A small auto micropipette system is developed to improve the reliability and accuracy of the automatic
enzyme immunoassay analyzer’s microscale pipetting system. A sophisticated injection mechanism is designed by
the means of dislocation parallel distribution of the screw and injector piston rod. It possesses the function of
pipetting, taking and removing the pipette tips. In the control system, STM32 controller is used, controlling
the single-axis S-type acceleration/deceleration algorithm and multi-threaded coordinated motion. The acceleration/
deceleration curves are analyzed and optimized by using the method of segmentation; a minimum injection
rate of 1 μL and a step rate of 0.05μL are realized. The method of digital image processing is used to detect
the amount of pipetting in micro-pipetting quantitatively. The liquid area is extracted by background contrast
method, and the liquid volume in the tip is obtained by combining the geometric characteristics of the disposable
tip, when the pipetting capacity is not qualified to carry out specific guidance on the pipetting system, and avoid
the blocking needle, bubble and other abnormal pipetting phenomenon on the impact of pipetting accuracy. The
experimental results show that the combination of the automatic sampling system and the image flow detection
system can effectively improve the precision and reliability of the micro-pipetting system. Finally, the injection
accuracy of the system at the test points with 10, 50 and 100 μL liquid volumes reaches 1.8%, 1.28% and 1.15%
respectively.
SHANG Zhiwu (尚志武), ZHOU Xiangping (周湘平), LI Cheng (李成), ZHOU Xinyu (周昕宇)
. Design of Micropipette System with High Precision for Small Enzyme Immunoassay Analyzer[J]. Journal of Shanghai Jiaotong University(Science), 2019
, 24(5)
: 605
-615
.
DOI: 10.1007/s12204-019-2104-4
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