Measuring normal and friction forces acting on individual fine particles

Abstract

Interparticle and surface forces are of great importance in many fields of pure and applied science. We present an apparatus to measure the normal and friction forces acting between a particle (radius of 0.5–20 μm) and another solid surface. The apparatus is based on the principle of an atomic force microscope. For quantitative friction measurements we propose a method to determine the lateral spring constants of atomic force microscope cantilevers with attached spherical particles.

Friction between Individual Microcontacts

“…All experiments were done with the particle interaction apparatus (15), which has a design similar to that of an AFM. Spherical silica particles (Bangs Laboratories, USA) were glued to AFM cantilevers using a small amount of epoxy resin (Epikote 1004, Shell; Fig.…”

“…Torsional spring constants of AFM cantilevers with attached particles were measured with a special setup (15). A lateral force was applied to the particle by a calibrated tipless cantilever under microscopic control (Fig.…”

Measurement of friction coefficients with the atomic force microscope

“…[1] for a critical review of calibration techniques.) The main methods that have proved quantitatively reliable [2,3,4,5,6] all involve an ex situ calibration that is separate to the friction measurement, and they all require special modifications to the substrate or to the cantilever, and very particular care in reassembling the cell for the actual measurement to preserve the calibration parameters.…”

Lateral force calibration in atomic force microscopy: A new lateral force calibration method and general guidelines for optimization

“…Several lateral force calibration methods work around the challenge of measuring the lateral sensitivity ͑Table I͒. The optical geometry method of Liu et al, 19 static friction method of Cain et al, 17 and vertical lever method of Ecke et al 20 each describe lateral force calibration procedures that are analogous to the normal force calibration described above. Here, we briefly review the established methods.…”