Optical manipulation of paramagnetic particles with on-chip detection using spin valve sensors

Abstract

In this work, we present a combinatory approach where optical tweezers were used to trap and position a single superparamagnetic particle over a spin valve sensor, with the particle then detected by the sensor. This approach is demonstrated using superparamagnetic particles of 2 μm together with a spin valve sensor with dimensions of 2×4 μ m2, 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 magnetic dipole. © 2008 American Institute of Physics.