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Description
Over the past decade, nitrogen-vacancy (NV) centers in diamond have emerged as a powerful platform for quantum sensing, generating increasing interest in biomedical applications due to their high spatial resolution, inherent biocompatibility, and ability to operate under ambient conditions. One of the key advantages of NV-based sensors is the chemical and mechanical robustness of the diamond host material, which allows direct contact with biological samples while enabling the detection of nearby magnetic signals such as those produced by muscle activity or nerve impulses.
While a variety of fiber-integrated NV sensor configurations have been demonstrated, most suffer from limited portability, restricting their usability in surgical or in vivo environments where compactness and flexibility are a crucial requirement.
This work presents a compact, flexible, and portable fiber-based NV sensor specifically designed to address these challenges. Our device is fabricated using direct laser writing, to create functional microstructures composed of silver and polymer materials directly on the tip of an optical fiber. The silver structure enables efficient microwave excitation of the NV centers, while the polymer component provides mechanical stabilization for a 40 μm diamond crystal mounted at the fiber tip and assists in the alignment of optical excitation and fluorescence collection.
We validate the sensor's performance by detecting bioinspired electrical signals. The device achieves a magnetic field sensitivity of 6 nT/√Hz under ambient conditions. This demonstration is a step towards future use in minimally invasive biomedical diagnostics and intraoperative applications.
