Chinese magnetic sensor breakthrough may help smartwatch detect submarine 500 metres deep

Compact chip containing Hall-effect sensor can pick up faint magnetic fields by generating a tiny voltage without increasing noise output

Far‑fetched as it sounds, Chinese scientists have just taken a decisive step towards making that scenario real.

Their findings, published on July 17 in the journal Physical Review Letters, shatter a decades-old sensitivity-versus-noise trade-off that has kept everyday magnetic sensors from hearing the quietest signals.

But until now, shrinking them and making them more sensitive came with a punishing side‑effect: more noise, much like cranking up a radio’s volume also amplifies the hiss.