Cleaning AFM colloidal probes by mechanically scrubbing with supersharp “brushes”

Contamination control of atomic force microscope (AFM) tips (including standard but supersharp imaging tips and particle/colloidal probes) is very important for reliable AFM imaging and surface/interface force measurements. Traditional cleaning methods such as plasma, UV–ozone and solvent treatments have their shortcomings. Here, we demonstrate that calibration gratings with supersharp spikes can be employed to scrub away contaminants accumulated on a colloidal sphere probe by scanning the probe against the spikes at high load at constant-force mode. The present method is superior to traditional cleaning methods in several aspects. First, accumulated lump-like organic/inorganic material can be removed; second, removal is non-destructive and highly efficient based on a “targeted removal” strategy; third, removal and probe shape/morphology study can be completed in a single step (we report, to our best knowledge, the first evidence of the wear of the colloidal sphere during force measurements); and fourth, both colloidal/particle probes and standard but supersharp AFM imaging tips can be treated.