A terahertz water quality detection chip based on phase change materials and its detection method

Abstract

This invention discloses a terahertz water quality detection chip based on phase change materials and its detection method. The detection chip comprises a substrate, interdigitated electrodes, and a phase change film. The interdigitated electrodes are disposed on the substrate, and a microstructure array is arranged between the interdigitated electrodes. The phase change film covers the interdigitated electrodes and the microstructure array. The area covered by the phase change film serves as a droplet sample loading area. The phase change film transforms between an amorphous and crystalline state, thus being suitable for two detection modes. The phase change film is a thin film formed by GST phase change material, which is a compound formed by the combination of Ge, Sb, and Te elements. The above-mentioned detection chip excites the GST phase change material to generate a photoconductive effect through terahertz radiation, and utilizes the high conductivity of pollutants in water to modulate the local terahertz field. It uses the change in photocurrent with particle concentration to form a quantitative detection relationship, thereby significantly improving the sensitivity of water quality detection while reducing the size of the detection equipment.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, and in particular to a terahertz water quality detection chip based on phase change materials and its detection method. Background Technology

[0002] Terahertz waves, operating in the 0.1–10 THz frequency band, possess advantages such as non-ionization, sensitivity to dielectric materials, and non-contact detection capabilities, and have been widely used in materials characterization, food safety, and drug detection. However, applying terahertz technology to water pollutant detection still faces the following challenges: 1. Traditional terahertz spectroscopy detection systems are bulky, expensive, and unsuitable for integration and on-site detection; 2. Water strongly absorbs terahertz waves, resulting in low signal-to-noise ratios and high detection limits; 3. Existing terahertz detectors based on metal wire grids have limited sensitivity, making it impossible to further enhance the local electric field enhancement effect. Therefore, existing terahertz devices for water quality detection suffer from poor detection sensitivity. Summary of the Invention

[0003] This invention provides a terahertz water quality detection chip based on phase change materials and its detection method, aiming to solve the problem of poor detection sensitivity of terahertz devices used for water quality detection in existing technologies.

[0004] In a first aspect, embodiments of this application provide a terahertz water quality detection chip based on phase change materials, wherein the detection chip includes a substrate, interdigitated electrodes, and a phase change thin film;

[0005] The interdigitated electrodes are disposed on the substrate, and a microstructure array is provided between the interdigitated electrodes. The phase change film covers the interdigitated electrodes and the microstructure array. The area covered by the phase change film serves as a droplet sample loading area. The phase change film transforms between an amorphous and crystalline state, thus being suitable for two detection modes. The phase change film is a thin film formed from GST phase change material. The GST phase change material is a compound formed by the combination of Ge, Sb, and Te elements.

[0006] The terahertz excitation module is located on one side of the detection chip, and the two ends of the interdigitated electrode are respectively connected to the two connection terminals of the microcurrent sampling module.

[0007] Secondly, embodiments of this application also provide a detection method, wherein the detection method is applied to the terahertz water quality detection chip based on phase change materials as described in the first aspect above, and the detection method includes:

[0008] The contaminant liquid is added dropwise to the droplet sample-carrying area;

[0009] The terahertz excitation module is activated so that the detection chip is continuously irradiated with terahertz waves. The terahertz waves generate photoconductivity on the surface of the phase change film, and the interdigitated electrodes enhance the local field.

[0010] The current change is obtained through the microcurrent sampling module; the current change includes the current when irradiated by terahertz waves and the current when not irradiated.

[0011] The current change is analyzed and calculated according to the preset calculation rules to obtain the corresponding liquid pollutant concentration.

[0012] This invention provides a terahertz water quality detection chip based on phase change materials and its detection method. The chip comprises a substrate, intercalation electrodes, and a phase change film. The intercalation electrodes are disposed on the substrate, and a microstructure array is arranged between them. The phase change film covers the intercalation electrodes and the microstructure array. The area covered by the phase change film serves as a droplet sample loading area. The phase change film transitions between an amorphous and crystalline state, thus being suitable for two detection modes. The phase change film is a thin film formed from GST phase change material, which is a compound formed by the combination of Ge, Sb, and Te elements. A terahertz excitation module is disposed on one side of the detection chip, and the two ends of the intercalation electrodes are respectively connected to the two connection terminals of a microcurrent sampling module. This detection chip excites the GST phase change material through terahertz radiation to generate a photoconductive effect, and utilizes the high conductivity of pollutants in the water to modulate a local terahertz field. It uses the change in photocurrent with particle concentration to form a quantitative detection relationship, thereby significantly improving the sensitivity of water quality detection while reducing the size of the detection equipment. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is an overall structural diagram of the terahertz water quality detection chip provided in an embodiment of the present invention;

[0015] Figure 2 A partial structural diagram of the terahertz water quality detection chip provided in an embodiment of the present invention;

[0016] Figure 3 This is another partial structural diagram of the terahertz water quality detection chip provided in an embodiment of the present invention;

[0017] Figure 4 A flowchart of the detection method provided in the embodiments of the present invention;

[0018] Figure 5 This is a schematic diagram illustrating an application scenario of the detection method provided in an embodiment of the present invention.

[0019] Reference numerals: 10, water quality detection chip; 11, substrate; 12, interdigitated electrode; 14, microstructure array; 20, terahertz excitation module; 30, microcurrent sampling module; 121, first main electrode; 122, second main electrode; 123, first electrode microstrip; 124, second electrode microstrip; 141, first microstructure; 142, second microstructure. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0022] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0023] This invention also provides a terahertz water quality detection chip based on phase change materials, such as... Figure 1 and Figure 2As shown, the detection chip includes a substrate, intercalation electrodes, and a phase change film. The intercalation electrodes are disposed on the substrate, and a microstructure array is arranged between the intercalation electrodes. The phase change film covers the intercalation electrodes and the microstructure array. The area covered by the phase change film serves as a droplet sample carrying area. The phase change film transforms between an amorphous and a crystalline state, thus being suitable for two detection modes. The phase change film is a thin film formed by GST phase change material. The GST phase change material is a compound formed by the combination of Ge, Sb, and Te elements. A terahertz excitation module is disposed on one side of the detection chip, and the two ends of the intercalation electrodes are respectively connected to the two connection terminals of the microcurrent sampling module.

[0024] The water quality detection chip disclosed in this application comprises a substrate, intercalation electrodes, and a phase change film. A microstructure array is further disposed on the surface of the substrate between the intercalation electrodes. By placing the microstructure array between the intercalation electrodes, conductivity is enhanced while terahertz response is achieved. A terahertz excitation module is disposed on one side of the detection chip; in this embodiment, the terahertz excitation module is disposed on the upper side of the detection chip. The intercalation electrodes include two electrodes, each corresponding to a connection terminal of a microcurrent sampling module. Specifically, during water quality measurement, the phase change film is excited by terahertz radiation to generate a photoconductive effect, and the high conductivity of pollutants in the water body is used to modulate the local terahertz field. The photocurrent output by the detection chip changes with particle concentration, thereby forming a quantitatively detectable relationship.

[0025] Specifically, the substrate can be SiO2 / Si substrate, glass substrate or ceramic substrate, wherein the material of the microstructure array is the same as the material of the substrate, and the interdigitated electrodes are made of metal material.

[0026] In a more specific embodiment, the phase change film is a Ge2Sb2Te5 film. The thickness of the phase change film is 30-150 nm.

[0027] The GST phase change material used in this application embodiment is a typical phase change material, and a Ge2Sb2Te5 thin film is prepared using this phase change material. There is a significant jump in physical quantities such as conductivity, refractive index, and dielectric constant between the amorphous and crystalline states of the Ge2Sb2Te5 thin film. In particular, the conductivity can vary by 1–3 orders of magnitude in the terahertz band, making it suitable as a terahertz enhancement layer for water quality detection. In specific applications, the thickness of the phase change film can be set to 30–150 nm. If the thickness of the phase change film is too thin (e.g., <20 nm), the overall conductivity change caused by the phase change is too small; if the thickness of the phase change film is too thick (e.g., >200 nm), the terahertz transmission is significantly reduced, the advantage of the amorphous / crystalline difference is weakened, and the obtained detection sensitivity will also be poor.

[0028] In a more specific embodiment, such as Figure 1 As shown, the interdigitated electrode includes a first main electrode, a second main electrode, multiple first electrode microstrips, and multiple second electrode microstrips; the first electrode microstrips and the second electrode microstrips are parallel and spaced apart; each of the first electrode microstrips is connected to a first main electrode on one side; and each of the second electrode microstrips is connected to a second main electrode on the other side.

[0029] The first electrode microstrip and the second electrode microstrip can be arranged alternately and parallel to each other. Furthermore, a first main electrode connected to the first electrode microstrip can be provided on the left side, thus establishing electrical conductivity between the first main electrode and each first electrode microstrip; a second main electrode connected to the second electrode microstrip can be provided on the right side, thus establishing electrical conductivity between the second main electrode and each second electrode microstrip.

[0030] Furthermore, the length and width of the first electrode microstrip and the second electrode microstrip can be set to be equal; the width of the first main electrode and the width of the second main electrode can be equal, and the width of the first main electrode is greater than the width of the first electrode microstrip.

[0031] The ratio of the front end spacing to the length of the first electrode microstrip can be set to 1:30 to 1:15; the front end spacing is also the spacing between the front end of the first electrode microstrip and the second main electrode. The spacing between the first electrode microstrip and the adjacent second electrode microstrip can be set to 250-600 μm, and in a preferred embodiment, the spacing between the first electrode microstrip and the adjacent second electrode microstrip can be set to 400 μm. Furthermore, the thickness of the first electrode microstrip and the second electrode microstrip is equal, and the thickness is 80-200 nm.

[0032] In a more specific embodiment, such as Figure 2 and Figure 3 As shown, the microstructure array includes multiple sets of microstructures, each set consisting of a first microstructure and a second microstructure. These multiple sets of microstructures are arranged in a matrix at the gaps between the first electrode microstrip and the second electrode microstrip. Specifically, multiple microstructures are arranged sequentially along a direction parallel to the first electrode microstrip, forming multiple rows of microstructures. Each row of microstructures is positioned at the gap between one first electrode microstrip and one second electrode microstrip. The first main electrode and the second main electrode are parallel and both are elongated strips, with the first main electrode perpendicular to the first electrode microstrip.

[0033] The microstructure array can be configured to consist of multiple groups of microstructures, each group including a first microstructure and a second microstructure. The first and second microstructures differ in size and shape. The structures of the first and second microstructures are as follows: Figure 3As shown, the first microstructure is located in the upper right and the second microstructure is located in the lower left. In practical applications, the relative positions of the first and second microstructures can be flexibly adjusted, such as adjusting the first microstructure to the lower right and the second microstructure to the upper left. The first microstructure consists of four arrow-shaped protrusions, the tips of which all face the center of the first microstructure and are evenly distributed around it. The four arrow-shaped protrusions in the first microstructure have the same shape and size. Specifically, the vertical distance A between the front end and the side of the arrow-shaped protrusion in the first microstructure is 0.03 mm; the distance C between the front end of the arrow-shaped protrusion and the center of the first microstructure is 0.02 mm; the width B of the side of the arrow-shaped protrusion is 0.03 mm; the arrow-shaped protrusion is an axisymmetric structure, and the angle θ between the hypotenuse of the side of the arrow-shaped protrusion and the centerline of the arrow-shaped protrusion is 30°.

[0034] The second microstructure also consists of four V-shaped protrusions, with the tips of the protrusions all facing the center of the second microstructure and evenly arranged around it. The four V-shaped protrusions in the second microstructure are identical in shape and size. Specifically, the distance D between the front and rear ends of the V-shaped protrusions in the second microstructure is 0.06 mm; the distance E between the front end of the V-shaped protrusion and the center of the second microstructure is 0.01 mm; and the distance F between the front end of the V-shaped protrusion and the apex of its internal opening is 0.02 mm. The V-shaped protrusions are axially symmetric.

[0035] In a more specific embodiment, the height of the microstructure is 60-150 μm (micrometers). The characteristic size of the microstructures in the microstructure array is much smaller than the incident terahertz wavelength, thereby forming an artificial electromagnetic structure with significant resonance and local field enhancement effects.

[0036] In a more specific embodiment, the phase change film is prepared by the following method: intercalation electrodes are prepared on a substrate using a process combining photolithography and magnetron sputtering of metal thin films; an amorphous phase change film is prepared on the surface of the intercalation electrodes and the microstructure array using magnetron sputtering; and the resulting chip is annealed at 150–250°C for 2–8 minutes to form a crystalline phase change film.

[0037] In practical applications, the substrate can be cleaned first, and a cross-sectional pattern can be drawn point by point / line by line on the surface of the resin tank using a scanning laser (405 nm). The resin tank with the pattern is filled with curing material (the curing material is the same as the substrate after curing). After the curing material is cured, the platform is raised and lowered and the curing material is refilled. The microstructure array is prepared on the surface of the substrate by 3D curing and layer stacking.

[0038] Further employing photolithography combined with magnetron sputtering of metal thin films, intercalation electrodes are fabricated on a substrate with a microstructure array. Magnetron sputtering is then used to fabricate a phase transition film with a thickness of 30–150 nm on the surface of the intercalation electrodes and the microstructure array; at this stage, the phase transition film is amorphous. Depending on the specific requirements, the fabricated detection chip is annealed at 150–250°C for 2–8 minutes to form a crystalline phase transition film. In subsequent applications, the phase transition film can be remelted and quenched back to an amorphous state using an electrical pulse, thus achieving a reversible phase transition.

[0039] This invention aims to provide a terahertz water quality detection chip based on phase change materials, which can achieve the following functions: 1. Signal enhancement is achieved by utilizing the terahertz conductivity and dielectric constant jump between the amorphous and crystalline states of GST thin films. Combined with subwavelength microstructures, it can generate a better response to terahertz waves, and the preparation process is simple, controllable, and easy to adjust; 2. The chip sensitivity is controlled by phase change to achieve dual-mode detection (sensitive mode / wide dynamic range mode); 3. It solves the problem of insufficient sensitivity in traditional terahertz detection, enabling the detection of pollutants at concentrations of 0.1 mg / L or even lower; 4. It provides an integrable and on-chip terahertz detection solution, suitable for rapid on-site water quality testing, and the detection equipment is smaller in size.

[0040] Compared with traditional terahertz detection equipment, the detection chip in this embodiment has the following significant advantages: 1. Significant phase transition enhancement: The conductivity of the crystalline GST thin film increases by 1–3 orders of magnitude under terahertz, resulting in a significant enhancement of photocurrent and thus improving the accuracy of water quality detection; 2. Low detection limit: It can detect pollutants at concentrations of 0.1 mg / L or even lower; 3. Support for multi-mode detection: Sensitivity and dynamic range can be adjusted through different phase states; 4. Strong signal interference resistance: Phase transition can be used to compensate for changes in water background, improving robustness; 5. Chip-based advantages: Simple structure, easy integration, low cost, and small size, suitable for portable water quality monitoring equipment. Therefore, the above-mentioned detection chip has the advantages of high sensitivity, adjustability, low cost, and easy integration, and can be widely used in industrial wastewater detection, environmental monitoring, and rapid on-site analysis.

[0041] This application discloses a detection method in specific embodiments, wherein the detection method is applied to a terahertz water quality detection chip based on phase change materials as described in the above embodiments; please refer to... Figure 4 The detection method includes steps S1 to S4, and the application scenarios of the detection method are as follows: Figure 5As shown, the terahertz excitation module is located on one side of the detection chip, and the two ends of the interdigitated electrodes in the detection chip are respectively connected to the two connection terminals of the microcurrent sampling module. The terahertz excitation module uses a continuous wave source of approximately 0.1 THz, such as a common terahertz avalanche diode. The microcurrent sampling module records the dark current (current without terahertz irradiation) and photocurrent (current under terahertz wave irradiation), which are used to calculate parameters such as external quantum efficiency and for concentration inversion calculations, ultimately monitoring the pollutant concentration.

[0042] S1. Add the contaminant liquid droplets to the droplet sample loading area.

[0043] Add the contaminant liquid (such as urea) dropwise to the droplet loading area.

[0044] S2. Activate the terahertz excitation module to continuously irradiate the detection chip with terahertz waves. The terahertz waves generate photoconductivity on the surface of the phase change film, and the interdigitated electrodes enhance the local field.

[0045] The terahertz excitation module is activated, subjecting the chip to continuous irradiation at 0.1 THz. The terahertz wave induces photoconductivity on the surface of the phase-change thin film, and the interdigitated electrodes enhance the local field. When a 0.1 THz terahertz electromagnetic wave is incident, the equivalent LC units in the microstructure are excited (related to the terahertz resonant frequency), generating a strong local electric field and surface current distribution on the device surface. This makes the Ge2Sb2Te5 thin film covering it and the adjacent suspended contaminant particles highly sensitive to even small changes in the dielectric constant and conductivity of the terahertz wave. Compared to planar electrodes without subwavelength structures, the device structure in this application can significantly amplify the modulation of the terahertz photocurrent by changes in contaminant particle concentration, thereby improving the sensitivity and signal-to-noise ratio of water pollution detection. The enhanced electric field is more pronounced in the sharp-cornered structures of the microstructure, forming surface plasmon polaritons. The shape of the structure forms an LC loop.

[0046] S3. Obtain the current change through the microcurrent sampling module; the current change includes the current when irradiated by terahertz waves and the current when not irradiated.

[0047] The system collects changes in light and dark current. The photocurrent in the current change is the current when terahertz waves irradiate, and the dark current in the current change is the current when there is no irradiation. The higher the pollutant concentration, the greater the response.

[0048] S4. Analyze and calculate the current change according to the preset calculation rules to obtain the corresponding liquid pollutant concentration.

[0049] The current change is analyzed and calculated using calculation rules, such as calculating parameters like external quantum efficiency, and the particle concentration is inverted using partial least squares or a linear fitting model to obtain the final liquid pollutant concentration.

[0050] The phase transition of the phase transition film (GST) provides two different detection modes. In the amorphous state, it features low conductivity and low noise, making it suitable for a wide concentration range. In the crystalline state, it features high conductivity and strong absorption, which can enhance the terahertz response and is suitable for low-concentration detection. By controlling the phase transition state of the GST, the sensitivity can be configured according to the detection requirements, enabling multi-mode detection.

[0051] This invention provides a terahertz water quality detection chip based on phase change materials and its detection method. The chip comprises a substrate, intercalation electrodes, and a phase change film. The intercalation electrodes are disposed on the substrate, and a microstructure array is arranged between them. The phase change film covers the intercalation electrodes and the microstructure array. The area covered by the phase change film serves as a droplet sample loading area. The phase change film transitions between an amorphous and crystalline state, thus being suitable for two detection modes. The phase change film is a thin film formed from GST phase change material, which is a compound formed by the combination of Ge, Sb, and Te elements. A terahertz excitation module is disposed on one side of the detection chip, and the two ends of the intercalation electrodes are respectively connected to the two connection terminals of a microcurrent sampling module. This detection chip excites the GST phase change material through terahertz radiation to generate a photoconductive effect, and utilizes the high conductivity of pollutants in the water to modulate a local terahertz field. It uses the change in photocurrent with particle concentration to form a quantitative detection relationship, thereby significantly improving the sensitivity of water quality detection while reducing the size of the detection equipment.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A terahertz water quality detection chip based on phase change materials, characterized in that, The detection chip includes a substrate, interdigitated electrodes, and a phase change thin film; The interdigitated electrodes are disposed on the substrate, and a microstructure array is provided between the interdigitated electrodes. The phase change film covers the interdigitated electrodes and the microstructure array. The area covered by the phase change film serves as a droplet sample loading area. The phase change film transforms between an amorphous and crystalline state, thus being suitable for two detection modes. The phase change film is a thin film formed from GST phase change material. The GST phase change material is a compound formed by the combination of Ge, Sb, and Te elements. The phase change thin film is film; The terahertz excitation module is located on one side of the detection chip, and the two ends of the interdigitated electrode are respectively connected to the two connection terminals of the microcurrent sampling module; The interdigitated electrode includes a first main electrode, a second main electrode, multiple first electrode microstrips, and multiple second electrode microstrips; The first electrode microstrip and the second electrode microstrip are parallel and spaced apart; each of the first electrode microstrips is connected to a first main electrode on one side; each of the second electrode microstrips is connected to a second main electrode on the other side; the thickness of the phase change film is 30-150 nm; the microstructure array includes multiple sets of microstructures, each set of microstructures being composed of a first microstructure and a second microstructure. Multiple sets of the microstructures are arranged in a matrix in the gap between the first electrode microstrip and the second electrode microstrip.

2. The terahertz water quality detection chip based on phase change materials according to claim 1, characterized in that, Multiple microstructures are arranged sequentially along a direction parallel to the first electrode microstrip to form multiple rows of microstructures; each row of microstructures is correspondingly disposed in the gap between a first electrode microstrip and a second electrode microstrip.

3. The terahertz water quality detection chip based on phase change materials according to claim 1, characterized in that, The first main electrode and the second main electrode are parallel and both are elongated strips, with the first main electrode perpendicular to the first electrode microstrip.

4. The terahertz water quality detection chip based on phase change materials according to claim 2, characterized in that, The height of the microstructure is 60-150 μm.

5. The terahertz water quality detection chip based on phase change materials according to claim 3, characterized in that, The phase change thin film was prepared using the following method: Interdigitated electrodes were fabricated on a substrate using a process combining photolithography and magnetron sputtering of metal thin films; Amorphous phase change thin films were prepared on the surface of interdigitated electrodes and microstructure arrays by magnetron sputtering. The obtained chip is annealed at 150–250°C for 2–8 minutes to form a crystalline phase change thin film.

6. A detection method, characterized in that, The detection method is applied to the terahertz water quality detection chip based on phase change material as described in any one of claims 1-5, and the detection method includes: The contaminant liquid is added dropwise to the droplet sample-carrying area; The terahertz excitation module is activated so that the detection chip is continuously irradiated with terahertz waves. The terahertz waves generate photoconductivity on the surface of the phase change film, and the interdigitated electrodes enhance the local field. The current change is obtained through the microcurrent sampling module; the current change includes the current when irradiated by terahertz waves and the current when not irradiated. The current change is analyzed and calculated according to the preset calculation rules to obtain the corresponding liquid pollutant concentration.

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