Researchers from the National University of Singapore (NUS) have developed a hybrid magnetic sensor that is reportedly more sensitive than most commercially available sensors. This could encourage the development of smaller and cheaper sensors for areas like consumer electronics, information and communication technology and automotive, as well as applications like thermal switches, hard drives and magnetic field sensors.
The sensor is made of graphene and boron nitride, and includes layers of carrier-moving channels, each of which can be controlled by the magnetic field. The researchers characterized the sensor by testing it at various temperatures, angles of magnetic field, and with a different pairing material. Graphene-based magnetoresistance sensors hold immense promise over existing sensors due to their stable performance over temperature variation and eliminating the necessity for expensive wafers or temperature correction circuitry. Production cost for graphene is also much lower than silicon and indium antimonide.
The scientists found that a bilayer structure of graphene and boron nitride displays an extremely large response with magnetic fields. Compared to other existing sensors, which are commonly made of silicon and indium antimonide, the group’s hybrid sensor displayed higher sensitivity to magnetic fields. In particular, when measured at 127°C, the researchers observed a gain in sensitivity of more than eightfold over previously reported laboratory results and more than 200 times that of most commercially available sensors.
Another achievement in this research was the discovery that mobility of the graphene multilayers can be partially adjusted by tuning the voltage across the sensor, enabling the sensor’s characteristics to be optimized. In addition, the sensor showed very little temperature dependence over room temperature to 127°C range.
Following this proof-of-concept study, the researchers plan to scale up their studies and manufacture industry-size wafers for industrial use.