An innovative supersensitive magnetic sensor has been developed using #graphene and #boronnitride. The sensor is smaller, two hundred times more sensitive and shows less temperature-variation than commercially avaiable sensors.
Magnetoresistance is the modification in electrical resistance that is caused by the deflection of electrons in a material when it is exposed to an external magnetic field. #Magnetoresistance enables the use of magnetic field sensors in devices such as hard disk drives and has changed the way data can be stored and read.
Researchers aim to develop 'ideal' magnetoresistance sensor which display tunability, show minute variations in resistance due to temperature and that have a high sensitivity to magnetic fields.
In this study, the team used graphene and boron nitride to produce a new sensor. This sensor possed two layers of mobile charge carrier channels which could be controled by the application of a magnetic field. The sensor was tested at different temperatures and magentic field angles, and also paired with different materials.
We started by trying to understand how graphene responds under the magnetic field. We found that a bilayer structure of graphene and boron nitride displays an extremely large response with magnetic fields. This combination can be utilised for magnetic field sensing applications.
Dr. Kalon Gopinadhan - National University of Singapore
Magnetoresistant sensors are traditionally made using silicon and indium antimonide which perform less effectively than the new graphene/boron nitride sensors. At a temperature of 127°C, the new sensor operated more than 200 times better than any commercially available sensors and eight times better than other novel sensors being developed. The temperature of 127°C was chosen as this is the maximum temperature at which electronics are typically operated at.
The researchers also discovered that when a voltage was applied across the sensor the mobility of electrons in the graphene multilayers could be partially adjusted. This enables optimization of the sensor's behavior, which is something commercially available sensors are not capable of. The new sensor also demonstrated very low temperature dependence between temperatures of 20 °C to 127 °C. This makes it favorable for use in high temperature environments.
The magnetoresistance sensor industry is forecast to increase by 60% from $1.8 billion to $2.9 billion by 2020. Graphene-based magnetoresistance sensors demonstrate stable performance with respect to varying temperatures, preventing the need for expensive, temperature-correcting, wafers or circuits. The graphene sensors can also be produced more economically than traditional sensors which use rare and expensive elements such as indium and antimony.
Our sensor is perfectly poised to pose a serious challenge in the magnetoresistance market by filling the performance gaps of existing sensors, and finding applications as thermal switches, hard drives and magnetic field sensors. Our technology can even be applied to flexible applications
Prof Yang - National University of Singapore
The team has sought a patent for its invention and plans to advance its studies produce industry-size wafers.
The research paper has been published in the journal, Nature Communications.
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