Optical Manipulation of Paramagnetic Particles with On-Chip Detection Using Spin Valve Sensors

In this work, we present a new combinatory approach where an optical tweezers was used to trap and position a single super-paramagnetic particle over a Spin Valve sensor, with the particle then detected by the sensor. This approach is demonstrated using super-paramagnetic particles of 2 $\mu $m (Micromer$^{\mbox{{\textregistered}}}$-M, Micromod) together with a Spin Valve sensor with dimensions of 2 x 4 $\mu $m$^{2}$ whereby a single magnetic particle was positioned over the sensor and a corresponding drop in the voltage across the sensor was detected. The results are explained using a simple model where the particle is treated as a pure dipole.