3 October 2025
Faculty of Sciences University of Porto (FCUP)
Europe/Lisbon timezone

Color centers in diamond for neuronal signalling studies: Fabrication and transient signalling detection

Not scheduled
20m
Faculty of Sciences University of Porto (FCUP)

Faculty of Sciences University of Porto (FCUP)

Departamento de Física e Astronomia FCUP Rua do Campo Alegre, 4169-007 Porto
Contributed Talk (20 minutes)

Speaker

João Silva (Faculdade de Ciencias da Universidade do Porto)

Description

Non-invasive, high-resolution detection of neuronal activity remains a key challenge in neuroscience and bioimaging. Nitrogen-vacancy (NV) center magnetometry is a promising quantum sensing technology capable of detecting the weak magnetic fields generated by neuronal currents.A key requirements to obtain good quantum sensors with optimal properties is the fabrication. While ion implantation is the dominant method, laser irradiation has shown promising but is still comparatively less explored.~
In the first part of this talk, I present the creation of NV centers using a 500 kHz, 515 nm laser in a single step process with no separate seed/vacancy diffusion pulses and no annealing step. By varying energy per pulse, laser exposure time and depth, we identify how this parameters affect the writing process and the impact of other laser writing processes such as graphitization, ablation and self-focusing.
In the second part, we present a novel approach using bias-free, single-frequency continuous-wave optically detected magnetic resonance (CW-ODMR) to enable sensitive, non-invasive neuronal signal detection with single-cell resolution using a commercial diamond. By removing the bias magnetic field, we avoid perturbing natural neuronal behavior, enhancing biocompatibility. Restricting detection to a single frequency further reduces acquisition time, enabling fast imaging. Our method achieves a temporal resolution of 0.2 ms. We validated our system using a biomimetic gold wire model, applying a 5 V, 2 ms stimulus. A reproducible 1% contrast was observed in single-shot measurements, clearly correlating with the input signal. We also present analysis of signal origin, contrast sensitivity, and system limitations.
Together, these studies advance both the fabrication and application of NV centers paving the way toward real-time quantum bioimaging tools with high sensitivity and resolution.

Which topic best fits your talk? Optics and Photonics

Author

João Silva (Faculdade de Ciencias da Universidade do Porto)

Co-authors

Prof. Paulo V. S. Marques (INESC TEC, CAP – Centre for Applied Photonics, Rua do Campo Alegre 687, Porto, Portugal) Dr Jana B. Nieder (INL - International Iberian Nanotechnology Laboratory, Ultrafast Bio- and Nanophotonics group, Av. Mestre José Veiga s/n, Braga, Portugal)

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