Abstract Any existing method of visualization of magnetic nanoparticles in biological objects provides for imposing of an external magnetic field on the object under study. The field can considerably change the space distribution and properties of the nanomagnetic ensemble under study. In our work a SQUID-based magnetoencephalography device was used for the measurement of a magnetic noise generated by superparamagnetic nanoparticles based ferrofluid in the stationary standing vial without imposing of an external magnetic field. It was demonstrated that the ferrofluid generates spontaneous magnetic fields sufficient for its localization inside the experimental setup. Besides it was revealed that the spontaneous magnetic fields at certain frequencies have a strong spatial anisotropy. The detected effect can essentially increase the spatial resolution of the proposed method of visualization of magnetic nanoparticles in biological objects without using the external magnetic field.

中文翻译：

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地磁场中磁粒子产生的磁噪声各向异性研究

摘要 任何现有的生物对象中磁性纳米粒子的可视化方法都提供了在研究对象上施加外部磁场的条件。该场可以显着改变所研究的纳米磁性集合的空间分布和特性。在我们的工作中，基于 SQUID 的脑磁图设备用于测量由基于超顺磁性纳米颗粒的铁磁流体在固定立瓶中产生的磁噪声，而无需施加外部磁场。结果表明，铁磁流体产生的自发磁场足以使其在实验装置内定位。此外还揭示了某些频率下的自发磁场具有很强的空间各向异性。