Paragraf is a 2015 spin-out from the gallium nitride group of Professor Sir Colin Humphreys and has developed a graphene based Hall effect magnetic sensor with a number of beneficial features. These include the lack of a planar Hall-Effect, high sensitivity, and the ability to be used in wide temperature ranges and harsh environments.
The magnetic measurements section at CERN is in charge of testing the normal and superconducting magnets used to steer and focus beams within its particle accelerators
The lack of planar Hall effect within Paragraf's sensors is a significant development. Sensors with thick magnetic layers tend to measure fields that are not perpendicular to the sensing plane producing false signals. False signals, together with the non-linear response to the field strength, increase the measurement uncertainty and separating the true signals from the systematic errors is a time-consuming process.
Because the active layer in Paragraf' sensors is a single atom layer thick it is effectively two-dimensional. Thus the sensor only senses magnetic fields perpendicular to the sensor with negligible planar Hall effect allowing for higher precision mapping of the local magnetic field.
Paragraf's GHS series of sensors also operate over a wide temperature range from 80 degrees C down to cryogenic temperatures of 1.5K.
"This collaboration with CERN demonstrates the potential of graphene-based Hall effect sensors to improve accuracy in magnetic measurement applications," said Simon Thomas, CEO of Paragraf, in a statement.
Stephan Russenschuck, head of the magnetic measurement section at CERN, said: "Using Hall effect sensors without planar effect would open the door to a new mapping technique by mounting a stack of sensors on a rotating shaft. The compelling advantage would be measurements of the harmonic content in accelerator magnets almost point-like along the magnet axis."
Paragraf and CERN will also be releasing a joint white paper communicating the work to date in more detail and showcasing the lack of planar Hall effect in Paragraf’s sensors, as well as detailing its high performance across a range of magnetic fields.
Paragraf’s graphene Hall effect sensors are available to lead partners in small volumes.
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