Methods for fabricating microstructures

Patent metadata

Field	Value
Publication number	US-9238309-B2
Application number	US-200913201408-A
Country	US
Kind code	B2
Filing date	May 8, 2009
Priority date	Feb 17, 2009
Publication date	Jan 19, 2016
Grant date	Jan 19, 2016

Abstract

Described herein are casting and molding methods useful for making microstructured objects. By including a plurality of microfeatures on the surface of an object, other characteristics may be imparted to the object, such as increased hydrophobicity. Some of the casting and molding methods described herein further allow for manufacture of objects having both microfeatures and macro features, for example microfeatures on or within macro features or selected macro feature regions.

First claim

We claim:

1. A method of making a microstructured object, the method comprising the steps of:
providing a semiconductor wafer;
patterning the semiconductor wafer with a preselected pattern of microfeatures;
molding an uncured first polymer to the patterned semiconductor wafer;
curing the first polymer, thereby forming a microstructured flexible polymer having the preselected pattern of microfeatures on a surface of the microstructured flexible polymer;
removing the microstructured flexible polymer from the patterned semiconductor wafer;
providing a macro mold having one or more macro scale features, wherein the macro scale feature of the macro mold is one of a recessed feature and a relief feature;
deforming at least a portion of the microstructured flexible polymer so as to conform the microstructured flexible polymer to at least a portion of the surface of the one or more macro scale features of the macro mold wherein the microstructured flexible polymer is placed so that a surface of the microstructured flexible polymer opposite to the surface having the preselected pattern of microfeatures faces the portion of the surface of the one or more macro scale features of the macro mold;
providing a large-area prototype having one or more macro scale features, wherein the macro scale feature of the large-area prototype is the other of a recessed feature and a relief feature;
depositing an uncured second polymer onto at least a portion of a surface of the one or more macro scale features of the prototype;
molding the uncured second polymer by bringing the macro mold and microstructured flexible polymer into contact with the prototype and the uncured second polymer;
curing the uncured second polymer, thereby making a microstructured second polymer having the preselected pattern of microfeatures;
releasing the macro mold and microstructured flexible polymer from the prototype and microstructured second polymer; and
casting or molding a material to the prototype and microstructured second polymer, thereby replicating the preselected pattern of microfeatures in at least a portion of a cast or molded object.

2. The method of claim 1 , wherein at least a portion of the pattern of microfeatures of the microstructured flexible polymer is positioned on a curved surface of the macro mold and at least a portion of the pattern of microfeatures of the cast or molded object are positioned on a curved surface of the cast or molded object.

3. The method of claim 1 wherein in the deforming step at least a portion of the microstructured flexible polymer is deformed to radius of curvature selected over the range of 100 μm to 3 m, wherein at least a portion of the microstructured flexible polymer is deformed to a strain level selected over the range of 1% to 1300% or wherein at least a portion of the microstructured flexible polymer is deformed to radius of curvature selected over the range of 100 μm to 3 m and to a strain level selected over the range of 1% to 1300%.

4. The method of claim 1 wherein the microfeatures have dimensions selected over the range of 10 nm to 100 μm and a pitch of the microfeatures is selected over the range of 10 nm to 100 μm.

5. The method of claim 4 , wherein at least a portion of microfeatures have an aspect ratio of height or depth to width of 1:2 to 7:1.

6. The method of claim 1 wherein 80% to 100% of at least a portion of the surface of the macro scale features is covered by the preselected pattern of microfeatures.

7. The method of claim 1 wherein the preselected pattern of microfeatures is replicated in each casting and/or molding step with a replication fidelity selected over the range of 50% to 100%.

8. The method of claim 1 , wherein the material of the cast or molded object is tire rubber, thereby making a microstructured tire.

Assignees

• King William P
• Cannon Andrew H
• Univ Illinois

Inventors

• King William P
• Cannon Andrew H

Classifications

• B29C2059/023

  Microembossing · CPC title

• B29C33/3878

  used as masters for making successive impressions · CPC title

• B29C2033/426

  Stampers · CPC title

• B29C33/405

  Elastomers, e.g. rubber (B29C33/50 takes precedence) · CPC title

• B29C45/2673

  with exchangeable mould parts, e.g. cassette moulds (B29C45/1756 takes precedence) · CPC title