  The excellent electronic and mechanical properties of graphene provide a
perfect basis for high performance flexible electronic and sensor devices.
Here, we present the fabrication and characterization of flexible graphene
based Hall sensors. The Hall sensors are fabricated on 50 um thick flexible
Kapton foil using large scale graphene grown by chemical vapor deposition
technique on copper foil. Voltage and current normalized sensitivities of up to
0.096 V/VT and 79 V/AT were measured, respectively. These values are comparable
to the sensitivity of rigid silicon based Hall sensors and are the highest
values reported so far for any flexible Hall sensor devices. The sensitivity of
the Hall sensor shows no degradation after being bent to a minimum radius of 4
mm, which corresponds to a tensile strain of 0.6%, and after 1,000 bending
cycles to a radius of 5 mm.
