the present invention relates to methods for detecting polymeric analytes , especially biopolymers , and sensors for detecting the polymeric analytes . the present invention uses magnetic beads in a rotating magnetic field to provide a visual detection of the presence of a polymeric analyte , such as nucleic acids , lipids , polysaccharides , proteins , etc . when a polymeric analyte binds to the magnetic beads , application of a rotating magnetic field to the beads results in unique pinwheel formations . without the presence of the polymeric analyte , the movement of the magnetic beads induced by the rotating magnetic field differs significantly from the pinwheel formations . the pinwheel , therefore , is used to detect the presence of polymeric analytes .