Thinking laterally - probing the force holding the oxide layer to a liquid metal interface

This is the authors' abstract. We don't add key points for this paper.

Liquid metal systems are increasingly important due to their versatility in applications, including catalysis, flexible electronics, and synthesis processes. The ultra-thin native oxide skin that forms at the liquid metal-air interface can influence these applications positively or negatively, depending on whether a dynamic or static interface is required. We hypothesise that a deeper understanding of the oxide layer's behaviour and interaction forces could enable advancements in liquid metal applications. We developed a method to create liquid metal micro-islands—hemi-spherical regions of liquid metal adhered to solid substrates with a fluidic nature and an outer native oxide layer. Using atomic force microscopy (AFM), including surface-normal and lateral force spectroscopy, we investigated the forces between the oxide layer and the underlying liquid metal. Our AFM measurements reveal that the scalar force needed to delaminate the oxide layer from the liquid metal interior is ∼1 µN, with a force per unit area of ∼69 nN/nm². Moreover, this work suggests that the developed protocol for creating liquid metal micro-islands could serve as a platform technology for in-situ analysis of liquid metal systems, facilitating further research in this area.