Quantum on a budget: Developing a 3d-printed microscope for Optically Detected Magnetic Resonance of nanodiamond  

Session

Stream 6 (Frontiers): Correlative Imaging of Organelle Organization and Architecture

Authors

Mr Ryan Corbyn (1, 3), Miss Rebecca Craig (1), Miss Gemma Cairns (1, 2), Dr Brian Patton (1)

Affiliations

1. University of Strathclyde
2. 3. Optima CDT, University of Edinburgh
3. Diamond Science and Technology CDT, University of Warwick

Keywords

3D printed microscopes, Optical sensing

Abstract text

Even high-purity diamonds contain crystallographic defects, some of which have been shown to be fluorescent under optical excitation [1]. The Nitrogen-Vacancy (NV) defect, comprised of a substitutional nitrogen beside a vacancy, has seen a lot of interest due to its optical activity, with an emission spectra reaching into the near IR [2]. The extra electron in the negatively charged NV centre (NV-) leads to quantum-mechanical spin effects in the emission that can be exploited for optically detected sensing of magnetic fields and remote thermometry [3].  

After excitation by a green light source, the NV- centre can decay via either the emission of a photon (637-800nm) or via a phonon mediated intersystem crossing event [2]. This dual decay pathway is exploited in Optically Detected Magnetic Resonance (ODMR) experiments: The ground state of the NV- is split into 3 levels by spin state, with the ±1 spin states 30% more likely to decay via the intersystem crossing decay path without the emission of a visible photon [4]. Therefore, if the fluorescence intensity from the defect is monitored while an applied variable frequency microwave field is scanned around the resonant frequency of the NV- centre, the spin-state transition energies can be determined.   

We are particularly interested in the applications of fluorescent nanodiamonds (FNDs), diamond crystals that are between 5-100nm in diameter and contain NV centres upon which we can perform ODMR. Previous work has shown that nanodiamonds are biocompatible [5] and have been successfully integrated into live biological samples to measure local environmental temperature changes within the sample by monitoring the (microwave) resonant frequency of the NV- centre [7 ,8].  

The work cited above used costly, complex microscopes systems to perform these experiments. For the best sensitivity and flexibility, it is likely that many future applications will still need similar systems. However, low-cost alternatives can also offer significant benefits. In this presentation we will outline the progress made so far to develop a 3D printed, lower-cost microscope system capable of performing ODMR measurements on nanodiamonds. We will discuss the parameters that need to be taken into consideration when designing and testing the system, such as: Microscope design, camera quality, sample tracking, sample illumination, the microwave source, and present our latest results from test systems, including our initial estimations of the scope of experiments which are feasible using this system within realistic timescales and budgets.  

References

[1] Jelezko, F. & Wrachtrup, J. Single defect centres in diamond: A review. phys. stat. sol. (a) 203, 3207–3225 (2006). 

[2] Doherty, M. W. et al. The nitrogen-vacancy colour centre in diamond. Physics Reports 528, 1–45 (2013). 

[3] Wojciechowski, A. M. et al. Precision temperature sensing in the presence of magnetic field noise and vice-versa using nitrogen-vacancy centers in diamond. Appl. Phys. Lett. 113, 013502 (2018). 

[4] Rondin, L. et al. Magnetometry with nitrogen-vacancy defects in diamond. Rep. Prog. Phys. 77, 056503 (2014). 

[5] Schrand, A. M. et al. Are Diamond Nanoparticles Cytotoxic? J. Phys. Chem. B 111, 2–7 (2007). 

[6] Kucsko, G. et al. Nanometre-scale thermometry in a living cell. Nature 500, 54–58 (2013). 

[7] Fujiwara, M. et al. Real-time nanodiamond thermometry probing in vivo thermogenic responses. Science Advances 6, (2020).