Development Of A Contact Automatic Microarrayer With Drying Function

In the past ten years,Matrix assistant laser desorption ionization--Time of flight Mass Spectrometer(MALDI-TOFMS)has been developed continuously.MALDI-TOFMS has been widely used in not only gene sequencing,microbial identification and environmental pollution monitoring,but also clinical diagnosis and other fields.At present,the sample is spotted on the target plate usually by manually.This method results in not only inefficient and inaccuracy of the sample volume,but also affects the final analysis results.In addition,the automatic microarrayer sale on the market has very simple function.It only can drop samples automatically,and it cannot finish the drying of the target board automatically.Therefore,it is necessary to develop a special automatic microarrayer instrument for MALDI-TOFMS to solve these disadvantages,and increase the accuracy and efficiency of the sample preparation,and finally improve the accuracy of the analysis and identification results of the MALDI-TOFMS.This project has developed a cost-effective fully automatic microarrayer for MALDI-TOFMS.It can has three major functions:automatic sampling accurately,cleaning,and drying as well.In order to realize these three functions,this research involves three aspects of research contents and works,including mechanism,electrical system and software development.In the aspect of mechanical structure design,a set of 5 axises motion mechanism is designed.The drying of the sample target plate is realized by small vacuum pump.In the design of electrical system.The electrical system includes the MCU module,the communication module,the stepping motor drive module,the limit switch module,the drying control module and the power module.As to software system,it includes three parts:single chip control program,user operation program and interface software.Finally,the volume precision of the sampling is tested by weighing method,and the sampling error of the automatic microarrayer is 4.28%(less than 5%),which meets the design requirements.The microorganism(Escherichia coli)protein extraction was selected as the test sample.The target plate prepared by the automatic microarrayer was sent to MALDI-TOFMS for actual spectrum acquired.The relative standard deviation(RSD)of eight protein molecules relative intensity is less than 15%,which showed that the mass spectrum had good repeatability,and proved that the automatic microarrayer can meet the requirements of the analysis and identification of MALDI-TOFMS as well.The main innovations of this paper are to design a set of five axis motion mechanism to achieve fully automatic sampling and an efficient communication protocol is designed.