| The content of somatic cells in milk is one of the important indexes to measure the quality of milk and the health status of dairy cows.It is a good method to construct a sensitive,fast,accurate,stable micro-finger electrode cell sensor.Firstly,interdigitated microelectrode was made.Then P-selectin and nano-ZnO thin films were modified on the surface of the electrode.Finally,interdigitated microelectrode cell sensor for detecting milk somatic cells was obtained.The main contents of the study are as follows:1)An indium tin oxide(ITO)sensor with a width of 50?m and a gap of 100?m was designed for electrodeposition of nano-ZnO and P-selectin on the electrode surface.The redox reaction was analyzed by CV and the results were observed by scanning electron microscope(SEM)and electron microscope respectively.The AC voltage amplitude was set at 1mV~600mV,the frequency range was set between 10Hz~1MHz and the milk sample was tested.The contrast experiment of cell culture medium was added to determine the best test signal is 300mv.2)The impedance measurement of electrode size,surface modification,cell concentration milk sample and electrode material were carried out and discussed.The equivalent circuit model was established to fit and analyze the impedance spectrum.It was found that the sensitivity and the detection accuracy of the modified sensor were the best,which could distinguish several milk samples correctly,and there was a linear relationship between the impedance and milk concentration.When the frequency of 10kHz is below the frequency,there was a good linear relationship between the impedance mode value of the two modified sensors and the concentration of0~8×10~5/mL.The parameters of the detection threshold were set to 5 and the determination coefficient R~2 of the P-selectin and nano-ZnO were 0.909 and 0.874,respectively.The sensor could predict the mastitis grade of dairy cattle better.It can also detect the national standard 4×10~5/mL.Figure46;Table10;Reference 58. |
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