Design of current sensor using a magnetorheological fluid in shear mode

A new approach to measure the direct current (dc) using magnetorheological (MR) fluids with a resonance concept is proposed in this work. The current measurement system is designed using a piezolaminated cantilever beam coupled with an electromagnetic coil-based MR fluid shearing set-up. The cantilever beam is maintained at resonance using simple closed-loop electronics. The current-induced magnetic field produced by the coil changes the viscosity of the MR fluids and produces an additional stiffness to the resonating cantilever beam. The shift in resonant frequency due to the change in viscosity of the MR fluid is measured, and the shift in frequency is related to the input electrical current to the coil. The analytical model of the current measurement system is derived, and the results are compared with the experimental results. The resonance-based current measurement system is evaluated for the input current range of 0 to 1 A.