Optimization and experimental test of a miniature permanent magnet structure for a microfluidic magnetic resonance chip

Article type: Research Article

Authors: Lu, Rongsheng^{a; b} | Yi, Hong^{a; b} | Wu, Weiping^{a; b} | Jiang, Yun^{a; b} | Ni, Zhonghua^{a; b; *}

Affiliations: [a] Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing, Jiangsu, China | [b] School of Mechanical Engineering, Southeast University, Nanjing, Jiangsu, China

Correspondence: [*] Corresponding author: Zhonghua Ni, School of Mechanical Engineering, Southeast University, Nanjing 211189, China. Tel.: +86 25 5209 0518; Fax: +86 25 5209 0504; E-mail: nzh2003@seu.edu.cn

Abstract: We propose a general global optimal algorithm to optimize the miniature permanent magnet structure of a micro magnetic resonance chip (μ NMR-chip). For this purpose, we analyze the sensitivity of the permanent magnet structure to the design variables and determine the optimization variables. After this, radial basis function neural networks (RBFNNs) are constructed to model the objective functions, and the nondominated sorting genetic algorithm II (NSGA II) is improved by introducing a different weighting factor for each objective function in calculating the crowding distance. Combining the RBFNN with the improved NSGA II optimizes the miniature permanent magnet structure. Through comparison, the optimization solutions are proven effective. Finally, the optimized permanent magnet structure is manufactured and tested experimentally. After optimization, the volume of the permanent magnet block is reduced by 39%, and the permanent magnet becomes easier to manufacture.

Keywords: Microfluidic chip, nuclear magnetic resonance, permanent magnet, multiobjective optimization

DOI: 10.3233/JAE-131678

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 4, pp. 479-489, 2013