Two-dimensional nuclear magnetic resonance spectroscopy with a microfluidic diamond quantum sensor

Abstract

Quantum sensors based on nitrogen-vacancy centers in diamond have emerged as a promising detection modality for nuclear magnetic resonance (NMR) spectroscopy owing to their micrometer-scale detection volume and noninductive-based detection. A remaining challenge is to realize sufficiently high spectral resolution and concentration sensitivity for multidimensional NMR analysis of picoliter sample volumes. Here, we address this challenge by spatially separating the polarization and detection phases of the experiment in a microfluidic platform. We realize a spectral resolution of 0.65 ± 0.05 Hz, an order-of-magnitude improvement over previous diamond NMR studies. We use the platform to perform two-dimensional correlation spectroscopy of liquid analytes within an effective ∼40-picoliter detection volume. The use of diamond quantum sensors as in-line microfluidic NMR detectors is a major step toward applications in mass-limited chemical analysis and single-cell biology.

Sensitivity optimization for NV-diamond magnetometry

“…Realizing NV-diamond magnetometers with improved sensitivity could enable a new class of scientific and industrial applications poorly matched to bulkier SQUID and vapor-cell technologies. Examples include noninvasive, real-time magnetic imaging of neuronal circuit dynamics (Barry et al, 2016), high throughput nanoscale and micron-scale NMR spectroscopy (Bucher et al, 2018;Glenn et al, 2018;Smits et al, 2019), nuclear quadrupole resonance (NQR) (Lovchinsky et al, 2017), human magnetoencephalography (Hämäläinen et al, 1993), subcellular magnetic resonance imaging (MRI) of dynamic processes (Davis et al, 2018), precision metrology, tests of fundamental physics (Rajendran et al, 2017), and simulation of exotic particles (Kirschner et al, 2018). This review accordingly focuses on understanding present sensitivity limitations for ensemble-NV − magnetometers to guide future research efforts.…”

Principles and techniques of the quantum diamond microscope

“…An HPHT diamond with uniform NV volume density can be cut into ∼35 µm thin slice. Alternatively, an HPHT diamond can be implanted with helium ions to form a shallow NV layer [80][81][82].…”

Artificial intelligence enhanced two-dimensional nanoscale nuclear magnetic resonance spectroscopy

“…Thank to high sensitive atomical-scale nitrogen-vacancy (NV) centers 1,2 , nanoscale magnetic resonance spectroscopy has been developed rapidly over the past years. Single spin sensitivity NMR 3 , single-molecule magnetic resonance 4,5 , and microscopic 2D NMR 6 have been realized with NV centers. While these works on nanoscale NMR make it possible to provide an insight into molecule structure, 2D nanoscale NMR 7,8 is a crucial step.…”