Anal Chem. 2018 Aug 7;90(15):9226-9233. doi: 10.1021/acs.analchem.8b01724. Epub 2018 Jul 11.
Magnetic levitation is a recent research hot spot; however, most of the extant configurations use two magnets with like poles facing each other. This paper proposes a novel magnetic levitation configuration that is based on a single ring magnet, and this configuration opens a wide operational space that enables object manipulation and density-based measurement. We develop a mathematical model to calculate the magnetic field around the magnet and to numerically correlate the levitation height and density of the object. Experimental results prove that this novel configuration can achieve a high accuracy (±0.0005 to ±0.0078 g/cm) in density measurement for small-sized (∼5 μL) samples. It can manipulate particles, powders, and oil droplets effectively without any direct contact, and it has high sensitivity in the separation of multiple diamagnetic objects with slight differences in densities as well. The accuracy and sensitivity of the proposed configuration are both higher than those of the extant configurations. All of these results are expected to promote deeper study and applications of the magnetic levitation configuration in the field of density-based characterizations and manipulations.
磁悬浮是当前的研究热点；然而，现有的大多数配置都使用两个彼此相对的同极磁铁。本文提出了一种基于单个环形磁铁的新型磁悬浮配置，该配置开辟了广阔的操作空间，可实现物体的操纵和基于密度的测量。我们开发了一个数学模型来计算磁铁周围的磁场，并对悬浮高度和物体密度进行数值关联。实验结果证明，这种新型配置可以对小尺寸（约 5μL）样品实现高精度（±0.0005 至 ±0.0078g/cm）的密度测量。它可以有效操纵颗粒、粉末和油滴，而无需任何直接接触，并且在分离密度略有差异的多个抗磁物体时具有很高的灵敏度。所提出的配置的准确性和灵敏度均高于现有的配置。所有这些结果都有望促进磁悬浮配置在基于密度的特性和操作领域的更深入研究和应用。
