Surfaces physically transformable by environmental changes

1. An apparatus, comprising:

a substrate having a top surface;

a substantially regular array of raised structures located over the top surface, distal surfaces of the structures being farther from the top surface than remaining portions of the structures;

a layer being located over the top surface and filling a portion of a volume between the structures, the layer being able to contract such that in a first state the distal surfaces of the structures protrude through the layer, the layer being able to swell such that in a second state the distal surfaces of the structures are closer to the top surface of the substrate than one surface of the layer; and

wherein the raised structures form an effective hydrophobic surface on which a liquid is supported in the first state, and the layer forms an effective hydrophilic surface on which a liquid is to rest in the second state.

2. The apparatus of claim 1 , wherein the one surface of the layer is chemically functionalized with antibodies, nucleic acid, or protein.

3. The apparatus of claim 1 , wherein the one surface of the layer is chemically functionalized with molecules that change a wettability of the layer.

4. The apparatus of claim 1 , wherein the one surface of the layer is coated with a fluorinated polymer.

5. The apparatus of claim 1 , wherein the structures comprise one of posts, on-edge planes, and closed cells.

6. The apparatus of claim 1 , further comprising an anchoring layer bonded to the substrate and the layer.

7. The apparatus of claim 1 , wherein the layer comprises a hydrogel.