Scientists at the National University of Singapore have constructed a new hybrid type of magnetic sensor that is more responsive that the existing varieties. This innovation holds promise for the creation of cheap and compact sensors and detectors in areas like information technology, electronics, health sciences and automotive industry.
Professor Yang Hyunsoo, who has directed the design of the device, has explained the findings in the September 2015 issue of the periodical Nature Communications.
Using the concept of magneto resistance
Just as electric resistance develops when an electric current passes through a conductor, a similar feature called magneto resistance comes into being when certain substances are placed in a magnetic field. Scientists at the university have utilized this newly discovered feature in developing the magnetic field sensor.
Although the feature is exhibited by all magnetic materials, the university team has been on the lookout for an ideal material, which would be particularly receptive to low and high fields, while remaining immune to temperature variations. In other words, the magneto resistance should vary appreciably with any change in the magnetic field but should be stable when the temperature changes.
Graphene and boron nitride combination
The scientists tried out several groupings of different materials. These trials led to a hybrid arrangement comprising graphene and boron nitride that suggests great potential as a sensing device. The team experimented with the material placed at various angles with the field and at different temperatures. According to Dr. Kalon Gopinadhan of the university, a two-layer structure of the two materials shows a sizeable response to small changes in magnetic fields. The researchers found that the hybrid structure was 200 times more receptive than sensors currently in use.
A significant gain of using this sensor is that the combination shows very high sensitivity at and around 127 degree Celsius, the temperature at which most electronics function. The sensor is small and can be easily fitted into other devices. Furthermore, the manufacturing cost of graphene is very low as compared to that for existing sensors made from indium antimonide.
Complying with industry requirements
The demand for reliable magneto resistance is expected to rise steadily. Indium antimonide sensors used in the automotive industry suffer a change in properties due to temperature changes caused by the air conditioning or the sun’s heat and do not function reliably. Cars and other vehicles use several sensor systems in interlocks, flow meters and position sensors that make use of complicated temperature correction circuitry to offset the errors. The new hybrid sensor eliminates the necessity of these rectification procedures.
Professor Yang declares that the graphene and boron nitride combination is prepared to take on the current sensors in the market. Apart from finding use in applications like hard drives, thermal switches and magnetic field detectors, they can be incorporated in flexible electronics, as well.
The university team has applied for a patent for the innovation. They now plan to scale up their production in order to turn out wafers of several sizes to meet the demands of the sensor industry.
