title: An autonomous actuator driven by fluctuations in ambient humidity.
abstract: Devices that respond to negligibly small fluctuations in environmental conditions will be of great value for the realization of more sustainable, low-power-consumption actuators and electronic systems. Herein we report an unprecedented film actuator that seemingly operates autonomously, because it responds to the adsorption and desorption of a minute amount of water (several hundred nanograms per 10 mm(2)) possibly induced by fluctuations in the ambient humidity. The actuation is extremely rapid (50 ms for one curl) and can be repeated >10,000 times without deterioration. On heating or light irradiation, the film loses adsorbed water and bends quickly, so that it can jump vertically up to 10 mm from a surface or hit a glass bead. The film consists of a π-stacked carbon nitride polymer, formed by one-pot vapour-deposition polymerization of guanidinium carbonate, and is characterized by a tough, ultralightweight and highly anisotropic layered structure. An actuator partially protected against water adsorption is also shown to walk unidirectionally.
authors.affiliation: RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Arazoe
authors.affiliation: RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Daigo
authors.initials: D
authors.lastname: Miyajima
authors.affiliation: RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Kouki
authors.initials: K
authors.lastname: Akaike
authors.affiliation: RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Fumito
authors.identifier: 0000-0002-9387-6081
authors.initials: F
authors.lastname: Araoka
authors.affiliation: RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Emiko
authors.initials: E
authors.lastname: Sato
authors.affiliation: RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Hikima
authors.affiliation: RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Masuki
authors.initials: M
authors.lastname: Kawamoto
authors.affiliation: RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.|Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Takuzo
authors.initials: T
authors.lastname: Aida