Abstract

Using selective dissolution, we create α-Fe/DyPrFeCoB microwires with a parabolic tip for focusing the magnetic flux and enhancing the magnetic attraction of particles. The conditions for sharpening the end of the microwire by etching with HNO₃ and with mixtures of HNO₃ + HCl and H₂SO₄ + HNO₃ are also optimized. The magnetic force of a single microwire with a pointed end (up to 880 pN) makes it possible to capture and hold a DyPrFeCoB microparticle with a size of 1 µm in the region of ~5 µm. A significant magnetic-field gradient (up to ~3.5 × 10⁵ T/m), created at the tip of the microwire, is sufficient to affect biological processes inside cells even without magnetic markers. The conditions for the attachment/detachment of a magnetic microparticle are controlled by the exchange bias arising at the interface between the α-Fe ferromagnetic core and the PrDyFeCoB ferrimagnetic shell and by four magnetic states of the microwire, which are switched by a weak external uniform magnetic field of ~0.1–2 kA/m.

中文翻译：

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基于DyPrFeCoB合金的微镊子的化学设计

摘要

使用选择性溶解，我们创建了具有抛物线形尖端的α-Fe/ DyPrFeCoCoB微线，用于聚焦磁通量并增强粒子的磁引力。还优化了通过用HNO ₃以及HNO ₃ + HCl和H ₂ SO ₄ + HNO _3的混合物进行蚀刻来使微丝末端变尖锐的条件。具有尖端（最大880 pN）的单根微线的磁力使得可以捕获和固定大小约为1 µm的DyPrFeCoCoB微粒，其粒径约为5 µm。明显的磁场梯度（高达〜3.5×10 ⁵即使在没有磁性标记的情况下，在微丝尖端产生的T / m也足以影响细胞内的生物过程。磁性微粒的附着/脱离条件由在α-Fe铁磁芯和PrDyFeCoB亚铁壳之间的界面处产生的交换偏压以及微丝的四个磁性状态控制，这些状态由弱的外部均匀性来切换磁场为〜0.1–2 kA / m。