Abstract: Methods of detecting one or more genetic variants, including allelic variants, in one or more query samples include providing one or more sensors that each include capture nucleic acids disposed on a functionalized surface of one or more giant magnetoresistance (GMR) sensors. The methods detect the presence of one or more analytes in one or more query samples by measuring magnetoresistance change of the one or more GMR sensors based on determining magnetoresistance before and after passing magnetic particles over the one or more sensors.