A laterally sensitive colloidal probe for accurately measuring nanoscale adhesion of textured surfaces

Adhesion assessment of nanoscale contacts is a critical capability for the development of future nanoelectromechanical systems and nanobiotechnology devices. However, experimental approaches to investigate interactions on micro- and nanostructured surfaces have predominantly been restricted to capturing adhesion force in the normal direction. This provides limited information about the multidimensional nature of surface texture and related interaction mechanisms. Here the design, fabrication, and application of a unique atomic force microscope probe is presented that consists of a focused ion beam-milled cantilever decorated with a colloidal particle. The probe is specifically developed for characterizing textured surfaces with lateral force feedback. Pull-off tests that map the adhesive interaction in microscale cavities are performed to examine the capability of the probe. Normal and lateral adhesive forces during nanoscale contact are accurately obtained and the adhesion energy of the contact interface is thus determined. An in-depth understanding of the effects of surface texture and the correlation of adhesion and friction is demonstrated. The proposed methodology enables dedicated investigations of interfacial interaction on various non-planar surfaces. It can be used for understanding the complex interplay of adhesion, contact, and friction forces at nanoscale, which may facilitate significant advances in challenging research areas such as fibrillar adhesion.