On-demand blood glucose monitoring system

Abstract

The invention provides an on-demand blood glucose monitoring system which comprises an indwelling needle connector, a valve, a detection / controller, a micro-fluidic chip and a waste liquid pool, the indwelling needle connector is connected with the valve through a catheter, the valve is connected with the control end of the detection / controller through a wire, the micro-fluidic chip is composed of an interface layer, a detection layer and a sensor layer, and the interface layer is connected with the detection / controller through a wire. A working electrode and a reference / auxiliary electrode in the micro-fluidic chip are provided with hydrophilic layers formed by mixing dopamine and methacryloylethyl sulfobetaine, so that the problem that blood is adhered to the surfaces of the electrodes and cannot be completely discharged out of a detection cavity after each detection is solved; meanwhile, the enzyme coating obtained by mixing the chitosan, the glacial acetic acid, the glycerol and the glucose oxidase has a cross-linked network of the chitosan and the glucose oxidase, so that the glucose oxidase can be better fixed on the surface of the electrode, and the problem that the glucose oxidase falls off due to blood flow is reduced; therefore, the detection service life and the detection precision of the sensor are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of blood glucose detection devices, and particularly relates to an on-demand blood glucose monitoring system. BACKGROUND

[0002] Diabetes is one of the most common chronic diseases in the world, and both high and low blood sugar can have very adverse effects on the body and even be life-threatening. Clinically, patients in emergency, critical and severe conditions need to collect blood samples multiple times for blood biochemical index detection, so as to provide a basis for timely and accurate judgment of the condition for clinicians, and therefore, blood glucose monitoring and detection of patients is of great significance for the diagnosis and treatment of diabetes.

[0003] Common blood biochemical index detection methods mainly include end blood sampling monitoring and venous blood monitoring, however, both methods have certain limitations in actual operation, repeated blood sampling increases the workload of medical staff, and the blood sampling and testing process consumes relatively long time, which may affect the judgment of the physiological condition of the patient by the doctor.

[0004] Venous catheterization is a kind of venipuncture applied in clinical practice in recent years, which uses a venous indwelling needle to puncture and collect venous blood samples, can quickly obtain samples, save time for rescue or treatment, avoid local injury complications caused by repeated puncture, and thus affect the diagnosis and treatment of diseases, and can also reduce the workload of medical staff. Under the premise of collecting blood samples by an indwelling needle, an on-demand blood glucose monitoring system is needed, which can detect accurate blood glucose indicators by detecting a small amount of blood according to the actual needs of the doctor during treatment, and the time required to obtain the detection results is short, and the whole process is easy and fast to operate. SUMMARY

[0005] The technical problem to be solved by the present application is to provide an on-demand blood glucose monitoring system.

[0006] The technical scheme adopted by the present application is:

[0007] An on-demand blood glucose monitoring system, comprising an indwelling needle interface 1, a valve 2, a detection / controller 3, a microfluidic chip 4 and a waste pool 5, the indwelling needle interface 1 is connected with the valve 2 through a conduit, the valve 2 is connected with the control end of the detection / controller 3 through a wire, the microfluidic chip 4 is composed of an interface layer, a detection layer and a sensor layer, wherein,

[0008] The interface layer comprises an interface layer body 6, and a sample inlet 7 and a sample outlet 8 connected with a conduit joint with external threads, and an electrochemical sensor working electrode interface 9 and an electrochemical sensor reference / auxiliary electrode interface 10 connected with the detection end of the detector / controller 3 through wires respectively; the valve 2 is connected with the sample inlet 7 of the microfluidic chip 4, and the sample outlet 8 in the microfluidic chip 4 is connected with the waste liquid pool 5 through a conduit;

[0009] The detection layer comprises a detection layer body 11, and a liquid inlet hole 12 and a liquid outlet hole 13 penetrating through the detection layer body 11 and connected with a flow channel 14, the flow channel 14 and a detection cavity 15 connected with each other and arranged on the bottom of the detection layer, and the surface of which is treated by polyvinyl alcohol hydrophilic modification, and an electrochemical sensor working electrode hole 16 and an electrochemical sensor reference / auxiliary electrode hole 17, the electrochemical sensor working electrode hole 16 is aligned with the electrochemical sensor working electrode interface 9, and the electrochemical sensor reference / auxiliary electrode hole 17 is aligned with the electrochemical sensor reference / auxiliary electrode interface 10;

[0010] The sensor layer comprises a sensor layer body 18, and a double electrode system attached to the surface of the sensor layer body 18 by screen printing, the double electrode system comprises a working electrode strip-shaped wire 19, a reference / auxiliary electrode strip-shaped wire 20, a working electrode 21 and a reference / auxiliary electrode 22, the working electrode 21 is connected with the working electrode strip-shaped wire 19, and finally connected with the detector / controller 3 through the electrochemical sensor working electrode interface 9 and the electrochemical sensor working electrode hole 16; the reference / auxiliary electrode 22 is connected with the reference / auxiliary electrode strip-shaped wire 20, and finally connected with the detector / controller 3 through the electrochemical sensor reference / auxiliary electrode hole 17 and the electrochemical sensor reference / auxiliary electrode interface 10.

[0011] Preferably, the on-demand blood glucose monitoring system can further replace the double electrode system with a three-electrode system, the three-electrode system comprises a working electrode strip-shaped wire, a reference electrode strip-shaped wire, an auxiliary electrode strip-shaped wire, a working electrode, a reference electrode and an auxiliary electrode, the working electrode is connected with the working electrode strip-shaped wire and connected with the electrochemical sensor working electrode hole, the reference electrode is connected with the reference electrode strip-shaped wire and connected with the electrochemical sensor reference electrode hole, and the auxiliary electrode is connected with the auxiliary electrode strip-shaped wire and connected with the electrochemical sensor auxiliary electrode hole; the three strip-shaped wires are connected with the external detector / controller through the corresponding holes and interfaces respectively, forming an independent three-electrode channel; the electrochemical sensor reference / auxiliary electrode hole 17 is replaced with an electrochemical sensor reference electrode hole and an electrochemical sensor auxiliary electrode hole, and is also arranged on the detection layer body 11.

[0012] Preferably, the above-mentioned on-demand blood glucose monitoring system, the interface structure of the sample inlet 7, the sample outlet 8, the valve 2 and the waste pool 5 is the same, which includes an interface shell 6', a catheter joint shell 7', an interface gasket 8' and a catheter 9', the interface shell 6' is threadedly connected with the catheter joint shell 7', the interface gasket 8' is arranged at the bottom of the interface shell 6', the catheter joint shell 7' is sleeved on the outer periphery of the catheter 9', the catheter 9' passes through the center hole of the interface gasket 8' and is fixed with the interface shell 6' through the catheter joint shell 7'.

[0013] The shape and thickness of the above-mentioned interface layer, detection layer and sensor layer can be changed arbitrarily to meet the requirements of different application environments. Similarly, the shape and thickness of the above-mentioned working electrode 21 and reference / auxiliary electrode 22 can also be changed to match the size of the interface layer, detection layer and sensor layer to better cope with different detection environments.

[0014] Preferably, the above-mentioned on-demand blood glucose monitoring system, the working electrode 21 is arranged from bottom to top in a layered and stacked manner with a conductive layer 1', a working electrode layer 2', a hydrophilic layer 4' and an enzyme coating layer 5'.

[0015] Preferably, the above-mentioned on-demand blood glucose monitoring system, the reference / auxiliary electrode 22 is arranged from bottom to top in a layered and stacked manner with a conductive layer 1', a reference / auxiliary electrode layer 3' and a hydrophilic layer 4'.

[0016] Preferably, the above-mentioned on-demand blood glucose monitoring system, the material of the working electrode strip conductor 19 and the reference / auxiliary electrode strip conductor 20 is gold, silver, copper or platinum.

[0017] Preferably, the above-mentioned on-demand blood glucose monitoring system, the material of the conductive layer 1' is gold, silver, copper or platinum, the material of the working electrode layer 2' is carbon, and the material of the reference / auxiliary electrode layer 3' is silver / silver chloride. This material configuration makes the electrode have good conductivity and does not react with ions in the solution, so the consistency of the detection result is good.

[0018] Preferably, the above-mentioned on-demand blood glucose monitoring system, the material of the hydrophilic layer 4' is a thin film formed by mixing dopamine and methacryloyl ethyl sulfobetaine, wherein the concentration of dopamine is 10 mg / dL-30 mg / dL, and the concentration of methacryloyl ethyl sulfobetaine is 20 mg / dL-50 mg / dL. This material configuration can make the working electrode 21 and the reference / auxiliary electrode 22 have good anti-blood adsorption function.

[0019] Preferably, in the on-demand blood glucose monitoring system, the enzyme coating 5' is prepared by adding 0.1-0.2 g of chitosan, 30-60 uL of 0.3% glacial acetic acid and 1-2 mL of 10% glycerol into 10-20 mL of deionized water, mixing and stirring, then adding 0.1-0.2 mL of platinum nanoparticles, and mixing and stirring 10-100 mg / mL of glucose oxidase and the above solution at a volume ratio of 1-3:1 to obtain a glucose oxidase and chitosan mixed solution, and then dropping 2-5 uL of the mixed solution onto the surface of the working electrode layer 2' and refrigerating to obtain the enzyme coating 5'.

[0020] Preferably, in the on-demand blood glucose monitoring system, the enzyme coating 5' is prepared by adding 0.1-0.2 g of chitosan, 30-60 uL of 0.3% glacial acetic acid and 1-2 mL of 10% glycerol into 10-20 mL of deionized water, mixing and stirring, then adding 0.1-0.2 mL of platinum nanoparticles, and mixing and stirring 10-100 mg / mL of glucose oxidase and the above solution at a volume ratio of 1-3:1 to obtain a glucose oxidase and chitosan mixed solution, and then dropping 2-5 uL of the mixed solution onto the surface of the working electrode layer 2' and refrigerating to obtain the enzyme coating 5'.

[0021] Preferably, in the on-demand blood glucose monitoring system, the detection cavity 15 is circular or elliptical in shape.

[0022] Preferably, in the on-demand blood glucose monitoring system, the flow channel 14 and the detection cavity 15 are modified by polyvinyl alcohol solution hydrophilization, and the polyvinyl alcohol solution is obtained by mixing and stirring polyvinyl alcohol and ultrapure water, and the mass ratio of polyvinyl alcohol to ultrapure water is 1:70-120.

[0023] Preferably, in the on-demand blood glucose monitoring system, the working electrode 21 is circular, elliptical or rectangular in shape, and the reference / auxiliary electrode 22 is a circular ring with an angle of not less than 120°.

[0024] Preferably, in the on-demand blood glucose monitoring system, the interface layer 6 and the sensor layer 18 are made of glass or acrylic.

[0025] Preferably, in the on-demand blood glucose monitoring system, the detection layer 11 is made of polydimethylsiloxane, polydimethylsiloxane-polyethylene glycol and polydimethylsiloxane crosslinking agent, which are mixed, heated and cured, and the mass of polydimethylsiloxane is 8-12 times that of polydimethylsiloxane-polyethylene glycol and polydimethylsiloxane crosslinking agent, and the mass ratio of polydimethylsiloxane-polyethylene glycol to polydimethylsiloxane crosslinking agent is 1-2:2-1.

[0026] The beneficial effects of the present application are:

[0027] The on-demand blood glucose monitoring system, the user draws blood from the indwelling needle interface, and after the valve is turned on by the detection / controller to inject the blood into the microfluidic chip and the entire detection cavity is automatically filled, the current data is obtained by the detection / controller, the blood glucose detection is realized, after the detection is completed, the liquid in the microfluidic chip is transferred to the waste pool, and the next detection is waited. The system building process is simple, the detection process time is short, the system operation is simple, the device manufacturing cost is low, in the microfluidic chip, the working electrode and the reference / auxiliary electrode have a hydrophilic layer formed by mixing dopamine and methacryloyl ethyl sulfobetaine, which solves the problem that the blood adheres to the electrode surface and cannot be completely discharged from the detection cavity after each detection. At the same time, the enzyme coating obtained by mixing chitosan, glacial acetic acid, glycerol and glucose oxidase has a cross-linked network of chitosan and glucose oxidase, so that the glucose oxidase can be better fixed on the electrode surface, reducing the problem of glucose oxidase falling caused by blood flow, thereby improving the detection life and detection accuracy of the sensor. By combining with the clinical indwelling needle, the real-time blood glucose data is detected by extracting a small amount of blood, which greatly reduces the waiting time of blood glucose detection, and can be used to realize rapid, accurate and wide detection range of whole blood glucose real-time detection. Specifically:

[0028] 1. The system realizes on-demand blood glucose detection, and according to the actual needs of doctors or patients, accurate blood glucose indicators are quickly detected by a small amount of blood, which greatly reduces the detection waiting time; for some patients who need to repeatedly measure blood, this microfluidic chip combined with the indwelling needle can repeatedly and quickly detect blood glucose by a small amount of blood drawn by the indwelling needle without pulling out the indwelling needle.

[0029] 2. The whole on-demand blood glucose monitoring system is convenient and fast to build, meets the requirements of ICU intensive care room surgery and emergency, and for different patients to measure blood glucose, only the microfluidic chip needs to be replaced in the whole system, and the cost of the microfluidic chip is very low. It can be used as a rapid blood glucose detection method to reduce the pressure of hospital blood test medical staff.

[0030] 3. The hydrophilic layer formed by mixing dopamine and methacryloyl ethyl sulfobetaine on the electrode surface effectively solves the key problem encountered in the whole blood measurement of the microfluidic chip, that is, the blood adheres to the electrode surface after each detection and cannot be completely discharged from the detection cavity.

[0031] 4. By doping polydimethylsiloxane-polyethylene glycol in the polydimethylsiloxane material of the detection layer body and modifying polyvinyl alcohol on the surface, the surface hydrophilicity is greatly improved, thereby improving the uniformity of blood flow in the microfluidic chip, avoiding the generation of cavities, and improving the accuracy and consistency of each blood detection.

[0032] 5. By forming a cross-linked network between glucose oxidase and chitosan, glucose oxidase can be better immobilized on the electrode surface, reducing leakage of glucose oxidase from the electrode surface when it is introduced into the blood, thereby improving the catalytic rate of the sensor. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the on-demand blood glucose monitoring system described in this invention;

[0034] Figure 2 This is a schematic diagram of the microfluidic chip in the on-demand blood glucose monitoring system described in this invention;

[0035] Figure 3 This is a schematic diagram of the layer structure of the reference electrode and the working electrode described in this invention;

[0036] Figure 4 This is a schematic diagram showing the connection between the inlet, outlet, and conduit connector of the present invention.

[0037] In the diagram: 1-Indwelling needle interface, 2-Valve, 3-Detector / controller, 4-Microfluidic chip, 5-Waste liquid tank, 6-Interface layer, 7-Inlet, 8-Outlet, 9-Electrochemical sensor working electrode interface, 10-Electrochemical sensor reference / auxiliary electrode interface, 11-Detection layer, 12-Inlet hole, 13-Outlet hole, 14-Flow channel, 15-Detection chamber, 16-Electrochemical sensor working electrode hole, 17-Electrochemical sensor reference / auxiliary electrode hole, 18-Sensor layer, 19-Working electrode strip wire, 20-Reference / auxiliary electrode strip wire, 21-Working electrode, 22-Reference / auxiliary electrode, 1'-Conductive layer, 2'-Working electrode layer, 3'-Reference / auxiliary electrode layer, 4'-Hydrophilic layer, 5'-Enzyme coating, 6'-Interface shell, 7'-Conduit connector shell, 8'-Interface gasket, 9'-Conduit. Detailed Implementation

[0038] To further illustrate the present invention, the technical solution will be clearly and completely described in conjunction with the following embodiments.

[0039] Example 1

[0040] like Figures 1-4 As shown, the on-demand blood glucose monitoring system includes an indwelling needle interface 1, a valve 2, a detector / controller 3, a microfluidic chip 4, and a waste liquid tank 5. The indwelling needle interface 1 is connected to the valve 2 via a conduit, and the valve 2 is connected to the control terminal of the detector / controller 3 via a wire. The microfluidic chip 4 consists of an interface layer, a detection layer, and a sensor layer.

[0041] The interface layer includes an interface layer body 6 and a sample inlet 7, a sample outlet 8, an electrochemical sensor working electrode interface 9 and an electrochemical sensor reference / auxiliary electrode interface 10 arranged on the interface layer body 6, the material of the interface layer body 6 is glass or acrylic, the sample inlet 7 is connected with a conduit joint with external threads and connected to the interface of the valve 2, the sample outlet 8 is connected with a conduit joint with external threads and connected to the interface of the waste pool 5 through a conduit, the interfaces of the sample inlet 7, the sample outlet 8, the valve 2 and the waste pool 5 are the same structure and all include an interface housing 6', a conduit joint housing 7', an interface gasket 8' and a conduit 9', the interface housing 6' is threadedly connected with the conduit joint housing 7', the interface gasket 8' is arranged at the bottom of the interface housing 6', the conduit joint housing 7' is sleeved on the outer periphery of the conduit 9' led out by the retention needle, the conduit 9' passes through the central hole of the interface gasket 8' and is fixed with the interface housing 6' through the conduit joint housing 7', the electrochemical sensor working electrode interface 9 and the electrochemical sensor reference / auxiliary electrode interface 10 are respectively connected with the electrode male line of the detection end of the detector / controller 3;

[0042] The detection layer includes a detection layer body 11 and a liquid inlet hole 12, a liquid outlet hole 13, a flow channel 14, a detection cavity 15, an electrochemical sensor working electrode hole 16 and an electrochemical sensor reference / auxiliary electrode hole 17 arranged on the detection layer body 11, the detection layer body 11 is obtained by mixing and heating curing 50g of polydimethylsiloxane, 5g of polydimethylsiloxane-polyethylene glycol and 5g of polydimethylsiloxane crosslinking agent, and pouring the mixed material into a laser-engraved acrylic mold to obtain other structures of the detection layer; the liquid inlet hole 12 and the liquid outlet hole 13 penetrate through the detection layer body 11 and are connected with the flow channel 14, the flow channel 14 and the detection cavity 15 are connected and arranged at the bottom of the detection layer, and the surface is treated by polyvinyl alcohol hydrophilic modification; the electrochemical sensor working electrode hole 16 is aligned with the electrochemical sensor working electrode interface 9, and the electrochemical sensor reference / auxiliary electrode hole 17 is aligned with the electrochemical sensor reference / auxiliary electrode interface 10;

[0043] The sensor layer includes a sensor layer body 18 and a double electrode system attached on the surface of the sensor layer body 18 by silk screen printing, the double electrode system includes a working electrode strip conductor 19, a reference / auxiliary electrode strip conductor 20, a working electrode 21 and a reference / auxiliary electrode 22, the material of the sensor layer body 18 is glass or acrylic, other structures are attached on the surface of the sensor layer body 18 by silk screen printing, the shape of the working electrode 21 is circular (also can be oval or rectangular), the shape of the reference / auxiliary electrode 22 is a 120° circular ring, the shape design occupies small space and is suitable for most detection environments, the working electrode 21 is connected with the working electrode strip conductor 19 and connected with the detection / controller 3 finally through the electrochemical sensor working electrode interface 9 and the electrochemical sensor working electrode hole 16; the reference / auxiliary electrode 22 is connected with the reference / auxiliary electrode strip conductor 20 and connected with the detection / controller 3 finally through the electrochemical sensor reference / auxiliary electrode hole 17 and the electrochemical sensor reference / auxiliary electrode interface 10.

[0044] The working electrode 21 is modified from bottom to top with a conductive layer 1', a working electrode layer 2', a hydrophilic layer 4' and an enzyme coating layer 5', and the reference / auxiliary electrode 22 is modified from bottom to top with a conductive layer 1', a reference / auxiliary electrode layer 3' and a hydrophilic layer 4', and the hydrophilic layer 4' is used to improve the blood adsorption resistance of the electrode.

[0045] The manufacturing method of the microfluidic chip 4 in the on-demand blood glucose monitoring system includes the following specific steps:

[0046] (1-1) Interface layer preparation

[0047] The material of the interface layer body 6 is glass or acrylic, first, the apertures are obtained by laser cutting according to the pre-designed pattern, then the microfluidic interface and the sample inlet 7 and the sample outlet 8 are aligned and fixed with the corresponding apertures, and the electrochemical sensor working electrode interface 9 and the electrochemical sensor reference / auxiliary electrode interface 10 are assembled with the detection / controller 3 interface on the surface of the corresponding apertures.

[0048] (1-2) Detection layer preparation

[0049] The detection layer body 11 is obtained by mixing 50 g of polydimethylsiloxane, 5 g of polydimethylsiloxane-polyethylene glycol and 5 g of polydimethylsiloxane crosslinking agent, pouring the mixed material into a laser-engraved acrylic mold, removing bubbles in the mixed material through vacuum treatment, and then placing the mixed material in an oven for heating and curing, wherein the thickness of the acrylic is 1 mm, the mold requires a circular or elliptical detection cavity 15 capable of accommodating the electrode structure of the sensor layer, the inlet hole 12 and the outlet hole 13 can be aligned with the sample inlet 7 and the sample outlet 8 of the interface layer respectively, and the electrochemical sensor working electrode hole 16 and the electrochemical sensor reference / auxiliary electrode hole 17 can be aligned with the electrochemical sensor working electrode interface 9 and the electrochemical sensor reference / auxiliary electrode interface 10 respectively. The heating temperature of the oven is 60-80°C, and the heating time is 2 h. After curing, cut into a shape matching the shape of the interface layer and the sensor layer, then mix polyvinyl alcohol with ultrapure water at a mass ratio of 1:100 and heat at 80-100°C for 60 min; then reduce the temperature to 50-70°C and stir for 12 h to obtain a hydrophilic modification solution; after filling the flow channel 14 and the detection cavity 15 with the solution, soak at room temperature for 20 min, then take out and heat at 50-70°C for 20 min to complete the surface hydrophilic modification. Drop 1 uL of deionized water on the surface of the flow channel 14 and the detection cavity 15 before and after hydrophilic modification respectively, and place them in a full-automatic contact angle measuring instrument to measure the water contact angle. The water contact angle is reduced from 100°-120° to 20°-40°, indicating that the hydrophilicity of the flow channel 14 and the detection cavity 15 is significantly improved. The improvement of hydrophilicity makes it easy for water molecules to spread on the surface to form a continuous liquid film, and the capillary pressure increases, reducing the liquid droplet residue caused by surface tension and improving the uniformity of liquid flow.

[0050] (1-3) Sensor layer preparation

[0051] The sensor layer body 18 is made of glass or acrylic and has a rectangular shape with a length of 70 mm and a width of 50 mm. The schematic diagram of the screen-printed electrode structure is as follows: Figure 1The structures of the working electrode strip-shaped lead 19, the reference / auxiliary electrode strip-shaped lead 20, the working electrode 21, and the reference / auxiliary electrode 22 are shown, and the screen plate is prepared according to the drawing before electrode printing. First, prepare the carbon paste, Ag / AgCl paste, Ag paste, and screen plate. According to the different electrode materials and layer structures, different screen plates are prepared for printing. First, print the conductive layer 1' of the working electrode and the reference / auxiliary electrode, and the working electrode strip-shaped lead 19 and the reference / auxiliary electrode strip-shaped lead 20. After the Ag paste is applied to the screen plate corresponding to the structure of the conductive layer 1', the screen plate is placed tightly against the substrate, and the squeegee is moved from top to bottom to evenly print the paste on the substrate. After confirming that the electrode pattern is complete, the substrate is removed and placed in a baking tray or oven at 100-150°C for 10 min for sintering. The working electrode layer 2' material is carbon paste, and the reference / auxiliary electrode layer 3' material is Ag / AgCl paste, and the printing steps are the same as above.

[0052] (1-4) After the sensor layer is prepared, 20 mg / mL dopamine and 30 mg / mL methacryloyl ethyl sulfobetaine are dissolved in a Tris-HCL buffer solution with a pH of 8.5 and a concentration of 50 mmol / L to obtain a hydrophilic layer modification solution. The substrate with the electrode pattern is completely immersed in the solution at room temperature for 20 h. After modification, the electrode surface is thoroughly washed with deionized water to obtain a hydrophilic layer 4'. 1 uL of deionized water is dropped on the electrode surface before and after the hydrophilic layer modification, respectively, and the water contact angle is measured using a full-automatic contact angle measuring instrument. The water contact angle of the working electrode 21 is reduced from 60°-70° to 20°-30°, and the water contact angle of the reference / auxiliary electrode 22 is reduced from 70°-80° to 30°-40°. This hydrophilic layer can generate a strong hydration repulsive force on the electrode surface. When blood contacts, the hydration layer effectively blocks the direct contact of proteins, cells, and other components in the blood with the electrode surface, thereby significantly reducing the non-specific adsorption of biomolecules and liquid retention, making the droplets or fluid more easily flow and not easily adhere.

[0053] (1-5) After the hydrophilic layer 4' is prepared, 0.1 g of chitosan, 30 uL of 0.3% by volume of glacial acetic acid and 1 mL of 10% by volume of glycerol are added to 10 mL of deionized water, and after stirring at 80°C for 2 h, 0.1 mL of 1000 ppm concentration of platinum nanoparticle aqueous solution is added, and then the glucose oxidase with a concentration of 100 mg / mL is mixed with the above solution at a volume ratio of 2:1 to obtain a mixed solution of glucose oxidase and chitosan, 3 uL of the mixed solution is added dropwise to the surface of the working electrode layer 2', and then the enzyme coating layer 5' is obtained after being refrigerated at 2-5°C for 2 h. The enzyme coating layer 5' containing chitosan has good biocompatibility and film-forming property, and the glucose oxidase can form a stable enzyme-chitosan three-dimensional network structure by cross-linking with chitosan, effectively fixing the enzyme molecules on the surface of the sensor. By observing and comparing the residual conditions of the two types of glucose oxidase with and without chitosan after each blood glucose test, it is found that the glucose oxidase without chitosan almost completely separates from the electrode surface, and the blood glucose measurement result is poor, which cannot correctly reflect the rise and fall of blood glucose; while the glucose oxidase containing chitosan does not separate from the electrode surface, and can achieve accurate and repeated blood glucose detection.

[0054] (1-6) The detection layer is placed in a beaker containing anhydrous ethanol, and then placed in an ultrasonic cleaning machine for cleaning for 5 min, and then the anhydrous ethanol in the beaker is replaced with deionized water and the above steps are repeated. After cleaning, the detection layer is wiped clean and placed in a full-automatic vacuum plasma cleaning machine, and the detection layer is treated by oxygen plasma, the glow power is 300 w, and the treatment time is 30 s. After treatment, the detection layer with the detection cavity 15 on one side and the electrode on the other side of the sensor layer are aligned and attached, so that the working electrode 21 and the reference / auxiliary electrode 22 are in the detection layer cavity, and then the other side of the detection layer is aligned and attached with the bottom surface of the interface layer, so that the layers are bonded, and the microfluidic chip 4 is obtained.

[0055] The construction process of the on-demand blood glucose monitoring system is as follows: the indwelling needle interface 1 is connected to the liquid inlet end of the valve 2 through the catheter, and the liquid outlet end of the valve 2 is fixedly installed with the sample inlet 7 of the microfluidic chip 4, the sample outlet 8 of the microfluidic chip 4 is fixedly installed with the interface of the waste liquid pool 5, then the control end of the detection / controller 3 is connected with the valve 2, and the detection end of the detection / controller 3 is connected with the working electrode interface 9 and the reference / auxiliary electrode interface 10 of the electrochemical sensor in the microfluidic chip 4, and the entire on-demand blood glucose monitoring system is obtained.

[0056] The interface installation process of the microfluidic chip 4 is as follows: firstly, the interface gasket 8' is placed at the bottom of the interface shell 6' and aligned with the hole below, then the conduit joint shell 7' is sleeved on the conduit 9', and after being aligned with the interface shell 6', the connection of the sample inlet 7 is completed by tightening, and the connection of the sample outlet 8 is the same as the above.

[0057] The detection process of the on-demand blood glucose monitoring system is as follows: the valve 2 is controlled to be turned on by the detection / controller 3 to inject blood into the microfluidic chip 4 and automatically fill the entire detection cavity 15, then the valve 2 is closed and the detection / controller 3 is switched to the detection state, after waiting for 60s, the detection result is read to obtain the blood glucose value, after the detection is completed, the valve 2 is opened again to inject physiological saline into the microfluidic chip 4 for cleaning, after there is no blood residue, air is injected into the microfluidic chip 4 to discharge all the liquid, and the next detection is waited for.

[0058] The above-described embodiments are only used to describe the preferred embodiments of the present application, and do not limit the scope of the present application, and various modifications and improvements to the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope of the claims of the present application.

Claims

1. A system for on-demand blood glucose monitoring, the system comprising: The application relates to a microfluidic chip for detecting blood glucose, which comprises a remaining needle interface, a valve, a detection / controller, a microfluidic chip and a waste liquid pool, the remaining needle interface is connected with the valve through a conduit, the valve is connected with a control end of the detection / controller through a wire, the microfluidic chip is composed of an interface layer, a detection layer and a sensor layer, wherein, the interface layer comprises an interface layer body and a sample inlet, a sample outlet, an electrochemical sensor working electrode interface and an electrochemical sensor reference / auxiliary electrode interface arranged on the interface layer body, the sample inlet and the sample outlet are connected with conduit joints with external threads, the electrochemical sensor working electrode interface and the electrochemical sensor reference / auxiliary electrode interface are connected with a detection end of the detection / controller through wires respectively; the valve is connected with the sample inlet of the microfluidic chip, and the sample outlet in the microfluidic chip is connected with the waste liquid pool through a conduit; the detection layer comprises a detection layer body and a liquid inlet hole, a liquid outlet hole, a flow channel, a detection cavity, an electrochemical sensor working electrode hole and an electrochemical sensor reference / auxiliary electrode hole arranged on the detection layer body, the liquid inlet hole and the liquid outlet hole penetrate through the detection layer body and are connected with the flow channel, the flow channel and the detection cavity are connected and are arranged on the bottom of the detection layer, and the surface is subjected to polyvinyl alcohol hydrophilic modification treatment; the electrochemical sensor working electrode hole is aligned with the electrochemical sensor working electrode interface, and the electrochemical sensor reference / auxiliary electrode hole is aligned with the electrochemical sensor reference / auxiliary electrode interface; the sensor layer comprises a sensor layer body and a double electrode system attached to the surface of the sensor layer body through silk screen printing, the double electrode system comprises a working electrode strip-shaped wire, a reference / auxiliary electrode strip-shaped wire, a working electrode and a reference / auxiliary electrode, the working electrode is connected with the working electrode strip-shaped wire and connected with the detection / controller through the electrochemical sensor working electrode interface and the electrochemical sensor working electrode hole; the reference / auxiliary electrode is connected with the reference / auxiliary electrode strip-shaped wire and connected with the detection / controller through the electrochemical sensor reference / auxiliary electrode hole and the electrochemical sensor reference / auxiliary electrode interface.

2. The on-demand blood glucose monitoring system of claim 1, wherein: The double electrode system can be replaced by a three electrode system, the three electrode system comprises a working electrode strip-shaped wire, a reference electrode strip-shaped wire, an auxiliary electrode strip-shaped wire, a working electrode, a reference electrode and an auxiliary electrode, the working electrode is connected into the electrochemical sensor working electrode hole through the working electrode strip-shaped wire, the reference electrode is connected into the electrochemical sensor reference electrode hole through the reference electrode strip-shaped wire, and the auxiliary electrode is connected into the electrochemical sensor auxiliary electrode hole through the auxiliary electrode strip-shaped wire; three strip-shaped wires are connected with an external detection / controller through corresponding holes and interfaces respectively, forming an independent three electrode channel; the electrochemical sensor reference / auxiliary electrode hole is replaced by an electrochemical sensor reference electrode hole and an electrochemical sensor auxiliary electrode hole and is also arranged on the detection layer body.

3. The on-demand blood glucose monitoring system of claim 1, wherein: The interface structure of the sample inlet, sample outlet, valve and waste pool is same, and each includes an interface shell, a conduit joint shell, an interface gasket and a conduit, the interface shell is threadedly connected with the conduit joint shell, the interface gasket is arranged at the bottom of the interface shell, the conduit joint shell is sleeved on the outer periphery of the conduit, the conduit passes through the center hole of the interface gasket and is fixed with the interface shell through the conduit joint shell.

4. The on-demand blood glucose monitoring system of claim 1, wherein: The working electrode is provided with a conductive layer, a working electrode layer, a hydrophilic layer and an enzyme coating layer from bottom to top; the reference / auxiliary electrode is provided with a conductive layer, a reference / auxiliary electrode layer and a hydrophilic layer from bottom to top.

5. The on-demand blood glucose monitoring system of claim 1, wherein: The material of the working electrode strip-shaped lead and the reference / auxiliary electrode strip-shaped lead is gold, silver, copper or platinum; the material of the interface layer body and the sensor layer body is glass or acrylic.

6. The on-demand blood glucose monitoring system of claim 4, wherein: The material of the conductive layer is gold, silver, copper or platinum, the material of the working electrode layer is carbon, and the material of the reference / auxiliary electrode layer is silver / silver chloride; the material of the hydrophilic layer is a thin film formed by mixing dopamine and methacryloyl ethyl sulfobetaine, wherein the concentration of dopamine is 10 mg / dL-30 mg / dL, and the concentration of methacryloyl ethyl sulfobetaine is 20 mg / dL-50 mg / dL; the material of the enzyme coating layer is obtained by mixing and stirring chitosan, glacial acetic acid and glycerol, and then adding platinum nanoparticles and glucose oxidase.

7. The on-demand blood glucose monitoring system of claim 4 or 6, wherein: The enzyme coating layer is prepared by the following method: 0.1-0.2 g of chitosan, 30-60 uL of 0.3% glacial acetic acid and 1-2 mL of 10% glycerol are added to every 10-20 mL of deionized water, mixed and stirred, then 0.1-0.2 mL of platinum nanoparticles is added, and then 10-100 mg / mL of glucose oxidase is mixed with the solution in a volume ratio of 1-3:1 to obtain a mixed solution of glucose oxidase and chitosan, 2-5 uL of the mixed solution is added to the surface of the working electrode layer, and then low-temperature refrigeration is carried out to obtain the enzyme coating layer.

8. The on-demand blood glucose monitoring system of claim 1, wherein: The shape of the detection cavity is circular or elliptical; the shape of the working electrode is circular, elliptical or rectangular, and the shape of the reference / auxiliary electrode is a circular ring not less than 120°.

9. The on-demand blood glucose monitoring system of claim 1, wherein: The flow channel and the detection cavity are hydrophilically modified by a polyvinyl alcohol solution, which is obtained by mixing and stirring polyvinyl alcohol and ultrapure water and then heating, and the mass ratio of polyvinyl alcohol to ultrapure water is 1:70-120.

10. The on-demand blood glucose monitoring system of claim 1, wherein: The material of the detection layer body is obtained by mixing and heating polydimethylsiloxane, polydimethylsiloxane-polyethylene glycol and polydimethylsiloxane crosslinking agent and then curing, the mass of polydimethylsiloxane is 8-12 times that of polydimethylsiloxane-polyethylene glycol and polydimethylsiloxane crosslinking agent, and the mass ratio of polydimethylsiloxane-polyethylene glycol to polydimethylsiloxane crosslinking agent is 1-2:2-1.

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