A way to measure the dispersion forces near the van der Waals-Casimir transition

TL;DR

This paper introduces an innovative experimental setup using adhered cantilevers to measure dispersion forces near the van der Waals-Casimir transition, overcoming previous instability issues and applicable to various materials and media.

Contribution

The study proposes a novel cantilever-based method to measure quantum fluctuation-induced forces at nanometer scales without instability limitations.

Findings

Method is feasible and sensitive to forces near the transition

Applicable to diverse materials and media

Addresses electrostatic and contact distance issues

Abstract

Forces induced by quantum fluctuations of electromagnetic field control adhesion phenomena between rough solids when the bodies are separated by distances ~10nm. However, this distance range remains largely unexplored experimentally in contrast with the shorter (van der Waals forces) or the longer (Casimir forces) separations. The reason for this is the pull-in instability of the systems with the elastic suspension that poses a formidable limitation. In this paper we propose a genuine experimental configuration that does not suffer from the short distance instability. The method is based on adhered cantilever, whose shape is sensitive to the forces acting near the adhered end. The general principle of the method, its possible realization and feasibility are extensively discussed. The dimensions of the cantilever are determined by the maximum sensitivity to the forces. If the adhesion is defined by strong capillary or chemical interactions, the method loses its sensitivity. Special discussion is presented for the determination of the minimum distance between the rough solids upon contact, and for the compensation of the residual electrostatic contribution. The proposed method can be applied to any kind of solids (metals, semiconductors, dielectrics) and to any intervening medium (gas or liquid).