Researchers at the University of Warwick led by Professor Gavin Morley, one of our Co-Investigators, have built a new diamond-based magnetic field sensor that could be used to help find tumours by tracing magnetic fluid injected into the body.

Published in Physical Review Applied, the device harnesses the unique properties of diamonds containing nitrogen vacancy (NV) centres, which are highly sensitive to magnetic fields.

Using a tiny diamond just half a cubic millimetre in size, the team created a handheld sensor sensitive enough to detect magnetic tracers already in use for procedures like sentinel lymph node biopsies.

Alex Newman, PhD student at the University of Warwick and first author on the paper, said, “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, which means it is the first diamond sensor to be able to detect magnetic tracer fluid while being small enough for endoscopic use and keyhole surgery.”

“It is also very sensitive, capable of detecting one hundredth of the typical full clinical dose of magnetic tracer fluid.”

*The magnetometer sensor head measures just 10mm*

Utilising NV diamonds

The sensor uses a laser to shine light into the diamond, which causes the NV centres to emit a faint glow. When magnetic particles are nearby, they subtly change the glow pattern. By analysing these changes, the sensor can detect even tiny amounts of magnetic material. This is done using a technique called optically detected magnetic resonance (ODMR), which involves sending microwaves to the diamond and measuring how the light emission changes in response to magnetic fields.

Tracing cancer metastasis

A cancer diagnosis is most problematic when cells from the tumour have spread (metastasised) to other organs. This most often occurs through the lymph nodes. Using tests to find whether cancer cells are in the lymph nodes is the gold-standard for determining whether the cancer has spread and directing the course of treatment.

Traditional methods for tracing the spread of cancer include using radioactive tracers, which aren’t available in all hospitals due to the extra precautions required when handling radioactive materials, or blue dyes, which can trigger an allergic reaction in some patients.

The use of magnetic tracers to detect the spread of breast cancer is already used in many hospitals. A fluid containing iron oxide particles is injected into the tumour and then travels to the lymph nodes alongside metastasised cancer cells. Using a magnetic field sensor, clinicians can then detect the tracer fluid and locate the lymph nodes that need to be surgically removed to prevent the cancer from spreading further.

Thanks to its compact size and enhanced sensitivity, the new diamond sensor could expand the use of magnetic tracers beyond breast cancer surgery to other cancer types, including lung, liver, colorectal, and oesophageal cancers.

Clinical collaboration

The sensor was developed with the support of clinicians at University Hospitals Coventry and Warwickshire NHS trust.

Stuart Robertson, Consultant Breast Cancer Surgeon, said, “I now regularly utilise magnetic localisation 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 optimise magnetic technology further.”

We look forward to seeing how this technology develops further over the course of the Q-BIOMED Hub!

Read the paper