A Review of Smart Lubricant-Infused Surfaces for Droplet Manipulation

Abstract

The nepenthes-inspired lubricant-infused surface (LIS) is emerging as a novel repellent surface with self-healing, self-cleaning, pressure stability and ultra-slippery properties. Recently, stimuli-responsive materials to construct a smart LIS have broadened the application of LIS for droplet manipulation, showing great promise in microfluidics. This review mainly focuses on the recent developments towards the droplet manipulation on LIS with different mechanisms induced by various external stimuli, including thermo, light, electric, magnetism, and mechanical force. First, the droplet condition on LIS, determined by the properties of the droplet, the lubricant and substrate, is illustrated. Droplet manipulation via altering the droplet regime realized by different mechanisms, such as varying slipperiness, electrostatic force and wettability, is discussed. Moreover, some applications on droplet manipulation employed in various filed, including microreactors, microfluidics, etc., are also presented. Finally, a summary of this work and possible future research directions for the transport of droplets on smart LIS are outlined to promote the development of this field.

Bioinspired Lubricated Slippery Magnetic Responsive Microplate Array for High Performance Multi‐Substance Transport

“…[ 1 ] The on‐demand droplet manipulation is desired for lab‐on‐a‐chip devices, oil/water separation, water‐collecting, and filtration. [ 2 ] Controllable transport of solid substance also has alluring prospects in drug delivery, micro‐object sorting, and self‐cleaning. [ 3 ] Till now, researchers have prepared a series of stimulus‐responsive surfaces to enable the directional transport of gases, liquids, and solids.…”

“…In particular, compared with other stimulus methods, magnetic stimulus has the advantages of remote controllable, battery‐free, fast response, and good biosafety, which has been widely used for the controllable substance transport. [ 2c,d ] For example, the lubricant‐infused magnetically responsive microcone‐structured surface (carpets) can reversibly switch the adhesion state of the bubble or droplet between the pin and slip states by controlling the alignment response of the microcone structures with a traveling magnetic field wave, thus realizing the continuous and controllable manipulation of bubble [ 7c ] or droplet. [ 7d ] By the bending deformation of microstructure or the local dent deformation of elastomer, droplet can be transported by the superhydrophobic magnetically responsive elastomer surface.…”

“…[ 13 ] Nepenthes has the slippery peristome surface that is fully wetted by water and nectar, enabling efficient capture of insect into the pitcher. [ 2a,d,14 ] Respiratory cilia can oscillate in a certain direction to actively transport the pathogens out in order to protect the respiratory system. [ 3b,c,15 ]…”

Bioinspired materials for droplet manipulation: Principles, methods and applications

“…In general, there is a diverse range of droplet manipulation methods on surfaces, as droplets can land on solid surfaces and liquid injection surfaces. 20,25 Remarkably, research on droplet manipulation involves many knowledge aspects, including bionic functional surfaces with wettability, 35 responsive surfaces 33 and the effect of light and magnetic fields on particles. At present, many manipulation methods and applications have been reviewed for only one situation or a combination of several situations, 20 such as droplet manipulation on liquid injection surfaces 25 or droplet control by an external field.…”

“…20,25 Remarkably, research on droplet manipulation involves many knowledge aspects, including bionic functional surfaces with wettability, 35 responsive surfaces 33 and the effect of light and magnetic fields on particles. At present, many manipulation methods and applications have been reviewed for only one situation or a combination of several situations, 20 such as droplet manipulation on liquid injection surfaces 25 or droplet control by an external field. 21 However, it is difficult to obtain a comprehensive understanding of the principle, method and application of droplet manipulation through the developmental demonstration of several parts in this area.…”