Construction of black phosphorus incorporated film by a brick-on-cement strategy for highly sensitive humidity sensor and triple-stimuli-driven actuator

Abstract

The identification and design of intelligent driving materials that can be prepared by a simple method and that are mechanically reliable and responsive to multiple environmental stimuli remain challenges in the development of soft robots and intelligent control. In this study, a film actuator with a good response to humidity, near-infrared (NIR) light, and magnetism was developed using a simple process. This actuator consists of “bricks” and “cement”: the “brick” is black phosphorus (BP)@ polydopamine (PDA)@Fe3O4 (BPPF) obtained by the gradual modification of BP, and the “cement” is 2,2,6,6-tetramethylpiperidinooxy (TEMPO)-oxidized bacterial cellulose (TOBC). The mechanical properties of the TOBC film were highly enhanced after the introduction of BPPF, so the BPPF@TOBC film had high mechanical strength (51.88MPa) and toughness (3.93 MJ/m3). The BPPF@TOBC film showed good responses to three environmental stimuli, with a response speed of 33.41°/s for humidity and 5.33°/s for NIR light; further, it could be driven by a magnetic field. Therefore, the BPPF@TOBC film actuators could reliably perform tasks such as grasping objects, connecting circuits, and realizing directional displacement in different environments. This work thus lays the groundwork for designing multi-responsive composite-film actuators with a wide range of applications involving intelligent control.