Method for In-Solution, High-Throughput T1 Relaxometry Using Fluorescent Nanodiamonds

This is the authors' abstract. We don't add key points for this paper.

Fluorescent nanodiamonds (FNDs) have been exploited as sensitive quantum probes for nanoscale chemical and biological sensing applications, with the majority of demonstrations to date relying on the detection of single FNDs containing either single nitrogen vacancies or nitrogen-vacancy ensembles. This places significant limits on the measurement time, throughput and statistical significance of a measured result as there is usually marked inhomogeneity within FND samples. Here, we have developed a measurement platform that can report the T₁ spin relaxation time from a large ensemble of FNDs in solution. We first describe a refined sensing protocol for this modality and then use it to identify the optimal FND size for the detection of paramagnetic targets. Our approach is simple to set up, robust and can be used for rapid material characterization for a variety of in-situ quantum sensing applications.