Chinese magnetic sensor breakthrough may help smartwatch detect submarine 500 metres deep
Picture a fisherman hauling in his nets on a calm morning at sea, when his smartwatch suddenly vibrates with an alert: “Magnetic anomaly detected – possible submarine passing 500 metres below.” Far‑fetched as it sounds, Chinese scientists have just taken a decisive step towards making that scenario real. A team from the Hefei Institutes of Physical Science and the Ningbo Institute of Materials…
Chinese scientists have developed a revolutionary Hall-effect magnetic sensor that could soon enable smartwatches to detect submarines passing just 500 metres beneath the surface. Led by researchers at the Hefei Institutes of Physical Science and the Ningbo Institute of Materials Technology and Engineering, both affiliated with the Chinese Academy of Sciences, the team created a sensor so sensitive it could theoretically pick up the faint magnetic signature of a steel-hulled submarine from half a kilometre away.
Published in July in the prestigious journal Physical Review Letters, their findings overcome a long-standing trade-off between sensor sensitivity and noise, enabling these devices to detect the quietest magnetic signals. Hall-effect sensors, already common in wearables like smartwatches and smartphones, work by generating a small voltage in response to magnetic fields.
These sensors are inexpensive, fast, and compact, making them ideal for portable devices. However, miniaturising them while boosting sensitivity has traditionally resulted in increased noise – much like turning up a radio's volume also boosts the static. The team discovered that noise levels within magnetic materials correlate directly with the speed of spin texture motion.
Slower spinning creates more noise, while faster spinning reduces noise. By precisely controlling the thickness of magnetic layers and optimizing the annealing process, the researchers achieved a material with exceptionally rapid spin texture dynamics, significantly improving the sensor's sensitivity. The resulting device, described in their paper, boasts a detection area just 20 micrometres by 20 micrometres, significantly smaller than existing magnetic sensors.
This miniaturization, coupled with its low noise, could usher in a new era of compact, high-sensitivity sensors for applications ranging from biomedical research to industrial scanning. While long-range submarine detection remains a future challenge, the new sensor's immediate impact is likely to be felt in fields like biomedical imaging, where it could help detect the minuscule magnetic fields associated with human heartbeats and brain activity.
Written by urgent.news from South China Morning Post's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
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