| Resumo: | When one thinks of color, the first thing which comes to mind is often absorption by pigments and dyes or emission by lights and displays. However, there is another mechanism known as structural color, most commonly seen in the swirling colors of a soap bubble. This is a wave phenomenon, where incident and reflected light interfere with each other to selectively reflect certain wave-lengths. More complex examples can often be seen in nature, such as the bright coloration of the blue morpho butterfly caused by intricate nanostructures on the wing.
Developing synthetic versions of the structurally-colored materials found in nature has been a longstanding goal of the research community, with many notable successes and potential applications. One particularly interesting area is mechanically-responsive structural color, where the optical properties of the material change when strained. Yet current examples of these materials suffer from a number of drawbacks such as poor optical or mechanical performance, limited colors or patterns, high cost, and slow or low-volume production.
The core of this thesis is the development of a new manufacturing process capable of producing sheets of mechanically-responsive, structurally-colored materials in a tunable, scalable, and affordable way. These are elastic materials which reversibly and predictably change color when stretched or compressed, achieved by combining 19th century research on color photography with recent research on holography. An assortment of sample materials created with this process are thoroughly analyzed.
The thesis then extends this concept, suggesting a wide variety of alternative functional structurally-colored materials that might be created by modifying the manufacturing process in key ways. This is demonstrated by the creation of mechanically-responsive, structurally-colored fibers.
With such a rich design space now accessible, exploring it experimentally becomes challenging. Therefore this thesis also presents a software platform that was developed, allowing the user to create a three-dimensional model of any desired object coated with any photonic structure. The user can then deform the object in real-time and observe the change in visual appearance.
Finally, a number of applications for dynamic structurally-colored materials are demonstrated or discussed, making use of their ability to convert invisible physical forces into visible color change. This spans fields including healthcare, fashion, robotics, and human-computer interaction.
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