In some embodiments, an apparatus and a system, as well as a method and an article, may operate to advance a sampling and guard probe (100) with a surrounding sealing pad (108) against a borehole wall, to adjust the size of the area associated with a fluid flow inlet of the probe, where the size of the inlet area (104) is selectably and incrementally variable, and to draw fluid into the fluid flow inlet by activating at least one pump (344) coupled to at least one fluid passage (128) in the probe. Additional apparatus, systems, and methods are disclosed.