▎ 摘　　要

NOVELTY - An electric sensor is prepared by (A) preparing ferrite-graphene composite material; (B) preparing copper-titanium oxide under water bath condition of 50-60 degrees C; and (C) adding graphene composite ferrite and copper-titanium oxide to ethanol water solution, magnetic stirring for 20-30 minutes to obtain suspension, dropping to covering surface of insulating ceramic tube, and vacuum drying at room temperature. The step (A) comprises (i) preparing graphene oxide, (ii) preparing reduced graphene oxide, and (iii) preparing nickel ferrite graphene composite material. The step (i) comprises putting graphite powder and potassium permanganate into vessel, adding mixed acid, reacting for 15-20 hours at 30-50 degrees C, quickly putting vessel into ice water bath, adding 1/10 hydrogen peroxide, magnetically stirring for 0.5-2 hours, centrifugally separating product by ethanol after centrifuging and washing for 3-5 times at 35 degrees C,vacuum drying to obtain graphene oxide solid powder. USE - Electric sensor. ADVANTAGE - The prepared sensor has high sensitivity and good stability. DETAILED DESCRIPTION - Electric sensor is prepared by (A) preparing ferrite-graphene composite material; (B) preparing copper-titanium oxide under water bath condition of 50-60 degrees C; and (C) adding graphene composite ferrite and copper-titanium oxide to ethanol water solution, magnetic stirring for 20-30 minutes to obtain suspension, dropping to covering surface of insulating ceramic tube, and vacuum drying at room temperature. The step (A) comprises (i) preparing graphene oxide, (ii) preparing reduced graphene oxide, and (iii) preparing nickel ferrite graphene composite material. The step (i) comprises putting graphite powder and potassium permanganate into vessel, adding mixed acid, reacting for 15-20 hours at 30-50 degrees C, quickly putting vessel into ice water bath, adding 1/10 hydrogen peroxide, magnetically stirring for 0.5-2 hours, centrifugally separating product by ethanol after centrifuging and washing for 3-5 times at 35 degrees C,vacuum drying to obtain graphene oxide solid powder. The mixed acid is concentrated sulfuric acid and concentrated phosphoric acid mixed solution. The step (ii) comprises ultrasonically dispersing graphene oxide solid powder in dimethyl formamide water solution for 15-25 minutes at 40-50, adding sodium borohydride, reacting at 85-90 degrees c for 15-20 hours, centrifugal washing with water to neutral, and vacuum drying at 50-60 degrees C to obtain reduced graphene oxide. The step (iii) comprises ultrasonically dispersing reduced graphene oxide into anhydrous ethanol, adding 0.2 mol/mL iron nitrate 3 solution, 0.2 mol/L nickel aqueous solution and ammonia water, stirring at 70-80 degrees C for 15-20 hours, transferring to high pressure reaction kettle, reacting at 120 degrees C at 1-2 hours, raising temperature to 150 degrees C for 1-2 hours, raising temperature to 200 degrees C, reacting for 10-20 minutes, reducing temperature to 170 degrees C for 2-3 hours, cooling to room temperature, centrifugal separating solid at 50 degrees C, and drying to obtain nickel ferrite graphene composite material. The step (B) comprises preparing copper-titanium oxide under water bath condition of 50-60 degrees C, adding mixed solution of copper sulfate and tetrabutyl titanate into hydrofluoric acid solution, stirring for 50-70 minutes, reacting at 100-150 degrees C for 2-5 hours, raising temperature to 180-200 degrees C for 15-20 hours, cooling to room temperature, vacuum drying, grinding solid into powder after drying at 50 degrees C, and using deionized water and absolute ethyl alcohol for centrifugal washing.