A microfluidic device for detection of an analyte in a fluid is described. The microfluidic device comprises a substrate having a first surface defining entrances to one or more chambers defined in the substrate, surfaces of the chambers defining a second surface of the substrate, the first surface being modified for selective targeting and capture of at least one analyte to operably effect a blocking of the entrance to at least one of the chambers, and wherein a response characteristic of the microfluidic device is operably varied by the blocking of the entrance to the at least one of the chambers, thereby providing an indication of the presence of the analyte within the fluid.