1. Biomimetic Materials and Structures for Sensor Applications

Diverse biological tissues and structures that often exhibit remarkable physical and chemical properties can be found throughout nature. Starting from very few and simple building blocks such as collagen fibrils, nature effortlessly makes hierarchical and complex structures which are often hard to imitate with the current top-down microfabrication techniques. With the recent development of diverse assembly methods of nanobiomaterials, we have started to build biomimetic structures with diverse optical, mechanical, and electrical properties using bottom-up approaches. The properties of such biomimetic materials, when exposed to certain physical or chemical stimuli, sometimes change enough and may be utilized for sensing applications. For example, some filamentous viruses can be assembled into colorful films on solid substrates, the colors of which can change when exposed to organic solvents and volatile organic compounds. These same films, when applied with mechanical pressure, can exhibit piezoelectric properties, where mechanical pressure can be transduced to electrical signals, allowing the utilization of these structures as mechanical force sensors. In this chapter, we will discuss the current state of the biomimetic materials and structures for sensor applications, giving emphasis on hierarchical structures based on fiber building blocks.