Anisotropic Wetting on Microstrips Surface Fabricated by Femtosecond Laser

Abstract

In this paper, we present a new method to realize anisotropy by restricting a droplet on an unstructured Si hydrophobic domain between two superhydrophobic strips fabricated by femtosecond laser. The water contact angles and corresponding water baseline length were investigated. The results showed that anisotropy would vary with the volume-induced pinning-depinning-repinning behavior of the droplet. Furthermore, through the observation of water response on small Si domain, the adhesive force of the structure is proven to be the key factor giving rise to the anisotropy wetting. This phenomenon could potentially be used as a model for fundamental research, and such structures could be utilized to control large volume in microfluidic devices, lab-on-chip system, microreactors, and self-cleaning surfaces.

Anisotropic Wetting of Hydrophobic and Hydrophilic Surfaces–Modelling by Lattice Boltzmann Method

“…Structured texture and/or chemical heterogeneity can be potentially used to manipulate droplets in case of hydrophobic surfaces [1]. …”

“…Surfaces with static contact angle θ s < 90 • are considered to be hydrophilic and generally have good wettability properties. Surfaces with contact angle θ s = 90 − 150 • are hydrophobic and surfaces with θ s > 150 • and sliding angle less than 10 • are considered to be super-hydrophobic and are often used for liquid repelling applications [1].…”

“…Nature has created several example of anisotropic wetting like butterfly wings, shark skin or water striders legs [1]. Nature inspired biomimetic surfaces have attracted in recent years significant attention thanks to new microfabrication techniques like femto-second lasers machining [5], direct writing or interface lithography as reviewed by Cheng et al [6].…”

Modification of wettability property of titanium by laser texturing

“…Since the company of Kao in Japan firstly prepared superhydrophobic surface with contact angle of 174º [9], many techniques have been reported to produce superhydrophobic surfaces, including self-assembly, electrospinning, polymer imprinting, plasma-treated surfaces, lithography, and so on [10][11][12][13][14][15][16]. In recent years, more and more researches focus on manufacturing hydrophobic surface based on the technology of laser-induced microstructure.…”

Reversible Underwater Lossless Oil Droplet Transportation

“…The details of the experimental setup and the scanning method are described in our previous work. [38][39][40] A p-type silicon wafer was irradiated by a regenerative amplifi ed Ti:sapphire laser system (pulse duration: 50 fs; center wavelength: 800 nm; repetition: 1 kHz). The laser beam (constant average power of 20 mW) was focused on the sample by a microscope objective lens (NA = 0.45).…”