DIAMOND-CONNECT

“The DIAMOND-CONNECT project shall combine the advances in quantum metrology approaches with the state-of-the-art sensing of 2D neuronal signaling. A highly promising quantum metrology technique is based on the fluorescence emission of Nitrogen Vacancy (NV) centers in diamonds, which can be used to assess various physical parameters such as temperature and magnetic field in their nanoscale surroundings. This project aims at developing a diamond photonics sensing platform delivering the quantum sensing units, the NV centers, in close nanoscale proximity to axons of neuronal cells, to obtain a quantum photonic read-out of the neuronal activity and connectivity in 2D cellular neuronal networks. The DIAMOND-CONNECT platforms shall be developed in a bulk diamond using a femtosecond laser to implant NV-centers at specific locations. Such technology was recently demonstrated by researchers from Oxford (2019)and will allow us, with existent laser technology at INL laser laboratory, to design the sensing units at desired locations, for optimized and targeted sensing conditions. The implantation depths and pattern shall be optimized for the sensing of within a neuronal cellular network. The Action Potentials (AP) in this type of model reach about 100mV, which creates a magnetic field that is strong enough to be detected in the tens of nanometer distance using Optically Detected Magnetic Resonance Readout (ODMR) on NV center containing diamonds. This has recently been shown using neuron-mimicking microelectrodes (Barry, 2017). A fluorescence widefield microscopy setup, with high quantum efficiency ( Nikon Ti-E, with Andor iXON EM CCD camera), will allow us to read out the simultaneous signal from all NV sensors in the designed grid allowing to investigate the of neuronal activity, connenctivity and potentailly plasticiity upon stimulation. An addition to the implanted NV centers, the diamond platform a micro-electrode shall be added to the platform, which shall be used to locally stimulate the neurons electrically. The DIAMOND-CONNECT sensing platforms shall improve the AP sensing technology compared to existent technology that is either not scalable (single measurement sites, such as in patch-clamp sensing) or is not specific ( e.g. in Ca+ imaging, where it is difficult to distinguish signals from different axons.) Therefore, DIAMOND-CONNECT includes benchmarking of the technology by comparison with current state-of-the-art genetically encoded voltage protein Ca+ fluorescence contrast microscopy which will be performed by our collaborators at U Aveiro (de Almeida lab).”