Diamond sensor picks up the heart's magnetic signals express
A tiny defect in diamond is like a microscopic ear, able to pick up the magnetic 'breath' of the heart. Such sensors work at room temperature and are no bigger than a grain of sand.
To hear a faint signal in a noisy room, engineers used two sensors: just as our ears compare sound to discern speech, a pair of diamond 'ears' subtracts the magnetic background. This made it possible to record a magnetocardiogram without bulky shielding.
The irony is that the sensor is not a perfect diamond, but its flaw — a nitrogen atom next to a vacancy in the lattice. It is precisely this defect that, under the light of optical spectroscopy, turns into a supersensitive element. In the future, such sensors could form the basis of contactless diagnostic patches — cheaper and more portable than traditional magnetometers.
Original abstract
as written by the authors arXiv:2601.18843
We demonstrate direct, non-invasive and non-contact detection of human cardiac magnetic signals using quantum sensors based on nitrogen-vacancy (NV) centers in diamond. Three configurations were employed recording magnetocardiography (MCG) signals in various shielded and unshielded environments. The signals were averaged over a few hundreds up to several thousands of heart beats to detect the MCG traces. The compact room-temperature NV sensors exhibit sensitivities of 6-26 pT/Hz^(1/2) with active sensing volumes below 0.5 mm^3, defining the performance level of the demonstrated MCG measurements. While the present signals are obtained by averaging, this performance already indicates a clear path toward single-shot MCG sensing. To move beyond shielded environments toward practical clinical use, strong noise suppression is required. To this end, we implement NV-based gradiometry and achieve efficient common-mode noise rejection, enabled by the intrinsically small sensing volume of NV sensors. Together, these multi-platform results obtained across diverse magnetic environments provide a solid foundation for translating quantum sensors into human medical diagnostics such as MCG and magnetoencephalography (MEG).
The heart's magnetic pulse was first captured in 1963—the setup was the size of a car and required expensive magnetic shielding.
The medical tricorder from Star Trek is closer than it seems: a compact diamond sensor reads magnetic rhythms without contact.