Superhydrophobic and superoleophobic nanosurfaces
Devices, systems and techniques are described for producing and implementing articles and materials having nanoscale and microscale structures that exhibit superhydrophobic, superoleophobic or omniphobic surface properties and other enhanced properties. In one aspect, a surface nanostructure can be formed by adding a silicon-containing buffer layer such as silicon, silicon oxide or silicon nitride layer, followed by metal film deposition and heating to convert the metal film into balled-up, discrete islands to form an etch mask. The buffer layer can be etched using the etch mask to create an array of pillar structures underneath the etch mask, in which the pillar structures have a shape that includes cylinders, negatively tapered rods, or cones and are vertically aligned. In another aspect, a method of fabricating microscale or nanoscale polymer or metal structures on a substrate is made by photolithography and/or nano imprinting lithography.
1. A method of imparting superhydrophilic surface properties to a metal or semiconductor surface, the method comprising:
depositing a buffer layer on the metal or semiconductor surface;
depositing a film layer over the buffer layer;
annealing the film layer into an etch mask comprising a plurality of balled-up islands on the buffer layer, the buffer layer having exposed portions around the balled-up islands;
etching the exposed portions of the buffer layer to create a plurality of pillar structures, each pillar comprising buffer layer capped by a balled-up island, wherein the pillar structures have a shape that includes at least one of a substantially straight cylinder, negatively tapered rod, or cone and are aligned substantially vertical; and
coating the plurality of pillar structures with a layer of a hydrophilic material, wherein coating the plurality of pillar structures further comprises impregnating a hydrophilic liquid between nanopillars.
2. The method of claim 1 , wherein depositing the film layer further comprises periodic patterning of the film layer such that the resulting plurality of pillar structures are in a patterned array.
3. The method of claim 1 , wherein etching further comprises reactive ion etching.
4. The method of claim 3 , wherein the pillar structures are configured to a size and shape based on the time, power, and gas pressure of the reactive ion etching.
5. The method of claim 1 , further comprising etching partially into the metal or semiconductor surface such that each pillar comprises part of the metal or semiconductor surface and buffer layer capped by a balled-up island.
6. The method of claim 1 , further comprising removing the balled-up islands from the pillars prior to coating the plurality of pillar structures with a layer of a hydrophilic material.
7. The method of claim 1 , wherein the coating comprises dip coating the plurality of pillars to form a mushroom-shaped tip on each pillar.
8. The method of claim 1 , wherein the buffer layer comprises SiO 2 or silicon nitride.
9. The method of claim 1 , wherein the film layer comprises silver, gold, copper, platinum, copper, or nickel.
10. The method of claim 1 , wherein the buffer layer has a thickness in a range of 0.5 nanometers (nm) to 50 micrometers (μm).
11. The method of claim 1 , wherein the film layer has a thickness in a range of 0.5 nm to 1 μm.
12. The method of claim 1 , wherein the annealing is performed at a temperature in a range of 200° C. to 1,000° C.
13. The method of claim 1 , wherein the etching includes performing an anisotropic chemical etching process that uses at least one of a directional jet flow of an etchant solution, directional blow of nanoparticles or microparticles for sand blasting, or a mixture of liquid solution or etchant with nanoparticles or microparticles.
14. A method of imparting superhydrophilic surface properties to a metal or semiconductor surface, the method comprising:
depositing a buffer layer on the metal or semiconductor surface;
depositing a film layer over the buffer layer;
annealing the film layer into an etch mask comprising a plurality of balled-up islands on the buffer layer, the buffer layer having exposed portions around the balled-up islands;
etching the exposed portions of the buffer layer to create a plurality of pillar structures, each pillar comprising buffer layer capped by a balled-up island, wherein the pillar structures have a shape that includes at least one of a substantially straight cylinder, negatively tapered rod, or cone and are aligned substantially vertical;
etching partially into the metal or semiconductor surface such that each pillar comprises part of the metal or semiconductor surface and buffer layer capped by a balled-up island; and
coating the plurality of pillar structures with a layer of a hydrophilic material.
15. The method of claim 14 , wherein depositing the film layer further comprises periodic patterning of the film layer such that the resulting plurality of pillar structures are in a patterned array.
16. The method of claim 14 , wherein the coating comprises dip coating the plurality of pillars to form a mushroom-shaped tip on each pillar.
17. The method of claim 14 , further comprising removing the balled-up islands from the pillars prior to coating the plurality of pillar structures with a layer of a hydrophilic material.
18. A method of imparting superhydrophilic surface properties to a metal or semiconductor surface, the method comprising:
depositing a buffer layer on the metal or semiconductor surface;
depositing a film layer over the buffer layer;
annealing the film layer into an etch mask comprising a plurality of balled-up islands on the buffer layer, the buffer layer having exposed portions around the balled-up islands;
etching the exposed portions of the buffer layer to create a plurality of pillar structures, each pillar comprising buffer layer capped by a balled-up island, wherein the pillar structures have a shape that includes at least one of a substantially straight cylinder, negatively tapered rod, or cone and are aligned substantially vertical; and
coating the plurality of pillar structures with a layer of a hydrophilic material, wherein the coating comprises dip coating the plurality of pillars to form a mushroom-shaped tip on each pillar.
19. The method of claim 18 , wherein depositing the film layer further comprises periodic patterning of the film layer such that the resulting plurality of pillar structures are in a patterned array.
20. The method of claim 18 , further comprising removing the balled-up islands from the pillars prior to coating the plurality of pillar structures with a layer of a hydrophilic material.