A wafer transfer robot for a wafer processing system, such as a wet bench system, and a method for utilizing the robot. The wafer transfer robot can be constructed by a robot arm that is equipped with a plurality of wafer blades each adapted for picking-up and carrying one of a plurality of wafers. The plurality of wafer blades each has a predetermined thickness, a top surface, a bottom surface and a predetermined spacing from adjacent wafer blades. A plurality of sensors, such as optical sensors, capacitance sensors or magnetic sensors, with at least one mounted on the bottom side of one of the plurality of wafer blades for sensing the presence of metal on a wafer carried on an adjacent wafer blade immediately below the one of the plurality of wafer blades.