Mainz, Stuttgart, Freiburg and Q.ANT Recorded a Human Magnetocardiogram With Room-Temperature Diamond Sensors: What the 16 September 2026 Science Advances Paper Shows
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Three research groups in Germany have measured the magnetic field of a beating human heart with diamond sensing crystals smaller than half a cubic millimeter, at room temperature and without touching the skin. The paper appeared in Science Advances on 16 September 2026 under the coordination of Muhib Omar and Arne Wickenbrock of Johannes Gutenberg University Mainz, with Dmitry Budker and Jörg Wrachtrup among its 30 authors.
The instruments are diamond nitrogen-vacancy magnetometers: a nitrogen atom sitting beside a missing carbon atom in the diamond lattice, whose electron spin shifts its energy in proportion to the surrounding magnetic field. The three systems, built independently at Mainz, at the University of Stuttgart and by the Stuttgart startup Q.ANT GmbH, each produced a human magnetocardiogram in proof-of-concept self-experiments on members of the research groups, with sensitivities between 6 and 26 picotesla per square-root hertz. The result is a laboratory measurement on a handful of volunteers from the teams themselves, with no patient involved. It establishes that room-temperature diamond sensors can read the heart's field at all, after averaging, which is the step a cryogenic SQUID cleared decades ago and an optically pumped magnetometer clears with a heated vapor cell. The half-cubic-millimeter figure describes the sensing crystal, not the complete instrument with its fiber, optics and electronics, and the diamond heads recorded without touching the skin while a conventional electrocardiogram supplied the timing reference for the averaging, so the experiments did not show an electrode-free workflow.
The heart's magnetic signal is faint. The paper puts the average R-peak, the sharpest feature of each beat, at about 25 picotesla, roughly two million times weaker than the field of the Earth. That is why magnetocardiography has stayed inside hospitals that could afford superconducting detectors and the shielding around them, and why a SQUID magnetocardiograph still counts as deployable news when a Chinese manufacturer places one. The Mainz group's own line of work reached a related milestone on 6 August 2026 with a levitated-magnet sensor at 32 femtotesla per square-root hertz, a sensitivity reached only in a narrow resonance near 305 hertz, on a benchtop device that is far less suited than a diamond to sitting near a chest.
A Diamond Magnetometer Closes the Distance to Biomagnetism
A smaller gap between sensor and signal
Biomagnetic fields weaken sharply with distance, so the physical gap between a detector and the body is part of the sensitivity budget. Yuta Araki and colleagues have built a diamond NV magnetometer whose sensing head can sit about 2.0 millimeters from a sample. A compact microwave antenna helps set that geometry, while a light-trapping diamond waveguide makes more efficient use of the green laser that initializes and reads the sensor's nitrogen-vacancy centers. The integrated device addresses the heat and bulk that have limited high-sensitivity Ramsey measurements near biological samples.
What the laboratory result establishes
The peer-reviewed paper reports 2.93 picotesla per square-root hertz sensitivity across 100 to 400 hertz at 210 milliwatts of laser power. The measured temperature increase was approximately 13 kelvin. In a controlled test, the sensor detected a 77.7-picotesla field from a dry brain-field phantom at a 2.5-millimeter standoff, without signal averaging and with a signal-to-noise ratio of approximately 4.3. Quentir assesses the assembled system at TRL 4 of 9: a quantum sensing device validated in the laboratory on a phantom that imitates a brain-field pattern.
The clinical distance remains
The phantom does not reproduce movement, anatomy, variable spacing or the environmental interference of a living-subject recording. The authors also state that sub-picotesla brain signals will require further accumulation and improved sensitivity. A future magnetoencephalography or magnetocardiography instrument would need stable arrays, calibration and clinical comparisons as well. The current paper supplies no human dataset, workflow study, regulatory record or manufacturing claim. Those absences keep the result at the laboratory-instrument stage even though its geometry addresses a genuine near-body constraint. Quentir reads the paper as a bounded hardware advance. It joins optical efficiency to a short sensor-to-sample distance, reports each operating constraint quantitatively, and makes the next test easy to name: a living-subject measurement with a defined physiological signal and an established comparator.