Abstract: A magnetostrictive ligand sensor device (MLSD), system and method are provided having at least one magnetostrictive particle (MSP) to which is bound at least one binding element. The MSP may be dispersed in a sample containing a target ligand such that the target ligand binds thereto. A driver is also provided to emit a varying magnetic field such that the MSP produces a resonance response detectable by a measurement device configured to receive and detect changes in the resonance response that are due to alterations of the binding element. The MLSD and assays find use in identifying and quantitating ligands as well as chemicals and environmental conditions in a sample or patient.