Enhancing Magnetic Sensor Sensitivity by Grooved Grating Patterned Soft Magnetic Films

Etching the grating on the magnetic film surface is able to increase the film effective longitudinal permeability (
$\mu _{\textit {eL}}$
) significantly, which has been demonstrated by a magnetic sensor consisting of a solenoid and grooved grating patterned film. The feasibility that the magnetic polarization field generated by the groove end faces compensates for the shape demagnetization field and intensifies
$\mu _{\textit {eL}}$
is verified theoretically. After the optimal structural parameters are obtained, the planar and patterned films are manufactured with the microfabrication process. The effects of groove width, sensor dimensions, and excitation frequency on the sensor performance are systematically investigated. For the prototype with the patterned magnetic film of
$10~\mu \text{m}$
groove width, the impedance ratio and impedance sensitivity are 4049% and 347 %/Oe at 1 MHz. Compared with the prototype with the same thickness planar smooth magnetic film core, they are improved by 436% and 659%, respectively. It is revealed that the grooved grating patterned films offer the possibility of developing film-based microsensors, making their performance comparable to that of wire-based sensors.