- Researchers in China have shrunk their technology to the size of a computer chip but much more work needs to be done to get it into the field
Chinese researchers have developed a compact sensor that can detect extremely weak magnetic fields and one day might be used to track submarines or act as a backup navigation system.
The sensor, an atomic magnetometer developed by Professor Gu Sihong and his colleagues at the Wuhan Institute of Physics and Mathematics, can fit into a capsule the size of a bean and operate at room temperature, according to research published in the journal Physical Review Applied.
"Using microelectromechanical system technology, the sensor can be fabricated on the chip scale," Gu wrote.
The device can pick up signals as weak as 20 femtotesla, or about one-fifth the strength of the magnetic field generated by a human brain. Although other devices known as magnetic anomaly detectors are much more sensitive, they are bulkier and can only be mounted on planes or helicopters.
Magnetic anomaly detectors used in anti-submarine warfare must operate at temperatures near absolute zero and require lasers, power supplies and gas chambers to achieve high sensitivity. The US military is reportedly working on technology that can fit on a drone and be used in anti-submarine warfare.
The new sensor developed by Gu's team fits into a volume less than half a centimetre (0.2 inches) wide, allowing it to potentially be installed on a small drone and be deployed to gather information over a bigger area, according to Chinese government researchers not directly involved in the study.
The technology has a wide range of applications, including monitoring brain activity, they said.
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Xu Xinye, professor of physics at the State Key Laboratory of Precision Spectroscopy Atomic, Molecular and Optical Physics in Shanghai, said the chip-sized magnetic sensor's potential applications were attracting a lot of attention from researchers and government.
"But it will still take a long time for the technology to get out of the laboratory," he said.
The magnetometer would need to be much more sensitive for use in many applications, according to Xu.
Some atomic magnetometers developed by other teams in China to be mounted on planes or satellites can detect fields as weak as 0.08 femtotesla, making them more than 20 times more sensitive than Gu's device.
"There is still room for improvement if they want to see things of interest," Xu said.
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The chip-sized sensor could also be used in navigation, according to a Beijing-based physicist researching atomic magnetometers.
Magnetic fields vary depending on the thickness and metallic composition of the Earth's crust and such variations could be used to generate a detailed magnetic map to guide planes or underwater vessels, she said.
Also, the magnetic signal is almost impossible to jam, making it a possible backup for the military if other guidance systems such as GPS and BeiDou are disrupted, she said.
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