Design Of Protein Chip Automatic Sampling System

At present,in the world of clinical diagnosis,more than 80 percent of the cases are in vitro testing.In vitro detection has been widely used in clinical medicine in China because of its advantages such as fast,simple and clean detection process without any pollution.Protein chip analyzer,as one of the important instruments for in vitro detection,involves a series of key technologies such as manipulator motion control,microsample addition,and breeding module control.Most of these technologies are monopolized by foreign medical enterprises,and there is still a big gap in the performance of domestic instruments compared with imported ones.In view of this situation,a small protein chip detection instrument with high precision,high efficiency,high stability and low cost has been developed,and the nationalization of its core technology is of great significance to the development of the medical industry.This paper introduces the structure and principle of the protein chip automatic sample adding system,and analyzes the working flow of the system.The overall scheme of the control system is proposed combined with the requirements of engineering design.The structure and function of each module are analyzed and designed.According to the overall design scheme,the hardware part of the control system is designed.It mainly includes the selection of components and circuit design of microcontroller,manipulator module,sample filling module and temperature-breeding module.The software workflow of the control system is designed,and the functions such as manipulator movement control,needle suction and sample discharging operation,temperature detection and heating are realized.This paper analyzes the engineering problems of the automatic sample adding system,and designs its solution strategy and control algorithm.1)Aiming at the mechanical arm movement in the process of the motor lost step,overshoot and other problems.The stepper motor adopts simplified S-type acceleration and deceleration curve to control,and combined with position sensor to assist positioning,which improves the positioning accuracy of single axis of the system.The multi-axis linkage adopts the cross-coupling control strategy,which effectively reduces the vibration and noise generated in the control process of the manipulator.2)In order to avoid pipetting error caused by sample level and motor control during pipetting of sample filling module.The position-speed double closed-loop PID control strategy is adopted to improve the positioning accuracy of the system and the stability of the sampling process.3)Too high or too low temperature and fluctuation of temperature in the incubating chamber will lead to insufficient or failure of sample reaction,resulting in low sensitivity and large reproducibility error of sample test results.In this paper,PI heating film is used for heating in different regions,and fuzzy PID control algorithm is used to control the temperature silo,which effectively improves the heating efficiency and anti-interference ability of the system.Finally,software simulation and experiment are carried out to verify the control performance and detection accuracy of the key parts of the automatic sample adding system.By comparing the experimental results with the system design requirements,the protein chip automatic sample adding system designed in this paper has good control performance and the test accuracy meets the design requirements.