We present an innovative experimental set-up that uses Nitrogen-Vacancy centres in diamonds to measure magnetic fields with the sensitivity of $\eta =68\pm 3~\mathrm{nT}/\sqrt{\mathrm{Hz}}$ at demonstrated (sub)cellular scale. The presented method of magnetic sensing, utilizing a lock-in based ODMR technique for the optical detection of microwave-driven spin resonances induced in NV centers, is characterized by the excellent magnetic sensitivity at such small scale and the full biocompatibility. The cellular scale is obtained using a NV-rich sensing layer of 15 nm thickness along z axis and a focused laser spot of $(10 \times 10)~\mu\mathrm{m}^{2}$ in x-y plane. The biocompatibility derives from an accurate choice of the applied optical power. For this regard, we also report how the magnetic sensitivity changes for different applied laser power and discuss the limits of the sensitivity sustainable with biosystem at such small volume scale. As such, this method offers a whole range of research possibilities for biosciences.

中文翻译：

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利用氮空位中心在（亚）细胞范围内感应磁场的生物兼容技术

我们介绍了一种创新的实验装置，该装置使用钻石中的氮气空缺中心来测量磁场，灵敏度为$ \ eta = 68 \ pm 3〜\ mathrm {nT} / \ sqrt {\ mathrm {Hz}} $证实的（亚）细胞规模。所提出的磁感应方法，利用基于锁定的ODMR技术对在NV中心诱发的微波驱动的自旋共振进行光学检测，其特点是在如此小的规模下具有出色的磁灵敏度和完全的生物相容性。使用沿z轴厚度为15 nm的富含NV的传感层和xy平面中的$（10×10）〜\ mu \ mathrm {m} ^ {2} $的聚焦激光光斑来获得细胞尺度。生物相容性源自对所施加光功率的准确选择。在这方面，我们还报告了在不同的激光功率下磁灵敏度如何变化，并讨论了在如此小的体积规模下生物系统可持续的灵敏度极限。这样，该方法为生物科学提供了广泛的研究可能性。