University of Warwick scientists have unveiled an innovative handheld magnetic field sensor that harnesses the extraordinary properties of diamonds, potentially revolutionizing the way metastatic breast cancer is detected during surgery. This groundbreaking device leverages nitrogen vacancy (NV) colour centres within diamonds—quantum defects that are exquisitely sensitive to minute magnetic fields—to non-invasively trace magnetic fluids injected into the patient’s body, enabling more precise identification of cancerous lymph nodes.
The fight against metastatic cancer—when malignant cells spread from the original tumour to distant organs—has long challenged physicians due to the difficulty of accurately locating secondary tumours. Typically, oncologists rely on the meticulous examination of lymph nodes, where metastasised cells frequently lodge, guiding surgical decisions and therapeutic plans. Current clinical methods involve radioactive tracers or blue dyes to mark these nodes, but both have significant limitations including safety concerns and allergic reactions. Warwick’s diamond sensor offers a promising alternative that is non-toxic, non-radioactive, and ultra-sensitive.
This device represents a remarkable leap forward in sensor miniaturization combined with quantum technology. The sensor head measures a mere 10 millimeters and contains an ultra-small diamond, only 0.5 cubic millimeters in volume, equipped with nitrogen vacancy centres. These NV centres act as highly sensitive magnetic field detectors, able to sense the minute fields produced by iron oxide nanoparticles within the magnetic tracer fluid introduced into the body. A small permanent magnet coupled to the probe introduces a stable magnetic bias, which, in conjunction with the diamond, enhances the detection capability while keeping the overall footprint compact.
The diamond sensor operates by detecting the magnetic signature of the tracer fluid after it is injected directly into the tumour site. This ferrofluid then travels naturally through the lymphatic system alongside the metastatic cancer cells. By sensing the precise magnetic fields emanating from these nanoparticles, surgeons can accurately locate sentinel lymph nodes that are critical to remove during breast cancer surgery to prevent further spread. Such real-time intraoperative guidance could drastically improve surgical outcomes and reduce unnecessary tissue removal.
The fundamental innovation lies in the quantum sensing capabilities of NV centres within the diamond lattice. These vacancies, consisting of a nitrogen atom adjacent to a lattice vacancy, possess a spin state that can be optically initialized and read out, enabling the measurement of magnetic fields with exceptional sensitivity and spatial resolution. This quantum metrology technique surpasses traditional magnetometers by providing localized, high-fidelity data without the need for bulky cooling systems or complicated electronics.
What makes this advancement particularly exciting is its usability in minimally invasive procedures. The sensor’s compact size allows it to be integrated into endoscopic tools, facilitating keyhole surgeries where accessibility is limited. Unlike conventional bulky magnetometers that are impractical in such settings, the diamond-based sensor provides surgeons with a practical tool for real-time magnetic tracing, enhancing precision without increasing procedural complexity.
Clinical translation has also been a core consideration throughout the device’s development. The team collaborated closely with breast cancer surgeons to ensure the technology meets the demands of actual surgical workflows. Notably, magnetic tracers have been increasingly adopted as a safer alternative to radioactive substances, gaining traction in numerous hospitals worldwide. However, current magnetic detection systems remain large or lack sufficient sensitivity. Warwick’s device addresses these limitations by delivering both portability and heightened sensitivity, capable of detecting just one-hundredth of a full clinical dose of magnetic tracer.
Beyond oncology, the team’s vision extends to broader applications of these diamond-based magnetometers. Quantum sensors utilizing NV centres have the potential to detect subtle magnetic phenomena in fusion reactors or even in the harsh environment of space exploration, where remote and robust sensing are paramount. This versatility underscores the transformative potential of integrating quantum materials into applied physics and medical technologies.
Traditional metastatic detection methods face notable drawbacks: radioactive tracers require stringent handling protocols and are unavailable in some clinical settings, while blue dyes carry risks of allergic reactions in a small percentage of patients. The diamond sensor’s approach circumvents these issues by eschewing radioactivity and toxic dyes altogether, offering a safer, more widely deployable alternative. Such a non-invasive and precise tool is poised to benefit patient safety and comfort tremendously.
Technologically, this ultra-sensitive magnetometer exemplifies the convergence of quantum physics, materials science, and biomedical engineering. Employing a diamond host for NV centres takes advantage of diamond’s remarkable optical transparency, thermal conductivity, and chemical inertness, which together facilitate stable and long-lived quantum sensing under room-temperature conditions. The integration of this sensor into a handheld device capable of clinical use marks a significant step toward real-world quantum-enabled diagnostics.
Stuart Robertson, a Consultant Breast Cancer Surgeon closely involved in the research, highlighted the clinical implications: “Magnetic localisation is becoming a valuable technique for detecting impalpable breast lesions and lymph nodes. Collaborating with Warwick to refine this magnetic technology promises to optimize surgical accuracy and patient outcomes.” Such endorsements from clinical practitioners reflect growing confidence in quantum sensing technologies for everyday medical applications.
As magnetic tracer fluids gain popularity for tumour localization, this diamond-based sensor represents the next frontier in surgical navigation. The authors suggest that the platform could be adapted to other cancers, like those affecting the lungs, liver, colon, and oesophagus, where precise detection of metastatic spread remains critical. Adoption of this sensor could usher in a new era of minimally invasive, quantum-enhanced cancer diagnostics that dramatically improve survival rates.
This study, recently published in Physical Review Applied, illustrates how fundamental research on quantum defects in diamonds is being translated into practical, life-saving innovations. By detecting magnetic nanoparticles at ranges and sensitivities previously unattainable with such small instruments, Warwick’s diamond magnetometer embodies the promise of converging physics and medicine. The next steps include clinical trials and refinement for broader surgical integration, aiming to bring this quantum technology into operating rooms worldwide.
In summary, the University of Warwick’s pioneering diamond-based magnetic field sensor leverages nitrogen vacancy centres to revolutionize cancer surgery. Miniaturized and highly sensitive, it offers a non-toxic, non-radioactive alternative to existing metastasis detection methods, poised to enhance precision in tumour resection and improve patient outcomes. This interdisciplinary breakthrough heralds a transformative application of quantum sensing, with wide-reaching implications for cancer care and beyond.
Subject of Research:
Not applicable
Article Title:
Endoscopic diamond magnetometer for cancer surgery
News Publication Date:
12-Aug-2025
Web References:
Physical Review Applied article
References:
DOI: 10.1103/znt3-988w
Image Credits:
Gavin Morley / University of Warwick
Keywords:
Diamond, Magnetometry, Cancer, Breast cancer, Health and medicine, Physical sciences
