The invention relates to a method and a sensor device (100) for the detection of clusters (C) of magnetic particles (MP) in a sample volume (111), particularly of clusters (C) consisting of two magnetic particles (MP) with different binding sites that are bound to a target molecule in a sandwich configuration. Output light (L2) originating from an interaction of input light (L1) with clusters (C) of magnetic particles (MP) is detected. Moreover, the magnetic particles (MP, C) are actuated by a magnetic actuation field (B), wherein said actuation is at least once interrupted by a pause. In this way a high output signal can be achieved that properly reflects the amount of specifically bound clusters (C).