His research has involved study of molecular and interfacial forces. His work is applicable to a wide range of industrial and fundamental science problems. In particular, he has contributed significantly to the understanding of colloidal dispersions, biological systems, and polymer engineering applications. He has studied interfacial phenomena, the physics of thin films, and fundamental questions in rheology and tribology of surfaces.
Israelachvili has developed numerous techniques for the static and dynamic measurement of material and molecular properties of vapors, liquids, and surfaces. In particular, he pioneered a sensitive interfacial force-sensing technique known as the surface forces apparatus (SFA). This instrument involves carefully approaching two surfaces (usually immersed in a solvent, such as water), and measuring the force of attraction and repulsion between them. Using piezoelectric positional movement and optical interferometry for position sensing, this instrument can resolve distances to within 0.1 nanometer, and forces at the 10 N level. This technique is similar to measuring the force of interaction between an atomic force microscope (AFM) and a sample surface, except that the specialized SFA can measure much longer-range forces and is intended for surface-surface interaction measurements (as opposed to tip-surface or molecule-surface measurements). The results of SFA experiments can be used to characterize the nature of intermolecular potentials and other molecular properties.
Israelachvili is also well known as the author of the textbook "Intermolecular and Surface Forces," published by Academic Press. This authoritative book describes the fundamental concepts and equations applicable to all intermolecular and interfacial science disciplines.
Israelachvili was also founder of SurForce, LLC. The company specializes in researching surface force interactions and producing SFA systems.[https://www.surforcellc.com/about-us/]