Magnetic force and optical force sensing with ultrathin silicon resonator

The magnetic force and optical force measurements using an extremely sensitive resonating silicon cantilever with a thickness of 20 nm or 50 nm, were demonstrated. Force balancing between the electrostatic and magnetic torque determined the magnetic moment of the sample, and the same technique was extended to optical force measurement. The cantilever was actuated by applying an alternating current voltage to a metal electrode, and the vibration was detected via an optical window by a laser Doppler vibrometer. The measurement of the magnetic moment of Fe particle with a diameter of 1.5 μm was achieved.