Sensor uses magnetics to track heartbeat
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Researchers from the US National Institute of Standards and Technology (NIST) and the German national metrology institute have used a miniature atom based magnetic sensor to track a human heartbeat. The research team says this confirms the device's potential for biomedical applications.
In the experiments – carried out at the Physikalisch Technische Bundesanstalt (PTB) in Berlin in a building described as having the world's best magnetic shielding – the NIST sensor was placed 5mm above the left chest of a person lying face up on a bed. The sensor successfully detected the weak, but regular, magnetic pattern of the heartbeat. The same signals were recorded using a superconducting quantum interference device – or squid – and a comparison of the signals confirmed NIST's sensor correctly measured the heartbeat and identified many typical signal features.
The NIST sensor – which contains about gaseous 100billion rubidium atoms, a low power infrared laser and optics – measured the heart's magnetic signature in picoTeslas. By comparison, the Earth's magnetic field is measured in microTeslas.
NIST says the results suggest its mini sensors could be used to make magnetocardiograms, which can supplement or replace electrocardiograms. The study also demonstrated for the first time that atomic magnetometers can offer sensing stability lasting tens of seconds, an important parameter in an emerging technique called magnetorelaxometry, which measures the magnetisation decay of magnetic nanoparticles. This technique can be used to localise, quantify and image magnetic nanoparticles inserted into biological tissue for medical applications such as targeted drug treatments.
