is acquired by a data acquisition module and transmitted to an intelligent sensing signal processing module and an image display module. Based on image reconstruction requirements, a deep convolutional neural network unit and an image reconstruction unit are used to preprocess the terahertz biological signal and perform image reconstruction and display.

[0056] Compared with traditional focal plane array terahertz detection imaging systems, the programmable spatial modulation metasurface module used in this invention is a two-dimensional planar structure with mature and easy-to-manufacture technology. Moreover, due to the use of deep learning and holographic imaging technology, compared with traditional point-by-point mechanical scanning imaging, this imaging system has fewer data acquisitions, faster imaging speed, and lower data storage requirements. In addition, this imaging system does not require the use of terahertz lenses and terahertz cameras, which effectively improves imaging efficiency and reduces imaging costs.

[0057] The imaging method of the terahertz biological tissue imaging system based on metasurface antennas described above includes the following steps:

[0058] The ultra-wideband terahertz wave signal generated by the terahertz signal generator is programmably modulated by the first terahertz metasurface unit in the terahertz signal transmitter, and the modulated ultra-wideband terahertz wave signal is transmitted to biological tissues and organs; the scattered signals inside and around the biological tissues and organs are re-modulated by the second terahertz metasurface unit in the terahertz signal receiver; the modulated terahertz biological signal is detected by the terahertz receiving antenna of the terahertz signal receiver clock; the detected terahertz biological signal is acquired by the data acquisition module.

[0059] The acquired terahertz biosignals are preprocessed and reconstructed by the intelligent sensing signal processing module and the image display module. Based on the preprocessed data, deep convolutional neural networks and holographic reconstruction algorithms are used to reconstruct the image of the imaging target.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A terahertz bio-tissue imaging system based on a metasurface antenna, characterized in that, include: Terahertz signal generator, used to generate ultra-wideband terahertz wave signals; The intelligent system control device controls the terahertz signal generator to continuously generate ultra-wideband terahertz wave signals; A terahertz signal transmitter is used to programmatically modulate the ultra-wideband terahertz wave signal and then transmit it to biological tissues and organs; the terahertz signal transmitter includes a first metasurface control unit, a first terahertz metasurface unit, and a terahertz transmitting antenna. A terahertz signal receiver is used to receive terahertz biological signals scattered inside and around the biological tissues and organs, and to modulate the received terahertz biological signals. The terahertz signal receiver includes a second metasurface control unit, a second terahertz metasurface unit, and a terahertz receiving antenna. The first terahertz metasurface unit and the second terahertz metasurface unit each comprise an array of M*N metasurface cell units, where M≥2 and N≥2. The data acquisition module acquires the terahertz biosignals; The intelligent sensing signal processing module processes the terahertz biological signal to obtain terahertz images of the biological tissues and organs; The first metasurface control unit individually controls any metasurface cell unit of the first terahertz metasurface unit, enabling programmable modulation of the ultra-wideband terahertz wave signal. The modulated terahertz signal is transmitted to the terahertz signal transmitting antenna and then emitted to the biological tissue or organ under test. The terahertz biological signal scattered inside and around the biological tissue or organ is re-modulated by the second hertz metasurface unit of the terahertz receiver. The second metasurface control unit individually controls any metasurface cell unit of the second terahertz metasurface unit, enabling modulation of the terahertz biological signal. The modulated terahertz biological signal is detected by the terahertz receiving antenna, and the detected terahertz biological signal is acquired by the data acquisition module and transmitted to the intelligent sensing signal processing module.

2. The metasurface antenna based terahertz bio-tissue imaging system of claim 1, wherein, The first metasurface control unit and the second metasurface control unit include a semiconductor substrate and an epitaxial layer located on the surface of the semiconductor substrate. The epitaxial layer is provided with ohmic electrodes and the metasurface cell unit array.

3. The metasurface antenna based terahertz bio-tissue imaging system of claim 1, wherein, The metasurface cell unit array includes: a first dielectric substrate, a first metal structure printed on the bottom of the first dielectric substrate, a second metal structure printed on the top of the first dielectric substrate, a second dielectric substrate, a third metal structure printed on the top of the second dielectric substrate, a third dielectric substrate, a first metal via distributed on the first dielectric substrate, and a second metal via distributed on the second dielectric substrate. The first metal structure has a first slit groove etched on it, the second metal structure has a 1×4 second slit groove etched on it, the third metal structure has a 4×4 third slit groove etched on it, and the center of the third slit groove is aligned with the fourth metal structure. The fourth metal structure is composed of a 4×4 metasurface cell unit array, with a gap between adjacent metasurface cell units.

4. The metasurface antenna based terahertz bio-tissue imaging system of claim 1, wherein, The intelligent sensing signal processing module includes a deep convolutional neural network unit and a signal processing unit.

5. The metasurface antenna based terahertz bio-tissue imaging system of claim 1, wherein, It also includes an image display module for displaying the terahertz image.

6. The metasurface antenna based terahertz bio-tissue imaging system of claim 5, wherein, The image display module includes a two-dimensional image display unit, a three-dimensional image display unit, an image reconstruction unit based on a deep convolutional network, and an image reconstruction unit based on holographic digital signals.

7. The imaging method of the terahertz biological tissue imaging system based on a metasurface antenna as described in any one of claims 1 to 6, characterized in that, include: The ultra-wideband terahertz wave signal generated by the terahertz signal generator is programmably modulated by the first terahertz metasurface unit in the terahertz signal transmitter, and the modulated ultra-wideband terahertz wave signal is transmitted to biological tissues and organs. The scattered signals inside and around biological tissues and organs are remodulated by the second terahertz metasurface unit in the terahertz signal receiver; The modulated terahertz biosignal is detected by the terahertz receiving antenna in the terahertz signal receiver; The detected terahertz biosignals were acquired by the data acquisition module; The acquired terahertz biosignals are preprocessed and reconstructed by the intelligent sensing signal processing module and the image display module. Based on the preprocessed data, deep convolutional neural networks and holographic reconstruction algorithms are used to reconstruct the image of the imaging target.

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