Researchers have created a new technique that exploits defects in nanoscale and microscale diamonds to potentially enhance the sensitivity of magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) systems while eliminating the need for superconducting magnets.
According to the UC Berkeley scientists who developed the technique, this could offer a simple solution to a longstanding imaging issues and make NMR and MRI cost-effective for a wider range of applications. Without the bulky magnets, this could also reduce the instruments from room-sized to benchtop-sized. The technique is described in Science Advances.
While this is not the first effort to incorporate diamonds into MRI and NMR, previous attempts have been unsuccessful. In this study, the scientists used a novel technique of zapping a collection of microscale diamonds with green laser light, subjecting it to a weak magnetic field, and sweeping across the sample with a microwave source. This enhanced the controllable spin polarization property of the diamonds by hundreds of times compared to conventional MRI and NMR techniques.
A special tool created to measure the spin polarization properties of the diamond samples aided in evaluating the success of efforts. The device helped the scientists home in on a good size for the diamond crystals. At first, crystals of about 100 microns were being used, but testing revealed a size of approximately 1 to 5 microns performed about twice as well.
The tiny diamonds can be manufactured in a cost-effective way by techniques such as the conversion of graphite to diamond. The scientists have already developed a miniaturized system that uses of-the-shelf components to produce the laser light, microwave energy, and magnetic field required to produce the spin polarization necessary and have applied for patents on the technique and components. Prototypes of the system cost just several thousand dollars, according to the researchers.
While the spin is short-lived, the team is working on ways to continuously polarize the sample and are researching how to transfer this polarization to liquids.
Image: The device in the diagram was used to study diamonds subjected to green laser light and low-field microwave energy. After they were pulsed with laser light, the diamond samples were quickly hoisted up to a high-field superconducting magnet to measure a property known as 'hyperpolarization.' Image courtesy of Berkeley Lab, UC Berkeley.