Researchers at Johannes Gutenberg University Mainz (JGU) have successfully measured the heart’s magnetic field using a novel diamond-based quantum sensor that works without an external magnetic bias field. The breakthrough brings portable, room-temperature cardiac and brain diagnostics one step closer to clinical reality.
Muhib Omar developed the JGU sensor during his doctoral research in the group led by Prof. Dmitry Budker, a member of the PRISMA++ Cluster of Excellence and the Helmholtz Institute Mainz. Omar also serves as the coordinating author of the study.
“These results are the product of over ten years of development work,” explained Wickenbrock, highlighting the long-term research effort behind the technology.
What Makes the JGU Sensor Different?
For the study, researchers measured the heart’s magnetic field using three independent systems developed by project partners at JGU, the Universities of Stuttgart and Freiburg, and the startup Q.ANT GmbH.
The JGU instrument stands apart in its measurement approach. It operates without a magnetic bias field, which is an externally applied magnetic field. The other two systems rely on such bias fields to filter out magnetic interference from the surrounding environment. Together, the parallel measurements demonstrated the real potential of diamond quantum sensors for medical applications. Furthermore, the comparison clearly identified the technical improvements still needed to make the systems practical for hospitals and clinics.
Inside DIAQNOS: The Flagship Project Driving the Research
The research forms part of DIAQNOS, short for Diamond-based Quantum Sensing for Neurosurgery. DIAQNOS is a flagship project funded by the German Federal Ministry of Research, Technology, and Space. Therefore, the project unites academic excellence with industrial innovation. It actively bridges the gap between fundamental quantum physics research and urgent neurosurgical needs.
How Flux Concentrators Amplify the Heart’s Weak Magnetic Signal
A major challenge in magnetocardiography is the heart’s extremely weak magnetic signal. Consequently, researchers are focusing on amplifying that signal directly at the sensor level. One promising route involves concentrating more magnetic flux into the tiny diamond. Scientists use structures called flux concentrators to gather magnetic flux into the sensing region, thereby strengthening the signal significantly.
The small volume of NV (nitrogen-vacancy) sensors allows amplification by more than a factor of 100. Moreover, combining these detectors with optimized flux concentrators could eventually produce recordings with ECG-like quality but without any contact electrodes. Developing flux concentrators that work efficiently at room temperature is one of Omar’s main research areas. “Adapting magnetic structures to optimally concentrate the magnetic field lines from a source within the diamond is the path to bringing these quantum technologies into practical use,” Omar said.
From Lab to Clinic: Toward Portable Brain Monitoring
The broader goal extends far beyond cardiology. Researchers ultimately want to develop sensitive sensors for magnetic signals from both the heart and the brain. Potential future applications include the early detection of myocarditis, an inflammation of the heart muscle, and epilepsy monitoring. Additionally, the technology could support real-time monitoring during surgery.
“We work closely with neurosurgeons to ensure that our technologies do not remain confined to the laboratory but find clear practical applications. Our primary goal is to develop highly sensitive sensors that function outside the laboratory and can fulfill important societal needs,” Wickenbrock said.
Analysis: Why Room-Temperature, Bias-Free Sensing Matters
Why is operating without a bias field a breakthrough? Traditional quantum magnetometers often need strong, stable bias fields and heavy magnetic shielding. That requirement makes them bulky, expensive, and confined to specialized labs. The JGU sensor’s bias-free operation actively removes a major barrier to portability.
What makes NV diamond sensors unique? NV sensors measure a wide range of field strengths, suppress noise effectively, and accommodate different sizes and arrangements. Therefore, they offer unmatched flexibility compared to superconducting SQUID systems that require cryogenic cooling.
The Gradiometer Advantage: For advanced biomedical applications, researchers measure how a magnetic field changes between two locations rather than at a single point. Two spatially separated sensors can form a gradiometer, which records the difference in magnetic field between them.
This approach has powerful clinical implications. It supports monitoring nerve activity during operations in environments without magnetic shielding. Its sensitivity to spatial field changes could also help separate a fetus’s heart signal from the mother’s without an invasive procedure. Ultimately, NV gradiometers could enable portable, room-temperature systems for magnetoencephalography (MEG), which records magnetic signals from the brain. Such systems could support neurological diagnosis and future brain-computer interfaces that use brain activity to communicate with external devices.
Q&A Section
Q: Who developed the JGU sensor?
A: Muhib Omar developed the sensor during his doctoral research in Prof. Dmitry Budker’s group at JGU. Budker is affiliated with the PRISMA++ Cluster of Excellence and Helmholtz Institute Mainz.
Q: How was the heart’s magnetic field measured?
A: Researchers used three independent systems from JGU, Universities of Stuttgart and Freiburg, and Q.ANT GmbH to cross-validate measurements and prove clinical feasibility.
Q: What is the next step for improvement?
A: The next step is developing room-temperature flux concentrators that amplify the magnetic signal by over 100 times to achieve ECG-like quality.
FAQ
1. What is DIAQNOS?
DIAQNOS stands for Diamond-based Quantum Sensing for Neurosurgery. It is a German flagship project funded by the Federal Ministry of Research, Technology, and Space to bring quantum sensors into neurosurgery.
2. What is an NV sensor?
An NV sensor uses nitrogen-vacancy defects in diamond to detect magnetic fields with extreme sensitivity at room temperature, without needing cryogenic cooling.
3. Can this technology replace ECG?
Not yet. Researchers aim to eventually produce recordings with ECG-like quality using flux concentrators, offering a contact-free, more informative alternative for detecting conditions like myocarditis.
4. What are gradiometers used for in medicine?
Gradiometers measure magnetic field differences between two points. Doctors can use them for cancer surgery guidance, intraoperative nerve monitoring, and non-invasive fetal heart monitoring.
5. When will portable brain monitoring be available?
While still in research phase, NV gradiometers are paving the way for portable MEG systems for epilepsy diagnosis and brain-computer interfaces in the next 5-10 years.
