ABSTRACT
The measurement of adhesion force itself is not foolproof either. For measurements in ambient air, a number of precautions must be taken. Capillary bridging has been shown to significantly alter the magnitude of adhesion force measured [31,32]. This is due to condensation of water in nanoscale separations formed around the probe-substrate contact area. The subsequent meniscus force often dominates the measured pull-off force. The size of the condensed water bridge and, therefore, the operating capillary forces, depend on the humidity level and the wetting characteris-
F =x7tRWAt (1)
WA = yi3 + K23 - 712, (2)
tic of the interacting surfaces. Operation in liquids or, conversely, dry environments, has been shown to reduce or eliminate the capillary bridging effect [4, 21, 31-36].
