| At present,the small mass spectrometer has become a necessary analytical instrument in many fields,which is widely used in food safety inspection,environmental monitoring,airport security,aerospace and military technology.The development of miniaturized mass spectrometer is a hot topic in the field of mass spectrometry,such instruments are small in size,light in weight,and low in power consumption,and have significant advantages in terms of effectiveness and cost compared with conventional mass spectrometers.The measurement and control system is a key part of the mass spectrometer.It is used to control the instrument for sample collection,quality analysis,state switching,data acquisition and transmission,and is the control center of the entire mass spectrometer.The traditional mass spectrometer measurement and control system has problems such as large volume,high power consumption,large number of board cards,and low intelligence,and cannot be used for a small-scale mass spectrometer.In fact,the miniaturization design of the measurement and control system is one of the technical bottlenecks for the miniaturization of the mass spectrometer,its design difficulty is reflected in the following aspects: The volume,weight,and power consumption are greatly reduced compared with the traditional measurement and control system,but the control is required that complexity and performance cannot be reduced;miniaturized mass spectrometry requires fast analysis,and therefore puts high requirements on the real-time processing capabilities,data storage and data exchange rates of the measurement and control system;The use environment of miniaturized mass spectrometry is complex,and it is a major test for the environmental adaptability of the measurement and control system;it is necessary to achieve amplification and data acquisition of weak mass spectrometry signals under external interference conditions.According to the technical difficulties,this paper designed a set of novel miniaturized mass spectrum measurement and control system,its main technical characteristics and innovation as follows:(1)Based on ARM + FPGA dual-core architecture design,cope with the control complexity and real-time requirements of the miniaturized mass spectrometer;(2)In the system control and data transmission process,dual-process cycle control technology is adopted to realize the parallel operation of the instrument timing control and data transmission,and eventually improve the analysis speed of the miniaturized mass spectrometer;(3)The use of optocoupler bidirectional isolation and data differential transmission technology ensure the ultra-low noise performance of weak signal amplification and mass spectrometry data acquisition systems;(4)Using the new Ethernet chip W5500 to complete the Ethernet communication between the measurement and control system and the PC,to achieve high-speed data exchange between the measurement and control system and the PC;(5)Using FSMC bus interface of ARM to complete the high-speed communication between ARM and FPGA,To solve the problems of slow rate of serial communication and big design complexity of parallel communication between the traditional processors.(6)Adopted the technology of multilayer PCB,miniature and low power electronic components to realize the highly integrated system design,greatly reduces the overall power consumption and volume of the measurement and control system.In the actual work process,the program verification and system design of the entire measurement and control system were first completed,and the schematic design and PCB diagram design were performed on this basis;then the overall design and programming of the ARM processor’s embedded software were performed.The Verilog language has designed the logic program of FPGA,realized the communication between ARM and FPGA and the data exchange between ARM and host computer,as well as the control function of mass spectrometer;then,it realized the joint debugging and performance testing of the entire measurement and control system;finally,The designed mass spectrometry control system was successfully applied to the miniaturized mass spectrometer developed by this group.The final design of the measurement and control system based on the dual-core architecture of ARM and FPGA completed a total of 2 PCB boards,the integrated installation of the overall volume of 16×14×4.5cm3,weight 0.48 kg,steady-state power consumption of 24W;through the Ethernet interface with the PC to achieve data transfer and human-machine interaction,the data transmission rate of the selected Ethernet chip is up to 80MHz;the average noise of the weak signal amplification and data acquisition system is lower than 0.5m V.The overall performance of the miniaturized mass spectrometer using this measurement and control system was excellent,and good results were obtained in mass resolution,mass range,detection sensitivity,analysis speed,and instrument stability.In particular,the analysis speed of the instrument can reach 6 times per second(that is,6 analyses per second can be achieved,and 6 spectra can be obtained),which is higher than that of an ordinary ion trap mass spectrometer. |
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