Soft actuators and microrobots that can move spontaneously and continuously without artificial energy supply and intervention have great potential in industrial, environmental, and military applications, but still remain a challenge. Here, a bioinspired MXene-based bimorph actuator with an asymmetric layered microstructure is reported, which can harness natural sunlight to achieve directional self-locomotion. We fabricate a freestanding MXene film with an increased and asymmetric layered microstructure through the graft of coupling agents into the MXene nanosheets. Owing to the excellent photothermal effect of MXene nanosheets, increased interlayer spacing favoring intercalation/deintercalation of water molecules and its caused reversible volume change, and the asymmetric microstructure, this film exhibits light-driven deformation with a macroscopic and fast response. Based on it, a soft bimorph actuator with ultrahigh response to solar energy is fabricated, showing natural sunlight-driven actuation with ultralarge amplitude and fast response (346°in 1 s). By utilizing continuous bending deformation of the bimorph actuator in response to the change of natural sunlight intensity and biomimetic design of an inchworm to rectify the repeated bending deformation, an inchwormlike soft robot is constructed, achieving directional self-locomotion without any artificial energy and control. Moreover, soft arms for lifting objects driven by natural sunlight and wearable smart ornaments that are combined with clothing and produce three-dimensional deformation under natural sunlight are also developed. These results provide a strategy for developing natural sunlight-driven soft actuators and reveal great application prospects of this photoactuator in sunlight-driven soft biomimetic robots, intelligent solar-energy-driven devices in space, and wearable clothing.

Mimicking the intelligence of biological organisms in artificial systems to design smart actuators that act autonomously in response to constant environmental stimuli is crucial to the construction of intelligent biomimetic robots and devices, but remains a great challenge. Here, a light-driven autonomous carbon-nanotube-based bimorph actuator is developed through an elaborate structural design. This curled droplet-shaped actuator can be simply driven by constant white light irradiation, self-propelled by a lightmechanical negative feedback loop created by light-driven actuation, time delay in the photothermal response along the actuator, and good elasticity from the curled structure, performing a continuously self-oscillating motion in a wavelike fashion, which mimics the human sit-up motion. Moreover, this autonomous self-oscillating motion can be further tuned by controlling the intensity and direction of the incident light. The autonomous actuator with continuous wavelike oscillating motion shows immense potential in light-driven biomimetic soft robots and optical-energy-harvesting devices. Furthermore, a self-locomotive artificial snake with phototaxis is constructed, which autonomously and continuously crawls toward the light source in a wave-propagating manner under constant light irradiation. This snake can be placed on a substrate made of triboelectric materials to realize continuous electric output when exposed to constant light illumination.

Developing self‐oscillating soft actuators that enable autonomous, continuous, and directional locomotion is significant in biomimetic soft robotics fields, but remains great challenging. Here, an untethered soft photoactuators based on covalently‐bridged black phosphorus‐carbon nanotubes heterostructure with self‐oscillation and phototactic locomotion under constant light irradiation is designed. Owing to the good photothermal effect of black phosphorus heterostructure and thermal deformation of the actuator components, the new actuator assembled by heterostructured black phosphorus, polymer and paper produces light‐driven reversible deformation with fast and large response. By using this actuator as mechanical power and designing a robot configuration with self‐feedback loop to generate self‐oscillation, an inchworm‐like actuator that can crawl autonomously towards the light source is constructed. Moreover, due to the anisotropy and tailorability of the actuator, an artificial crab robot that can simulate the sideways locomotion of crabs and simultaneously change color under light irradiation is also realized.

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In article number 1908842, Ying Hu and co‐workers construct an artificially autonomous soft robot based on a curled droplet‐shaped carbon nanotube bimorph structure, which can produce a constant white light‐driven continuous oscillating motion in a wavelike fashion. It can also autonomously and continuously crawl towards the light source in a wave‐propagating manner under constant light irradiation, exhibiting phototactic self‐locomotion.

Soft actuators can respond to electricity, [1][2][3][4] light, [5][6][7][8] heat, [9,10] and humidity [11,12] and produce mechanical deformation output. Owing to a wide range of applications in soft robots, [13] intelligent biomimetic devices, [14,15] biomedical sensing and diagnosis, [16] and wearable devices, [17] they have received more and more research interests recently. According to the external stimuli and actuation mechanism, soft actuators can be divided into many types, such as electrical-induced actuator, [1][2][3][4] optical-induced actuator, [5][6][7][8] magnetic actuator, [18] and so on. Among them, actuators driven by electrical voltage or light have been widely studied due to their unique characteristics. For the electrical-induced actuator, electrical energy has the advantages of simple operation, easy storage and utilization, and good controllability, whereas the light-induced actuator has unique features, including wireless actuation, remote control, and no contact with the sample. [19][20][21] Therefore, by combing the advantages of the two types of actuators, the application range and utilization convenience can be largely improved. For example, in microrobot applications, the power system it carries may be restricted due to the limited size of the microrobot. When the electricity is exhausted, the light energy can be supplied to drive the microrobot to continuously work. In space, the sunlight can be used as the driving source of the actuator, and the electric energy is used as the driving source of the actuator once it is in the dark environment, ensuring the normal operation of the actuator and save energy. However, most of the actuators studied only respond to one singe stimulus. It is still of great importance to fabricate actuators with highperformance and multistimuli response.Developing new types of materials with multistimuli responsive property is the key to achieve multistimuli responsive actuators. As a new type of 2D nanomaterials, transition metal dichalcogenide (TMD) nanosheets have attracted enormous attention due to their excellent properties, including tunable bandgap, [22] excellent optical properties, high strength, [23] and so on, which makes them great potential in sensors, [24] batteries, [25] supercapactitors, energy storage and conversion, [26] and actuators. As one of the typical TMDs, molybdenum disulfide (MoS 2 ) has good photothermal conversion characteristics.

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Developing self-oscillating soft actuators that enable autonomous,c ontinuous,a nd directional locomotion is significant in biomimetic soft robotics fields,b ut remains great challenging.Here,anuntethered soft photoactuators based on covalently-bridged black phosphorus-carbon nanotubes heterostructure with self-oscillation and phototactic locomotion under constant light irradiation is designed. Owing to the good photothermal effect of blackp hosphorus heterostructure and thermal deformation of the actuator components,t he new actuator assembled by heterostructured black phosphorus, polymer and paper produces light-driven reversible deformation with fast and large response.B yu sing this actuator as mechanical power and designing ar obot configuration with self-feedbackl oop to generate self-oscillation, an inchwormlike actuator that can crawl autonomously towards the light source is constructed. Moreover,d ue to the anisotropya nd tailorability of the actuator,a na rtificial crab robot that can simulate the sideways locomotion of crabs and simultaneously change color under light irradiation is also realized.