Uni-, Bi-, and Tri-Directional Wetting Caused by Nanostructures with Anisotropic Surface Energies

Wetting is a pervasive phenomenon that governs many natural and artificial processes. Asymmetric wetting along a single axis, in particular, has generated considerable interest but has thus far been achieved only by the creation of structural anisotropy. In this paper, we report that such directional wetting can also be achieved by anisotropically coating nanostructure surfaces with materials that modify the nanostructure surface energy, a phenomenon that has not been observed in natural or artificial systems thus far. Moreover, by combining this newfound chemical influence on wetting with topographic features, we are able to restrict wetting in one, two and three directions. A model that explains these findings in terms of anisotropy of the pinning forces at the triple phase contact line is presented. Through the resulting insights, a flexible method for precise control of wetting is created

Uni-, Bi-, and Tri-Directional Wetting Caused by Nanostructures with Anisotropic Surface Energies

Wetting is a pervasive phenomenon that governs many natural and artificial processes. Asymmetric wetting along a single axis, in particular, has generated considerable interest but has thus far been achieved only by the creation of structural anisotropy. In this paper, we report that such directional wetting can also be achieved by anisotropically coating nanostructure surfaces with materials that modify the nanostructure surface energy, a phenomenon that has not been observed in natural or artificial systems thus far. Moreover, by combining this newfound chemical influence on wetting with topographic features, we are able to restrict wetting in one, two and three directions. A model that explains these findings in terms of anisotropy of the pinning forces at the triple phase contact line is presented. Through the resulting insights, a flexible method for precise control of wetting is created

Uni-, Bi-, and Tri-Directional Wetting Caused by Nanostructures with Anisotropic Surface Energies

Wetting is a pervasive phenomenon that governs many natural and artificial processes. Asymmetric wetting along a single axis, in particular, has generated considerable interest but has thus far been achieved only by the creation of structural anisotropy. In this paper, we report that such directional wetting can also be achieved by anisotropically coating nanostructure surfaces with materials that modify the nanostructure surface energy, a phenomenon that has not been observed in natural or artificial systems thus far. Moreover, by combining this newfound chemical influence on wetting with topographic features, we are able to restrict wetting in one, two and three directions. A model that explains these findings in terms of anisotropy of the pinning forces at the triple phase contact line is presented. Through the resulting insights, a flexible method for precise control of wetting is created

Experimental approach and and set-up for photo-attachment.

<p>A: Chemical reaction approach for photo-attachment of biomolecules on nanowire surface. B: Simple set up for photo-attachment. The black parts in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116539#pone.0116539.g001" target="_blank">Fig. 1B</a> represents opaque region of photomask. The yellow region represents photo-attached nanowires.</p

Hybridization of target oligo on photo-attached substrates.

<p>A: Psoralen functionalized substrates, B: Diazirine functionalized substrates, C: Psoralen functionalized substrate with passivation, and D: Diazirine functionalized substrate with passivation.</p

Results of discrimination of nucleotide with single base mismatch.

<p>A: Without formamide and B: With formamide on Psoralen functionalized surface.</p

Estimation of surface bound amine group for flat Si wafer and GLAF-MACE (Chip1 and Chip 2) surfaces.

<p>Estimation of surface bound amine group for flat Si wafer and GLAF-MACE (Chip1 and Chip 2) surfaces.</p

Photo-attachment to crosslink sense oligo on nanowire substrates.

<p>A: Psoralen functionalized nanowire substrate, B: Diazirine functionalized nanowire substrate, C: Psoralen functionalized polished silicon substrate with the inset shows the same chip scanned at maximum power and PMT gain, D: Diazirine functionalized polished silicon substrate with the inset shows the same chip scanned at maximum power and PMT gain, E: Psoralen functionalized with passivated substrate, and F: Diazirine functionalized with passivated substrate.</p

Probe crosslinking on nanowires with different probe structures.

<p>A: On psoralen functionalized surface passivated with adipic acid and B: On diazirine functionalized surface passivated with adipic acid.</p

Results of photo-attached spots of different diameters.

<p>A: Array Fabrication of photo-attached spots of various diameter, yellow arrow pointing anomaly surface area resulted from nanowire fabrication process. B: Schematic diagram showing the approach to immobilize different probes at different positions separated by specially designed gaskets (black portion) and C: Piezo dispensing by Scienion AG, with permission to reproduce image.</p