VOC sensor based on terahertz BIC metasurface

Abstract

The invention relates to a terahertz BIC metasurface-based VOC (volatile organic compound) sensor, which comprises a dielectric substrate, a microfluidic channel substrate and a microfluidic channel, and further comprises an array structure formed by periodically arranging four groups of all-dielectric cylindrical high-resistance silicon structures on one side of the dielectric substrate, the dielectric substrate and the four groups of all-dielectric cylindrical high-resistance silicon structures form an all-dielectric continuum bound state BIC metasurface, the Q value can be remarkably improved, and the continuum bound state BIC metasurface and the microfluidic channel substrate are integrated. The full-dielectric structure in one unit is composed of four groups of cylindrical high-resistance silicon, the four groups of cylindrical high-resistance silicon form a C4v symmetric tetramer cluster, and the four groups of full-dielectric cylindrical high-resistance silicon are connected through thin fins and are integrated with a microfluidic channel, so that accurate measurement of a volatile organic compound (VOC) object to be measured can be realized. The VOC sensor based on the terahertz BIC metasurface, provided by the embodiment of the invention, is combined with a terahertz time-domain spectroscopy system, can realize effective measurement of VOC under different solution concentration conditions, is simple in structure and mature in manufacturing process, and has important application prospects in multiple fields such as terahertz source devices and terahertz sensing.

Description

Technical Field

[0001] The present invention relates to the field of terahertz sensing and VOC measurement in an environment, and in particular to a VOC sensor based on a terahertz BIC metasurface. Background Art

[0002] In recent years, due to the rapid development of industry, volatile organic compounds (VOC) in the environment are endangering the environment and human health. There is an urgent need for a technology to measure VOC in the environment to reduce its impact on the environment and human health. Sensors combined with terahertz technology have great application possibilities in this regard. Terahertz (THz) technology has great application prospects in many fields such as medical imaging, sensor detection, security inspection and anti-terrorism, high-speed wireless communication, etc., and is an internationally recognized frontier research field.

[0003] A VOC sensor based on a terahertz BIC metasurface integrates the BIC metasurface and the microfluidic channel. By precisely designing the geometry and surface structure of the BIC metasurface, it can achieve highly specific detection of specific VOC molecules. In addition, the sensor based on the terahertz BIC metasurface also has the advantages of integration and rapid response. Using the terahertz-time domain spectroscopy (THz-TDS) system, the concentration of VOCs remaining in the water area can be obtained by analyzing the spectrum. At the same time, due to the presence of the microfluidic channel, the problem of strong absorption interference of terahertz waves due to the presence of water can be reduced during detection. In terms of environmental pollution monitoring, industrial process control and safety detection, it provides new possibilities for efficient and accurate chemical detection and analysis. At the same time, due to the characteristics of local resonance enhancement and high sensitivity of the BIC metasurface, the BIC metasurface has an ultra-high Q value when performing terahertz sensing detection, which is expected to achieve high-sensitivity rapid detection of VOCs.

[0004] After searching, the application publication number CN117589714B, a high-Q value terahertz metasurface sensor excited by a ring dipole, includes: a substrate; a metal film formed on the surface of the substrate; a plurality of metasurface unit structures, arranged in a periodic array on the surface of the metal film away from the substrate; wherein the metasurface unit structure includes two L-shaped metal structures with short sides arranged opposite to each other, and the two L-shaped metal structures are arranged at a distance. The present invention adopts a periodically arranged double L-shaped metal structure metasurface. When the terahertz electric field is incident in the vertical direction, the ring dipole resonance mode in the metasurface is excited, the interaction between the terahertz wave and the analyte is enhanced, causing a strong change in the spectrum, thereby improving the sensor sensing performance. Thereby, the detection of small changes in the dielectric environment of the metasurface structure surface caused by changes in the concentration of trace analytes can be realized. It has the advantage of high detection sensitivity and can achieve high-sensitivity detection of analytes.

[0005] The sensor in the above patents uses a metal structure, while this patent uses a fully dielectric material to form the sensor structure. Compared with the metal structure in the above patents, the fully dielectric material structure avoids the high inherent loss associated with metal metamaterials and improves the Q value. The BIC sensor in this patent has a simple structure and can be mass-produced industrially using laser etching. The structure in the above patents is relatively complex and delicate, and technical problems may be encountered during production, resulting in manufacturing difficulties. In addition, most importantly, the present invention addresses the problem that liquid water exists in the VOC liquid sample to be tested and strongly absorbs and interferes with the terahertz wave. It proposes combining the BIC metasurface with a microfluidic channel, and using the microfluidic channel to adjust the micron-level capacity of the VOC liquid to be tested to reduce the interference of liquid water and improve detection sensitivity and accuracy. Summary of the invention

[0006] The present invention aims to solve the above problems of the prior art. A VOC sensor based on a terahertz BIC metasurface is proposed. The technical solution of the present invention is as follows:

[0007] A VOC sensor based on a terahertz BIC supersurface, characterized in that it includes: a dielectric substrate, a microfluidic channel substrate and a microfluidic channel, and an array structure formed by periodically arranging four groups of all-dielectric cylindrical high-resistance silicon structures on one side of the dielectric substrate, the dielectric substrate and the four groups of all-dielectric cylindrical high-resistance silicon structures constitute a full-dielectric continuum bound state (Bound State in the Continuum, BIC) supersurface, and the full-dielectric continuum bound state BIC supersurface is integrated with the microfluidic channel substrate to constitute a volatile organic compound VOC sensor based on a terahertz BIC supersurface containing a microfluidic channel. The dielectric substrate is the substrate of the actual working part of the sensor, the all-dielectric silicon structure is the actual working detection part of the sensor, the microfluidic channel substrate is the part where the actual microfluidic channel is located, and the microfluidic channel is a groove microfluidic channel cut out from the inside of the microfluidic channel substrate, which is used to place the full-dielectric BIC supersurface sensor and provide an ultra-thin sample chamber for the VOC liquid sample to be tested, detect a small amount of the liquid sample to be tested, and finally reduce the interference of water in the sample on the detection result.

[0008] Furthermore, the four groups of all-dielectric cylindrical high-resistance silicon structures are all attached to the surface of one side of the dielectric substrate, and the four groups of all-dielectric cylindrical high-resistance silicon structures are periodically distributed on the dielectric substrate without crossing or overlapping, and the period length is 600um. The four groups of all-dielectric cylindrical high-resistance silicon are connected by thin fins, and the interconnected thin fin line width is 25um. Each group of all-dielectric silicon structures is composed of one all-dielectric cylindrical high-resistance silicon, and two adjacent groups of all-dielectric silicon structures are axially symmetrically distributed in pairs.

[0009] Furthermore, the four groups of all-dielectric silicon structures include a first group of all-dielectric silicon structures, a second group of all-dielectric silicon structures, a third group of all-dielectric silicon structures, and a fourth group of all-dielectric silicon structures, wherein the first group of all-dielectric silicon structures is composed of a first all-dielectric cylindrical high-resistance silicon; the second group of all-dielectric silicon structures is composed of a second all-dielectric cylindrical high-resistance silicon; the third group of all-dielectric silicon structures is composed of a third all-dielectric cylindrical high-resistance silicon; and the fourth group of all-dielectric silicon structures is composed of a fourth all-dielectric cylindrical high-resistance silicon.

[0010] Furthermore, the first all-dielectric silicon structure, the second all-dielectric silicon structure, the third all-dielectric silicon structure and the fourth all-dielectric silicon structure are all composed of a fully dielectric cylindrical high-resistance silicon structure with a radius of 125um and a height of 100um. The parts of each cylindrical high-resistance silicon facing the four corners are removed, and the line width of the removed part is 14um. The openings formed face the four corners respectively. The two adjacent groups of all-dielectric silicon structures are axially symmetrically distributed in pairs, and the distance between the two adjacent groups of all-dielectric silicon structures is 50um. The two adjacent groups of all-dielectric silicon structures are connected by thin fins, and each all-dielectric silicon structure is 25um away from the boundary. The all-dielectric BIC metasurface composed of all-dielectric silicon can reduce losses, improve Q value, and improve detection accuracy.

[0011] Furthermore, the sensor is integrated with a microfluidic channel substrate, and the microfluidic channel substrate is made of polymethyl methacrylate (PMMA) with a thickness of 0.9 mm and a side length of 40 mm.

[0012] Furthermore, the microfluidic channel is in the shape of a regular hexagon with a side length of 17.32 mm and a depth of 50 um. There are capillary channels on both sides of the microfluidic channel. The capillary channels are used to inject the test liquid into the microfluidic channel. The diameter of the capillary channel is 0.5 mm.

[0013] Furthermore, the dielectric substrate is a flexible polyethylene terephthalate (PET) substrate with a dielectric constant of 3+0.06i, a thickness of 15um, and a length of 600um.

[0014] Furthermore, the all-dielectric silicon structure is made of high-resistance silicon, with a dielectric constant of 11 and a loss tangent of 2.52×10 at 600 GHz. -6 , thickness is 100um.

[0015] The advantages and beneficial effects of the present invention are as follows:

[0016] 1. The present invention supports the sensing detection of VOCs in the terahertz band. Compared with spectral detection in other bands, terahertz band detection has the advantages of less impact on the human body, higher detection sensitivity, and rapid detection.

[0017] 2. The present invention integrates the bound state in the continuum (BIC) with the terahertz VOC sensor, which has the advantages of high Q factor, extremely narrow linewidth and high detection sensitivity compared with traditional terahertz sensors.

[0018] 3. The full dielectric layer of the present invention uses four groups of full dielectric cylindrical high-resistance silicon to form a C4v symmetric tetramer cluster, which together with the flexible PET substrate constitutes a BIC supersurface with mature technology, low cost and easy integration.

[0019] 4. The present invention can be integrated with microfluidic channels or other soft surfaces, which greatly improves the applicability of the present invention. Compared with traditional terahertz sensors, integration with microfluidic channels can ignore the influence of water on the detection results, ensure the accuracy and stability of the detection, and can detect biochemical solutions of different types and concentrations.

[0020] (1) The present invention supports the sensing and detection of VOCs in the terahertz band. Compared with spectral detection in other bands, terahertz band detection has the advantages of less impact on the human body, higher detection sensitivity, and rapid detection. (2) The present invention integrates the bound state in the continuum (BIC) with the terahertz VOC sensor. Compared with traditional terahertz sensors, it has the advantages of high Q factor, extremely narrow linewidth and high detection sensitivity. (3) The full dielectric layer in the present invention uses four groups of full dielectric high-resistance silicon to form a C4v symmetric tetramer cluster, which together with the flexible PET substrate constitutes a BIC super surface, with mature technology, low cost and easy integration. (4) The present invention can be integrated with a microfluidic channel or on other soft surfaces, which greatly improves the applicability of the present invention. At the same time, compared with traditional terahertz sensors, integration with a microfluidic channel can reduce the impact of water on the detection results, improve the accuracy and sensitivity of the detection, and can also expand the detection of other biochemical solutions. Information such as concentration and solutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the unit structure of a VOC sensor based on the terahertz BIC metasurface of the present invention. For a clearer display, only one of the connected thin fins is marked in the figure.

[0022] Figure 2 This is a front view of a VOC sensor based on a terahertz BIC metasurface according to a preferred embodiment of the present invention. For a clearer display, the four groups of periodically arranged all-dielectric silicon structures are not shown in the figure.

[0023] Figure 3 This is a schematic diagram of a VOC sensor array based on a terahertz BIC metasurface of the present invention. For a clearer display, only a portion of the periodically arranged array structure is shown in the figure.

[0024] Figure 4 This is a schematic diagram of a microfluidic channel of a VOC sensor based on a terahertz BIC metasurface of the present invention.

[0025] Figure 5 Schematic diagram of the transmission resonance frequency of a VOC sensor based on the terahertz BIC metasurface of the present invention.

[0026] Marks and corresponding parts names in the attached drawings:

[0027] 1- dielectric substrate, 2- first all-dielectric silicon, 3- second all-dielectric silicon, 4- third all-dielectric silicon, 5- fourth all-dielectric silicon, 6- thin fins, 7- microfluidic channel substrate, 8- microfluidic channel, 9- capillary channel. DETAILED DESCRIPTION

[0028] The following will describe the technical solutions in the embodiments of the present invention in detail in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention.

[0029] The technical solution of the present invention to solve the above technical problems is:

[0030] A VOC sensor based on a terahertz BIC supersurface, characterized in that it includes: a dielectric substrate, a microfluidic channel substrate and a microfluidic channel, and an array structure formed by periodically arranging four groups of all-dielectric cylindrical high-resistance silicon structures on one side of the dielectric substrate, the dielectric substrate and the four groups of all-dielectric cylindrical high-resistance silicon structures constitute a full-dielectric continuum bound state (Bound State in the Continuum, BIC) supersurface, and the full-dielectric continuum bound state BIC supersurface is integrated with the microfluidic channel substrate to constitute a volatile organic compound VOC sensor based on a terahertz BIC supersurface containing a microfluidic channel. The dielectric substrate is the substrate of the actual working part of the sensor, the all-dielectric silicon structure is the actual working detection part of the sensor, the microfluidic channel substrate is the part where the actual microfluidic channel is located, and the microfluidic channel is a groove microfluidic channel cut out from the inside of the microfluidic channel substrate, which is used to place the full-dielectric BIC supersurface sensor and provide an ultra-thin sample chamber for the VOC liquid sample to be tested, detect a small amount of the liquid sample to be tested, and finally reduce the interference of water in the sample on the detection result.

[0031] The four groups of all-dielectric cylindrical high-resistance silicon structures are all attached to the surface of one side of the dielectric substrate. The four groups of all-dielectric cylindrical high-resistance silicon structures are periodically distributed on the dielectric substrate without crossing or overlapping, and the period length is 600um. The four groups of all-dielectric cylindrical high-resistance silicon are connected by thin fins, and the interconnected thin fin line width is 25um. Each group of all-dielectric silicon structures is composed of one all-dielectric cylindrical high-resistance silicon, and two adjacent groups of all-dielectric silicon structures are axially symmetrically distributed in pairs.

[0032] In this embodiment, the dielectric substrate is a flexible PET substrate with a dielectric constant of 3+0.06i, a thickness of 15 um, and a period length of 600 um.

[0033] The first all-dielectric silicon structure, the second all-dielectric silicon structure, the third all-dielectric silicon structure and the fourth all-dielectric silicon structure are all composed of an all-dielectric cylindrical high-resistance silicon structure with a radius of 125um and a height of 100um. The parts of each cylindrical high-resistance silicon facing the four corners are removed, and the line width of the removed part is 14um. The openings formed face the four corners respectively. The two adjacent groups of all-dielectric silicon structures are axially symmetrically distributed in pairs, and the distance between the two adjacent groups of all-dielectric silicon structures is 50um. The two adjacent groups of all-dielectric silicon structures are connected by thin fins, and each all-dielectric silicon structure is 25um away from the boundary. The all-dielectric BIC metasurface composed of all-dielectric silicon can reduce losses, improve Q value, and improve detection accuracy.

[0034] The sensor is integrated with a microfluidic channel substrate, and the microfluidic channel substrate is made of PMMA, has a thickness of 0.9 mm, and a side length of 40 mm.

[0035] The sensor is integrated with a microfluidic channel substrate. The microfluidic channel is in the shape of a regular hexagon with a side length of 17.32 mm and a depth of 50 um. There are capillary channels on both sides of the microfluidic channel. The capillary channels are used to inject the test liquid into the microfluidic channel. The capillary channels have a diameter of 0.5 mm.

[0036] The material of each group of all-dielectric silicon structures is high-resistance silicon, with a dielectric constant of 11 and a loss tangent of 2.52×10 at 600Ghz. -6 , thickness is 100um.

[0037] In this embodiment, the relationship between the transmission coefficient and the frequency obtained by the CST simulation software is as follows: Figure 5 As shown, it can be seen that when the frequency f=0.516Thz, the transmission coefficient is the lowest, which means that the resonant frequency of the sensor is reached at this time, and the frequency f=0.516Thz is the resonant frequency point of the sensor at this time.

[0038] The VOC sensor based on the terahertz BIC metasurface is integrated with the BIC metasurface, which enables it to guide light waves into a longer dwell state at a specific frequency. This dwell state not only enhances the interaction between the light waves and the VOC molecules on the sensor surface, but also significantly improves the sensitivity and selectivity of the sensor. By precisely designing the geometry, material composition and surface structure of the BIC metasurface, highly specific detection of specific VOC molecules can be achieved.

[0039] The VOC sensor based on the terahertz BIC super surface is integrated with a microfluidic channel, and the microfluidic channel can greatly overcome the strong water absorption under the terahertz frequency, greatly eliminate various interferences that may be caused by the presence of water, and significantly enhance the performance and function of the sensor. The VOC sensor based on the terahertz BIC super surface is integrated with a microfluidic channel, and the super surface is pasted to the microfluidic channel substrate with epoxy resin glue, and the silicon tube is connected to the microfluidic channel. Then, the solution to be tested is slowly injected into the microfluidic channel from the inlet end of the capillary channel with a syringe. When the solution to be tested completely fills the microfluidic channel and flows out from the outlet end of the capillary channel, the inlet and outlet pipes are quickly clamped and sealed with calipers. At this time, the sensor is placed in the THz-TDS system for detection to obtain a more accurate detection result, which greatly eliminates the influence of water on the test results. Therefore, a VOC sensor based on the terahertz BIC super surface with an integrated microfluidic channel is more conducive to measuring biochemical solutions of different types or concentrations, which makes the sensor have better detection accuracy and detection sensitivity.

[0040] The VOC sensor based on the terahertz BIC metasurface provided by the example of the present invention, combined with the terahertz time-domain spectroscopy system, can realize the effective measurement of VOC under different solution concentration conditions. It has a simple structure and a mature manufacturing process, and has important application prospects in multiple fields such as terahertz source devices and terahertz sensing.

[0041] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions.

[0042] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0043] The above embodiments should be understood to be only used to illustrate the present invention and not to limit the protection scope of the present invention. After reading the contents of the present invention, technicians can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A VOC sensor based on terahertz BIC metasurface, characterized in that: include: A dielectric substrate (1), a microfluidic channel substrate (7) and a microfluidic channel (8); one side of the dielectric substrate (1) also includes an array structure formed by periodically arranging four groups of all-dielectric cylindrical high-resistance silicon structures; the dielectric substrate (1) and the four groups of all-dielectric cylindrical high-resistance silicon structures constitute an all-dielectric continuum bound state BIC supersurface; the all-dielectric continuum bound state BIC supersurface is integrated with the microfluidic channel substrate (7) to constitute a terahertz BIC supersurface-based volatile organic compound (VOC) sensor containing a microfluidic channel (8); wherein the dielectric substrate (1) is the substrate of the actual working part of the sensor; the all-dielectric silicon structure is the actual working detection part of the sensor; the microfluidic channel substrate (7) is the part where the actual microfluidic channel (8) is located; the microfluidic channel (8) is a groove microfluidic channel cut out from the inside of the microfluidic channel substrate (7), used to place the all-dielectric BIC supersurface sensor, and provide an ultra-thin sample chamber for the VOC liquid sample to be tested, detect a small amount of the liquid sample to be tested, and ultimately reduce the interference of water in the sample on the detection result.

2. A VOC sensor based on a terahertz BIC metasurface according to claim 1, characterized in that: The four groups of all-dielectric cylindrical high-resistance silicon structures are all attached to the surface of one side of the dielectric substrate (1). The four groups of all-dielectric cylindrical high-resistance silicon structures are periodically distributed on the dielectric substrate (1) without crossing or overlapping, and the period length is 600um. The four groups of all-dielectric cylindrical high-resistance silicon are connected by thin fins (6), and the interconnected thin fin line width is 25um. Each group of all-dielectric silicon structures is composed of one all-dielectric cylindrical high-resistance silicon, and two adjacent groups of all-dielectric silicon structures are axially symmetrically distributed.

3. A VOC sensor based on terahertz BIC metasurface according to claim 2, characterized in that: The four groups of all-dielectric silicon structures include a first group of all-dielectric silicon structures, a second group of all-dielectric silicon structures, a third group of all-dielectric silicon structures, and a fourth group of all-dielectric silicon structures. The first group of all-dielectric silicon structures is composed of a first all-dielectric cylindrical high-resistance silicon (2); the second group of all-dielectric silicon structures is composed of a second all-dielectric cylindrical high-resistance silicon (3); the third group of all-dielectric silicon structures is composed of a third all-dielectric cylindrical high-resistance silicon (4); and the fourth group of all-dielectric silicon structures is composed of a fourth all-dielectric cylindrical high-resistance silicon (5).

4. A VOC sensor based on terahertz BIC metasurface according to claim 3, characterized in that: The first all-dielectric silicon structure (2), the second all-dielectric silicon structure (3), the third all-dielectric silicon structure (4) and the fourth all-dielectric silicon structure (5) are all composed of an all-dielectric cylindrical high-resistance silicon structure with a radius of 125um and a height of 100um. The parts of each cylindrical high-resistance silicon facing the four corners are removed, and the line width of the removed parts is 14um. The openings formed face the four corners respectively. Two adjacent groups of all-dielectric silicon structures are axially symmetrically distributed, and the distance between the two adjacent groups of all-dielectric silicon structures is 50um. The two adjacent groups of all-dielectric silicon structures are connected by thin fins (6), and each all-dielectric silicon structure is 25um away from the boundary. The all-dielectric BIC metasurface composed of all-dielectric silicon can reduce loss, improve Q value, and improve detection accuracy.

5. The VOC sensor based on the terahertz BIC metasurface according to claim 1, characterized in that: The sensor is integrated with a microfluidic channel substrate (7), wherein the microfluidic channel substrate (7) is made of polymethyl methacrylate (PMMA) with a thickness of 0.9 mm and a side length of 40 mm.

6. A VOC sensor based on terahertz BIC metasurface according to claim 5, characterized in that: The microfluidic channel (8) is in the shape of a regular hexagon, with a side length of 17.32 mm and a depth of 50 um. There are capillary channels (9) on both sides of the microfluidic channel (8). The capillary channels (9) are used to inject the test liquid into the microfluidic channel (8). The diameter of the capillary channel (9) is 0.5 mm.

7. A VOC sensor based on terahertz BIC metasurface according to claim 1, characterized in that: The dielectric substrate (1) is a flexible polyethylene terephthalate (PET) substrate with a dielectric constant of 3+0.06i, a thickness of 15 um and a length of 600 um.

8. The VOC sensor based on the terahertz BIC metasurface according to claim 1, characterized in that: The all-dielectric silicon structure is made of high-resistance silicon with a dielectric constant of 11 and a loss tangent of 2.52×10 at 600Ghz. -6 , thickness is 100um.

Images