China has invented a tiny sensor capable of detecting submarines at a depth of 500 meters

A fisherman is fishing in the ocean. Suddenly, a warning message appears on his smartwatch - the presence of a submarine has been detected at a depth of about 500 meters. Although it sounds like science fiction, Chinese scientists have brought such technology closer to reality.

Researchers from the Hefei Institutes of Physical Science and Ningbo Institute of Materials Technology and Engineering under the Chinese Academy of Sciences have developed a highly sensitive magnetic sensor based on the 'Hall-effect'. The researchers claim that this sensor is theoretically capable of detecting even the faint magnetic signals of a steel submarine at a depth of about 500 meters in the sea.

The most surprising thing is that this technology can be integrated into a chip whose size is smaller than a grain of dust.

The results of the research were published on July 17 in the physics journal Physical Review Letters. According to the researchers, the new sensor technology has overcome a major limitation for a long time. Until now, increasing the sensitivity of the sensor would have increased noise or unnecessary signals. New technology has provided an effective solution to that problem.

Currently, Hall-effect sensors are used in smartphones, smartwatches, car speedometers and various medical devices. When a magnetic field is created in the vicinity, it generates a small electric voltage and detects the signal. Being small, low-cost and fast, it is quite suitable for wearable technology.

The researchers' new innovation has made this sensor more powerful. As a result, it will be possible to detect even very weak magnetic signals.

Generally, the smaller and more sensitive the sensor is, the more noise is generated. Much like increasing the volume of a radio, the buzz increases along with the main sound. The researchers found that noise is directly related to the dynamics of the 'spin texture' inside the magnetic material. Noise increases with slow changes, and noise decreases with fast changes.

Based on this idea, they created an artificial ferromagnetic structure with fast spin texture. In addition, the sensitivity of the sensor is further enhanced by precisely controlling the structure of the magnetic layer and the annealing heat-treatment process.

The effective detection area of ​​the new ‘anomalous Hall magnetic sensor’ is only 20×20 micrometers.

The currently used proton magnetometer is relatively heavy and consumes a lot of power. On the other hand, expensive cooling systems are required to operate the highly sensitive SQUID device. In comparison, the new Hall-effect-based sensor is much more cost-effective and user-friendly.

According to the South China Morning Post report, researchers believe that this technology can also be applied to other magnetic materials. If the spin mobility of those materials can be further increased, the noise level can be reduced several times.

However, researchers are cautious about whether this sensor can directly detect submarines. Although it is theoretically possible, there are still several technical challenges in military applications.

Currently, ‘magnetic anomaly detection’ technology is used to detect submarines. Steel submarines, when moving within the Earth's magnetic field, slightly change the local magnetic field. The sensor's job is to detect those subtle changes.

According to the researchers, the new sensor is capable of detecting submarines in close proximity, but is not yet sufficient for long-range military surveillance. However, its potential in the medical and industrial sectors is very high.

The human heart rate and the brain's neural activity produce extremely small magnetic signals, which are in the picotesla to nanotesla range. The new sensor's ability to detect these signals could open up new horizons in the future for early detection of heart disease and brain research.

According to the Chinese Academy of Sciences, this highly sensitive and low-noise sensor can also play an important role in fields such as the automobile industry, electronics manufacturing, materials science and scanning probe microscopy.

As a result, in addition to the potential for military technology, this small but powerful innovation can usher in a new era in medicine, research and industry.