Paper-based micro-fluidic chip structure for rapid detection of pesticide residues

Abstract

The utility model relates to the technical field of micro-fluidic chips, in particular to a paper-based micro-fluidic chip structure for quickly detecting pesticide residues, which is designed after a hydrophobic plate and filter paper are integrally formed, so that the hydrophobic barrier effect is obviously enhanced. The hydrophobic plate serves as an entity physical barrier, liquid is effectively prevented from breaking through the boundary of the hydrophilic channel, the probability of cross contamination between the channels is greatly reduced, the detection process is more stable, and the accuracy and reliability of the detection result are improved. A sample is dropped through the sample adding opening and then flows in the hydrophilic channel. A sample firstly passes through the enzyme reaction area, then passes through the enzyme reaction area, and then flows into the color development area. And the three-electrode system in the color development area synchronously performs electrochemical detection on the reaction system. An operator can directly observe the color change of the color developing area through the observation window corresponding to the position of the color developing area on the covering layer, and preliminary qualitative judgment is carried out; and related electric signal data detected by the three-electrode system can be read. The micro-fluidic chip can be widely applied to the technical field of micro-fluidic chips.

Description

TECHNICAL FIELD

[0001] The utility model relates to micro -fluidic chip technical field, concretely, paper -based micro -fluidic chip structure for rapid detection of pesticide residues. BACKGROUND

[0002] Traditional pesticide residue detection technology often relies on laboratory large instrument such as chromatograph, mass spectrometer, and there is expensive equipment, complex operation, timeliness poor etc. Paper-based micro -fluidic chip because of its low cost, portability and fast response characteristics become alternative scheme, the prior art mainly utilizes wax printing to form water inlet channel on filter paper surface, and the wax printing forms the hydrophobic barrier by melting through heating, but the wax penetration depth has significant difference, leading to the fuzzy boundary of hydrophilic channel. Liquid is easy to break through the hydrophobic zone under the capillary action, and the hydrophobic boundary of wax printing filter paper leads to liquid diffusion out of control due to uneven wax penetration depth, and cross contamination is easy to occur between channels.

[0003] In addition, the existing paper-based micro -fluidic chip also needs to be improved in detection sensitivity. Although it can realize the preliminary rapid detection of pesticide residues, but for the detection of some trace pesticide residues, often cannot reach the ideal precision. This is because the fixed detection reagent on the chip is not perfect in signal amplification mechanism when reacting with the sample. UTILITY MODEL CONTENT

[0004] In view of the problems in the prior art, the utility model provides a paper-based micro -fluidic chip structure for rapid detection of pesticide residues.

[0005] In order to solve the above technical problem, the utility model is solved through the following technical scheme:

[0006] The paper-based micro -fluidic chip structure for rapid detection of pesticide residues comprises a hydrophobic substrate layer, at least two hydrophobic plates are arranged on the upper surface of the hydrophobic substrate layer, the hydrophobic plate is integrally formed with the hydrophobic substrate layer, a hydrophilic channel is formed between the adjacent two hydrophobic plates, and an enzyme reaction zone and a color development zone are sequentially arranged in the hydrophilic channel; A three-electrode system is arranged in the color development zone; Further comprising a cover layer located above the hydrophobic substrate layer, a sample adding port and an observation window are arranged on the cover layer, and the observation window corresponds to the position of the color development zone.

[0007] The hydrophobic plate is integrally formed with the filter paper, which significantly enhances the hydrophobic barrier effect. The hydrophobic plate acts as a physical barrier, effectively preventing liquid from breaking through the boundary of the hydrophilic channel, greatly reducing the probability of cross contamination between channels, making the detection process more stable, and improving the accuracy and reliability of the detection results.

[0008] The sample is dripped into the hydrophilic channel through the sample inlet and flows inside the hydrophilic channel. The sample first passes through the enzyme reaction area, in which the pesticide in the sample reacts with the specific enzyme fixed therein. For example, for the detection of organophosphorus and carbamate pesticides, the activity of cholinesterase is inhibited, thereby changing the catalytic function of the enzyme.

[0009] After passing through the enzyme reaction area, the sample flows into the color development area. The chemicals in the color development area will undergo a color development reaction according to the degree of inhibition of enzyme activity. The higher the pesticide residue content, the greater the degree of inhibition of enzyme activity, and the more obvious the color change produced by the color development reaction, and vice versa. The color change is smaller, thereby preliminarily judging the pesticide residue content.

[0010] The three-electrode system in the color development area simultaneously performs electrochemical detection on the reaction system. The reaction between the pesticide residue and the enzyme changes the electrochemical properties of the solution in the color development area, such as conductivity and redox potential. The three-electrode system can sensitively perceive these changes and convert them into electrical signals. Through analysis and processing of the electrical signals, the pesticide residue content is further accurately judged, providing a more accurate basis for the detection result. The operator can directly observe the color change of the color development area through the observation window corresponding to the position of the color development area on the cover layer, and preliminarily qualitatively judge; and can also read the relevant electrical signal data detected by the three-electrode system, realize more accurate quantitative analysis, and thus comprehensively and accurately judge the pesticide residue situation.

[0011] As a preferred embodiment, the hydrophilic channel has at least two, and each hydrophilic channel is sequentially provided with an enzyme reaction area and a color development area at the end, and different enzyme reagents are fixed in each enzyme reaction area.

[0012] The plurality of hydrophilic channels and the different enzyme reagents provided in each channel enable the chip to simultaneously detect multiple pesticide residues. Without the need for multiple detections of the sample or the use of multiple detection devices, the detection efficiency is greatly improved, the actual situation of pesticide residues in agricultural products can be more comprehensively reflected, and the needs of complex pesticide residue detection scenarios can be met.

[0013] As a preferred embodiment, the hydrophobic base layer is provided with a storage ring located below the sample inlet, the storage ring is made of a hydrophobic material, and sample inlet holes corresponding to each hydrophilic channel are formed in the side wall of the storage ring, and the sample inlet holes are located at the same horizontal height.

[0014] The presence of the storage ring provides a buffer area for the sample, effectively preventing the sample from splashing when it drips from the sample inlet due to direct impact on the surface of the chip. This not only avoids waste of the sample, but more importantly, prevents the splashed sample from contaminating other areas of the chip or the surrounding environment, ensuring the cleanliness of the detection environment and helping to maintain the accuracy and reliability of the detection. After the sample accumulates to a certain amount, the sample will flow into different hydrophilic channels through the sample inlet holes corresponding to each hydrophilic channel simultaneously and uniformly due to the characteristics of static pressure and the same horizontal height of the sample inlet holes.

[0015] As preferred, the height of the sample inlet hole is between 0.5mm and 1mm.

[0016] When the height of the sample inlet hole is less than 0.5mm, the buffer space provided by the sample reservoir is relatively insufficient. When the height of the sample inlet hole is between 0.5mm and 1mm, sufficient buffer space can be provided to effectively reduce the risk of splashing and control the splashing probability at a low level, such as less than 10%. If the height of the sample inlet hole is greater than 1mm, the liquid needs to overcome a greater gravitational potential energy to flow into the channel, which can cause a delay in the diversion of the liquid into the hydrophilic channel.

[0017] As preferred, a partition plate is arranged between the enzyme reaction zone and the color development zone, and the height of the partition plate is less than the height of the hydrophobic plate.

[0018] The arrangement of the partition plate can control the rate and amount of sample entering the color development zone from the enzyme reaction zone to a certain extent. The sample needs to flow over the partition plate to enter the color development zone, which avoids the sample from rushing into the color development zone too quickly, so that the enzyme reaction has more time to proceed, ensuring the accuracy and stability of the detection reaction. For example, the reaction of certain enzymes with pesticides requires a certain time to achieve a stable inhibitory effect. The partition plate can prevent the sample that has not been fully reacted from entering the color development zone too early, resulting in inaccurate color development results.

[0019] As preferred, the upper end surface of the hydrophobic plate is provided with colorimetric paper on both sides of the color development zone.

[0020] After the sample completes the enzymatic reaction in the hydrophilic channel, it enters the color development zone to undergo a color development reaction. At this time, the colorimetric paper arranged on the upper end surface of the hydrophobic plate on both sides of the color development zone begins to play a role. The color change produced in the color development zone will be compared with the colorimetric paper. Since the colorimetric paper has a standard color scale, the operator can directly compare the color of the color development zone with the color scale on the colorimetric paper to intuitively judge the approximate content of pesticide residues in the sample. BRIEF DESCRIPTION OF DRAWINGS

[0021] Fig. 1 It is an exploded view of the paper-based microfluidic chip of the embodiment;

[0022] Fig. 2 It is a structural schematic diagram of the hydrophobic substrate layer and the hydrophilic channel in the embodiment;

[0023] Fig. 3 It is a structural schematic diagram of the cover layer in the embodiment.

[0024] The names of the parts referred to by the respective numbers in the drawings are as follows:

[0025] 110. Hydrophobic base layer; 120. Hydrophobic plate; 1201. Connecting plate; 130. Hydrophilic channel; 1301. Enzyme reaction zone; 1302. Color development zone; 140. Covering layer; 1401. Sample dispensing port; 1402. Observation window; 150. Storage ring; 1501. Sample inlet; 160. Separator plate. Detailed Implementation

[0026] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments are merely illustrative of this utility model and are not intended to limit it.

[0027] Example

[0028] like Figs. 1-3 As shown, the paper-based microfluidic chip for rapid detection of pesticide residues has a core structure of a hydrophobic substrate layer 110, which provides support for the entire chip. In this embodiment, two sets of four hydrophobic plates 120 are integrally formed with the hydrophobic substrate layer 110 on the upper surface of the hydrophobic substrate layer 110. Waxed filter paper can be used as the constituent material of the hydrophobic substrate layer 110 and the hydrophobic plates 120. The location of the water inlet channel does not need to be waxed to enhance the capillary effect of the water inlet channel.

[0029] A hydrophilic channel 130 is formed between adjacent hydrophobic plates 120. An enzyme reaction zone 1301 and a chromogenic zone 1302 are sequentially distributed at the ends of the two hydrophilic channels 130. Different enzyme reagents are fixed in each enzyme reaction zone 1301 to detect different pesticides. A connecting plate 1201 is also provided at the ends of the two hydrophilic channels 130, located behind the chromogenic zone 1302. The connecting plate 1201 is connected to the hydrophobic plates 120 at both ends, preventing sample from flowing out of the chromogenic zone 1302.

[0030] A separator 160, with a height less than that of the hydrophobic plate 120, is provided between the enzyme reaction zone 1301 and the chromogenic zone 1302. On the upper surface of the hydrophobic plate 120, colorimetric papers with standard color levels are placed on both sides of the chromogenic zone 1302. A cover layer 140, equipped with a sample dispensing port 1401 and an observation window 1402, covers the chip. The sample dispensing port 1401 is used to dispense the sample to be tested, and the observation window 1402 corresponds to the position of the chromogenic zone 1302 for easy observation of the test results. Furthermore, a storage ring 150 made of hydrophobic material is located below the sample dispensing port 1401 on the hydrophobic substrate layer 110. Its sidewall has sample inlet holes 1501, corresponding one-to-one with each hydrophilic channel 130 and located at the same horizontal level, at a height of 0.5mm-1mm from the hydrophobic substrate layer 110, for uniform sample distribution.

[0031] The working principle of the paper-based microfluidic chip used for rapid detection of pesticide residues is as follows:

[0032] In detection, the sample is dropped from the sample inlet 1401 of the cover layer 140 and falls into the storage ring 150, which buffers the sample to prevent splashing. When the sample accumulates to a certain extent, it flows into each hydrophilic channel 130 uniformly under the action of static pressure. In the hydrophilic channel 130, the sample first enters the enzyme reaction area 1301 and reacts with the corresponding enzyme reagent to inhibit enzyme activity. Then, the sample flows over the partition plate 160 into the color development area 1302 and develops color according to the degree of enzyme activity inhibition. The color change of the color development area 1302 is compared with the standard color scale on both sides of the colorimetric paper, and the operator can visually judge the approximate content of the pesticide residue. At the same time, the three-electrode system in the color development area 1302 detects the electrochemical change to further accurately determine the content of the pesticide residue. Finally, the operator comprehensively judges the pesticide residue situation by combining the colorimetric and electrochemical detection data.

[0033] The colorimetric paper makes the reading of the detection result intuitive, and the approximate content of the pesticide residue can be quickly judged by naked eye comparison without the need for complex instruments and professional skills, which is suitable for on-site rapid detection.

[0034] The partition plate 160 precisely prolongs the residence time of the sample in the enzyme reaction area 1301, ensures sufficient enzyme reaction, reduces the interference between the two areas, and improves the detection sensitivity. The design of the storage ring 150 and the sample inlet 1501 ensures that the sample enters each hydrophilic channel 130 uniformly, avoids detection errors caused by uneven distribution, and improves the accuracy of simultaneous detection of multiple pesticide residues.

[0035] In summary, the above is only a preferred embodiment of the present embodiment, and any changes and modifications made within the scope of the patent application of the present embodiment should be included in the scope of the present embodiment.

Claims

1. A paper-based microfluidic chip structure for rapid detection of pesticide residues, characterized in that: The application relates to a hydrophobic substrate layer (110) provided with at least two hydrophobic plates (120) on the upper surface, the hydrophobic plates (120) are integrally formed with the hydrophobic substrate layer (110), a hydrophilic channel (130) is formed between two adjacent hydrophobic plates (120), an enzyme reaction area (1301) and a color developing area (1302) are sequentially arranged in the hydrophilic channel (130), a three-electrode system is arranged in the color developing area (1302), a cover layer (140) is arranged above the hydrophobic substrate layer (110), a sample adding port (1401) and an observation window (1402) are arranged on the cover layer (140), and the observation window (1402) corresponds to the position of the color developing area (1302). 2.The paper-based microfluidic chip structure for rapid detection of pesticide residues according to claim 1, characterized in that: The hydrophilic channel (130) is at least two, an enzyme reaction area (1301) and a color developing area (1302) are sequentially arranged at the end of each hydrophilic channel (130), and different enzyme reagents are fixed in each enzyme reaction area (1301). 3.The paper-based microfluidic chip structure for rapid detection of pesticide residues according to claim 2, characterized in that: A storage ring (150) is arranged below the sample adding port (1401) on the hydrophobic substrate layer (110), the storage ring (150) is made of a hydrophobic material, sample holes (1501) corresponding to the hydrophilic channels (130) are arranged on the side wall of the storage ring (150), and the sample holes (1501) are located at the same horizontal height. 4.The paper-based microfluidic chip structure for rapid detection of pesticide residues according to claim 3, characterized in that: The distance between the sample holes (1501) and the hydrophobic substrate layer (110) is 0.5mm-1mm. 5.The paper-based microfluidic chip structure for rapid detection of pesticide residues according to claim 1, characterized in that: A partition plate (160) is arranged between the enzyme reaction area (1301) and the color developing area (1302), and the height of the partition plate (160) is smaller than that of the hydrophobic plate (120). 6.The paper-based microfluidic chip structure for rapid detection of pesticide residues according to claim 1, characterized in that: Colorimetric paper is arranged on the upper end surface of the hydrophobic plate (120) and located on both sides of the color developing area (1302).

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