High-speed Automatic Biochemical Analyzer High-precision Sample Loading Technology Research

Nowadays, with the increase of national healthy awareness, the number of biochemical detection increases rapidly in major hospitals and Clinical Laboratory Center, while precise treatment of many diseases increasingly depends on the high precision of biochemical quantitative analysis, which prompted automatic biochemical analyzer to develop in the direction of high speed and high precision. However, the sample speed and accuracy is one of the key factors to affect the biochemical detection speed and precision, if only considering the increase of sampling speed, which will have effect on sampling accuracy to a certain extent. Because of the mount of test sample and reagent are all in the order of μl, and then the reduced sample accuracy is bound to cause a large deviation of measurement results, and even appears a false positive. Therefore, it is significant to increase the sample speed on the premise of ensure the sample accuracy.Based on the sample characteristics of automatic biochemical analyzer, the paper analyzes the factors that affect the sample speed and precision, including sample methods, sample structure, sample timing, pipe vibration, dynamic characteristics of the aspirating sample pipe, droplet falling of sample needle. A beam model with both ends fixed is established between plunger pump and sample needle connecting pipe, based on the principle of Hamilton, then solve the vibration equation and get the liquid velocity, system pressure, pipe length and diameter to the influence law of pipeline vibration and then the theoretical basis is to avoid the pipeline vibration; An equivalent circuit model is established for the sample drawing process, the influence of factors, such as pipe length, pipe diameter, isolated air column volume, sample volume, sample viscosity, on steady-state characteristics during sample absorption process are analyzed to provide theoretical basis for sampling latency; A finite element emulation analysis is proceed for the phenomenon of droplet falling, then Reynolds number, Webber number, surface features of sample needle and sample velocity influence on the droplets fall off, so as to get the conditions of the droplet falls off smoothly, is for the needle selection and liquid droplet departure provides the theory basis. The influencing rule of various parameters on sampling speed and precision is analyzed comprehensively, which provided theoretical guidance for the study of high speed and high precision.In the context, it is not only concerned with the precise control of plunger pump in sampling system but also combined with hydromechanics theory to analyze the factors that affect sample speed and accuracy, then showing the various factors that how to affect the sample speed and accuracy during sample process. The platform for high speed and high precision sampling is set up; experiments on the influence factors of sampling speed and precision are conducted. According to the theoretical analysis, the numeric calculation and the experimental results, a sampling scheme suitable for the features of the automatic biochemical analyzer is designed. Results of experiment show that based on this scheme, the sample cycler is up to 3.6 seconds with single needle and unilateral arm, the sample error reached ±3% and the coefficient of variation less than 2% in 2μl sample volume, which reaches advanced level at home and abroad.