Multiresponsive Ti₃C₂T_x MXene-Based Actuators Enabled by Dual-Mechanism Synergism for Soft Robotics

Abstract

Multiresponsive and high-performance flexible actuators with a simple configuration, high mechanical strength, and lowpower consumption are highly desirable for soft robotics. Here, a novel mechanically robust and multiresponsive Ti 3 C 2 T x MXenebased actuator with high actuation performance via dual-mechanism synergistic effect driven by the hygroexpansion of bacterial cellulose (BC) layer and the thermal expansion of biaxially oriented polypropylene (BOPP) layer is developed. The actuator is flexible and shows an ultrahigh tensile strength of 195 MPa. Unlike the conventional bimorph-structured actuators based on a singlemechanism, the actuator developed provides a favorable architecture for dual-mechanism synergism, resulting in exceptionally reversible actuation performance under electricity and near-infrared (NIR) light stimuli. Typically, the developed actuator can produce the largest bending angle (∼400°) at the lowest voltage (≤4 V) compared with that reported previously for single mechanism soft actuators. Furthermore, the actuator also can be driven by a NIR light at a 2 m distance, displaying an excellent long-distance photoresponsive property. Finally, various intriguing applications are demonstrated to show the great potential of the actuator for soft robotics.

Role of MXenes in advancing soft robotics

“…21 In addition, monolithic MXene composites with multiresponsive actuating and energy-storage multifunctions were introduced, offering electro-, photo-, and thermoresponsive actuation. 112 Tang et al 23 reported multiresponsive MXene-based actuators enabled by a dual-mechanism synergism for soft robotics; this study demonstrated that these soft actuators had excellent actuation performance through the dual-mechanism synergistic effect driven by the hygroexpansion of a bacterial cellulose layer and the thermal expansion of a biaxially oriented polypropylene layer. 23…”

“…50,51 Multifunctional MXene-based soft actuators can be designed with stimuli-responsive behavior. 23,27,35,52 Bilayer actuators with programmable configurations and biomimetic behaviors were designed utilizing MXenes (Ti 3 C 2 T x ) and lowdensity polyethylene (LD-PE) benefiting from the fascinating light absorption as well as photo-and electrothermal properties of MXenes (Fig. 1).…”

“…21 Benefiting from rapid and low-power actuation and large shape deformation as well as multiresponsibility and programmability, MXene-based actuators have been employed to manufacture next-generation soft robots, 22 as exemplified in the cases of inchworm-inspired soft robots with a zigzag movement pattern. 23 MXenes have also been employed in designing artificial muscles and soft actuators, 20,24 based on ionically cross-linked Ti 3 C 2 T x electrodes that can be used for kinetic soft robotics. 25 However, there still exist challenges in designing stimuli-responsive MXene films for artificial muscles and biomedical devices with shape-deformation programmability.…”

Enable Multi-Stimuli-Responsive Biomimetic Actuation with Asymmetric Design of Graphene-Conjugated Conductive Polymer Gradient Film

“…Although bilayer actuators composed of PEDOT:PSS and insulating polymer layers have been developed to achieve electrothermal actuation by the desorption of water molecules and the shrinkage of PEDOT:PSS under Joule heating in the previous works, , high applied voltage is still required because of the low electrical conductivity of PEDOT actuators. In this work, highly electrical conductive graphene sheets are conjugated with PEDOT polymer matrix, resulting in enhanced electrothermal actuation performance of GCP actuators. − To form the conducting loop, GCP-10% films were cut into a “U” shape (Figure S12a) and pieces of Scotch tape were attached on the back side to direct actuation and improve durability . Low DC voltage in the range from 0.5 to 1.5 V was applied on the GCP-10% “U” shape sample through copper wires (Figure S12b), and the bending behavior was pictured in Figure a.…”

Multifunctional Actuator Based on Graphene/PDMS Composite Materials with Shape Programmable Configuration and High Photothermal Conversion Capability

“…The main materials used in the development of intelligent soft robots include hydrogels, , shape memory polymers, , two-dimensional transition metal carbides/nitrides (Mxenes), − and carbon materials (graphene − and its derivatives, − carbon nanotubes, , etc.). Among them, carbon materials have excellent light absorption and photothermal conversion capabilities. , Wang et al fabricated a three-layered composite soft robot composed of carbon nanotubes, polydimethylsiloxane (PDMS), and polyvinylidene fluoride (PVDF), which can rapidly respond to liquid, vapor, and light stimuli.…”