UC Berkeley

The rapid development of quantum sensors and associated sensing techniques over the last decade has yielded powerful new means to measure physical parameters such as magnetic fields, electric fields, temperature, and pressure with unprecedented sensitivity and resolution, even in challenging contexts such as nanoscale-localized areas of interest, biological systems, and under extreme pressures. Despite these advances, substantial challenges to the physical deployment of quantum sensors continue to hinder their practical application. This thesis explores the synergistic convergence of spin-active materials such as nitrogen vacancy (NV-) centers in diamond with advanced micro/nano fabrication methods to achieve novel and pragmatic sensing capabilities for a variety of unmet applications spanning thermometry, ion sensing, and magnetometry.As a first demonstration, nanodiamonds are incorporated into micro-structured materials produced using two-photon polymerization (TPP), and designer quantum sensor assemblies are fabricated to extract local temperature and magnetic field conditions using ensemble optically detected magnetic resonance (ODMR) imaging. These techniques are expanded to develop spatially selective 2D nanodiamond patterning capabilities and wide-field lock-in ODMR imaging techniques for resolving microscale temperature profiles. Furthermore, 3D optical reconstruction techniques are developed for optically investigating the interior of micro-architected materials. Employing single-photon confocal microscopy techniques, the reconstruction of complexly designed fluorescent structures is demonstrated. These techniques are further expanded to multiphoton fluorescence and third-harmonic generation techniques that can be employed for various other use cases, such as imaging deeper into structures and imaging non-fluorescent materials. Additionally, these materials are imaged during in-situ actuations to demonstrate the applicability of these imaging techniques in exploring dynamic stimuli. Culminating these advances, larger-scale 3D structures with controlled concentrations of nanodiamonds attached to the structure are fabricated, enabling proximal sensing of analytes of interest. Confocal ODMR techniques are developed for resolving temperature across three-dimensional volumes and taking high sensitivity transient temperatures using the structures as a point sensor. Avenues for continuing work and applications are also discussed. Other optically addressable spin-active systems can potentially be utilized in place of NV- centers. In preparation of exploring new material systems, advanced characterization equipment, including a novel in-situ TEM holder with in-situ optical characterization abilities is built and discussed.