Some examples provide a vacuum wafer chuck assembly for supporting a wafer. An example chuck assembly comprises a chuck hub and a centering hub disposed within the chuck hub. Chuck arms are mounted to the chuck hub, with each chuck arm extending radially between a proximal end adjacent the chuck hub, and a distal end remote therefrom. At least one vacuum pad is provided for supporting the wafer during a wafer centering or wafer processing operation. A vacuum sensor detects a presence or absence of a vacuum pressure at the vacuum pad during the wafer centering or processing operation, a detection indicative of a presence or absence of the wafer in the chuck assembly, or a presence of a defective wafer.