Plant Tendril-Inspired, Scalable, and Biodegradable Janus Soft Actuators with High Strength and Multiresponsiveness

Soft actuators have attracted increasing attention because of their promising applications in intelligent systems such as medical devices, bionic robots, and artificial muscles. However, the development of robust, biobased actuators with multiple responsive behaviors remains highly challenging. Inspired by the actuation mechanism and responsive behavior of plant tendrils, a Janus actuator with controllable and large deformation was fabricated. The actuator film consists of a flexible sodium alginate-gelatin composite layer and a rigid sodium alginate-cellulose nanocrystal-Ca 2+ composite layer, which were prepared through a simple casting process. Owing to the conformational transition of gelatin under temperature and pH stimuli, the Janus actuator undergoes pronounced bending deformation. The actuator exhibits effective responses to environmental changes, reaching a maximum bending angle of 146° in water at 60 °C and showing distinct responsiveness in solutions with pH values ranging from 1 to 5. In addition, the Janus actuator demonstrates high tensile strength of about 79.73 ± 0.95 MPa, excellent optical transparency of 80%, good thermal stability, and biodegradability. Combined with low-cost raw materials and a scalable fabrication strategy, this work provides a promising route for the preparation of large-area, multifunctional Janus actuators and offers valuable insights into the design of high-performance, sustainable, and green biobased intelligent materials.