Kinetics Analysis And Experiment Of High-speed Precision Pipette System During Aspirating Samples

Chemiluminescence immunoassay is the mainstream of the current clinicalexamination technology. As the basic platform of chemiluminescence immunoassaysystem, chemiluminescence immune analyzer consists of sampling system, thermostaticincubation module, immune complex washing and separating module, gleammeasurement module and control system. The trend of the analyzer goes towards higherspeed and precision. The key factors influencing test speed and precision of the analyzerare the sampling speed and precision. Pursuing only the sampling speed will certainlyaffect the sampling precision. As the measurement of the analyzer is based on thecombination of the specificity of antigen and antibody, the sample and chemical dozeare farely small. The reduction of sampling precision will inevitably cause largedeviation of measurement results, or even false positives. Therefore, the samplingprecision need to be ensured while the sampling speed is improved. According to thesampling properties of analyzer, the article has done a detailed study on factorsinfluencing the precision and speed of sampling to provide theoretical basis for theprecision control under high sampling speed. This is of great significance for furtherimproving the property of analyzer and the clinical examination technology.Firstly, the paper analyzes the impact factors of sampling precision and speed suchas temperature, density, viscosity, surface tension, pipe length and material, isolated airvolume, the thickness of needle wall, pumping speed, and evaporation. On this basis,the dynamic model of the sampling process is established. And a model with both endsfixed is established for arc-shaped connecting pipe, based on the principle offluid-structure interaction. Then the vibration equation and the critical flow velocity andpressure for piping vibration are obtained to provide theoretical basis for avoiding thesampling vibration phenomenon. The whole sampling system is likened to be amechanical model, whose dynamic model is established using lumped parametermethod. And the inherent frequency and the main formation of the system are obtained.Secondly, based on the model above, curves of rising shift and pressure fluctuationof samples proceeding are simulated. The influence of factors, such as sample viscosity,volume of isolated air, length of system liquid and pipetting speed, on displacement andpressure fluctuation are studied to get the corresponding influence rule. The articlestudies the following contents specifically: the bias and the compensating way caused by gravity and evaporation of the sample, pressure identification and detection atabnormal sampling, adsorption-touch sampling and the way of automatic sampling forchemiluminescence immune analyzer and the influencing rule of various parameters onsampling speed and precision.Finally, on the basis of theoretical analysis, the platform for liquid sampling is setup, experiments on the influence factors of sampling precision and speed are conducted.The results show that the influence rules of the above factors on the sampling areconsistent with the simulation. According to the theoretical analysis, simulation and theexperimental results, a sampling scheme suitable for the features of the analyzer isdesigned. Based on this scheme， the sample rate of the analyzer is increased to180perhour and the repeat accuracy reached1.3%, which is proved to be effective.