Multi-responsive actuators based on a graphene oxide composite: intelligent robot and bioinspired applications

Carbon-based electrothermal or photothermal actuators have attracted intense attention recently. They can directly convert electrical or light energy into thermal energy and exhibit obvious deformations. However, if the actuation mechanism is only limited to thermal expansion, the deformation amplitude is difficult to increase further. Moreover, complex shape-deformation is still challenging. Although a few materials were reported to realize twisting or untwisting actuation by cutting the samples into strips along different orientations, each single strip could perform only one shape-deformation mode. In this work, we propose multi-responsive actuators based on a graphene oxide (GO) and biaxially oriented polypropylene (BOPP) composite, which are designed with different shapes (strip-shape and helical-shape). The strip-shape GO/BOPP actuator shows great bending actuations when driven by humidity (curvature of up to 3.1 cm(-1)). Due to a developed dual-mode actuation mechanism, the actuator shows a bending curvature of 2.8 cm(-1) when driven by near infrared (NIR) light. The great actuation outperforms most other carbon-based actuators. Then, an intelligent robot based on the GO/BOPP composite is fabricated, which can switch between the protection mode and weightlifting mode with different external stimuli. Inspired from plant tendrils, a bioinspired helical GO/BOPP actuator is further realized to show both twisting and untwisting actuations in a single actuator, fully mimicking the deformation of plant tendrils. Finally, a robot arm consisting of strip-shape and helical GO/BOPP actuators can grasp an object that is 2.9 times heavier than itself, demonstrating promising bioinspired applications.

碳基电热或光热驱动器最近受到了广泛关注。它们能够将电能或光能直接转化为热能，并表现出明显的变形。然而，如果驱动机制仅仅局限于热膨胀，变形幅度就难以进一步增大。此外，复杂的形状变形仍然具有挑战性。尽管有少数材料被报道通过沿不同方向将样品切割成条带来实现扭转或解扭转驱动，但每条带只能执行一种形状变形模式。在这项工作中，我们提出了基于氧化石墨烯（GO）和双向拉伸聚丙烯（BOPP）复合材料的多响应驱动器，它们被设计成不同的形状（条带状和螺旋状）。条带状的GO/BOPP驱动器在湿度驱动下表现出显著的弯曲驱动（曲率高达3.1厘米⁻¹）。由于开发了一种双模驱动机制，该驱动器在近红外（NIR）光驱动下的弯曲曲率为2.8厘米⁻¹。这种出色的驱动性能优于大多数其他碳基驱动器。然后，制造了一个基于GO/BOPP复合材料的智能机器人，它可以在不同的外部刺激下在保护模式和举重模式之间切换。受植物卷须的启发，进一步实现了一种仿生螺旋状的GO/BOPP驱动器，在单个驱动器中同时表现出扭转和解扭转驱动，完全模拟了植物卷须的变形。最后，一个由条带状和螺旋状GO/BOPP驱动器组成的机械臂能够抓取比自身重2.9倍的物体，展示了有前景的仿生应用。