背景:在血液透析过程中,透析液的浓度直接决定了透析的效果.目的:旨在设计一种应用于测量透析液浓度的pH值和电导率的装置,并通过试验对测量仪的性能进行测试和分析.方法:开发用于测量透析液的pH值和电导率测量仪,提出一种频率可调的双极性间歇脉冲激励方法应用于电导率测量,极大地减少极化效应和电容效应对测量的影响,同时对电导率测量值进行温度校正.采用两点校正法对pH值进行标定,提高测量的精确度.结果与结论:测量仪样机在实际的透析液中进行相关试验.测量仪的pH值测量值和标准值的相对误差小于1%,电导率的测量值与标准值的相对误差小于0.5%.通过对比试验说明,可调频率的间歇双极性脉冲法比双极性脉冲法的误差小,能及时地跟踪透析液浓度的变化.结果表明,测量仪能够实现对透析液浓度的精确测量,满足血液透析机对透析液的实时检测要求,可以广泛应用于血液透析机中透析液的浓度检测中.%BACKGROUND: The dialysate concentration directly determines the efficacy of dialysis during the process of hemodialysis. OBJECTIVE: To design a measuring instrument of dialysate pH value and electrical conductivity and to test the performance of the measuring instrument through experiments.METHODS: The variable frequency of bipolar interim pulse method was put forward to reduce polarization and capacitance effect on the conductivity measurement tremendously while simultaneously temperature compensation was selected for electrical conductivity. Two-point correction method was used for calibration test to improve the accuracy measurement of pH value. RESULTS AND CONCLUSION: The trial manufactured carried experiment on the actual dialysate. The relative error between the calibration result and the accurate value for dialysate pH value was less than 1 % and that of electrical conductivity was less than 0.5%. Besides, comparative experiments between variable frequency of bipolar interim exciting pulse and bipolar exciting pulse were carried out. The former was less measure error and could follow up the response closely. The results show that the measuring instrument can realize the accurate measurement and be widely used in hemodialysis machine.
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