Electro-thermally driven flexible robot arms based on stacking-controlled graphite nanocomposites

Abstract

It stands as a huge technological challenge to develop flexible actuators with low driving voltage and cost-effective fabrication process. Here, we report a soft actuator based on polyimide (PI) film with a layer of graphite nanoplates (GNs) and sodium carboxymethyl cellulose (CMC) nanocomposite. The GN/CMC composite is anisotropic low-cost nanocomposites composed of stacking-controlled GNs and CMC. The GN/PI bi-layers exhibit premier bending capability due to the large difference in coefficient of thermal expansion (CTE) between GN and PI. The deformation of such heterogeneous bilayers can be accurately controlled by external voltages that produce the desired thermal gradient. GNs have unique merits as flexible electrodes for soft actuators: they are stable, inexpensive, with ultra-low CTE; their composites are highly oriented in surfactant-directed synthesis, resulting in low resistance (10–40 mΩ cm) and enabling low-voltage operation. We demonstrate prototypical architectures including GN-Fingers, Robot-Hands and Octopus-Arms. They can be reversibly bent up to 270° with low driving voltages of 3–48 V, and the maximum bending curvature can reach 2.2 cm−1. Moreover, GN-based Robot-Hands and Octopus-Arms can grasp and release objects, and GN-Arrays can lift objects, underscoring the potential of GN-based soft actuators.