Cancer diagnosis is notoriously difficult to track once it spreads beyond the primary tumor. Tumor cells usually metastasize through the lymphatic system, making lymph node checks critical in diagnosis and treatment planning.
There is a real demand for versatile non-toxic means of finding cancer. For this new diamond-based sensor, we managed to get the size of the sensor head down to just 10 mm.
Alex Newman, First Author and PhD Student, University of Warwick
The device relies on nitrogen-vacancy centers in tiny diamonds. These defects in the crystal lattice make the gem turn pink while allowing it to detect minute magnetic fields. When paired with a small permanent magnet, the diamond sensor becomes sensitive enough to locate one hundredth of a standard clinical dose of magnetic tracer fluid.
This level of performance has never been seen before in a probe head just 10 millimeters wide. This size is achieved by employing a tiny diamond (0.5 mm3) and a small permanent magnet attached to the probe and reduces the need for large electronics, resulting in a portable, versatile instrument.
The diamond can detect very small changes in magnetic field and give the diamonds a lovely pink color. We hope to use these magnetic field sensors not just for medical applications, but for spacecraft and fusion power too.
Gavin Morley, Study Senior Author, Group Leader, and Professor, Department of Physics, University of Warwick
Standard approaches to detecting cancers use radioactive tracers or simple blue dyes. This can cause problems as radioactive tracers are not available in all hospitals, and blue dyes can induce an allergic response (estimated to cause such a reaction once every hundred patients).
The Warwick method involves injecting iron oxide nanoparticles into the primary tumor. As they travel into nearby lymph nodes, they mark potential routes of metastasis. The diamond sensor can focus on the magnetic field of this iron-based tracer, guiding surgeons to the exact nodes that need to be removed.
I now regularly use magnetic localization in my breast cancer work, for impalpable breast lesions and detecting lymph nodes, as it offers advantages over more traditional techniques. It’s great to collaborate with the University of Warwick, exploring ways to optimize magnetic technology further.
Stuart Robertson, Consultant Breast Cancer Surgeon, University Hospitals Coventry
The use of magnetic tracer fluids is becoming more common, but this new diamond sensor could provide a smaller, more sensitive detector, without any radioactive risk. Applications to other cancers, such as lung, liver, colorectal, and esophageal, could provide even more advantages to patients.
Journal Reference:
Newman, A. J., et al. (2025) Endoscopic diamond magnetometer for cancer surgery. Physical Review Applied. doi.org/10.1103/znt3-988w.