Device and method for gas maintenance in microfeatures on a submerged surface

Abstract

A microstructured surface with microfeatures formed thereon and defining spaces between the microfeatures includes least one electrode of an electrode pair in the spaces, wherein electrodes of the pair are electrically connected to one another. The at least one electrode located in the space is configured to generate a gas in between the microfeatures when an electrolyte solution penetrates into the microfeatures. Importantly, the electrodes are not connected to any external power source. Because the microstructured surface is self-powered in replenishing the gas lost in a submerged condition, no additional provision to supply energy or regulate the replenishment is necessary for implementation and use.

1 . A microstructured surface comprising:
 a plurality of microfeatures disposed on a substrate and defining a space located between inner surfaces of the plurality of microfeatures, wherein the inner surfaces between the plurality of microfeatures are at least partially hydrophobic;   a gas generator comprising a first electrode of an electrode pair electrically connected to a second electrode of the electrode pair, the first electrode disposed within the space located between inner surfaces of the plurality of microfeatures and configured to generate a gas by a spontaneous electrochemical reaction when part of the space located between the microfeatures is filled with an electrolyte solution while the microstructured surface is submerged in the electrolyte solution.   
     
     
         2 . The microstructured surface of  claim 1 , wherein the first electrode of the electrode pair is located on the substrate between microfeatures. 
     
     
         3 . The microstructured surface of  claim 1 , wherein the first electrode of the electrode pair is located on the inner surface of at least one of the microfeatures. 
     
     
         4 . The microstructured surface of  claim 1 , wherein the first electrode and the second electrode of the electrode pair have respective standard electrode potentials that generate gas by spontaneous electrochemical reaction when contacted by the electrolyte solution, and the difference between the standard electrode potential of the electrolyte and the standard electrode potential of the second electrode is, in magnitude, larger than an overpotential for gas generation at the first electrode, and wherein the overpotential at the first electrode is, in magnitude, smaller than the overpotential at the second electrode. 
     
     
         5 . The microstructured surface of  claim 1 , wherein the first electrode of the electrode pair comprises one of a trace, track, porous layer, mesh, or wire. 
     
     
         6 . The microstructured surface of  claim 1 , wherein the first electrode comprises nickel and the second electrode comprises magnesium. 
     
     
         7 . A microstructured surface comprising:
 a plurality of microfeatures disposed on a substrate and defining a space located between inner surfaces of the plurality of microfeatures, wherein the inner surfaces between the plurality of microfeatures are at least partially hydrophobic;   a gas generator comprising a first electrode and a second electrode of an electrode pair electrically connected to one another, the first electrode and the second electrode disposed within the space located between inner surfaces of the plurality of microfeatures and configured to generate a gas in between the microfeatures by spontaneous electrochemical reaction when part of the space is filled with an electrolyte solution while the microstructured surface is submerged in the electrolyte solution.   
     
     
         8 . The microstructured surface of  claim 7 , wherein the electrode pair is located on the substrate between microfeatures. 
     
     
         9 . The microstructured surface of  claim 7 , wherein the electrode pair is located on the inner surface of at least one of the microfeatures. 
     
     
         10 . The microstructured surface of  claim 7 , wherein the electrodes of the electrode pair have respective standard electrode potentials that generate gas by spontaneous electrochemical reaction when contacted by the electrolyte solution, and the difference between the standard electrode potential of the electrolyte and the standard electrode potential of the second electrode is, in magnitude, larger than an overpotential for gas generation at the first electrode, and wherein the overpotential at the first electrode is, in magnitude, smaller than the overpotential at the second electrode. 
     
     
         11 . The microstructured surface of  claim 7 , wherein the electrode pair comprise one of a trace, track, porous layer, mesh, or wires. 
     
     
         12 . The microstructured surface of  claim 7 , wherein the first electrode comprises nickel and the second electrode comprises magnesium. 
     
     
         13 . A method of forming a microstructured surface comprising:
 depositing electrodes on a surface of a substrate;   securing a mold against the surface of the substrate containing the electrodes so as to form a tight contact between the mold and electrodes, the mold containing a plurality of cavities therein;   applying pressure between the mold and the substrate to force material from the substrate into the plurality of cavities to form a plurality of microfeatures; and   separating the mold from the substrate.   
     
     
         14 . The method of  claim 13 , wherein pressure is applied at an elevated temperature. 
     
     
         15 . The method of  claim 13 , further comprising removing any substrate material covering the electrodes after separating the mold from the substrate. 
     
     
         16 . The method of  claim 13 , further comprising coating the plurality of microfeatures with a hydrophobic layer. 
     
     
         17 . The method of  claim 16 , wherein the hydrophobic layer comprises polytetrafluoroethylene (PTFE). 
     
     
         18 . The method of  claim 13 , further comprising connecting the electrodes on the substrate to another electrode formed from a different material. 
     
     
         19 . A water-borne vehicle or watercraft having the microstructured surface of  claim 1  on at least a portion of a water-contacting surface. 
     
     
         20 . A water-borne vehicle or watercraft having the microstructured surface of  claim 7  on at least a portion of a water-contacting surface. 
     
     
         21 . A pipe having the microstructured surface of  claim 1  on an interior surface thereof. 
     
     
         22 . A pipe having the microstructured surface of  claim 7  on an interior surface thereof.