Diving–Surfacing Cycle Within a Stimulus‐responsive Smart Device Towards Developing Functionally Cooperating Systems

DOI: 10.1002/adma.201001577 Recently, functionally cooperating systems, which are defi ned as the integration of two or more smart materials or surfaces into one device which then act in an orderly manner for a complex function or a given intention, have gained increasing attention. Since nanomaterials were fi rst demonstrated by Feynmann in 1959, various functional materials have been created, particularly since the 1980s. [ 1 ] Nanomaterials not only lead to signifi cant progress in fundamental research but have also revolutionized technology and the economy. However, most of the research into nanomaterials is focused on passive fi elds. In order to promote materials science from the present passive level to active level materials, a great emphasis has been placed on the area of smart materials. Smart materials, [ 2 ] which respond to a stimulus or a change of environment to produce a dynamic and reversible transition in chemical or physical properties, have been well investigated in many fi elds, [ 3 , 4 ] including cantilever sensors, gene delivery, micropumps, and artifi cial muscles. Based on the above concept, various stimulus for smart materials have been introduced, such as humidity, [ 5 , 6 ] solvent composition, [ 7 ] light, [ 8–11 ] electric fi eld, [ 12 , 13 ] magnetic fi eld, [ 14–17 ] pH value, [ 18 , 19 ] and temperature. [ 20 , 21 ] Ichimura et al. [ 11 ] prepared a photo-responsive surface to realize a light-driven liquid motion. Langer and coworkers [ 12 ]