Recent progress in measurements of oscillatory forces and liquid properties under confinement

The present review paper focuses on direct measurements of oscillatory forces. Beside the surface forces apparatus (SFA), atomic force microscopy (AFM) has emerged as the most commonly used technique to measure surface forces. Recent instrumental advances of both methods are highlighted in the review. Different systems, showing oscillatory forces are classified. Principle distinction is made between 1-component liquids (water, organic liquids and liquid crystals), pseudo 1-component liquids (ionic liquids and microemulsions) and 2-component liquids (dispersions containing polyelectrolytes, micelles or nanoparticles). In the last few years, the oscillatory force studies address particle characterisation, synergistic effects in multicomponent systems, the introduction of ‘switchable’ forces, and resolving liquid properties under confinement. Last but not least, the ability of AFM and SFA to measure oscillatory forces is discussed.