Super-wetting, wafer-sized silicon nanowire surfaces with hierarchical roughness and low defects

Abstract

This paper reports the fabrication of wafer-sized silicon nanowire (SiNW) surfaces using a modified metal-assisted chemical etching method. The complete fabrication and coating process can be performed in less than three hours, is easily size-scalable, and produces surfaces with very low surface defects, complex, hierarchical surface roughness, and large nanowire height. These surfaces exhibit extreme wettabilities depending on surface coating: oxidized SiNW surfaces are superhydrophilic, while surfaces coated with a fluorinated hydrocarbon are superhydrophobic. The wetting and morphological properties of SiNW surfaces made with one and two etches of different duration are characterized vis-a `-vis their effect on water drop mobility. Compared to a single etch process, a double etch followed by coating with a fluorinated hydrocarbon more efficiently produces SiNW surfaces with high contact angles on which microliter-sized water drops roll-off at approximately 0u tilt angle. Due to their very low friction, extreme wetting properties, ease of fabrication, low-cost, and large-sizes, these SiNW surfaces may be advantageous in microfluidic devices, bioanalysis systems sensitive to cross-contamination that require disposable substrates, and other applications.

Ab initio and classical molecular dynamics studies of the structural and dynamical behavior of water near a hydrophobic graphene sheet

“…For comparison purposes, in terms of the observed contact angles, the contact angle of the two silicon surfaces was adjusted from ∼50 • to ∼150 • , a range amply covering the experimentally reported wettability of clean silicon. 29,34 Three independent simulation runs were conducted for each ε SiO value and the contact angles on the two silicon surfaces are illustrated in Fig. 4(a).…”

Osteoselection supported by phase separated polymer blend films

“…Their contact angle and rms roughness values are presented in Table . Surface roughness and chemical composition are two important factors that determine the wetting properties of a surface . All PPPE/PS (EtOH) polymer thin films had closely similar equilibrium water contact angles.…”

“…Surface roughness and chemical composition are two important factors that determine the wetting properties of a surface. 33 All PPPE/PS (EtOH) polymer thin films had closely similar equilibrium water contact angles. Furthermore, their h e values were comparable to those of PPPE (EtOH) surface regardless of their polymer composition ratio.…”

Anisotropic growth of Ni3(BO3)2 nanowhiskers on nickel substrates and its application in the fabrication of superhydrophilic surfaces

“…Notably, superhydrophilic surfaces with CA < 5 have presented remarkable prospects for application as surfaces with self-cleaning 25,26 or antifogging properties 27,28 as well as for the purposes of heat transfer 29 and biomolecular immobilization, 25 among others. Based on its water contact angle (CA), a material is characterized in terms of its surface wettability as either hydrophilic (CA < 90 ) or hydrophobic (CA > 90 ).…”