Development of an instrument for measuring inter-particle forces

Abstract

Abstract An understanding of the forces acting between individual particles is important because these forces dominate the behavior of fine particles in air and liquid. This understanding will facilitate improvements in particulate processes such as dispersion and agglomeration. Here we report on the development of an instrument, based on atomic force microscopy (AFM) technology, that enables the quantification of inter-particle force as a function of separation distance. The advantage of the instrument over commercial AFMs is in its greater flexibility and modest cost. The construction and calibration of the instrument are described along with details of a powerful arrangement for data acquisition. The issues of instrument calibration and manipulating individual particles of a few microns in size are addressed. The precision of the instrument for force measurement is estimated to be ±8%. The measurable force has a range of less than 1 nN to 100 μN depending on the magnitude of the cantilever spring constant selected for the study.