Nanodancing with Moisture: Humidity‐Sensitive Bilayer Actuator Derived from Cellulose Nanofibrils and Reduced Graphene Oxide

Bilayer actuators, traditionally consisting of two laminated materials, are the most common types of soft or hybrid actuators. Herein, a nanomaterial‐based organic–inorganic humidity‐sensitive bilayer actuator composed of TEMPO‐oxidized cellulose nanofibrils (TCNF‐Na+) and reduced graphene oxide (rGO) sheets is presented. The hybrid actuator displays a large humidity‐driven locomotion with an atypical fast unbending. Cationic exchange of the anionically charged TCNF‐Na+ and control of the layer thickness is used to tune and dictate the locomotion and actuator's response to humidity variations. Assembly of a self‐oscillating electrical circuit, that includes a conductive rGO layer, displays autonomous on‐and‐off lighting in response to actuation‐driven alternating electrical heating.