阅读说明：本技术 一种基于太赫兹光谱技术结合超表面传感器的重金属溶液检测方法 (Heavy metal solution detection method based on terahertz spectrum technology and combined with super-surface sensor ) 是由 邵咏妮 王雨田 熊鑫 彭滟 朱亦鸣 庄松林 于 2021-09-01 设计创作，主要内容包括：本发明提出一种基于太赫兹光谱技术结合超表面传感器的重金属溶液检测方法,通过设计带有双开口的圆形金属环阵列的超表面传感器以及微流控制装置；将多组不同浓度的铅离子溶液依次通过微流控制装置后,利用光谱仪进行光谱信号采集,获得不同Pb～(2+)浓度下溶液的透射谱图；根据透射谱图,从而得到铅离子浓度x和频移量y的线性参数与拟合公式；根据线性参数与拟合公式,将待测铅离子溶液的频移量y带入公式,即可得到溶液的重金属铅离子含量；本发明将超表面传感器应用于溶液重金属的检测,相比于传统的方法,高灵敏度的检测机制,使得待测样品的需求量大大减少,只需要2ml的样本,短时间内即可得到重金属溶液的重金属浓度,大大降低了检测成本,提高的检测效率。(The invention provides a heavy metal solution detection method based on a terahertz spectrum technology and combined with a super-surface sensor, which is characterized in that the super-surface sensor with a double-opening circular metal ring array and a micro-fluidic device are designed; after a plurality of groups of lead ion solutions with different concentrations sequentially pass through the microfluidic device, a spectrometer is used for collecting spectrum signals to obtain different Pb 2+ Transmission spectrum of the solution at concentration; obtaining linear parameters and a fitting formula of the lead ion concentration x and the frequency shift y according to the transmission spectrogram; substituting the frequency shift amount y of the lead ion solution to be detected into a formula according to the linear parameters and a fitting formula to obtain the heavy metal lead ion content of the solution; the invention applies the super-surface sensor to the detection of the heavy metal in the solution, compared with the traditional method and a high-sensitivity detection mechanism, the demand of the sample to be detected is greatly reduced, only 2ml of sample is needed, and the sample can be obtained in a short timeThe heavy metal concentration of the heavy metal solution is reduced greatly, the detection cost is reduced greatly, and the detection efficiency is improved.)

1. A heavy metal solution detection method based on a terahertz spectrum technology combined with a super-surface sensor is characterized by comprising the following steps:

step 1: designing a super-surface sensor with a double-opening circular metal ring array;

step 2: designing a micro-fluidic device;

and step 3: preparing a plurality of groups of lead ion solutions with different concentrations;

and 4, step 4: after a plurality of groups of lead ion solutions sequentially pass through the microfluidic device, the microfluidic device is placed under a spectrometer for spectrum signal acquisition to obtain different Pb²⁺Transmission spectrum of the solution at concentration;

and 5: according to the transmission spectrogram, a linear fitting trend of the frequency shift quantity of the super-surface sensor and the concentration of the heavy metal along with the increase of the concentration of the heavy metal is obtained, so that linear parameters and a fitting formula of the lead ion concentration x and the frequency shift quantity y are obtained;

step 6: and substituting the frequency shift amount y of the lead ion solution to be detected into a formula according to the linear parameters and the fitting formula to obtain the heavy metal lead ion content of the solution.

2. The method for detecting the heavy metal solution based on the terahertz spectroscopy combined with the super surface sensor as claimed in claim 1, wherein in step 1, the design method of the super surface sensor with the circular metal ring array with the double openings is as follows: a metal ohmic ring array is designed to be arranged on the surface of a substrate, the array is formed by periodically and equidistantly arranging a plurality of symmetrical double-opening gold circular rings, and Fano resonance is generated under the action of an electromagnetic field.

3. The method for detecting the heavy metal solution based on the terahertz spectrum technology combined with the super surface sensor as claimed in claim 2, wherein the substrate of the super surface sensor is a polyimide film with a dielectric constant of 3.5, the size of the sensor unit is 90 x 90 μm, and the thickness of the sensor unit is 2 μm; the polyimide film is deposited with a 200nm thick ring structure made of gold, the inner radius R1 of the ring structure is 24 μm, the outer radius R2 of the ring structure is 30 μm, the width g of the ring structure is 9 μm, and the opening a of the ring structure is 2 μm.

4. The method for detecting the heavy metal solution based on the terahertz spectroscopy combined with the super-surface sensor as claimed in claim 1, wherein in step 2, the microfluidic device comprises two upper plates and two lower plates made of polytetrafluoroethylene, the upper plates and the lower plates are fixedly connected through bolts, a sample cavity is formed between the upper plates and the lower plates, and the sensor is placed in the sample cavity.

5. The method for detecting the heavy metal solution based on the terahertz spectroscopy combined with the super-surface sensor, according to claim 4, wherein the whole thickness of the microfluidic device is 13mm, the solvent of the sample cavity is 2cm by 2cm, and the thickness is 50 μm; and a liquid inlet and a liquid outlet for filling and discharging the lead ion solution are preset at the left end and the right end of the sample cavity respectively.

6. The method for detecting the heavy metal solution based on the terahertz spectrum technology combined with the super surface sensor as claimed in claim 4, wherein in step 3, five lead ion solutions with the concentration of 0mg/L, 0.003mg/L, 0.005mg/L, 0.010mg/L and 0.020mg/L are prepared, and the lead ion solution with the concentration of 0-0.02mg/L is covered.

7. The method for detecting the heavy metal solution based on the terahertz spectrum technology combined with the super surface sensor as claimed in claim 1, wherein before the step 4, the microfluidic device and the spectrometer are dried by using a dry gas, so that the humidity of the whole device is below 4%.

8. The method for detecting the heavy metal solution based on the terahertz spectrum technology combined with the super-surface sensor as claimed in claim 1, wherein the spectrometer adopts a terahertz spectrum system TAS7400, adopts transmission spectrum, adopts frequency resolution of 7.6GHz and has single scanning time of 200 ms;

after the super-surface sensor is embedded into the bottom of the sample cavity layer, lead ion solution is injected into the sample cavity from the outside of a spectrometer system by means of a hose and a peristaltic pump, a 50-micrometer sample layer is formed for testing heavy metal solution, each sample is subjected to five times of sampling and then subjected to average treatment, and after the average treatment, normalization treatment is carried out;

9. the method for detecting the heavy metal solution based on the terahertz spectrum technology combined with the super-surface sensor as claimed in claim 6, wherein in step 5, as can be seen from the transmission spectrogram, as the concentration of the heavy metal solution increases, the frequency shift value increases, which is from 0 to 0.003mg/L, and the frequency shift variation is 1.91 GHz; 0 to 0.005mg/L, shift by 3.81 GHz; 0 to 0.010mg/L, frequency shift change 5.72 GHz; the frequency shift is changed by 15.2GHz from 0 to 0.020, so that the super-surface sensor frequency shift and the heavy metal concentration have a linear fitting trend along with the increase of the heavy metal concentration, and the super-surface sensor has good linear response; the formula y is 749.56x-0.15217, x is the lead ion concentration, and y is the frequency shift amount.

Technical Field

The invention relates to the technical field of solution heavy metal detection, in particular to a heavy metal solution detection method based on a terahertz spectrum technology combined with a super-surface sensor.

Background

Heavy metal pollution has become one of the most serious environmental problems in the world today, which can be attributed to natural processes (atmospheric deposition, erosion and mineral weathering) and to man-made activities (such as urban and industrial and agricultural developments, where industrial and agricultural waste water and domestic waste water are not effectively treated and discharged, unlike organic pollutants, heavy metals are not biodegradable, heavy metals tend to accumulate in organisms due to the enrichment of the food chain, eventually causing irreversible damage to human health. in the last 20 th century, with the increase of mining and industrial activities, pollution of the environment by metals Cd, Pb and Hg has become more and more serious, these pollutants contain various man-made sources (industrial waste water and waste, urban runoff, sewage treatment plants, ship activities, agricultural fungicides, dumping of household waste, mining operations, etc.), have caused more and more serious effects on the ecosystem, in China, due to the heavy metal pollution of the water body, the pollution not only causes harm to animals and plants in the nature, but also causes a plurality of harm events to human health. The characteristics of durability, difficult degradation and gradual increase of harmfulness along with the enrichment of a food chain of heavy metal harm cause that people have to pay attention to the problem of heavy metal pollution of a water body. The detection and quantification of water heavy metals in the environment are increasingly important for environmental governance. Many techniques have been developed for many years for heavy metal ion analysis, including atomic absorption spectroscopy, inductively coupled plasma, anodic stripping voltammetry, X-ray fluorescence spectroscopy, and electron microprobe methods. These techniques typically require expensive equipment, complex sample pre-treatment and analyte pre-concentration steps, and suffer from difficulties in reflecting the degree of contamination of aquatic organisms.

Due to the diversity of the actual water body, the detection of the micro low-concentration sample is difficult to realize by adopting the traditional terahertz spectrum technology, and the detection sensitivity of the sample to be detected is greatly improved along with the development of the super-surface sensor technology, so that the detection of the heavy metal pollution of the micro low-concentration water body becomes possible. Therefore, it is urgent for those skilled in the art to design a detection method for realizing high-sensitivity detection of heavy metals in a solution based on a super-surface sensor.

Disclosure of Invention

The invention aims to provide a detection method which is simple in structure, high in sensitivity and small in sample consumption.

In order to achieve the purpose, the invention provides a heavy metal solution detection method based on a terahertz spectrum technology and combined with a super-surface sensor, which comprises the following steps:

step 1: designing a super-surface sensor with a double-opening circular metal ring array;

step 2: designing a micro-fluidic device;

and step 3: preparing a plurality of groups of lead ion solutions with different concentrations;

and 4, step 4: after a plurality of groups of lead ion solutions sequentially pass through the microfluidic device, the microfluidic device is placed under a spectrometer for spectrum signal acquisition to obtain different Pb²⁺Transmission spectrum of the solution at concentration;

and 5: according to the transmission spectrogram, a linear fitting trend of the frequency shift quantity of the super-surface sensor and the concentration of the heavy metal along with the increase of the concentration of the heavy metal is obtained, so that linear parameters and a fitting formula of the lead ion concentration x and the frequency shift quantity y are obtained;

step 6: and substituting the frequency shift amount y of the lead ion solution to be detected into a formula according to the linear parameters and the fitting formula to obtain the heavy metal lead ion content of the solution.

Further, in step 1, the method for designing the super-surface sensor with the circular metal ring array with the double openings comprises the following steps: a metal ohmic ring array is designed to be arranged on the surface of a substrate, the array is formed by periodically and equidistantly arranging a plurality of symmetrical double-opening gold circular rings, and Fano resonance is generated under the action of an electromagnetic field.

Further, the substrate of the super-surface sensor is a polyimide film with the dielectric constant of 3.5, the size of a sensor unit is 90 multiplied by 90 μm, and the thickness of the sensor unit is 2 μm; the polyimide film is deposited with a 200nm thick ring structure made of gold, the inner radius R1 of the ring structure is 24 μm, the outer radius R2 of the ring structure is 30 μm, the width g of the ring structure is 9 μm, and the opening a of the ring structure is 2 μm.

Further, in step 2, the microfluidic device includes two upper plates and two lower plates made of teflon, the upper plates and the lower plates are fixedly connected through bolts, a sample cavity is formed between the upper plates and the lower plates, and the sensor is disposed in the sample cavity.

Further, the whole thickness of the microfluidic control device is 13mm, the solvent of the sample cavity is 2cm by 2cm, and the thickness is 50 μm; and a liquid inlet and a liquid outlet for filling and discharging the lead ion solution are preset at the left end and the right end of the sample cavity respectively.

Further, in step 3, five lead ion solutions with different concentrations, namely 0mg/L, 0.003mg/L, 0.005mg/L, 0.010mg/L and 0.020mg/L, are prepared, and the lead ion solution with the different concentrations covers the lead low concentration range of 0-0.02 mg/L.

Further, before step 4, the microfluidic device and the spectrometer are dried by using a dry gas so that the humidity of the whole device is 4% or less.

Further, the spectrometer adopts a terahertz spectrum system TAS7400 and a transmission spectrum, the frequency resolution adopts 7.6GHz, and the single scanning time is 200 ms;

after the super-surface sensor is embedded into the bottom of the sample cavity layer, lead ion solution is injected into the sample cavity from the outside of a spectrometer system by means of a hose and a peristaltic pump, a 50-micrometer sample layer is formed for testing heavy metal solution, each sample is subjected to five times of sampling and then subjected to average treatment, and after the average treatment, normalization treatment is carried out;

further, in step 5, as can be seen from the transmission spectrogram, as the concentration of the heavy metal solution increases, the frequency shift value increases, and the frequency shift variation is from 0 to 0.003mg/L, and is 1.91 GHz; 0 to 0.005mg/L, shift by 3.81 GHz; 0 to 0.010mg/L, frequency shift change 5.72 GHz; the frequency shift is changed by 15.2GHz from 0 to 0.020, so that the super-surface sensor frequency shift and the heavy metal concentration have a linear fitting trend along with the increase of the heavy metal concentration, and the super-surface sensor has good linear response; the formula y is 749.56x-0.15217, x is the lead ion concentration, and y is the frequency shift amount.

Compared with the prior art, the invention has the advantages that:

1. according to the invention, the super-surface sensor is applied to the detection of heavy metal in solution, the surface sensor is structurally designed, the circular metal ring array with double openings is designed into the terahertz sensor for realizing high-sensitivity detection, compared with the traditional method, the high-sensitivity detection mechanism greatly reduces the demand of samples, and the midcourse concentration of the heavy metal solution can be obtained in a short time by only 2ml of samples, so that the detection cost is greatly reduced, and the detection efficiency is improved.

2. Through the detection of lead ion solutions with different concentrations in the pair group, the relational expression between the lead ion concentration and the frequency shift amount is obtained, the subsequent steps of heavy metal detection are simplified, and the detection precision is guaranteed.

Drawings

Fig. 1(a) is a schematic structural view of a double-open-ring resonator.

FIG. 1(b) is an enlarged view of a single double-opening gold ring in FIG. 1 (a).

Fig. 2 is a schematic structural diagram of the microfluidic device.

Fig. 3 is a transmission spectrum of the Pb2+ solution after normalization.

FIG. 4 shows different concentrations of Pb²⁺And linearly fitting the frequency shift amount of the solution with the concentration of the heavy metal solution.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be further described below.

The invention adopts CST STIDIO SUITE 2019 software to design the super-surface sensor. A circular metal ring array with double openings is designed into a terahertz sensor for realizing high-sensitivity detection, as shown in fig. 1(a) and 1(b), a metal ohmic ring array is designed, the array is periodically composed of a plurality of symmetrical double-opening gold rings, and Fano resonance is generated under the action of an electromagnetic field. The substrate of the sensor is a Polyimide (PI) film with a dielectric constant of 3.5, the sensor unit size is 90X 90 μm, and the thickness is 2 μm. A 200nm thick circular ring structure was deposited on the film, the material being gold with an inner radius, an outer radius, a width and an opening size of R1 ═ 24 μm, R2 ═ 30 μm, g ═ 9 μm and a ═ 2 μm, respectively.

Meanwhile, a micro-fluidic device is designed, as shown in fig. 2, a cavity is divided into an upper plate and a lower plate which are fixed by screws, the whole thickness is 13mm, the sealing requirement under a non-pressure state can be ensured, the materials are all made of polytetrafluoroethylene, liquid inlet and outlet ports are arranged on the left and the right of the cavity, and a sample is filled into a sample cavity with the volume of 2cm multiplied by 2cm and the thickness of 50 mu m to form a sample layer. The lead standard solution is diluted to five concentrations of 0mg/L, 0.003mg/L, 0.005mg/L, 0.010mg/L and 0.020 mg/L. Then, the terahertz spectrum system TAS7400 produced by the Japan Advantest company is used for spectrum detection, and before the spectrometer is used, the device is dehumidified by dry gas, and the device can be used only when the humidity is stabilized below 4 percent so as to avoid the interference of water vapor on the terahertz signal. Transmission spectra were used with a frequency resolution of 7.6GHz and a single scan time of 200 ms.

And embedding the super-surface sensor into the bottom of the cavity layer, and injecting a heavy metal liquid sample into the sample cavity from the outside of the spectrometer system by virtue of a hose and a peristaltic pump to form a 50-micrometer sample layer for testing the heavy metal solution. Each sample is subjected to five times of sampling and then subjected to averaging treatment, and normalization treatment is performed after averaging treatment. After obtaining the normalized transmission spectrum, as shown in fig. 3, a relationship between the frequency shift amount and the concentration is modeled to obtain the formula y of 749.56x-0.15217, as shown in fig. 4, where x is the lead ion concentration, y is the frequency shift amount, and R is the same as R²Reaching 0.99772.

After the model is established, lead ion solutions with the concentrations of 0.008mg/L and 0.015mg/L are randomly prepared, the prepared solutions are pumped into a microfluidic cavity by using a peristaltic pump and placed in a TAS7400 for signal acquisition, and the signals are acquired five times for average normalization treatment. Compared with the 0mg/L locus, the two concentration translation amounts are 5.8772 and 11.1 respectively, and the calculated concentrations are 0.00804mg/L and 0.01501mg/L by substituting the two concentration translation amounts into a formula, so that the method can accurately detect the content of the low-concentration heavy metal solution.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.