Ultrafast Photothermal Actuators with a Large Helical Curvature Based on Ultrathin GO and Biaxially Oriented PE Films

Light-driven soft robot with compound motion patterns based on gas-liquid phase transition chamber

Light is increasingly being used to drive soft robots and soft actuators. In this paper, a light-driven soft robot with compound motion patterns based on gas-liquid phase transition chamber is proposed, which inspired by the frog and the larvae of gall midges. When a light source with a power density of about 1.25 W/cm2 is illuminated on the upper surface of the auxiliary pneumatic chamber, the previously non-existent main pneumatic chamber can be expanded quickly within less than 3 s, and generate enormous thrust. This allows the soft robot (length: 3 cm; width: 0.7 cm; weight: 0.36 g) to quickly release from the magnet attractive field and perform a jump with a height of 50.8 cm in less than 1 s, approximately 16 times the body length of the entire soft robot. The proposed soft robot can also be combined with a photothermal bending film to achieve directional crawling. At the same time, by fixing the foot of the soft robot on the base and using light irradiate it, an object weighing about 5 times the overall weight can be ejected to a horizontal distance of 16.9 cm. This untethered pneumatic soft robot has broad prospects in soft jumping robots and wireless actuators, and the proposed pneumatic triggered chamber can also be further applied to other application fields.

Leaf Vein-Inspired Programmable Superstructure Liquid Metal Photothermal Actuator for Soft Robots

Asymmetric-expansion photothermal actuators have attracted the attention of researchers owing to their simple structure, superior stability, rapid response, and precise controllability. However, their response speed, deformation capacity, and load-carrying capacity are mutually constrained by their thickness. Inspired by the veins and pulp in plant leaves, this study uses laser etching to apply a superstructure of ordered grooves to liquid metal (LM) photothermal actuators. The resulting LM@low-expansion polyimide (4.52 ppm K-1)/polydimethylsiloxane (LM@PI/PDMS) programmable photothermal actuators demonstrate exceptional performance, including a load-carrying capacity of 190 times their weight, a rapid oscillation frequency of 19 Hz, a response speed of 60.96 ± 3.08°/ s, and a bending angle of 159.05 ± 2.52°. Hence, the proposed design resolves the inherent conflict between the load-carrying capacity and response speed. Furthermore, incorporating LM microspheres into actuators increases their stability and allows them to endure more than 20 800 cycles without damage. The actuators are used to create versatile smart devices and robots, such as photothermally actuated robotic dogs that can function across various terrains. This study provides a novel strategy for the design and fabrication of programmable photothermal actuators and highlights their potential for applications in advanced robotics, which paves the way for their integration into complex environments.

From Coils to Crawls: A Snake-Inspired Soft Robot for Multimodal Locomotion and Grasping

Currently, numerous biomimetic robots inspired by natural biological systems have been developed. However, creating soft robots with versatile locomotion modes remains a significant challenge. Snakes, as invertebrate reptiles, exhibit diverse and powerful locomotion abilities, including prey constriction, sidewinding, accordion locomotion, and winding climbing, making them a focus of robotics research. In this study, we present a snake-inspired soft robot with an initial coiling structure, fabricated using MXene-cellulose nanofiber ink printed on pre-expanded polyethylene film through direct ink writing technology. The controllable fabrication of initial coiling structure soft robot (ICSBot) has been achieved through theoretical calculations and finite element analysis to predict and analyze the initial structure of ICSBot, and programmable ICSBot has been designed and fabricated. This robot functions as a coiling gripper capable of grasping objects with complex shapes under near infrared light stimulation. Additionally, it demonstrates multi-modal crawling locomotion in various environments, including confined spaces, unstructured terrains, and both inside and outside tubes. These results offer a novel strategy for designing and fabricating coiling-structured soft robots and highlight their potential applications in smart and multifunctional robotics.

Islet cell spheroids produced by a thermally sensitive scaffold: a new diabetes treatment

The primary issues in treating type 1 diabetes mellitus (T1DM) through the transplantation of healthy islets or islet β-cells are graft rejection and a lack of available donors. Currently, the majority of approaches use cell encapsulation technology and transplant replacement cells that can release insulin to address transplant rejection and donor shortages. However, existing encapsulation materials merely serve as carriers for islet cell growth. A new treatment approach for T1DM could be developed by creating a smart responsive material that encourages the formation of islet cell spheroids to replicate their 3D connections in vivo and controls the release of insulin aggregates. In this study, we used microfluidics to create thermally sensitive porous scaffolds made of poly(N-isopropyl acrylamide)/graphene oxide (PNIPAM/GO). The material was carefully shrunk under near-infrared light, enriched with mouse insulinoma pancreatic β cells (β-TC-6 cells), encapsulated, and cultivated to form 3D cell spheroids. The controlled contraction of the thermally responsive porous scaffold regulated insulin release from the spheroids, demonstrated using the glucose-stimulated insulin release assay (GSIS), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence assay. Eventually, implantation of the spheroids into C57BL/6 N diabetic mice enhanced the therapeutic effect, potentially offering a novel approach to the management of T1DM.

Programming gel automata shapes using DNA instructions

The ability to transform matter between numerous physical states or shapes without wires or external devices is a major challenge for robotics and materials design. Organisms can transform their shapes using biomolecules carrying specific information and localize at sites where transitions occur. Here, we introduce gel automata, which likewise can transform between a large number of prescribed shapes in response to a combinatorial library of biomolecular instructions. Gel automata are centimeter-scale materials consisting of multiple micro-segments. A library of DNA activator sequences can each reversibly grow or shrink different micro-segments by polymerizing or depolymerizing within them. We develop DNA activator designs that maximize the extent of growth and shrinking, and a photolithography process for precisely fabricating gel automata with elaborate segmentation patterns. Guided by simulations of shape change and neural networks that evaluate gel automata designs, we create gel automata that reversibly transform between multiple, wholly distinct shapes: four different letters and every even or every odd numeral. The sequential and repeated metamorphosis of gel automata demonstrates how soft materials and robots can be digitally programmed and reprogrammed with information-bearing chemical signals.

Height-renderable morphable tactile display enabled by programmable modulation of local stiffness in photothermally active polymer

Reconfigurable tactile displays are being used to provide refreshable Braille information; however, the delivered information is currently limited to an alternative of Braille because of difficulties in controlling the deformation height. Herein, we present a photothermally activated polymer-bilayer-based morphable tactile display that can programmably generate tangible three-dimensional topologies with varying textures on a thin film surface. The morphable tactile display was composed of a heterogeneous polymer structure that integrated a stiffness-tunable polymer into a light-absorbing elastomer, near-infra-red light-emitting diode (NIR-LED) array, and small pneumatic chamber. Topological expression was enabled by producing localized out-of-plane deformation that was reversible, height-adjustable, and latchable in response to light-triggered stiffness modulation at each target area under switching of stationary pneumatic pressure. Notably, the tactile display could express a spatial softness map of the latched topology upon re-exposing the target areas to modulated light from the NIR-LED array. We expect the developed tactile display to open a pathway for generating high-dimensional tactile information on electronic devices and enable realistic interaction in augmented and virtual environments.

Optomagnetic Coordination Helical Robot with Shape Transformation and Multimodal Motion Capabilities

Soft robots with magnetic responsiveness exhibit diverse motion modes and programmable shape transformations. While the fixed magnetization configuration facilitates coupling control of robot posture and motion, it limits individual posture control to some extent. This poses a challenge in independently controlling the robot's transformation and motion, restricting its versatile applications. This research introduces a multifunctional helical robot responsive to both light and magnetism, segregating posture control from movements. Light fields assist in robot shaping, achieving a 78% maximum diameter shift. Magnetic fields guide helical robots in multimodal motions, encompassing rotation, flipping, rolling, and spinning-induced propulsion. By controlling multimodal locomotion and shape transformation on demand, helical robots gain enhanced flexibility. This innovation allows them to tightly grip and wirelessly transport designated payloads, showcasing potential applications in drug delivery, soft grippers, and chemical reaction platforms. The unique combination of structural design and control methods holds promise for intelligent robots in the future.

Flexible Actuators with Hygroscopic Adaptability for Smart Wearables and Soft Grippers

Flexible actuators have garnered significant interest in the domains of biomedical devices, human-machine interfaces, and smart wearables. However, the mechanical properties of existing materials are not sufficiently robust, and the expensive and time-consuming pretreatment process and the ambiguous high-degree-of-freedom deformation mechanism make it difficult to meet the demands of industrialized production. Hence, drawing inspiration from the adaptable movement of living organisms in the natural world, this research created and engineered a fully textile-based humidity-sensitive flexible actuator (TbHs-FA) using high-cost-effective viscose/PET fibers as raw materials. The breakthrough development in actuation performance is covered, including substantial contraction force (92.53 cN), high actuation curvature (16.78 cm-1), and fast response (264 cN s-1 and 46.61 cm-1 s-1). Additionally, the programmable stiffness system and weave structure give TbHs-FAs low hysteresis and fatigue resistance, narrowing the gap between the conceptual laboratory-scale design of existing fully textile-based humidity-sensitive flexible actuators and actual textiles. The high-degree-of-freedom and large bending deformation mechanisms are elucidated for the first time by combining microscopic mechanical structure simulation and macroscopic energy conversion analysis. The novel humidity-sensitive flexible actuator possesses strong mechanical qualities, making it suitable for applications such as flexible robots, medicinal devices, and smart wearables.

Salt-Assisted Fabrication of a Water-Based Covalent Organic Framework Ink and Its Hybrid Films for Photothermal Actuators

The exceptional properties of two-dimensional covalent organic framework materials (2D-COFs), including their large π-conjugated structure at the molecular level and π-π multilayer stacking, have attracted interest for soft photothermal actuator applications. However, the conventional synthesis of COFs as microcrystalline powders limits their processing in water due to their limited dispersibility. Herein, we present a simple and environmentally friendly method to fabricate water-suspended COF inks by adjusting the surface potential of COF powders through adsorption of ionic species such as Na⁺ and Cl^-. This technique effectively prevents the accumulation and aggregation of COF powder, resulting in an aqueous COF ink that can be easily cast into homogeneous hybrid COF films by Mayer-rod coating. In addition, the resulting photothermal actuator exhibited a fast response time within 3 s at a curvature of 2.35 cm^-1 in the near-infrared light. This facile and practical approach to fabricating water-based COFs ink represents a promising strategy for the development of practical applications of COFs in photothermal actuators.