High-resolution and high-sensitivity nanoparticle based dual-comb magnetic field microscopy

Magnetic field imaging plays a crucial role in advancing science and technology, with applications ranging from studying physical systems to understanding biological processes. Recently, two innovative quantum sensors have gained attention for their ability to measure magnetic fields with high precision: the microfabricated optically pumped magnetometer (μOPM) and the nitrogen-vacancy (NV)-diamond magnetometer.

The μOPM is highly sensitive, capable of detecting extremely weak magnetic fields at the millimeter scale, making it ideal for measuring weak fields but less effective for capturing fine details. On the other hand, the NV-diamond magnetometer excels in providing nanometer-level detail, which is ideal for imaging but has lower sensitivity to weak fields.

This project aims to bridge the gap between these two technologies by developing a new type of magnetic field microscope that combines high sensitivity and high resolution. This will be achieved by advancing the synthesis of rare-earth-doped magnetic nanoparticles and utilizing cutting-edge dual-comb microscopy techniques. The resulting nanoparticle-based dual-comb magnetic field microscope will be the first of its kind, offering unparalleled sensitivity to detect extremely weak magnetic fields and the ability to capture fine details at the micrometer scale.

This breakthrough technology will enable cellular-level studies of magnetic fields in biology and precise mapping of magnetic patterns in integrated circuits, addressing key challenges in both fields.

We will leverage our complementary expertise to overcome the key limitations of the current state-of-the-art non-invasive magnetic field microscopy. In the first aim, we will build on our preliminary work to address several key issues needed to obtain high-quality magnetic nanoparticle-polymer composite with high Verdet constant and low absorption. Specifically, we will (1) obtain polymer nanocomposite films with high magnetite nanoparticle (MNP) loading, and low absorption to enable high resolution imaging, (2) investigate rare-earth doping in MNPs for higher Verdet constant, (3) develop silica coating to mitigate degradation of MNPs, and (4) explore other inverse spinel magnetic nanoparticles that might exhibit even higher Verdet constant.

In the second aim, we will build on our preliminary work to develop an innovative high-resolution and high-sensitivity magnetic field microscopy that uses magnetic nanoparticle thin film as the sensing unit and dual-comb microscopy as the readout unit. Specifically, we will (1) develop a high-power and low-noise single-cavity dual-comb light source, (2) build a 2D spatial disperser and RF electronics necessary for dual-comb microscopy, (3) retrofit the existing microscope with the free-running single-cavity dual-comb light source, 2D spatial disperser, and RF electronics, and (4) characterize its imaging performance with micromagnet array phantoms.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.