Magnetic sensor device

The present invention provides a sensor device and a method for detg. the presence and/or amt. of target moieties in a sample fluid, the target moieties being labeled with magnetic or magnetizable objects. The sensor device comprises a magnetic field generating means adapted for applying a retention field for retaining the labeled target moieties to the sensor surface during fluid manipulations. The sensor device comprises a giant magnetoresistance element. Through this the binding between the labeled target moieties and the sensor surface and/or the magnetic particles and the target moieties is substantially not disturbed during these fluid manipulations. This leads to a reliable and accurate sensor device. The magnetic sensor device of the invention is used in mol. diagnostics, biol. sample anal., or chem. sample anal. [on SciFinder (R)]