An apparatus and method for separating an analyte from a test sample, such as bacteria from blood components, based on their dielectric properties, localizing or condensing the analyte, flushing substantially all remaining waste products from the test sample, and detecting low concentrations of the analyte. Species movement is caused by a module array imparting opposing dielectrophoretic forces. The module array includes a plurality of microfluidic channels with connecting microfluidic waste channels for directing undesired material away from the analyte. An electric field is applied causing a positive dielectrophoretic force to the analyte to capture the analyte. The Clausius-Mossotti factor of the analyte is changed by flushing the analyte with a reference solution, which causes a negative dielectrophoretic force to facilitate release of the analyte. A field effect nanowire or nanoribbon sensor detects the analyte after capture.