基于微机电系统加工技术的微小型矩形离子阱的研制

Development of Micro-sized Rectangular Ion Trap Based on Micro-Electro-Mechanical System Processing Technology

矩形离子阱(RIT)不仅具有线性离子阱(LIT)捕获效率高和存储容量大等特点,还兼具圆柱形离子阱(CIT)易加工和装配的优点,具有小型化的优势。为了使RIT进一步微小型化,本研究采用微机电系统(MEMS)和激光切割技术加工微小型RIT,并通过模拟仿真分析RIT的各项参数与其内部电场成分的关系。结果表明:固定离子阱非出射方向的场半径为1.4 mm,拉伸离子出射方向的场半径为1.60 mm,在电极厚度为50μm时,分析m/z 119离子的质量分辨率可达到452。使用MEMS工艺可制备高精度、微米级的微小型RIT。质谱分析表明,制备的微小型RIT对m/z 391的邻苯二甲酸二辛酯具有高于500的质量分辨能力,该结果验证了其结构设计的正确性以及MEMS工艺制备的可行性,为矩形离子阱的进一步微小型化奠定了良好基础。

Rectangular ion trap(RIT)has the advantages of high capture efficiency and large storage capacity of linear ion trap(LIT),as well as the advantages of cylindrical ion trap(CIT)which is easy to process and assemble,so it is conducive to miniaturization.The miniaturization of ion trap has certain requirements on the accuracy of machining technology and the flatness of machining surface,but the conventional machining method can not produce enough accurate electric field on the scale of micrometer.In order to further study the microminiaturization of RIT,micro electromechanical system(MEMS)and laser cutting technology were used to fabricate the micro rectangular ion trap,and the relationship between the parameters of RIT and its internal electric field components was analyzed by simulation.The simulation results showed that the high-order fields inside the micro RIT are mainly octopolar field and duodecuple field.At the scanning speed of 2530 Th/s,when the field radius in the non-emission direction of the ion trap was 1.4 mm,the field radius in the ion emission direction was 1.60 mm,and the electrode thickness was 50μm,the mass resolution of the ion with m/z 119 could reach 452.The results of simulation analysis were combined with process characteristics to determine the structural parameters of micro RIT.Non silicon MEMS technology was used to prepare high-precision,micron level exit direction electrode,which had a great impact on the performance of ion trap.The overall alignment and assembly of the ion trap was achieved by laser cutting and precision tenon-and-mortise structure,and mass spectrometric analysis tests were performed to verify its performance.Experiment showed that micro RIT can analyze the mass of toluene and other ions with mass less than 100 and the mass resolution is higher than 200,which proves the correctness of structure design and the feasibility of MEMS process,and lays a good foundation for the development of the microminiaturization of the RIT.