Methods and apparatuses for detecting characteristics of a microelectronic substrate. A method in accordance with an embodiment of the invention includes positioning the microelectronic substrate proximate to and spaced apart from the first and second spaced apart electrodes, contacting the microelectronic substrate with a polishing surface of a polishing medium, removing conductive material from the microelectronic substrate by moving the substrate and/or the electrodes relative to each other while passing a variable electrical signal through the electrodes and the substrate, and detecting a change in the variable electrical signal or a supplemental electrical signal passing through the microelectronic substrate. The rate at which material is removed from the microelectronic substrate can be changed based at least in part on the change in the electrical signal.