We report the implementation of a magnetic tweezer using an inductive write head from a hard-disk drive for applying forces to micro-magnetic particles in a microscopy setup. Forces are generated by magnetic particles in reaction to the localized fields across the inductive head gap. This allow for mechanical manipulation and measurement of particles in fluid. The displacement is measured through image processing and particle tracking algorithm from the video capture data. We demonstrated the

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... gnetic tweezer system with application to 1-2 µm paramagnetic and 4.5 µm ferromagnetic microparticles and measured forces in the range of 0.1-4 pN.