Constructing Soft Substrate-less Platforms Using Particle-Assembled Fluid-Fluid Interfaces and Their Prospects in Multiphasic Applications

Particle-assembled fluid-fluid interfaces give rise to soft substrate-less platforms with wide-ranging applications, including remote and on-demand manipulation, optical modulation, catalysis, and multiphase and multiplex sensing, as well as in situ reaction kinetics elucidation. Notably, these soft platforms are easy to fabricate and can exhibit long-range order, both of which are challenging to achieve using traditional solid-based substrates. In this perspective, we provide an overview of the latest research in the fabrication and applications of these soft platforms. We begin with a brief discussion on the formation mechanism of two- and three-dimensional substrate-less platforms, followed by highlighting the unique properties of these platforms. We also discuss the application of these particle-assembled interfaces to three specific research areas, including dynamic tuning of optical properties, multiplex molecular sensing, and small-volume reaction modulation and kinetics monitoring. We end our perspective with an outlook on the promising research frontiers that can be achieved using these soft substrate-less platforms.