A multi-channel tunable terahertz sensing device

Abstract

A multi-channel tunable terahertz sensing device relates to the field of terahertz technology. The present invention aims to solve the problem that existing terahertz metamaterial sensing devices cannot achieve multi-channel tunable functions. The multi-channel tunable terahertz sensing device described in the present invention has a rectangular cavity that is a subwavelength dielectric grating integrated cavity, a strip-shaped gap is opened on the upper surface of the rectangular cavity, a gold reflective layer is located at the bottom of the rectangular cavity, two Au metal electrodes are parallel to each other and are respectively fixed on both sides of the strip-shaped gap, a single layer of graphene is mounted on the two Au metal electrodes and can cover the strip-shaped gap, and the internal space of the rectangular cavity is divided into three parallel microfluidic channels by two quartz glass sheets.

Description

Technical Field

[0001] The present invention belongs to the technical field of terahertz. Background Art

[0002] Due to the strong absorption of terahertz waves by liquids (especially liquid water), the sensitivity of terahertz sensors is generally low. The sensitivity of terahertz biosensors using liquid as the medium has always been the most urgent problem to be solved. Terahertz biochemical sensors can realize rapid and non-destructive detection of biological molecules and their interactions, which is of great significance for the early diagnosis of diseases. In practice, the current method of distinguishing cancer cells from healthy cells mainly relies on refractive index sensing. However, traditional terahertz biochemical sensors are mainly based on two mechanisms: surface plasmon resonance and localized surface plasmon resonance. They often suffer from shortcomings such as insufficient sensitivity and single function, which makes it difficult to meet the increasingly complex needs of practical applications. Multi-channel high-throughput detection technology has gradually become a hot topic of current research due to its advantages of rapid sensitivity and low cost. Due to the special properties of terahertz waves and the complexity of sensing methods and devices, it is a very challenging task and difficulty to achieve multi-channel and tunable functions for terahertz biochemical sensors.

[0003] To date, terahertz metamaterial sensing devices have been studied. For example, the patent application document "A Dynamic Terahertz Metasurface Sensor Based on Tunable Elements," published in publication number CN117388216A, uses tunable elements to rapidly and repeatedly switch between different states based on changes in external excitation conditions to tune the resonant mode of the sensing device. However, the resonant mode of the sensing device is highly dependent on external conditions and cannot achieve multi-channel functionality. The patent application document "A Terahertz Band Metamaterial Sensor," published in publication number CN109283155B, uses a metasurface metal resonant ring array to achieve high-sensitivity sensing using electromagnetically induced transparency, but does not address multi-channel and tunable functions. The patent application document "Liquid-Enhanced Sensing System and Measurement Method Based on Bowtie-Type Metal Aperture Terahertz Metamaterial," published in publication number CN118150512A, uses a complex structure to achieve high sensitivity to support terahertz sensing of different liquids. However, multi-channel tunable sensing functionality is not implemented, limiting the application of this sensing method. Summary of the Invention

[0004] The present invention aims to solve the problem that existing terahertz metamaterial sensing devices cannot achieve multi-channel tunable functions, and now provides a multi-channel tunable terahertz sensing device.

[0005] A multi-channel tunable terahertz sensing device, comprising: a rectangular cavity 1, a gold reflective layer 2, two Au metal electrodes 3 and a single-layer graphene 4;

[0006] The rectangular cavity 1 is a subwavelength dielectric grating integrated cavity. A strip-shaped gap is opened on the upper surface of the rectangular cavity 1. The gold reflective layer 2 is located at the bottom of the rectangular cavity 1. The two Au metal electrodes 3 are parallel to each other and fixed on both sides of the strip-shaped gap. The single-layer graphene 4 is mounted on the two Au metal electrodes 3 and can cover the strip-shaped gap. The internal space of the rectangular cavity 1 is divided into three parallel microfluidic channels by two quartz glass sheets 5.

[0007] Furthermore, each of the microfluidic channels is provided with a liquid injection port 6 and a liquid outflow port 7 .

[0008] Furthermore, the material of the rectangular cavity 1 is silicon dioxide or silicon.

[0009] Furthermore, the rectangular cavity 1 has a width of 30 μm, a height of 20 μm, and a top thickness of 0.6 μm. The walls of the rectangular cavity 1 on both sides of the strip-shaped gap have a width of 4 μm and a side wall thickness of 4 μm.

[0010] Furthermore, the total width of the three microfluidic channels arranged in parallel is 22 μm, the width of the microfluidic channels on both sides is 3.5 μm, and the width of the strip-shaped gap is 16 μm.

[0011] Furthermore, the thickness of the Au metal electrode 3 is 0.34 nm.

[0012] Furthermore, the thickness of the above-mentioned single-layer graphene 4 is 150 nm.

[0013] The multi-channel tunable terahertz sensing device described in this invention utilizes a novel subwavelength dielectric grating integrated rectangular cavity structure to develop a multi-channel tunable terahertz sensor. Leveraging microfluidics for precise manipulation and analysis, it achieves multi-channel, simultaneous, and accurate detection of multiple samples. This approach focuses on addressing the challenges of achieving high sensitivity, integrating microfluidics to achieve high-throughput, precise detection. The graphene-based multi-channel sensor is designed by combining graphene's high carrier mobility and electrically tunable optical properties. The sensor independently modulates the optical signal intensity of each channel by independently controlling the voltages of the graphene electrodes on each channel. This allows for simultaneous and independent control of multiple optical signal channels, thus achieving tunable multi-channel functionality. In summary, the multi-channel tunable terahertz sensing device described in this invention can significantly improve the performance, accuracy, and efficiency of terahertz sensing methods, while also reducing energy consumption and costs and simplifying processing, operation, control, and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A three-dimensional structural diagram of a multi-channel tunable terahertz sensing device;

[0015] Figure 2 A front view of a multi-channel tunable terahertz sensing device;

[0016] Figure 3 This is an experimental test diagram of a multi-channel tunable terahertz sensing device;

[0017] Among them, there are a rectangular cavity 1, a gold reflective layer 2, an Au metal electrode 3, a single-layer graphene 4, a quartz glass sheet 5, a liquid injection port 6, a liquid outflow port 7, a first microfluidic channel 8, a second microfluidic channel 9, a third microfluidic channel 10, a terahertz source emitter 11, a lens 12, a terahertz sensing sample 13, and a terahertz signal detector 14. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other in the absence of conflict.

[0019] Reference Figure 1 and Figure 2 Specifically describing this embodiment, a multi-channel tunable terahertz sensing device described in this embodiment includes: a rectangular cavity 1, a gold reflective layer 2, two Au metal electrodes 3, a single-layer graphene 4, two quartz glass sheets 5, a liquid inlet 6, a liquid outlet 7, a first microfluidic channel 8, a second microfluidic channel 9 and a third microfluidic channel 10.

[0020] The rectangular cavity 1 is a subwavelength dielectric grating integrated cavity, and a strip-shaped gap is formed on the upper surface of the rectangular cavity 1. The gold reflective layer 2 is located at the bottom of the rectangular cavity 1. The two Au metal electrodes 3 are parallel to each other and fixed on both sides of the strip-shaped gap. The graphene layer 4 is mounted on the two Au metal electrodes 3 and is capable of covering the strip-shaped gap. The two quartz glass sheets 5 are parallel to the two side walls of the rectangular cavity 1 and fixed inside the rectangular cavity 1, so that the internal space of the rectangular cavity 1 is divided into a first microfluidic channel 8, a second microfluidic channel 9, and a third microfluidic channel 10. Each microfluidic channel is provided with a liquid inlet 6 and a liquid outlet 7.

[0021] The rectangular cavity 1 excites guided mode resonance and Fabry-Perot resonance, resulting in strongly coupled coherent interaction. The gold reflective layer 2 provides total light reflection, enhancing the strong interaction between light and matter. The Au metal electrode 3 acts as a conductor, its primary function being to provide a channel for electron flow. The graphene monolayer 4 enables tunability through external electrostatic bias. The quartz glass plate 5 serves to isolate the microfluidic channel. The liquid inlet 6 is used to inject the liquid sample into the microfluidic channel of the sensing structure. The liquid outlet 7 is used to discharge the liquid sample from the microfluidic channel. The subwavelength dielectric grating achieves high-Q guided mode resonance under terahertz wave excitation, and the microcavity excites Fabry-Perot cavity resonance. The two resonances can coherently couple. The gold reflective layer enhances absorption through total light reflection, producing a higher-Q quasi-electromagnetically induced transparency resonance peak. Each microfluidic channel can be independently injected with microfluid. Utilizing the tunable nature of graphene, multi-channel, dynamic, and reversible control of terahertz waves is possible.

[0022] The working process of this embodiment is as follows:

[0023] When a terahertz electromagnetic wave is incident perpendicularly on the structure, the subwavelength grating excites guided mode resonance, and the microcavity excites Fabry-Perot resonance. The two resonances undergo strong coherent coupling, and the electric field is highly concentrated in the microfluidic channel. First, water can be injected into all three channels, and the terahertz spectral response can be tested using the BATOP terahertz time-domain spectroscopy system. The terahertz spectral response can then be tested with water, methanol, and water injected into the three channels, respectively. Finally, the terahertz spectral response can be tested with water, methanol, and glycerol injected into the three channels, respectively. Different substances exhibit distinct spectral characteristics within the terahertz band, such as specific absorption peaks and transmittance. Different biochemical substances can be distinguished based on their terahertz spectral response.

[0024] In this embodiment, the material of the rectangular cavity 1 is silicon dioxide or silicon, which reduces processing costs, has a simple structure, superior performance, is easy to mass-produce and is easy to clean after the experiment, meeting the cost-effectiveness requirements in the design of the sensing method. Among them, the period p of the rectangular cavity 1 is 30 μm, the total width w1 of the microfluidic channel is 22 μm, the width w2 of the strip gap is 16 μm, the width w3 of the first microfluidic channel 8 and the third microfluidic channel 10 is 3.5 μm, the height h of the rectangular cavity 1 is 20 μm, the thickness h1 of the upper edge of the rectangular cavity 1 is 0.6 μm, the width p1 of the two side plates of the upper edge is 4 μm, and the thickness t of the side wall is 4 μm. The thickness of the single-layer graphene 4 is 0.34 nm, and the thickness of the Au metal electrode 3 is 150 nm. Parameter setting is crucial for exciting specific physical phenomena (such as guided mode resonance and Fabry-Perot resonance). The role and significance of these parameter settings is that the method can operate under the expected conditions, thereby achieving the desired optical effect. When guided-mode resonance and Fabry-Perot resonance are excited simultaneously, they can interact and influence each other's resonance properties. By properly setting the aforementioned parameters (such as grating period and cavity length), these two resonance effects can be made to occur simultaneously and enhance each other under certain conditions.

[0025] Tiny recesses are etched into the upper and lower layers of the microfluidic channel. Quartz glass sheets (5), which have minimal impact on terahertz waves, are then placed within these recesses to achieve a multi-channel design. The guided-mode resonance of the dielectric grating and the coherent coupling of the Fabry-Perot cavity produce a high-Q electromagnetically induced transparency effect. This, combined with the ultra-strong slow-light effect and the strong field and time accumulation within each cavity, enables multi-channel, highly sensitive sensing through phase or polarization. Graphene's tunability enables multi-channel tunable sensing.

[0026] In summary, the multi-channel tunable terahertz sensing method described in this embodiment has an array structure unit with three microfluidic channels, so that different liquids can be injected independently in each channel, which brings significant flexibility and versatility to terahertz sensing technology. By independently injecting different liquids into each channel, it can be customized for specific application requirements or experimental conditions. This flexibility enables the testing of various combinations of liquids to explore the effects of different liquids on terahertz waves. Since each channel can accommodate different liquids, multiple samples can be detected and analyzed simultaneously. Compared with traditional single-channel sensing methods, multi-channel designs can significantly improve experimental efficiency.

[0027] The multi-channel tunable terahertz sensing method described in this embodiment is particularly suitable for the detection and analysis of liquid substances such as water, ethanol, methanol and sweat. Figure 3As shown. A tunable terahertz source emitter 11 is selected as the terahertz wave source, which can generate terahertz waves within a certain frequency range, with stable output and high frequency resolution to meet the detection needs of different substances. A sealed sample chamber is designed to place the liquid or sweat sample to be tested. The sample chamber should have good optical transparency and chemical stability to ensure that the terahertz wave can penetrate and interact with the sample. The liquid to be tested (water, ethanol, methanol) or sweat sample is injected into the sample chamber, and the sample chamber is ensured to be well sealed. The terahertz wave can produce a strong interaction with the hydrogen bond network in the polar liquid. The stronger the interaction, the stronger the absorption. In view of this property, the terahertz time-domain spectroscopy technology is used to detect the terahertz spectrum of liquid water / ethanol / methanol / sweat in the 0.5~2THz band.

[0028] Four substances exhibit distinct absorption and scattering properties in the terahertz band. By comparing their responses at different frequencies, it is possible to distinguish water, ethanol, methanol, and sweat, and assess their concentration and purity. Based on this, a multi-channel, tunable, ultrasensitive, high-throughput terahertz sensor, sensitive to the sample's dielectric constant, is employed to further examine different samples using the resulting resonance peak shift or amplitude depth. This study investigates the sensor's sensitivity and high-throughput detection capabilities, suggesting potential applications for the development of terahertz spectroscopy combined with microstructured devices in the detection of liquid chemical and biological samples.

[0029] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in conjunction with other described embodiments.

Claims

1. A multi-channel tunable terahertz sensing device, characterized in that: include: Rectangular cavity (1), gold reflective layer (2), two Au metal electrodes (3) and single-layer graphene (4); The rectangular cavity (1) is a subwavelength dielectric grating integrated cavity, a strip-shaped gap is formed on the upper surface of the rectangular cavity (1), the gold reflective layer (2) is located at the bottom of the rectangular cavity (1), the two Au metal electrodes (3) are parallel to each other and are respectively fixed on both sides of the strip-shaped gap, the single-layer graphene (4) is mounted on the two Au metal electrodes (3) and can cover the strip-shaped gap, and the internal space of the rectangular cavity (1) is divided into three parallel microfluidic channels by two quartz glass sheets (5); The width of the rectangular cavity (1) is 30 µm, the height is 20 µm, and the thickness of the upper edge is 0.6 µm. The width of the walls of the rectangular cavity (1) on both sides of the strip-shaped gap is 4 µm, and the thickness of the side walls is 4 µm. The total width of the three parallel microfluidic channels is 22 μm, and the width of the microfluidic channels on both sides is 3.5 μm; The thickness of the Au metal electrode (3) is 0.34 nm; The thickness of the single-layer graphene (4) is 150 nm.

2. The multi-channel tunable terahertz sensing device according to claim 1, characterized in that: Each microfluidic channel is provided with a liquid injection port (6) and a liquid outflow port (7).

3. The multi-channel tunable terahertz sensing device according to claim 1, characterized in that: The material of the rectangular cavity (1) is silicon dioxide or silicon.

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