Programmable paper chip, preparation method thereof and microfluidic analysis chip

Abstract

The invention discloses a programmable paper chip, a preparation method thereof and a microfluidic analysis chip, and belongs to the technical field of paper-based microfluidics, the programmable chip is of a laminated structure, and sequentially comprises a lower film layer, a paper layer and an upper film layer from bottom to top; adhesive force exists between the lower film layer and the paper layer and between the upper film layer and the paper layer; the paper layer comprises a paper sheet made of a paper-based material; a flow channel boundary drawn by oily ink is arranged on the paper sheet, and an area in the flow channel boundary is a fluid channel; the fluid channel is cut off by a timing valve, and the timing valve is an area dipped with water-based ink; a sample adding hole communicated with the fluid channel on one side of the timing valve is formed in the upper film layer; wherein the oil-based ink and the water-based ink are hydrophobic ink. The preparation of the timing valve specifically comprises the following steps: pre-cutting a boundary of a preset area, and then dip-dyeing to a saturated state by using water-based ink. According to the invention, fluid control can be accurately and quickly realized at low cost without introducing substances outside a system or depending on external large-scale equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of paper-based microfluidics, and more specifically, relates to a programmable paper chip and a preparation method thereof, and a microfluidics analysis chip. Background Art

[0002] At present, microfluidics has become an alternative with great application prospects in biochemical analysis, with advantages such as rapid mass and heat transfer, high-throughput detection capability, reduced sample consumption, high automation and strong integration capabilities. At present, PDMS-based soft lithography microfluidic chips are the mainstream choice, which have the characteristics of high processing accuracy, good optical transparency and biocompatibility. However, their complex manufacturing process, high cost and clean room requirements limit their application in point-of-care testing (POCT).

[0003] In the past decade, paper-based microfluidic devices have provided a technology for point-of-care testing (POCT) using inexpensive and portable devices. As a common material, paper is easily accessible, low-cost, and easy to mass-produce. As early as the 1930s and 1940s, researchers began to explore the use of paper to construct multi-well analysis plates and fluid systems for chemical analysis. The first paper-based semi-quantitative detection diagnostic device for glucose in urine was confirmed in the 1950s, and this achievement was further developed into an immunopaper test device and commercialized; the paper-based continuous flow microfluidic (p-CMF) device was first invented by Muller and Clegg in 1949; in 2007, the Whitesides group published a research report, and the concept of paper-based microfluidic analysis devices (μPADs) for point-of-care testing (POCT) began to emerge. Paper-based microfluidic devices have gradually become the research focus of many scholars and have begun to develop rapidly. The most essential feature of the current advanced paper-based microfluidic devices is the ability to realize the programming of transporting fluid samples to the target location within a set time. Programmable paper-based microfluidic devices can automatically transport fluids in sequence to complete the entire detection process. Therefore, they can be used in a wide range of analytical applications, especially multi-step detection processes. In summary, paper-based microfluidic technology has great application potential in many aspects such as home, medical, resource-scarce and detection under extreme conditions.

[0004] The main research direction of paper-based microfluidic technology is the preparation of paper-based microfluidic devices, which includes two aspects. One is the construction of fluid channels. At present, most studies have maturely constructed fluid channels on paper-based materials by using various hydrophobic materials. Among them, the more popular hydrophobic materials are photoresist, wax, polydimethylsiloxane, etc. Channels can be constructed on paper-based materials by inkjet printing / etching, plasma / laser processing or stamping. On the other hand, how to achieve fluid control on paper-based materials is the main bottleneck for improving the practicality of paper-based materials in analytical devices. The valves in paper-based microfluidic devices are crucial for controlling fluid flow and facilitating multi-step analytical processes.

[0005] Valves in paper-based microfluidic devices can be divided into active valves and passive valves. With active valves, users can adjust fluid flow and manipulate reagent release through practical operations such as folding, sliding or rotating. Passive valves include soluble substance control valves, absorption expansion control valves and electronic control valves, which can complete fluid control without user intervention. However, the above-mentioned fluid control methods may be subject to various limitations. For example, soluble substance control valves often introduce substances outside the system, absorption expansion control valves involve complex structures, and electronic control valves require external equipment. Summary of the invention

[0006] In view of the defects of the prior art and the need for improvement, the present invention provides a programmable paper chip and a preparation method thereof, and a microfluidic analysis chip, the purpose of which is to enable a paper-based microfluidic device to achieve fluid control accurately, quickly, and at low cost without introducing extrasystem substances or relying on external large-scale equipment.

[0007] To achieve the above object, according to one aspect of the present invention, a programmable paper chip is provided, which is a laminated structure and includes, from bottom to top, a lower film layer, a paper layer and an upper film layer; there is adhesion between the lower film layer and the upper film layer and the paper layer;

[0008] The paper layer includes: a paper sheet made of a paper base material; a flow channel boundary drawn with oily ink is arranged on the paper sheet, and the area within the flow channel boundary is a fluid channel; the fluid channel is separated by a timing valve, and the timing valve is an area soaked with water-based ink;

[0009] The upper membrane layer is provided with a sample addition hole connected with the fluid channel on one side of the timing valve;

[0010] Among them, oil-based ink and water-based ink are both hydrophobic inks.

[0011] According to another aspect of the present invention, there is provided a method for preparing the programmable paper chip, comprising:

[0012] Step S1: using oily ink to draw a flow channel boundary on the upper surface of a paper sheet made of a paper-based material; the area within the flow channel boundary is the fluid channel;

[0013] Step S2: using water-based ink to impregnate a preset area in the fluid channel that blocks the fluid channel, so that a timing valve formed in the area impregnated with water-based ink blocks the fluid channel; a paper sheet with a flow channel boundary drawn and a timing valve set thereon forms a paper layer;

[0014] Step S3: After the lower surface and the upper surface of the paper layer are covered with a lower film layer and an upper film layer respectively, the lower film layer, the paper layer and the upper film layer are laminated to obtain a programmable paper chip; there is adhesion between the lower film layer and the upper film layer and the paper layer, and the upper film layer is provided with a sample addition hole connected to the fluid channel on one side of the timing valve;

[0015] Among them, oil-based ink and water-based ink are both hydrophobic inks.

[0016] Furthermore, before step S1, the method further includes: determining the preparation parameters of the programmable paper chip according to the desired delay time, so that after the fluid is added through the sample addition hole and impregnates the fluid channel on one side of the timing valve, it breaks through the timing valve and enters the fluid channel on the other side after the desired delay time; the preparation parameters include:

[0017] The fiber orientation of the paper-based material, the hydrophobicity of the water-based ink, the width of the timing valve, the number of timing valves, the lamination temperature and the lamination pressure.

[0018] Further, step S2 includes:

[0019] After the boundary of the preset area is pre-cut, the area is impregnated with water-based ink, and a timing valve is formed after the paper-based material in the area absorbs the water-based ink to a saturated state.

[0020] According to another aspect of the present invention, there is provided a microfluidic analysis chip, comprising: M fluid control modules;

[0021] Each fluid control module comprises the above-mentioned programmable paper chip provided by the present invention and a reaction zone; the reaction zone is connected to the fluid channel in the programmable paper chip, and the side where the reaction zone is connected to the fluid channel and the side where the sample addition hole is connected to the fluid channel are located on different sides of the timing valve;

[0022] Wherein, M is a preset positive integer, and when M>1, the reaction areas of the M fluid control modules are connected, and the timing valves of the programmable paper chips in the M fluid control modules have different delay times, which are used to control the order in which the reagents of the programmable paper chips in different fluid control modules are released to the reaction areas through the sample addition holes.

[0023] In some optional embodiments, M>1, and each fluid control module further includes: a shell for accommodating the programmable paper chip and the reaction zone; in the shell, one side of the upper and lower surfaces of the portion where the reaction zone is located is convex and the other side is concave, forming a connection portion between the fluid control modules; a drainage hole is provided at the center of the connection portion, and the drainage hole is filled with a paper-based material;

[0024] Before assembly, each fluid control module is relatively independent; after assembly, adjacent fluid control modules are installed by interlocking the connecting parts, and the drainage holes of all fluid control modules overlap, so that the reaction areas in each fluid control module are connected through the paper-based material filled in the drainage holes.

[0025] Furthermore, the upper and lower surfaces of the connecting portion in the fluid control module are both circular.

[0026] According to another aspect of the present invention, a high-throughput microfluidic analysis device is provided, comprising: a water absorption layer and a plurality of the above-mentioned microfluidic analysis chips, each microfluidic analysis chip is arranged around the water absorption layer, and the reaction area of ​​each microfluidic analysis chip is connected to the water absorption layer.

[0027] According to another aspect of the present invention, another microfluidic analysis chip is provided, comprising a plurality of detection modules; the detection modules comprise the above-mentioned programmable paper chip provided by the present invention and a reaction zone; the reaction zone is connected to a fluid channel in the programmable paper chip, and a side where the reaction zone is connected to the fluid channel and a side where the sample addition hole is connected to the fluid channel are located on different sides of the timing valve;

[0028] In each detection module, the sample adding hole and the fluid channel on one side connected to the sample adding hole form the sample adding area of ​​the detection module, and the sample adding areas of each detection module overlap.

[0029] In some optional embodiments, the microfluidic analysis chip provided by the present invention is used for pesticide residue detection, and includes two detection modules; the timing valves of the programmable paper-based chips in the two detection modules have the same delay time, and the reaction area of ​​one of the detection modules is provided with a pesticide residue detection test paper based on a DTNB reaction system, and the reaction area of ​​the other detection module is provided with a pesticide residue detection test paper based on a MnO2 reaction system.

[0030] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0031] (1) The programmable paper chip provided by the present invention uses oily ink to draw the flow channel boundary, and uses water-based ink to draw the timing valve. Since the oily ink is highly hydrophobic, it is not easy to separate from the upper and lower film layers under the infiltration of the fluid, and the bonding force between the upper and lower film layers is strong, so a stable flow channel boundary can be formed; since the water-based ink is less hydrophobic, it is easy to separate from the upper and lower film layers after a certain period of time under the infiltration of the fluid, so that the fluid continues to flow forward through the gap formed by the separation after a corresponding period of time, thereby realizing the timing function. The materials required for the entire programmable paper chip only include the upper and lower film layer materials, paper, and ink. The production is simple, fast and low-cost. At the same time, the timing function is accurately realized by means of the bonding force between the water-based ink and the upper and lower film layers, without the need for external equipment and without generating substances outside the system.

[0032] (2) The present invention comprehensively explores the relevant factors that affect the delay time of the timing valve and takes them as key parameters. These key parameters are determined before the programmable chip is manufactured, thereby ensuring that the delay time of the timing valve is accurately controllable.

[0033] (3) In the preferred embodiment of the method for preparing the programmable paper chip provided by the present invention, the timing valve is manufactured by pre-cutting and local impregnation, that is, the boundary of the area where the timing valve is located is pre-cut, and then the area is impregnated with water-based ink. After the paper-based material in the area absorbs the water-based ink to a saturated state, a timing valve is formed. The timing valve manufactured in this way has a smoother boundary, and the parameters and functional stability of the timing valve are significantly improved. In addition, the manufacturing method can be carried out simultaneously on multiple layers of paper to achieve batch processing, thereby improving the manufacturing efficiency of programmable paper chips.

[0034] (4) The microfluidic analysis chip provided by the present invention may include one or more fluid control modules according to the specific analysis reaction. Each fluid control module includes the programmable timing valve provided by the present invention, which can accurately control the time when the fluid enters the reaction zone, thereby realizing accurate microfluidic analysis.

[0035] (5) The microfluidic analysis chip provided by the present invention, in its preferred embodiment, includes a plurality of fluid control modules, and a shell is designed for each fluid control module. The portion of the shell where the reaction zone is located is designed with a connection portion with one side raised and one side recessed, so that the plurality of fluid control modules are assembled by three-dimensional stacking through the connection portion. After assembly, the entire microfluidic analysis chip is fan-shaped. The modular design makes the microfluidic analysis chip flexible in structure, highly scalable, and easy to prepare and assemble. In its further preferred embodiment, the upper and lower surfaces of the connection portion are both circular, so that after assembly, the fluid control module can rotate with the rotating portion as the axis, so that the angle between adjacent fluid control modules can be adjusted according to the number of fluid control modules, thereby improving space utilization.

[0036] (6) The high-throughput microfluidic analysis device provided by the present invention utilizes a water-absorbing layer to aggregate multiple microfluidic analysis chips together, so that multiple analysis reactions can be performed simultaneously, thereby improving the analysis throughput. At the same time, the water absorption effect of the water-absorbing layer can promote the flow of fluids in each microfluidic analysis chip and accelerate the analysis reaction.

[0037] (7) Another microfluidic analysis chip provided by the present invention includes multiple detection modules, each of which includes the programmable timing valve provided by the present invention, and the sample addition areas of each detection module overlap. Based on this structural design, different detection reactions can be performed on the same sample at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of a programmable paper-based chip provided by the present invention;

[0039] Figure 2 The schematic diagram of the timing valve created by using hydrophobic ink provided by the present invention; wherein (a) is a schematic diagram of the bonding between paper soaked with two types of hydrophobic inks (three colors) and tape, (b) is an actual photograph of the contact angle between paper soaked with different inks and ultrapure water, (c) is a comparison diagram of the bonding ability of the tape, (d) is a schematic diagram of the valve delay principle, and (e) is a microscopic image of paper treated with different inks and tape after adhesion under an ultra-depth of field microscope;

[0040] Figure 3 Schematic diagrams of the preparation methods respectively using direct writing methods provided by the present invention;

[0041] Figure 4 The comparison of the characteristics of the fluid under different fiber distribution directions of the paper-based materials provided by the present invention; wherein (a) is the characteristics of the fluid under longitudinal distribution, and (b) is the characteristics of the fluid under transverse distribution;

[0042] Figure 5 The factors affecting the delay time of the timing valve provided by the present invention; wherein, (a) is a schematic diagram of the principle of lamination temperature affecting valve delay, (b) is a physical diagram of paper in a lamination structure when the processing temperature is changed, (c) is a relationship diagram between void ratio and processing temperature, (d) is a relationship diagram between the delay of a 0.5 mm valve and processing temperature, (e) is a dynamic diagram of the front position of a fluid over time at different processing temperatures, and (f) is a physical diagram of the delay of a valve prepared with different inks;

[0043] Figure 6Schematic diagram of the effect of the width and number of timing valves provided by the present invention on the delay time of the timing valves; wherein, (a) is a schematic diagram of the fluid when the width and number of the valves are changed, (b) is a real picture of the fluid when the width and number of the delay valves are changed by pigment verification, (c) is a relationship diagram between the delay and the valve width (the number of repetitions of the experiment N=5), and (d) is a relationship diagram between the delay and the number of valves (N=5);

[0044] Figure 7 A schematic diagram of the preparation method using pre-cutting and local impregnation provided by the present invention;

[0045] Figure 8 Performance comparison diagrams of programmable paper chips prepared by the two preparation methods provided by the present invention; wherein, (a) is a distribution comparison diagram of the grayscale value of the timing valve color, (b) is a comparison diagram of the discrete degree of the grayscale value of the straight line color, (c) is a comparison diagram of the discrete degree of the valve width (N=8), and (d) is a comparison diagram of the discrete degree of the delay of the 0.5mm valve (N=10);

[0046] Fig. 9 Schematic diagram of the microfluidic analysis chip provided by the present invention; wherein, (a) is a schematic diagram of a microfluidic analysis chip for controlling the fluid release sequence by controlling the width of the timing valve, (b) is a schematic diagram of a microfluidic analysis chip for controlling the fluid release sequence by controlling the number of timing valves, (c) is the dynamic grayscale data of each timing valve area in (a) read by ImageJ, and (d) is the dynamic grayscale data of each timing valve area in (b) read by ImageJ;

[0047] Fig.10 A schematic diagram of another microfluidic analysis chip provided by the present invention; wherein (a) is a schematic diagram of a fluid control module, (b) is a schematic diagram of a microfluidic analysis chip integrated with two fluid control modules and capable of realizing the timed release of two reagents, and (c) is a physical diagram of the pigment verification of the chip shown in (b);

[0048] Fig.11 A schematic diagram of another microfluidic analysis chip provided by the present invention; wherein (a) is a schematic diagram of a microfluidic analysis chip integrated with three fluid control modules and capable of realizing the timed release of three reagents, (b) is an actual structural diagram of a microfluidic analysis chip integrated with three fluid control modules and capable of realizing the timed release of three reagents, and (c) is a physical diagram of the pigment verification of the chip shown in (a);

[0049] Fig.12Schematic diagram of the pesticide residue detection chip provided by the present invention; wherein, (a) is a schematic diagram of the reaction principle of the DTNB (CA) pesticide residue detection system, (b) is a test paper manufacturing process for pesticide residue detection; (c) is a schematic diagram of the detection process of the single timing valve chip for the CA system; (d) is a color enhancement picture inside and outside the chip of the CA system; (e) is a normalized color intensity data diagram inside and outside the chip of the CA system at various concentrations of pesticide (N=3);

[0050] Fig.13 A schematic diagram of another pesticide residue detection chip provided by the present invention; wherein (a) is a schematic diagram of the reaction principle of the MnO2 (CE) pesticide residue detection system, (b) is an electron microscope image of MnO2 in the CE system with and without pesticides, (c) is a schematic diagram of the detection process of the single timing valve chip for the CE system, and (d) is a schematic diagram comparing the color change differences of the CA and CE reaction systems;

[0051] Fig.14 A schematic diagram of another pesticide residue detection chip provided by the present invention;

[0052] Fig.15 The high-throughput microfluidic analysis device provided by the present invention; wherein (a) is a schematic diagram of the structure of the high-throughput microfluidic analysis device, (b) is a color enhancement picture inside and outside the CE system chip, and (c) is a normalized color intensity data diagram inside and outside the CE system chip at various concentrations of pesticides (N=3);

[0053] Fig.16 A schematic diagram of another pesticide residue detection chip provided by the present invention; wherein, (a) is a schematic diagram of the sample detection process, (b) is a physical picture of the dual-mode chip function verification, (c) is a color-enhanced image of 20 positive samples and 20 negative samples, (d) is a heat map and a bar chart based on the grayscale values ​​of the samples, (e) is a box plot of the positive and negative samples in the CA system and the CE system, (f) is the ROC curve of the CA system, the CE system, and the CA+CE dual system, and (g) is a confusion matrix reflecting the classification performance of CA and CE mode samples and comparing the consistency of the results of the CA and CE systems. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0055] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the accompanying drawings are used to distinguish similar objects but not necessarily to describe a specific order or sequence.

[0056] In order to solve the problem that the passive valve in the existing paper-based microfluidic analysis device needs to rely on external equipment or introduce substances outside the system while realizing fluid control, the present invention provides a programmable paper chip and a preparation method thereof, and a microfluidic analysis chip, wherein the chip structure is based on the discovery that the binding force between inks with different hydrophobicities and membrane materials is different and the timing valve function can be realized. On the basis of the structural design, the present invention also improves the preparation method of the relevant structure. The following is a specific description in conjunction with the embodiments.

[0057] Embodiment 1:

[0058] A programmable paper chip, such as Figure 1 As shown, it is a laminated structure, and includes a lower film layer, a paper layer and an upper film layer from bottom to top; there is adhesion between the lower film layer and the upper film layer and the paper layer;

[0059] The paper layer includes: a paper sheet made of a paper base material; a flow channel boundary drawn with oily ink is arranged on the paper sheet, and the area within the flow channel boundary is a fluid channel; the fluid channel is separated by a timing valve, and the timing valve is an area soaked with water-based ink;

[0060] The upper membrane layer is provided with a sample addition hole connected with the fluid channel on one side of the timing valve;

[0061] Among them, oil-based ink and water-based ink are both hydrophobic inks.

[0062] The following combination Figure 2 The principle of using water-based ink to make a timing valve to achieve time delay in this embodiment is described. First, different hydrophobic inks (oil-based and water-based) are selected, such as Figure 2 As shown in (a), by measuring the contact angles of the paper after being stained with different inks, it is found that the contact angles of the water-based green ink and the water-based black ink are 99° and 109° respectively, which are both smaller than the 121° after being treated with the metallic oil-based ink. Figure 2 As shown in (b) in the figure. The ability of the papers treated with ink to adhere to the tape when fully soaked was further measured. It was observed that the more hydrophobic the ink, the more difficult it was to completely separate it. The papers treated with green water-based ink and black water-based ink were separated from the tape after soaking for 30s and 60s, respectively. Therefore, green water-based ink and black ink are called layered inks. The papers treated with metallic inks are difficult to separate from the tape. Therefore, metallic oil-based inks are called non-layered inks. Figure 2 As shown in (c) in .

[0063] On the other hand, at the microscopic level, paper is composed of fibers and has a rough surface. Under the laminated structure of tape-paper-tape, the protruding parts of the fibers adhere to the tape to form adhesion points with a blocking effect, while the concave parts form flow channel cavities. When water-based ink is impregnated, the rough structure of the paper is retained and the adhesion points are broken through one by one, while it is more difficult to break through when impregnated with oil-based ink, such as Figure 2 As shown in (d) in the figure, subsequent testing of fluid flow in laminated structures with different fiber orientations also supports this view. Under the ultra-depth microscope, it was observed that the laminated structure retained a rougher surface after being stained with water-based hydrophobic marker ink. In contrast, the rough paper surface structure was retained after treatment with water-based ink, and the surface of the paper was relatively smoother and had smaller gaps after treatment with metallic oily ink. Specifically, the metallic oily marker will be deposited on the surface of the paper after drying due to its special composition, reducing the surface roughness of the paper and forming a patch with good hydrophobicity, such as Figure 2 As shown in (e) in the figure, the contact area between them and the tape is increased and their adhesion to the tape is enhanced to avoid delamination.

[0064] Therefore, in this embodiment, the fluid control function is mainly the hydrophobic ink. Since the oily ink is highly hydrophobic and has a strong bonding force with the upper and lower film layers, it is not easy to separate from the upper and lower film layers under the infiltration of the fluid, and a stable flow channel boundary can be formed. Since the water-based ink is less hydrophobic and has a weak bonding force with the upper and lower film layers, it will separate from the upper and lower film layers after a certain period of time under the infiltration of the fluid, so that the fluid continues to flow forward after a corresponding period of time, thereby realizing the timing function.

[0065] Optionally, in this embodiment, the paper-based material is specifically Kimberly Clark 34155 dust-free wiping paper, which has a relatively neat fiber distribution; the upper film layer and the lower film layer are specifically selected from transparent tape, and specifically Scotch heavy-duty transport packaging tape.

[0066] Optionally, in this embodiment, the oil-based ink used to draw the flow channel boundary is specifically a Sharpie metallic permanent marker pen, and the width of the drawn flow channel boundary is 5 mm; the water-based ink used to make the timing valve is specifically a Sharpie ultra-fine marker pen, and the width of the constructed timing valve is determined by the required delay time.

[0067] The programmable paper chip provided in this embodiment requires only tape, paper and ink, and is simple, fast and low-cost to manufacture. At the same time, the timing function is accurately realized by means of the bonding force between the aqueous ink and the upper and lower film layers, without the need for external equipment and without generating any substances outside the system.

[0068] Embodiment 2:

[0069] A method for preparing a programmable paper chip, used to prepare the programmable paper chip provided in the above embodiment 1, such as Figure 3 As shown, including:

[0070] Step S1: using oily ink to draw a flow channel boundary on the upper surface of a paper sheet made of a paper-based material; the area within the flow channel boundary is the fluid channel;

[0071] Step S2: using water-based ink to impregnate a preset area in the fluid channel that blocks the fluid channel, so that a timing valve formed in the area impregnated with water-based ink blocks the fluid channel; a paper sheet with a flow channel boundary drawn and a timing valve set thereon forms a paper layer;

[0072] Step S3: After the lower surface and the upper surface of the paper layer are covered with a lower film layer and an upper film layer respectively, the lower film layer, the paper layer and the upper film layer are laminated to obtain a programmable paper chip; there is adhesion between the lower film layer and the upper film layer and the paper layer, and the upper film layer is provided with a sample addition hole connected to the fluid channel on one side of the timing valve;

[0073] Among them, oil-based ink and water-based ink are both hydrophobic inks.

[0074] The easiest way to imprint ink is to draw directly with a marker pen, which is also called direct writing. In this embodiment, in step S1, the flow channel boundary is drawn with oily ink, and in step S2, the timing valve is made with water-based ink, which adopts the direct writing method.

[0075] Accurately controlling the delay time is the key to manufacturing a timing valve. This embodiment conducts a comprehensive study on the factors that affect the delay time of the timing valve.

[0076] First, the characteristics of the fluid were analyzed for different fiber distributions of paper. After analysis, this embodiment found that when the paper fibers are distributed longitudinally (i.e., the paper fiber distribution direction is consistent with the fluid flow direction), using inks with different hydrophobicity to impregnate is equivalent to constructing capillaries with different wall hydrophobicity in the fiber gaps, and the fluid flows through the gaps. Figure 4 When the fluid shown in (a) passes through, a short delay will be generated. When distributed horizontally (i.e., the paper fiber distribution direction is perpendicular to the fluid flow direction), the layered properties of the two types of inks can be used to print the difficult-to-layer fluid channel and the timing valve area to be layered constructed by the water-based ink on the paper respectively, and finally the upper and lower layers of tape are bonded to complete the preparation of the timing valve channel quickly and at a low cost, which can form a relatively consistent flow at the fluid front and can produce a relatively long delay, such as Figure 4 (b) in the figure. It can be seen that the fiber distribution direction of the paper will affect the flow characteristics of the fluid.

[0077] Further analyze other processing conditions and parameters that affect the timing valve delay time.

[0078] In this embodiment, the tape, paper, and tape are finally combined together by lamination. The lamination temperature is an important factor affecting the time delay of the timing valve. Different processing temperatures affect the adhesion between paper and tape, further affecting the separation ability of the ink valve and the tape, thereby affecting the delay. Increasing the processing temperature promotes the melting of the adhesive polymer of the tape, increases the contact area between the polymer and the raised part of the paper fiber (i.e., the adhesion point area), generates a stronger adhesive force, and thus affects the delay. Figure 5 As shown in (a) in the figure, this embodiment uses image processing to obtain the porosity of the paper surface under the condition of glue coating to reflect the area of ​​the adhesion point: first, the structure of the laminated paper is photographed using an ultra-depth of field microscope, and then the image is processed using ImageJ software to obtain the porosity of the paper in the laminated structure under different processing temperature conditions. This method compares the data of the porosity and the corresponding delay (valve width: 0.5mm) under different processing temperature conditions, and a good correlation is obtained: as the temperature increases, the porosity decreases and the delay increases, as shown in FIG. Figure 5 As shown in (b), (c) and (d).

[0079] This embodiment also investigates the flow rate of the fluid on the paper after processing at different temperatures. According to the Lucas-Washburn equation, it can be deduced that as the temperature increases, the density of the paper in the laminated structure also increases. Figure 5 As shown in (e) in FIG. 5 , as the processing temperature increases, the fluid front at the same time point moves further back, which means a greater flow resistance.

[0080] In addition, the timing valves prepared with inks of different hydrophobicity also have different time delays. Both black and green are water-based inks, and both can be used as raw materials for the preparation of delay valves. However, since black ink is more hydrophobic than green, it exhibits a longer time delay. When the valve width is fixed at 0.5 mm, the time delay of the valve prepared with green ink is about 150 seconds, while that of the valve prepared with black ink is about 300 seconds. Figure 5 As shown in (f) in .

[0081] This embodiment further explores the relationship between the structural parameters of the timing valve and the delay time of the timing valve. The exploration found that with a wider valve width and a larger number of valves, the delay will increase accordingly as the number of fibers covered by ink increases. Figure 6 As shown in (a) in .

[0082] The delay time of different widths (0.5mm-3.0mm) was preliminarily verified using pigments, such as Figure 6 As shown in (b) in Figure 1, it can be observed that the smaller the width of the valve, the shorter the time it takes to break through. Independent repeated tests were performed on timing valves of different widths to obtain delay data, such as Figure 6 As shown in (c) in the figure, within the test range, as the valve width increases, the valve delay also increases, and shows a good linear trend. On the other hand, a good linear relationship can be observed between the number of different valves (0-3 1mm wide timing valves) and the delay, such as Figure 6 Based on this research result, it can be seen that the controllable delay change can be achieved by changing the ink immersion width and the number of valves.

[0083] Based on the above analysis, the fiber orientation of the paper-based material, the hydrophobicity of the water-based ink, the width of the timing valve, the number of timing valves, the lamination temperature and the lamination pressure will all affect the delay time of the timing valve, and a specific quantitative relationship can be obtained through experiments. In order to accurately control the delay time of the timing valve, this embodiment also includes before step S1: determining the preparation parameters of the programmable paper chip according to the desired delay time, so that after the fluid is added through the sample addition hole and impregnates the fluid channel on one side of the timing valve, it breaks through the timing valve after the desired delay time and enters the fluid channel on the other side; the preparation parameters include:

[0084] The fiber orientation of the paper-based material, the hydrophobicity of the water-based ink, the width of the timing valve, the number of timing valves, the lamination temperature and the lamination pressure.

[0085] In this embodiment, the selection of ink and paper may refer to the description in the above embodiment 1.

[0086] Embodiment 3:

[0087] A method for preparing a programmable paper chip, used to prepare the programmable paper chip provided in the above embodiment 1, this embodiment is similar to the above embodiment 2, except that, Figure 7 As shown, in step S2 of this embodiment, when the timing valve is made using water-based ink, a direct writing method is not adopted, but a pre-cutting and local impregnation method is adopted. Specifically, after the boundary of a preset area is pre-cut, the area is impregnated with water-based ink, and the timing valve is formed after the paper-based material in the area absorbs the water-based ink to a saturated state.

[0088] This embodiment further improves the method for manufacturing the timing valve. This is because, although it is easy to manufacture the timing valve using direct writing, direct writing with a marker pen has the following limitations in actual use: (1) The width of the line is limited by the thickness of the pen tip; (2) The thickness of the line and the depth of the color of the imprint are affected by the strength and drawing speed of the manufacturer, and the functional stability of the valve is therefore limited; (3) Batch production depends on machines.

[0089] Compared with the direct writing method, the pre-cutting and local dipping method adopted in this embodiment, although the production process is slightly complicated, the pre-cutting and local dipping processes can be carried out simultaneously on multiple layers of paper to achieve batch processing, which in the direct writing method largely depends on machines such as writing robots. In terms of the minimum processing width, the pre-cutting and local dipping production methods will pre-cut and isolate the area where the timing valve is expected to be constructed, so the minimum width depends on the cutting accuracy. The accuracy of the mold made by the laser engraving machine can be as low as 100μm, which is less than the 500μm limit of the pen tip during direct writing. In addition, after the dyeing step is added, the paper absorbs the ink to saturation, and presents a consistent processing effect on all dyed areas. This can be confirmed in the gray value-position diagram of a straight line printed by the two methods at the same time, such as Figure 8 As shown in (a) and (b) in .

[0090] In addition, after pre-cutting, the timing valve boundary is smoother, while the direct writing method is affected by the drawing speed and force, resulting in a very rough boundary. We used an ultra-depth of field microscope to test the valve width data prepared by the two methods under the same conditions for verification. The results showed that the coefficient of variation of the pre-cutting and local impregnation methods was reduced by 4.82% (7.68%-2.86%) compared with the direct writing method. Figure 8 This embodiment further tests the corresponding timing valve (valve width 0.5mm) data of the two methods, and the delay coefficient of variation of the pre-cutting and local dipping methods is reduced from 74.4% to 24.1%. Figure 8 As shown in (d) in the figure, this fully demonstrates the significant improvement in the parameters and functional stability of the valve after the introduction of the pre-cutting and dipping process.

[0091] A comparison of different timing valve manufacturing methods is shown in Table 1.

[0092] Table 1 Comparison of properties between pre-cutting and direct writing

[0093]

[0094] In general, the pre-cutting and partial impregnation timing valve manufacturing method proposed in this embodiment produces a timing valve with smoother boundaries, and the parameters and functional stability of the timing valve are significantly improved. In addition, the manufacturing method can be carried out simultaneously on multiple layers of paper to achieve batch processing, thereby improving the manufacturing efficiency of programmable paper chips.

[0095] Embodiment 4:

[0096] A microfluidic analysis chip, such as Fig. 9As shown, it includes: 3 fluid control modules; each fluid control module includes the programmable paper chip and the reaction area provided in the above embodiment 1; the reaction area is connected to the fluid channel in the programmable paper chip, and the side where the reaction area is connected to the fluid channel and the side where the sample addition hole is connected to the fluid channel are located on different sides of the timing valve;

[0097] In this embodiment, the reaction areas of the three fluid control modules are connected, and the timing valves of the programmable paper chips in the three fluid control modules have different delay times, which are used to control the order in which the reagents added to the programmable paper chips in different fluid control modules through the sample addition holes are released to the reaction areas.

[0098] In some optional embodiments, such as Fig. 9 As shown in (a) of FIG. 1 , the timing valves of the programmable paper chip in the three fluid control modules achieve different delay times through different timing valve widths. From left to right, the widths of the three timing valves are 3.0 mm, 0, and 1.0 mm, respectively. In other optional embodiments, as Fig. 9 As shown in (b), the timing valves of the programmable paper chips in the three fluid control modules achieve different delay times through different numbers of timing valves. The width of a single timing valve is fixed at 1.0 mm. From left to right, the numbers of timing valves in the three modules are 2, 0, and 1, respectively.

[0099] Different colors of pigments are added to the three fluid control modules, and the grayscale value changes of the local colors in the corresponding timing valve areas are read. Fig. 9 As shown in (c) and (d) in .

[0100] according to Fig. 9 The results show that the three pigments are released sequentially, and the release order is consistent with the delay time of the timing valve.

[0101] Embodiment 5:

[0102] A microfluidic analysis chip, such as Fig.10 As shown, it includes 2 fluid control modules. In this embodiment, the structure of the fluid control module is similar to that of the fluid control module in the above-mentioned embodiment 4, except that in this embodiment, a modular structural design method is adopted, and the programmable paper chip containing the timing valve is made into a modular structure.

[0103] In this modular structural design, in addition to the programmable paper chip and the reaction area, each fluid control module also includes a housing for accommodating the programmable paper chip and the reaction area, such as Fig.10Optionally, in this embodiment, the housing is obtained by laminating PMMA sheets, each layer is designed by AutoCAD software, and then a 0.3 mm thick PMMA sheet is cut by a laser engraving machine to obtain a corresponding structure, and each layer is adhered with double-sided tape to encapsulate the paper-based device in the housing.

[0104] In order to facilitate the assembly between the fluid control modules, in the shell of the fluid control module, the upper and lower surfaces of the reaction zone are convex on one side and concave on the other side to form a connecting portion between the fluid control modules; a drainage hole is provided at the center of the connecting portion, and the drainage hole is filled with a paper-based material;

[0105] Before assembly, each fluid control module is relatively independent. By stacking the fluid control modules in three dimensions through connecting parts, the assembly of the entire microfluidic analysis chip can be realized; after assembly, adjacent fluid control modules are installed by engaging the connecting parts, and the drainage holes of all fluid control modules overlap, so that the reaction areas in each fluid control module are connected through the paper-based material filled in the drainage holes.

[0106] As a preferred embodiment, the upper and lower surfaces of the connecting portion are both circular, so that after assembly, the fluid control module can rotate with the rotating portion as the axis.

[0107] In this embodiment, one of the two fluid control modules has no timing valve, and the other includes a 1.0 mm timing valve. Fig.10 As shown in (b) of Figure 2, the process is visualized by using different pigments, such as Fig.10 As shown in (c), the results show that in the fluid control module without a timing valve, the pigment first flows to the reaction zone, and after a certain delay, the pigment in the other fluid control module is also displayed in the reaction zone, which indicates that this embodiment achieves the sequential release of the two reagents.

[0108] Embodiment 6:

[0109] A microfluidic analysis chip, such as Fig.11 As shown, this embodiment is similar to the above-mentioned embodiment 5, except that this embodiment includes three fluid control modules, and from left to right, the timing valves in the three fluid control modules are 1.0 mm timing valve, 0.5 mm timing valve and no timing valve, as shown in FIG. Fig.11 As shown in (a) and (b) in the figure, the reaction zone is visualized by using different colored pigments, and the colors of the concentric circles are the same as the pigments added to the rightmost module, the middle module, and the leftmost module from the outside to the inside, which also shows that the three reagents are released sequentially in the expected order.

[0110] It is easy to understand that in a microfluidic analysis chip, the number of fluid control modules can be set according to the types of reagents actually involved in the reaction. Especially when a modular structure design is adopted, different analysis reactions can be achieved directly by stacking fluid control modules, and the entire microfluidic analysis chip has a flexible structure and strong scalability. In addition, Fig.11 As shown, when there are multiple fluid control modules, the entire microfluidic analysis chip is fan-shaped after assembly, and the angles between the fluid control modules can be controlled by rotating the fluid control modules to adapt to different numbers of fluid control modules.

[0111] Embodiment 7:

[0112] A microfluidic analysis chip for pesticide residue detection. Fig.12 As shown, this embodiment includes only one fluid control module, and in this embodiment, the structure of the fluid control module is the same as the fluid control module in the above-mentioned embodiment 4.

[0113] Pesticide residues are a very popular detection direction in the field of food safety. The current mainstream detection method is the enzyme inhibition method, which uses the inhibitory effect of organophosphorus pesticides on cholinesterase to reduce the activity of cholinesterase in promoting subsequent reactions. The principle of the common kits on the market is to use the thiol group in thiocholine (TCh) generated by thioacetylcholine (ATCh) under the catalysis of cholinesterase to react specifically with 5,5-dithio-2,2-dinitrobenzoic acid (DTNB) to generate yellow 5-mercapto-2-nitrobenzoic acid (TNB). When the pesticide content increases, the activity of the enzyme is more strongly inhibited, and the final yellow substance produced is also reduced accordingly. The lighter the color, the better. Fig.12 As shown in (a) in the figure, the chip based on this detection principle can be called a color attenuation system (CA).

[0114] This embodiment is a color reduction system. To achieve pesticide residue detection, in this embodiment, the reaction area of ​​the fluid control module is provided with a DTNB test paper for detecting pesticide residues. Fig.12 As shown in (b), in this embodiment, the preparation method of the DTNB test paper includes:

[0115] A filter paper with a diameter of 0.5 mm was used as the test paper substrate, 1 μL of ATCh solution and 1 μL of DTNB solution were added to the substrate and dried at 4°C to prepare a DTNB reaction system pesticide residue detection test paper.

[0116] This embodiment can effectively control the reaction process by combining a programmable paper chip with a timing valve and a DTNB test paper. Based on this reaction system, the test paper is combined with a single valve chip to produce a complete pesticide residue detection device. The single chip area is smaller than a thumb, and more than 10 samples can be detected in an area the size of a bank card. Different concentrations of phoxim solution are added to the programmable paper chip through the sample addition hole. At the same time, a corresponding control experiment is performed outside the chip, and images are uniformly taken at 25 minutes. Fig.12 As shown in (c) in the figure, the final on-chip and off-chip detection results are as follows Fig.12 As shown in (d) in the figure, it can be seen from the result that the experimental trends on the chip and off the chip are basically the same, which shows the effectiveness of this embodiment. The gray value is further measured and normalized using ImageJ software, and the data graph of the on-chip and off-chip results is drawn, and the concentration with a significant difference between the normalized intensity and the 0 value is taken as the detection sensitivity, as shown in FIG. Fig.12 As shown in (e) in the figure, it can be seen that the detection sensitivity on the chip is 6.45×10 -2 In addition, the color change degree on the chip is greater than that outside the chip at 0–12.9 μmol / mL, which reflects the higher sensitivity of this embodiment in the low concentration range.

[0117] Embodiment 8:

[0118] A microfluidic analysis chip for pesticide residue detection, such as Fig.13 This embodiment is similar to the above-mentioned embodiment 7, except that the detection test strips arranged in the reaction area in this embodiment are different from those in the embodiment 7.

[0119] Another reaction system for pesticide residue detection is based on MnO2 nanoparticles, which can undergo redox reactions with (thio)choline and are also widely used. Among them, 3,3',5,5'-tetramethylbenzidine (TMB) and MnO2 generate oxidized TMB, which is purple and is used for colorimetric detection of pesticide residues. When the pesticide content increases, the activity of cholinesterase is inhibited, and the generated thiocholine decreases, resulting in a decrease in the amount of manganese dioxide that ultimately participates in the reaction. The larger the excess, the darker the purple color. Fig.13 As shown in (a) and (b) in FIG. 5 , this reaction system is called a color enhancement system (CE). The change trend of this reaction system is exactly opposite to that of the above-mentioned color enhancement system.

[0120] This embodiment is a color enhancement system. To detect pesticide residues, in this embodiment, the reaction area of ​​the fluid control module is provided with a MnO2 test paper for detecting pesticide residues. Fig.12 As shown in (b), in this embodiment, the preparation method of MnO2 test paper includes:

[0121] A filter paper with a diameter of 5 mm was used as the test paper substrate. 5 μL of 0.2 mg / mL MnO2 solution was added to the substrate and dried at 60°C. Then 2 μL of ATCh solution was added and dried at 4°C to prepare the MnO2 test paper.

[0122] This embodiment can effectively control the reaction process by combining a programmable paper chip with a timing valve and a MnO2 test paper. Its effectiveness can be verified in preliminary single-channel chip testing, such as Fig.13 As shown in (c) in the figure, the color enhancement system is colorless in the absence of pesticides and increases in color in the presence of pesticides. Compared with the subtractive system, it is more conducive to naked eye recognition, such as Fig.13 As shown in (d) in .

[0123] Embodiment 9:

[0124] A microfluidic analysis chip for pesticide residue detection, such as Fig.14 As shown. This embodiment is also a detection and analysis chip based on color enhancement reaction, and its detection principle is the same as that of the above-mentioned embodiment 8. Structurally, the difference between this embodiment and the above-mentioned embodiment 8 is that the present embodiment includes two fluid control modules, the reaction areas of the two fluid control modules are connected, and MnO2 test paper is set in the reaction area. Among the two fluid reaction modules, one is used to add mixed reaction reagents, and the delay time of its timing valve is 5 minutes, during which the enzyme inhibition process is completed; the other is used to add TMB, and the delay time of its timing valve is 15 minutes (enzyme inhibition time 5 minutes + manganese dioxide reaction time 10 minutes). In this embodiment, the timed addition of TMB is completed by adding a timing valve to achieve a more complete sample-in-result-out detection.

[0125] During the test, the test solution is mixed with the enzyme solution and incubated for 5 minutes before flowing into the reaction zone to react with iodinated thioacetylcholine and manganese dioxide. After about 10 minutes of reaction, the delay valve of the other channel opens and TMB flows into the reaction zone to complete the color enhancement.

[0126] Embodiment 10:

[0127] A high-throughput microfluidic analysis device, such as Fig.15 As shown, including:

[0128] The water absorption layer and the plurality of microfluidic analysis chips provided in the above-mentioned embodiment 9, each microfluidic analysis chip is arranged around the water absorption layer, and the reaction area of ​​each microfluidic analysis chip is connected to the water absorption layer.

[0129] This embodiment utilizes a water-absorbing layer to aggregate multiple microfluidic analysis chips together, so that multiple analysis reactions can be performed simultaneously, the analysis throughput can be improved, and the chip processing efficiency can be optimized. At the same time, the water absorption effect of the water-absorbing layer can promote the flow of fluids in each microfluidic analysis chip and accelerate the analysis reaction.

[0130] Since the structure of the dual-valve chip in the above-mentioned embodiment 9 is relatively complex, the two-dimensional preparation method process is very complicated. In order to optimize the chip processing efficiency and realize high-throughput parallel detection, this embodiment proposes a disc-type paper chip, in which structures with different functions are stacked in a three-dimensional manner to contact each other. Finally, the entire chip includes a three-dimensionally stacked drainage layer, a color enhancement layer and a water absorption layer. In each microfluidic analysis chip, the two fluid control modules of the microfluidic analysis chip are located in the channel layer (below the drainage layer), and the reaction area of ​​the microfluidic analysis chip is located in the color enhancement layer (above the drainage layer), thereby realizing stacking on the three-dimensional level. The stacked structure is supported by a PMMA plate engraved with a specific pattern, such as Fig.15 Finally, seven concentrations ranging from 0 to 129 μM were used for on-chip and off-chip comparative tests. The visual test results are shown in Fig.15 As shown in (b) in FIG. 1 , the detection sensitivity on the chip and outside the chip is calculated to be 0.645 μM, which is basically consistent. At this concentration, the result on the chip shows a greater color change, which is more conducive to user identification, such as Fig.15 As shown in (c) in .

[0131] It is easy to understand that, except for the microfluidic analysis chip in Example 9, other microfluidic analysis chips composed of a single or multiple fluid control modules can be integrated into a high-channel microfluidic analysis device in the manner of this embodiment, and will not be listed one by one here.

[0132] Embodiment 11:

[0133] A microfluidic analysis chip, such as Fig.16 As shown, it includes multiple detection modules; the detection module includes the programmable paper chip and the reaction area provided in the above embodiment 1; the reaction area is connected to the fluid channel in the programmable paper chip, and the side where the reaction area is connected to the fluid channel and the side where the sample addition hole is connected to the fluid channel are located on different sides of the timing valve;

[0134] In each detection module, the sample adding hole and the fluid channel on one side connected to the sample adding hole form the sample adding area of ​​the detection module, and the sample adding areas of each detection module overlap.

[0135] This embodiment can simultaneously perform different detection reactions on the same reagent. Specifically, this embodiment is used for pesticide residue detection and specifically includes two detection modules, such as Fig.16As shown in (a) and (b), the two detection modules are a subtractive color system and an enhanced color system, respectively, thereby realizing a dual-system mode detection chip. Accordingly, in this embodiment, the programmable timing valves in the two detection modules have the same delay time, and the two timing valves are symmetrically arranged about the sample addition area, and the reaction area of ​​one detection module is provided with a pesticide residue detection test paper based on a DTNB reaction system (subtractive color), and the reaction area of ​​the other detection module is provided with a pesticide residue detection test paper based on a MnO2 reaction system (enhanced color).

[0136] In order to verify the performance of the microfluidic analysis chip provided in this embodiment, in this embodiment, a sticker with a 1cm×1cm square hole is attached to the surface of a clean apple to construct a sampling area, and 20μL of high-concentration pesticide is dripped into the area. After it is completely dried, 200μL of eluent is used to blow repeatedly three times in the hole, and the eluent after blowing is recovered to obtain a positive sample solution. The untreated area is extracted according to the above method to obtain a negative sample solution. The dual-mode chip is obtained by combining a paper-based chip with two symmetrically distributed valves and two color enhancement test papers. During the test, 36μL of a mixed solution of sample and enzyme (5:1) is added to the sample wells of the two detection modules. Finally, when the reaction is completed, the color enhancement area data can be obtained by taking a photo with a smartphone (2μLTMB needs to be added to the manganese dioxide system). Afterwards, positive and negative group samples are prepared by the method of manual labeling and sampling, such as Fig.16 As shown in (a) in .

[0137] When the sample solution is added, the fluid can reach the two timing valves at the same time, and after the same delay, it will synchronously enter the color enhancement area of ​​the two detection systems to obtain the detection results of the two systems, such as Fig.16 As shown in (b) in .

[0138] The dual-system mode detection chip provided in this embodiment was used to test 20 positive samples and 20 negative samples. The color enhancement area data were obtained by taking photos with a smartphone at 25 minutes. Fig.16 As shown in (c) in the figure, the color data of the two color enhancement test strips are read as features for analysis. Data graphs such as heat maps and bar graphs based on the grayscale values ​​of the sample color enhancement well reflect the color enhancement differences between positive and negative samples, such as Fig.16 As shown in (d) and (e) in .

[0139] The ROC (Receiver Operating Characteristic Curve) curves were further drawn for the data of the color reduction (CA) system and the color enhancement (CE) system, and their AUC (Area Under Curve) values ​​were 0.99 and 1.00, respectively. Fig.16As shown in (f) in the figure, it shows the good classification characteristics of the data. Specifically, for a total of 40 samples, the detection results of the two systems showed 100% sensitivity and higher than 95% and 97.5% specificity and accuracy. Only one sample showed a difference in the detection results of the two systems, as shown in Figure 1. Fig.16 As shown in (g), this shows the consistency of the test results. Through the mutual verification of the two systems, the test personnel can be reminded in time to conduct further test verification on the samples with different results to reduce the risk of wrong test results.

[0140] It is easy to understand that in some other embodiments of the present invention, other numbers and types of detection modules can be set according to the needs of analysis and detection to achieve analysis of different properties of the same reagent, or to use different means to perform comparative analysis on the same property of the same reagent.

[0141] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A programmable paper chip, characterized in that: It is a laminated structure, and includes a lower film layer, a paper layer and an upper film layer from bottom to top; there is adhesion between the lower film layer and the upper film layer and the paper layer; The paper layer comprises: a paper sheet made of a paper-based material; a flow channel boundary drawn with oil-based ink is arranged on the paper sheet, and the area within the flow channel boundary is a fluid channel; the fluid channel is blocked by a timing valve, and the timing valve is an area soaked with water-based ink; The upper film layer is provided with a sample addition hole connected to the fluid channel on one side of the timing valve; Wherein, the oil-based ink and the water-based ink are both hydrophobic inks.

2. The method for preparing the programmable paper chip according to claim 1, characterized in that: include: Step S1: using oily ink to draw a flow channel boundary on the upper surface of a paper sheet made of a paper-based material; the area within the flow channel boundary is a fluid channel; Step S2: using water-based ink to impregnate a preset area in the fluid channel that isolates the fluid channel, so that a timing valve formed in the area impregnated with water-based ink isolates the fluid channel; a paper sheet with a flow channel boundary drawn and a timing valve set thereon forms a paper layer; Step S3: After the lower surface and upper surface of the paper layer are covered with a lower film layer and an upper film layer respectively, the lower film layer, the paper layer and the upper film layer are laminated to obtain the programmable paper chip; there is adhesion between the lower film layer and the upper film layer and the paper layer, and the upper film layer is provided with a sample addition hole connected to the fluid channel on one side of the timing valve; Wherein, the oil-based ink and the water-based ink are both hydrophobic inks.

3. The preparation method according to claim 2, characterized in that: Before step S1, the method further includes: determining the preparation parameters of the programmable paper chip according to the desired delay time, so that after the fluid is added through the sample adding hole and impregnates the fluid channel on one side of the timing valve, it breaks through the timing valve and enters the fluid channel on the other side after the desired delay time; the preparation parameters include: The fiber orientation of the paper-based material, the hydrophobicity of the aqueous ink, the width of the timing valve, the number of the timing valves, the lamination temperature and the lamination pressure.

4. The preparation method according to claim 3, characterized in that: The step S2 comprises: After the boundary of the preset area is pre-cut, the area is impregnated with the water-based ink, and after the paper-based material in the area absorbs the water-based ink to a saturated state, the timing valve is formed.

5. A microfluidic analysis chip, characterized in that: include: M fluid control modules; Each of the fluid control modules comprises the programmable paper chip according to claim 1 and a reaction zone; the reaction zone is connected to the fluid channel in the programmable paper chip, and the side where the reaction zone is connected to the fluid channel and the side where the sample loading hole is connected to the fluid channel are located on different sides of the timing valve; Wherein, M is a preset positive integer, and when M>1, the reaction areas of the M fluid control modules are connected, and the timing valves of the programmable paper chips in the M fluid control modules have different delay times, which are used to control the order in which the reagents of the programmable paper chips in different fluid control modules are released to the reaction areas through the sample addition holes.

6. The microfluidic analysis chip according to claim 5, characterized in that: M>1, and each of the fluid control modules further comprises: a shell for accommodating the programmable paper chip and the reaction zone; in the shell, one side of the upper and lower surfaces of the reaction zone is convex and the other side is concave, forming a connecting portion between the fluid control modules; a drainage hole is provided at the center of the connecting portion, and the drainage hole is filled with a paper-based material; After assembly, adjacent fluid control modules are installed by engaging the connecting parts, and the drainage holes of all fluid control modules overlap, so that the reaction areas in each fluid control module are connected through the paper-based material filled in the drainage holes.

7. The microfluidic analysis chip according to claim 6, characterized in that: The upper and lower surfaces of the connecting portion in the fluid control module are both circular.

8. A high-throughput microfluidic analysis device, characterized in that: include: A water absorption layer and a plurality of microfluidic analysis chips according to any one of claims 5 to 7, wherein each microfluidic analysis chip is arranged around the water absorption layer, and the reaction areas of each microfluidic analysis chip are connected to the water absorption layer.

9. A microfluidic analysis chip, characterized in that: The invention comprises a plurality of detection modules; the detection modules comprise the programmable paper chip and a reaction zone as claimed in claim 1; the reaction zone is connected to a fluid channel in the programmable paper chip, and a side where the reaction zone is connected to the fluid channel and a side where the sample addition hole is connected to the fluid channel are located on different sides of the timing valve; In each detection module, the sample adding hole and the fluid channel on one side connected to the sample adding hole form the sample adding area of ​​the detection module, and the sample adding areas of each detection module overlap.

10. The microfluidic analysis chip according to claim 9, characterized in that: Used for pesticide residue detection, it includes two detection modules; the timing valves of the programmable paper-based chips in the two detection modules have the same delay time, and the reaction area of ​​one detection module is set with a pesticide residue detection test paper based on a DTNB reaction system, and the reaction area of ​​the other detection module is set with a pesticide residue detection test paper based on a MnO2 reaction system.

Images