26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Ion Concentration and Voltage Imaging with Fluorescent Nanodiamonds

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral ANZOS | Photonics and Optics (ANZCOP)

Speaker

Philipp Reineck (RMIT University)

Description

The nitrogen-vacancy (NV) center in diamond exists in different charge states with distinct photoluminescence properties, which are sensitive to the nanoscale electrochemical environment. Hence, the NV charge state is emerging as a powerful all-optical platform for nanoscale sensing and imaging. Although significant progress has been made in engineering near-surface NV centers in bulk diamond, controlling the NV charge state in fluorescent nanodiamonds (FNDs) has proven challenging, limiting the sensitivity and reliability of FND-based charge state sensing.
This presentation will highlight recent progress in developing fluorescent nanodiamonds as a reliable and versatile platform for sensing ion concentrations and voltages in 2D and 3D. We demonstrate reliable, reversible switching between the fluorescent NV0 and non-fluorescent NV+ charge states in sub-30 nm FNDs via surface oxidation and hydrogenation, respectively, for single particles and particle powder.[1] In aqueous electrochemical cells, we demonstrate voltage and ion concentration imaging based on the NV charge state in self-assembled FND layers on transparent substrates. Applied voltages reliably modulate the FND PL with a sensitivity of up to 16 mV Hz-1/2. Importantly, FND PL is also modulated by local changes in salt concentration with a sensitivity of up to 1.8% per millimolar NaCl, enabling all-optical imaging of ion concentration gradients at the microscale.[1]
Furthermore, our recent progress in the fabrication and characterisation of scalable 2D and 3D nanodiamond-based quantum sensing substrates for magnetic imaging,[2, 3] electric-field sensing,[4] and magnetic noise detection[5] will be summarised. Our results represent a significant step toward realizing fast, stable, and scalable nanoscale sensing and imagaing technologies with sub-micrometer spatial resolution based on fluorescent nanodiamonds.

References

[1] P. Voorhoeve, H. Abe, T. Ohshima, Q. Sun, A. Quigley, R. Kapsa, N. Dontschuk, P. Reineck, Ion Concentration and Voltage Imaging with Fluorescent Nanodiamonds, arXiv:2602.13975 (2026).