'Quantum' sensor validates banknotes

China's MultiDimension Technology has launched a new range of magnetic pattern recognition sensors designed for use in validating banknotes.

The range make use of a technology known as tunneling magnetoresistance (TMR) and is claimed to be the first commercial products to use TMR in banknote validation, banknote counting and sorting and magnetic card readers.

The science underpinning the sensors are the changes in electrical resistance that occur when small magnetic changes are applied to a mix of magnetic and non-magnetic materials. In the case of TMR, two ferromagnetic layers separated by a very thin layer of insulating material are used to detect quantum changes in magnetic properties of materials.

There are three sensors in the range - a single channel versions (MMGB01) plus two multi-channel units that can read six and 18 signals in parallel (MMGB06 and MMGB18, respectively).

The sensors "achieve high sensitivity and high signal-to-noise ratio for weak magnetic signal detection on banknotes by using customized TMR magnetic sensors and a bias magnet," according to MDT. They are also compatible with existing products on the market, it says.

"MDT's new TMR magnetic sensors are the first products using TMR technology on the financial anti-counterfeit appliances market, and they bring many unique benefits of TMR technology to our customers with high-sensitivity and high-resolution magnetic signal detection," said Dr. Song Xue, MDT's chief executive.

The TMR technology "is fully capable of high-resolution magnetic image retrieval to meet the stringent requirements of the next-generation financial anti-counterfeit appliances," he added.