原子核磁共振显微检测芯片的磁路设计

Development of micro-permanent magnet magnetic circuit for nuclear magnetic resonance microscopy chip

基于磁路设计理论首先设计了一种适用于原子核磁共振显微检测芯片的永磁磁路;然后根据磁路磁通折射定理和基尔霍夫第一定律对设计的磁路模型进行理论分析,提出了单一匀场环磁路性能优化方法;最后利用有限元方法分别计算了优化前的磁路、单一匀场环优化后磁路和传统的双匀场环优化后磁路.计算结果表明:相比优化前和采用传统的双匀场环优化后的磁路,采用单一"匀场环"优化后的磁路其性能最优,工作区域内磁场强度和均匀度都得到了极大的提高,磁场强度达到0.703 544 T,工作区域内磁场均匀度为14×10-6.因此所设计的磁路能够较好地满足原子核磁共振显微检测芯片的需求.

A micro-permanent magnet magnetic circuit specially applied in nuclear magnetic resonance microscopy chip was designed according to the theory of magnet circuit.Based on magnetic flux refraction law and Kirchhoff＇s first law,a concept called single shimming is proposed for optimizing the performance of the designed magnet circuit.At last,primary designed magnet circuit,magnet circuit optimized with single shimming and magnet circuit optimized with conventional double shimming are separately computed using Maxwell finite element（Ansoft）simulation.Results show that magnet circuit optimized with ＇single shimming＇ has the best performance compared with the other two magnet circuits.Both magnetic field strength and magnetic field homogeneity are improved greatly.A magnetic field strength of 0.703544 T with magnetic field homogeneity of 14×10-6 in sensitive spot is achieved after optimization.In conclusion,the developed micro-permanent magnet magnetic circuit in this paper meets the demands of nuclear magnetic resonance microscopy chip（NMRM-chip）.