Themed collection Droplet dynamics and manipulation
Bijels stabilized using rod-like particles
The effect of stabilizing bicontinuous interfacially jammed emulsion gels, in short ‘bijels’, using rod-like instead of spherical colloidal particles is investigated.
Near-post meniscus-induced migration and assembly of bubbles
A bubble near a post-induced meniscus moves to the highest position of the triple contact line.
Liquid plasticine: controlled deformation and recovery of droplets with interfacial nanoparticle jamming
An effective control of the shape and transparency of a water droplet is realized based on interfacial jamming of nanoparticles.
Insertion and confinement of air bubbles inside a liquid marble
We present an effect that enables the insertion and confinement of air bubbles inside a liquid marble, based on encapsulating an air bubble surrounded by surfactant molecules or hydrophilic colloidal particles. This finding can stimulate fundamental studies of this novel bubble-marble phenomenon, as well as development of various practical applications.
Retracted Article: Linear model of a T-junction microdroplet generator for precise control of droplet size
Growth kinetics of NaCl crystals in a drying drop of gelatin: transition from faceted to dendritic growth
Dynamics of transition between crystallization modes for NaCl in gelatin is studied through experiments and simulation.
Deformation of a floating liquid marble
We report the analytical and experimental characterisation of the deformation of a liquid marble floating on a liquid surface.
About this collection
Droplets are one of the most commonly observed fluidic objectives in nature and daily life. However, they play very important role in many fields, such as inkjet printing, 3D printing, spray coating and cooling, biotechnology, tribology, etc. More interestingly, a single droplet can also act as a micro-reactor where chemical reactions or bio-reactions occur in a different manner as in the bulk container. Due to the important applications and abundant fundamental issues involved in, to investigate the dynamics and manipulation of droplets is highly desirable and quite challengeable due to the failure of the continuum approximation and the emerging stability problems. Until now, many techniques have been developed for the purpose of droplet manipulation, for instance, fabrication of super-wettablility surfaces, driving droplet motion using Marangoni effect induced by light/thermal or concentration gradient, manipulation or levitation by external fields such as electrostatic, magnetic, acoustic fields, etc.
In this collection, the effect of particle adsorption at droplet surface is highlighted. The presence of particles can alter the shape deformation of liquid marbles floating on liquid surface or even enable the confinement of air bubbles inside it. Various intriguing non-spherical shapes can be achieved by the interfacial jamming of the particles. At the liquid-liquid interface, rod-like particle can result in bi-jel formation at a much higher packing fraction than expected due to “slippers”. The shape of the meniscus also plays an important role in both the assembly of tiny objectives including particles and air bubbles, and the drying patterns of droplet.
In the future, with the advances in droplet manipulation, novel droplet based-devices, such as smart liquid lens, bio-reactors, metamaterials with tunable functions, will be designed and fabricated.
Dr. Duyang Zang
Northwestern Polytechnical University, Xi’an, China