Design and Optimization of Moldable Microstructures for Structural Color Generation

The use of structural color, common in nature, has been slow to catch on in manufacturing. Recent work has identified many of the structural features that lead to the advanced structural colors seen in nature, and some have even been successfully recreated. However most of these features are complex, three dimensional structures, making them difficult to manufacturing in a research environment, much less a standard manufacturing setting. However these advanced shapes are not strictly required for structural color – simple quasi-2D shapes of a single material are capable of producing simpler color and iridescence, without the manufacturing difficulties. These shapes are also capable of being embossed or molded into a single material, allowing for many mass production opportunities. To investigate the optical properties of these simple moldable microstructures, microstructured silicon masters were fabricated with a variety of features to examine six design parameters: shape, size, spacing, depth, tone (holes or pillars), and multilayer effects. These were then photographed under constant lighting at various rotation and tilt angles and analyzed for brightness and color data. This data identified what effects each design parameter had on the color, brightness, rotational viewing angle, and tilt viewing angle of the microstructured surface. Using this information, several conclusions were able to be drawn about the use of these microstructured surfaces for optical effects. The ridge density between features, feature side orientation, and the depth were all shown to have major effects on the optical properties. In addition, limited color control was demonstrated. The lessons learned were then summarized in a set of design guidelines to assist a researcher or product designer in developing a microstructure with specific optical characteristics.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2010

Author dc:creator

• Harrell, Patrick A.

Contributors dc:contributor

• King, William P.

• structural color
• micromachining
• micropatterning
• micromolding
• microembossing

Statement dc:rights

• Copyright 2009 Patrick A. Harrell

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/17360

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/17360