Designing Diamonds for Medical Imaging Technologies

Medical Design Briefs INSIDER

Schematic illustration of the nin diamond junction in the xy plane (a) and in the z plane (b). Optical microscopy image of the nin diamond (c). Scanning confocal microscopy images of the mesa structures of d = 2 μm and (e) d = 10 μm (d). (Credit: Applied Physics Letters)

Researchers have optimized the design of laboratory-grown, synthetic diamonds, bringing the new technology one step closer to enhancing biosensing applications, such as magnetic brain imaging.

Chemical processes are used to create large sheets of diamonds for industrial applications. Artificial diamonds can be grown on various surfaces to increase the hardness and reduce the wear of tools, or to take advantage of diamond's high thermal conductivity as a heat sink for electronics. Scientists can manipulate the properties of artificial diamonds by altering their chemical composition. This chemical manipulation is called doping. These "doped" diamonds are proving to be a cheap alternative material for a range of technologies - from quantum information to biosensing - that would otherwise have been prohibitively expensive to develop.

The researchers had previously doped a simple diamond structure with phosphorus to stabilize the nitrogen-vacancy (NV) centers. Phosphorus doping pushed over 90 percent of NV centers to the negative charge state, enabling magnetic field detection. However, the phosphorus introduced noise to the readout, negating the positive result.

In this study, the team adapted the diamond design to preserve the stabilization of negative NV centers, but removed the phosphorus-induced noise. They used a layered structure, like a sandwich, with phosphorus doped diamond as the bread, and enclosed a 10-µm thick NV-center diamond filling. This stabilized 70-80 percent of NV centers in the negative charge state, while reducing the noise previously seen in the system.

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