Hierarchically structural and biphillic surface energy designs for enhanced condensation heat transfer

Abstract

An apparatus comprising a base layer, a distribution of separated micro-nucleation sites thereon. The apparatus also includes a distribution nanostructures located on the base layer, each of the micro-nucleation sites being adjacent to some of the nanostructures. Each of the micro-nucleation sites has a hydrophilic surface and the distribution of nanostructures form a superhydrophobic surface.

1 . An apparatus, comprising:
 a base layer having a distribution of separated micro-nucleation sites thereon; and   a distribution of nanostructures located on the base layer, each of the micro-nucleation sites being adjacent to some of the nanostructures; and wherein each of the micro-nucleation sites has a hydrophilic surface and the distribution of nanostructures form a superhydrophobic surface.   
     
     
         2 . The apparatus of  claim 1 , wherein the micro-nucleation sites and the nanostructures are located on a planar surface of the base layer. 
     
     
         3 . The apparatus of  claim 1 , wherein tops of the nanostructures are substantially coplanar with the hydrophilic surfaces of the micro-nucleation sites. 
     
     
         4 . The apparatus of  claim 1 , wherein some of the nanostructures surround each of the micro-nucleation sites. 
     
     
         5 . The apparatus of  claim 1 , wherein the hydrophilic surfaces of each of the micro-nucleation sites are substantially coplanar with bottoms of the nanostructures that contact the base layer. 
     
     
         6 . The apparatus of  claim 1 , wherein an area occupied by the hydrophilic surfaces of each of the micro-nucleation sites is in a range of 1 to 100 microns 2 . 
     
     
         7 . The apparatus of  claim 1 , wherein the hydrophilic surface of each of the micro-nucleation sites has a smooth surface. 
     
     
         8 . The apparatus of  claim 1 , wherein a separation distance between adjacent ones of the micro-nucleation sites is equal to or less than about 10 microns. 
     
     
         9 . The apparatus of  claim 1 , wherein the nanostructures are located on a region of the base layer having a lower thermal conductivity than a region of the base layer having the micro-nucleation sites thereon. 
     
     
         10 . The apparatus of  claim 1 , wherein tops of the nanostructures include a reentrant angled ledge. 
     
     
         11 . The apparatus of  claim 1 , wherein an area of the base layer having the nanostructures located thereon has a surface roughness where the following condition applies when a liquid droplet rests on the surface: −1/r*cos θa<1, wherein r is the surface roughness of the surfaces having the distribution of nanostructures located thereon and θa is an intrinsic advancing contact angle of the liquid droplet. 
     
     
         12 . The apparatus of  claim 1 , wherein a distance between adjacent ones of the nanostructures is greater than a critical condensation radius for a nucleating liquid droplet on the surface. 
     
     
         13 . A system, comprising:
 heat generating equipment; and   a heat transfer apparatus configured to remove heat generated by the heat generating equipment, wherein the apparatus includes:
 a base layer having a distribution of separated micro-nucleation sites thereon; and 
 a distribution of nanostructures located on the base layer, each of the micro-nucleation sites being adjacent to some of the nanostructures; and wherein each of the micro-nucleation sites has a hydrophilic surface and the distribution of nanostructures form a superhydrophobic surface. 
   
     
     
         14 . The system of  claim 13 , wherein the micro-nucleation sites are located on the surface of a condenser of the apparatus. 
     
     
         15 . The system of  claim 13 , wherein the condenser is part of a heat pipe or a vapor chamber. 
     
     
         16 . A method, comprising:
 manufacturing an apparatus, including:
 providing a base layer; 
 forming a distribution of separated micro-nucleation sites on the base layer, wherein each of the micro-nucleation sites has a hydrophilic surface; and 
 forming a distribution nanostructures on the base layer, wherein each of the micro-nucleation sites being adjacent to some of the nanostructures. 
   
     
     
         17 . The method of  claim 16 , wherein forming the micro-nucleation sites includes:
 forming a mask layer over the base layer; and   patterning the mask layer such that mask portions remain on the base layer in locations corresponding to the micro-nucleation sites.   
     
     
         18 . The method of  claim 16 , wherein forming the nanostructures on the base layer includes:
 modifying portions of the base layer not covered by mask portions located on the base layer that correspond to locations of the micro-nucleation sites.   
     
     
         19 . The method of  claim 18 , wherein forming the micro-nucleation sites includes:
 removing the mask portions to uncover the micro-nucleation sites such that tops of the nanostructures are substantially coplanar with the hydrophillic surfaces of the micro-nucleation sites.   
     
     
         20 . The method of  claim 16 , wherein forming the nanostructures on the base layer includes:
 forming a mask layer over the base layer;
 patterning the mask layer such that mask portions remain on the base layer corresponding to locations of the micro-nucleation sites; 
 forming a material layer on the base layer and the mask portions; and 
   modifying the material layer on the base layer and the mask portions to form the nano structures.