Researchers Develop Compact Diamond Magnetometer for Tumour Detection

Researchers at the University of Warwick in the UK have developed an innovative magnetometer that holds promise for early detection of metastatic tumours. This ultrasensitive device, based on nitrogen-vacancy centres in diamond, is compact enough for use in keyhole surgeries, potentially revolutionizing cancer diagnostics.

The magnetometer measures just 1 cm in diameter, and there are plans to make it even smaller. It is designed to identify small cancer metastases through techniques such as endoscopy or laparoscopy. Gavin Morley, a physicist leading the research, emphasized the critical importance of early detection: “It’s really bad news when tumour cells spread from their original site, and so it’s very important to detect this metastatic cancer as soon as possible.”

Current detection methods for metastatic tumours, such as MRI and CT scans, can only identify tumours that are at least 2 mm across. While alternatives like sentinel lymph node biopsy can detect tumours with a volume 1000 times smaller, these methods often involve radioactive tracers or dyes that may cause allergic reactions in a subset of patients.

Morley explained a recent technique developed by medical device company Endomag, which involves injecting a magnetic tracer into a breast cancer tumour. This tracer travels to lymph nodes, where a surgeon can identify and remove the metastatic cells. However, existing magnetometers used in this process are too large for minimally invasive procedures, prompting the Warwick team to create a more compact solution.

“The surgeons we’ve spoken to say that colorectal cancer could be the best place for us to focus on first for our magnetometer,” Morley noted. The research team has been investigating magnetic field sensors for over a decade, utilizing diamonds and lasers. The diamonds used in this project are produced by Element Six in Oxford and contain quantum defects known as nitrogen-vacancy (NV) centres.

These NV centres are formed when a nitrogen atom replaces a pair of adjacent carbon atoms in the diamond lattice, creating a vacancy. The isolated spin of an NV centre is highly sensitive to external magnetic fields and emits fluorescent light based on the intensity and direction of this field. This light can be measured to function as a magnetic sensor.

Newman, Morley’s doctoral student, played a crucial role in building the new sensor. Morley remarked, “Alex likes fixing old sports cars, and I liked the way he applied that thinking to this new technology. He tries different strategies and has built new types of diamond sensors that no one has managed to build before.”

The Warwick team is exploring various applications for their sensors beyond healthcare. They are investigating potential uses in space technology and future fusion power plants. Morley highlighted a project aimed at detecting damage in steel containers for the National Nuclear Laboratory, showcasing the versatility of their magnetometer technology.

The researchers are collaborating closely with surgeons in their quest to refine their work. “For example, Jamie Murphy at the Cleveland Clinic in London is an expert on keyhole surgery, with a significant interest in colorectal cancer,” Morley said. Another collaborator, Conor McCann, focuses on gut health at the UCL Great Ormond Street Institute of Child Health.

As part of the UK Quantum Biomedical Sensing Research Hub (Q-BIOMED), the team aims to further develop their magnetometer. They are also working on reducing the sensor’s size, with the goal of creating a probe measuring only 3 mm. Morley explained, “While 1 cm is small enough for keyhole surgery and endoscopy, getting it even smaller would make it useful for even more types of surgeries.”

The advancements made by Morley, Newman, and their colleagues represent a significant step forward in the early detection of metastatic cancers, potentially improving outcomes for patients worldwide.