Diamond-Based Magnetometers Could Enable New Approaches to Heart Monitoring

Noninvasive cardiac electrophysiology assessment is limited by the challenges of electrode-based electrocardiography and the complexity of magnetocardiography. Skin electrodes can be impractical for patients with burns or fragile skin, while tissue conductivity can distort electrical signals. Contactless magnetic measurements reduce these issues but typically require bulky, costly sensors. To make this approach more practical, researchers have developed a compact diamond-based quantum magnetometer designed to capture cardiac biomagnetic activity at room temperature.

Physicists at Johannes Gutenberg University Mainz (JGU), working within the PRISMA++ Cluster of Excellence and the Helmholtz Institute Mainz, have developed a nitrogen-vacancy (NV) diamond magnetometer for measuring biological magnetic fields. Described in a study published in Science Advances, the sensor uses defects in the diamond crystal formed by a nitrogen atom adjacent to a vacancy in the lattice. Monitoring changes in the energy levels of these NV centers enables the device to detect minute magnetic fields associated with cardiac or neural activity.

The JGU team designed a fiber‑based NV‑diamond magnetometer as a portable endoscope that operates without a magnetic bias field. In contrast, two independently developed systems used by project partners at the Universities of Stuttgart and Freiburg and at Q.ANT GmbH rely on bias fields to suppress environmental interference. All three systems were used to measure the heart’s magnetic field, demonstrating a pathway toward clinical magnetocardiography with room‑temperature quantum sensors and clarifying the remaining engineering steps.

The NV platform offers practical advantages over superconducting quantum interferepnce devices and optically pumped magnetometers because it works at room temperature and uses an ultracompact sensing element. The sensor is a truncated diamond pyramid with a volume below 0.5 cubic millimeters, allowing skin‑level placement and targeted measurements. This enables finer spatial mapping, including potential three‑dimensional reconstruction of cardiac conduction and measurement of fetal heart activity, and it could support early detection of conditions such as myocarditis or epilepsy.

Technical gaps persist in sensitivity and signal‑to‑noise performance compared with established systems, but strategies for improvement are identified. Flux concentrators that channel magnetic flux into the diamond could raise signal amplitude by more than a factor of 100, aided by the NV sensor’s small volume. NV gradiometers that compare signals between two separated sensors may further enable surgical oncology applications, intraoperative nerve monitoring in unshielded rooms, prenatal separation of maternal and fetal rhythms, and portable, room‑temperature magnetoencephalography for neurological diagnostics and brain‑computer interfaces.

The study, “Human Cardiac Measurements with Diamond Magnetometers,” was published in Science Advances on September 16, 2026.

“NV magnetometers are characterized by fast initialization, excellent biocompatibility, and stable operation over a wide temperature range. This makes them particularly attractive for biomedical applications,” said Arne Wickenbrock, coordinator of the DIAQNOS flagship project.

Related Links
Johannes Gutenberg University Mainz
PRISMA++ Cluster of Excellence
Helmholtz Institute Mainz