Electrochemical electrode, continuous glucose monitoring sensor and preparation method therefor

A method of making a sensor, comprising the following steps:

• {circle around (1)} Providing a film material;
• {circle around (2)} Depositing a polydopamine layer on the surface of the film material;
• {circle around (3)} Depositing a catalytic layer on the surface of the film material;
• {circle around (4)} Chemically depositing a gold layer on the surface of the film material;
• {circle around (5)} Adsorbing a carbon nanotube mesh layer on the surface of the film material.

A method of making a sensor, comprising the following steps:

• {circle around (1)} PI slice decontamination:
• cutting a polymer film material having a thickness of at least 20 μm into a sheet, and placing them in acetone, ethanol, deionized water for ultrasonic treatment for 5 min and drying, to remove the oil dirt on the surface;
• {circle around (2)} depositing polydopamine layer:
• immersing the cleaned sheet in a dopamine hydrochloride solution (pH 8.5, 2 mg/ml), placing it on a bleaching shaker at room temperature, and after oxidizing in air for 24 hours, a layer of polydopamine is formed on the surface of the sheet, after immersed and cleaned in deionized water for 8 hours, dried in a 80° C. oven;
• {circle around (3)} depositing catalytic layer:
• immersing the dried sheet in a 0.1 wt % Stearyl Trimethyl Ammonium Chloride (STAC) solution for 5 s, and taking out for drying, then placing it in platinum nanosol for 30 min, adsorbing a platinum nanoparticle layer on the surface of the sheet, and taking out, gently rinsing the surface with deionized water, to remove the unimmobilized platinum nanoparticles and dry;
• {circle around (4)} chemically depositing gold layer:
• placing the dried sheet into a gold plating liquid (containing 10 mM chloroauric acid and 20 mM hydrogen peroxide) for 15 minutes, and then quickly placing in a 120° C. oven for annealing for 50 min, and turning off the oven, when the temperature in the oven has dropped to room temperature, taking out the sheet, at this time, a layer of bright, compact and firm gold is deposited on the surface of the sheet;
• {circle around (5)} electrodepositing platinum layer:
• placing the cleaned gold-plated electrode on a platinum plating solution (3 wt % chloroplatinic acid, 0.25 wt % lead acetate), and setting the working potential at −2.5 V and the deposition time at 120 s by the constant-voltage method using platinum filament as a counter electrode;
• electrodepositing a compact platinum black layer on both sides of the electrode simultaneously, and sputtering or coating an insulating layer (8) on both sides of the sheet;
• {circle around (6)} parylene insulation treatment Sputtering or coating a Parylene insulating layer on both sides of the sheet;
• {circle around (7)} boring to form a working surface making a through hole (9) by laser on the surface of the set electrode working area to form a working area;
• {circle around (8)} adsorbing carbon nanotube mesh layer:
• immersing the electrode in aqueous dispersion liquid of carbon nanotube (carbon nanotube aqueous dispersion liquid:5 wt % Nafion=1:4), setting a working voltage of 1 V and a working time of 10 s by the potentiostatic method, to form a carbon nanotube mesh layer on the outer peripheral surface of the working electrode hole;
• {circle around (9)} crosslinking and curing:
• overhanging the electrode in a container with 25% glutaraldehyde at the bottom, cross-linked in a 40° C. oven for 60 min, and storing in a refrigerator at 4° C. for 2 h to firmly bond the carbon nanotube mesh layer with the substrate;
• {circle around (10)} electro-absorbing GOx enzyme layer:
• immersing the working part of the electrode in the GOx enzyme solution (BSA:GOx=1:3, concentration of 30 mg/ml), setting the working voltage at 0.3V and the working time at 2400 s by the potentiostatic method using the side of the carbon nanotube mesh layer as the working electrode and the other side as the counter electrode, then storing the electrode in a 4° C. refrigerator for 8 h, so that GOx is fully embedded in the carbon nanotube mesh layer to form the GOx enzyme layer;
• {circle around (11)} cutting electrode:
• cutting the sheet into a filament-like, single-layer double-sided electrode using an ultraviolet laser cutting machine;
• {circle around (12)} forming a polyurethane protection layer:
• dissolving 4 wt % of polyurethane in a mixed solution of 98 v % tetrahydrofuran and 2 v % dimethylformamide to form a polyurethane solution, slowly passing the electrode sensing portion through a steel wire ring with an inner diameter of 2 mm soaked with the polyurethane solution, to form a polyurethane protection layer on the surface of the electrode;
• {circle around (13)} assembling an electrode:
• fixing the electrode tail end to the base, and the lead wire area (7) on the electrode tail end is electrically connected to the sensing component in the base.