Study of Active Janus Particles in the Presence of an Engineered Oil–Water Interface

Abstract

We present a systematic study of motion of Pt@ SiO 2 Janus particles at a liquid−liquid interface. A special microfluidic trap is used for creating such an interface. The increased surface energy of the large surface results in partial wetting of the substrate, leaving patches of oil on the glass surface. This allows us to directly compare the motion at the two interfaces, i.e., oil−water and solid−water interface within the same setting, guaranteeing identical conditions in terms of additional parameters. The propulsion behavior of Janus particles is found to be quantitatively similar at both surfaces. The interplay of reaction product absorption by oil, slip locking by surfactant, microscale friction, lubrication efficiency, and potential Marangoni effect controls the resemblance of motion characteristics at the two interfaces. Additionally, we also observed guidance effect on the Janus particles by the pinning line of oil patches, similar to solid side walls.

Synthesis of Polymer Janus Particles with Tunable Wettability Profiles as Potent Solid Surfactants to Promote Gas Delivery in Aqueous Reaction Media

“…Janus particles represent a unique collection of functional hybrid materials because they provide asymmetry and can thus impart different chemical or physical properties and directionality within a single-particle system. , Due to unique amphiphilic, magnetic, catalytic, optical, or electrical properties, Janus particles can possess advantages over their single-component counterparts with implications for a wide range of applications in the fields of physics, chemistry, and biological science. , As such, Janus particles have been used as colloidal building blocks for self-assembled structure formation, , in optics and imaging applications, , and as motile particles with directional propulsion profiles, , transducers and signal amplifiers in sensing applications, , and powerful solid surfactants that allow us to control and influence the packing dynamics at interfaces. , …”

“…1,2 Due to unique amphiphilic, magnetic, catalytic, optical, or electrical properties, Janus particles can possess advantages over their singlecomponent counterparts with implications for a wide range of applications in the fields of physics, chemistry, and biological science. 3,4 As such, Janus particles have been used as colloidal building blocks for self-assembled structure formation, 5,6 in optics and imaging applications, 7,8 and as motile particles with directional propulsion profiles, 9,10 transducers and signal amplifiers in sensing applications, 11,12 and powerful solid surfactants that allow us to control and influence the packing dynamics at interfaces. 13,14 Amphiphilic Janus particles can mediate superior stability to multiphasic mixtures, such as emulsions, foams, or polymer blends, as opposed to their homogeneous counterparts.…”

Microfluidic Particle Reactors: From Interface Characteristics to Cells and Drugs Related Biomedical Applications

“…[42,43] Therefore, Janus structured emulsion templates have the potential to integrate two or more chemically discrepant composites into a micro-system. [44] Furthermore, the interfaces of heterogeneous compartments possess diverse surface modification proposals, which can simultaneously integrate more synergetic functions (such as response, movement, and reconfiguration). Briefly, Janus structure emulsion templates are effective in developing intelligent drug delivery vehicles since they are composed of two independent compartments with distinctive and selective surface modification potentiality.…”

Microfluidics for Microswimmers: Engineering Novel Swimmers and Constructing Swimming Lanes on the Microscale, a Tutorial Review

“…The high surface energy of the flat surface resulted in partial wetting of the substrate, easing direct comparison of motion of Pt@SiO 2 particles at a liquid and a solid substrate. [90]…”