Research And Design Of Micro Sampling Control System For Automatic Biochemical Analyzer

Automatic biochemical analyzer(ABA) has become one of the indispensable instruments which is widly applied in medical diagnosis and analysis of various biochemical indexes in human body in various kinds of hospitals.With the development of medical technology, modern medical science has increasingly high performance requirements for automatic biochemical analyzer, as a consequence, the relating researches need to go urgent deepening and strengthening. As a matter of fact,it is faced with many difficulties and technical bottlenecks in the independent research and development of ABA owing to the late start on the research of biochemical analyzer in China,there exist great problems such as low sampling precision, poor accuracy and weak operation stability especially in the field of micro sampling control technology.By making the micro sampling control technology as the starting point, the main structure of ABA and action process of micro sampling control system(MSCS) were described in detail,which were all on the basis of analyzing the development and trend of the ABA and the present research of micro sampling control technology home and abroad. Analyses on the factors to influence the micro sampling control system were conducted, further more, analysis and design of experimental study from the aspects of fluid mechanics were carried on. In this paper, the aim of the sdudy is to propose a micro sampling control system for ABA.The scheme design of micro sample adding control system was carried out, and the control mode of PC-MCU(Microcontroller Unit)-FPGA(Field Programmable Gate Array)-stepping motor was adopted. It combined the advantage of great analysis ability, sequential control on MCU and parallel procesing, multi-thread,high real time control on FPGA by using FPGA as a co processor while MCU as a main processor. Detailed analysis and design of the position location, sample adding, liquid level detection, stepping motor subdivision, speed control and the control scheme of the corresponding pumps and valves were conducted.The system controller, driver, components of the system were designed and selected in the hardware design part.Besides, the driving principles and methods of stepping motor, pump and valve were analyzed and designed, the system relating circuit diagrams were designed and drawed, and the structure of some components were improved, which should be more able to meet the functional requirements of the system.The implementation mechanism of control scheme for the stepping motor were analyzed in the software design part,including the accuracy calculation of the stepping motor, subdivision settings, the principle analysis and implementation methods of the specific acceleration and deceleration process etc. The main program flow and interrupt service program flow were written according to timing requirements of the control system.The emphasis and difficulties of the system was the control of stepping motor, This paper also designed friendly PC interfaces and perfect functional database, communication and the methods of reset for each part of control system were described in details, which finally realized the great accuracy, high precision and strong operation stability of micro samping control system in automatic biochemical analyzer.The control system was debugged in software and hardware, at the same time, experimental tests were carried out.Further more, analysis on the debugging process and summary of problems occurring during the process were conducted, the solutions were put forward,too.The debugging result and the experimental data showed that performance precision of the micro sampling control system can reach 2ul(10-6L), which could meet the requirements of the vast number of large and medium-sized ABAs on accuracy, operation stability and sampling precision. The control system has a certain value on adoptability and reference in the same industry.