Smart and Responsive Micro- and Nanostructured Materials

Abstract

As high levels of complexity and efficiency are required in advanced optoelectric devices and biomedical systems, there has been growing interest in smart materials. Also known as intelligent or responsive materials, smart materials output controllable and predictable responses to external inputs, which may include mechanical stimuli (stress, strain, pressure), physical stimuli (light, sound, temperature, color), chemical stimuli (changes in concentration, humidity, and pH), and electromagnetic stimuli (electric field, magnetic field, charge injection). Since the output response may also appear in the form of mechanical, physical, chemical, and electromagnetic changes, there can be countless combinations between stimuli and responses, making these materials extremely useful for a wide range of applications including electro‐optic and optoelectronic devices such as displays and solar cells, piezoelectric devices, electroactive polymers, electrochromic windows, and artificial muscles. Many smart material‐based devices have already been successful in commercialization.

In recent years, the fabrication of nanostructures and microstructures have been extensively investigated through both the bottom‐up and top‐down approaches. Advances in the fabrication techniques have further driven the development of smart materials to a higher level of performance, for example, exhibiting multi‐step responses to one stimulus or selectively responding to a stimulus under precisely defined conditions. As a result, novel systems with optical switching and mechanical actuation responding to a variety of stimuli have been developed and used in practical applications. Smart materials have also been employed to design promising biomedicines whose activities can be triggered by molecular recognition and physiochemical changes. Advances in other technical fields have also added momentum to the development of smart materials. For example, the emergence of mobile electronic devices requires energy storage components that are not only efficient but also have unconventional intelligence such as self‐healing and self‐charging.

To showcase recent advances in the relevant areas, we present this special issue of Advanced Functional Materials on the topic of “Smart and Responsive Micro‐ and Nanostructured Materials”. It brings together contributions from leading experts and covers the following six aspects in the design of smart materials.