A cancer diagnosis becomes most challenging when tumor cells metastasize and spread to other organs, most often through the lymph nodes and the lymphatic system. Detecting whether cancer cells are lodged in the lymph nodes is the gold standard for diagnosing metastasis and guiding treatment. However, traditional methods involve radioactive tracers or blue dyes, both of which pose limitations such as safety concerns or allergic reactions. Now, a new diamond-based magnetic field sensor offers a non-toxic approach to improve tumor detection by tracing magnetic fluid injected in the body.

Scientists at the University of Warwick (Coventry, UK) have created an endoscopic diamond magnetometer, a handheld device that leverages the properties of diamonds to detect tumors more effectively. The compact design uses a tiny diamond with nitrogen vacancy (NV) color centers and a small permanent magnet attached to a probe head, eliminating bulky electronics. The sensor detects magnetic tracer fluid made of iron oxide nanoparticles, which are injected into tumors and travel to lymph nodes alongside cancer cells.

In a study published in Physical Review Applied, the researchers demonstrated that this device is the first diamond sensor small enough for endoscopic use in keyhole surgery. The prototype reduced the sensor head to just 10 mm, making it highly versatile and minimally invasive. Despite its size, the sensor proved ultra-sensitive, capable of detecting one hundredth of a typical clinical dose of tracer fluid while still operating at long ranges.

Tracing cancer with magnetic tracers is already becoming more common, but existing detection systems lack portability and sensitivity. This new diamond-based sensor provides an upgraded solution that could be applied not only to breast cancer surgery but also to other cancers such as lung, liver, colorectal, and esophageal. With further development, it could also expand into non-medical uses, including spacecraft technology and fusion power applications.

The device has been designed with input from clinicians to ensure it meets surgical needs and offers a safer, more accurate alternative to current tracers. By providing surgeons with a more precise tool for locating lymph nodes, it could reduce complications, accelerate procedures and improve patient outcomes. Future work will focus on refining the sensor’s performance and incorporating more advanced quantum technology techniques to further boost its accuracy and usability.

“Diamonds can sense magnetic fields thanks to color centers in the diamond, called nitrogen vacancy centers. They allow the diamond to detect very small changes in magnetic field and give the diamonds a lovely pink color,” said Professor Gavin Morley, senior author of the study. “We hope to use these magnetic field sensors not just for medical applications, but for spacecraft and fusion power too.”

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