Soft robot has been one significant study in recent decades and soft gripper is one of the popular research directions of soft robot. In a static gripping system, excessive gripping force and large deformation are the main reasons for damage of the object during the gripping process. For achieving low-damage gripping to the object in static gripping system, we proposed a soft-rigid gripper actuated by a linear-extension soft pneumatic actuator in this study. The characteristic of the gripper under a no loading state was measured. When the pressure was >70 kPa, there was an approximately linear relation between the pressure and extension length of the soft actuator. To achieve gripping force and fingertip displacement control of the gripper without sensors integrated on the finger, we presented a non-contact sensing method for gripping state estimation. To analyze the gripping force and fingertip displacement, the relationship between the pressure and extension length of the soft actuator in loading state was compared with the relationship under a no-loading state. The experimental results showed that the relative error between the analytical gripping force and the measured gripping force of the gripper was ≤2.1%. The relative error between analytical fingertip displacement and theoretical fingertip displacement of the gripper was ≤7.4%. Furthermore, the low damage gripping to fragile and soft objects in static and dynamic gripping tests showed good performance of the gripper. Overall, the results indicated the potential application of the gripper in pick-and-place operations.

A universal soft gripper for fruit grasping is challenging to develop. In this study, a modular and reconfigurable soft pneumatic gripper was designed. The designed gripper was inspired by the dexterous grasping of the human hand for fruits of different shapes and sizes. It comprised three soft extension actuators (SEAs), two soft rotation actuators (SRAs), and three soft bending actuators (SBAs). By adjusting SRAs, two grasping poses (claw and clenching pose) could be made to hold fruits of different shapes. The grasping size under each pose could be continuously adjusted by SEAs to grasp fruits of different sizes. SBAs were used to mimic soft fingers for grasping. Theoretical and simulation models were established to predict the relationships between deformations and pressures of SEAs, SRAs, and SBAs. The deformation characteristics of these actuators were experimentally investigated. It was shown that, by inflating SEAs, the grasping sizes under the claw and clenching poses could be increased by 87.5% and 94.5%, respectively. Furthermore, a visual recognition system was designed for automatically controlling the grasping pose and size. Grasping tests showed that, by reconfiguring the grasping pose and size, various fruits, vegetables, and foods with weights from 32 to 786 g (24.6 folds) and diameters from 30 to 141 mm (4.7 folds) could be successfully grasped, indicating the broad applicability of our all-pneumatic soft gripper.

Soft robots have been significantly studied in recent decades, and among their key components are soft actuators. Vacuum is one of the main drivers of soft actuators. In this study, we propose a novel cylindrical soft vacuum actuator (CSVA) consisting of a top layer, bottom layer, and cylindrical internal chamber. Under a vacuum, the bottom layer was concaved into the internal chamber. A simplified analytical model was established to analyze the relationship between the vacuum pressure and the deformation height of the bottom layer. A validation experiment was conducted to verify the effectiveness of the proposed analytical model. The potential applications of the CSVA in the design of soft robots were also explored. A jellyfish-inspired swimming robot, an octopus-inspired suction cup, and a soft–rigid gripper were designed according to the concave deformation of the bottom layer. Then, the swimming speed of the swimming robot, the adsorption force of the suction cup, and the grasping capability of the soft–rigid gripper were investigated. The experimental results show that the maximum swimming speed of the swimming robot is 55.3 mm s ⁻¹ at a flapping frequency of 0.6 Hz. The adsorption forces of the suction cup both in air and underwater are 16.8 N and 17.5 N, respectively. The soft–rigid gripper with a pinching-grasping mode can grasp objects of various shapes and sizes in air and underwater. The experimental results demonstrate the feasibility of the soft vacuum actuator in the design of various soft robots.

Soft pneumatic actuators (SPAs) play an important role in leading the development of soft robotics. However, due to the inherent characteristics of soft materials, the low driving force limits the application of SPAs. This study presents a high-force soft pneumatic bending actuator (SPBA) that consists of a spring, an eccentric silicone cylinder, and a limiting fiber. Based on the Neo-Hookean model, a theoretical model is established to predict the relationship between the bending angle and the pressure of SPBA. Furthermore, we characterize the performance of SPBA in terms of the bending capability, tip force, as well as response time. The results demonstrate the effectiveness of the theoretical model, as well as the high tip force (10.2 N) and fast response capability of SPBA. Finally, SPBAs are used to construct a three-finger soft gripper. The load capacity of the gripper is proofed, which indicates that the gripping force of the gripper increases with the pressure of the fingers and the diameter of the object. The gripping test of the gripper is performed. The result shows that the gripper with the pinching mode can grip objects of various sizes and shapes in the air and underwater, and the gripper with enveloping mode can grip objects with weight up to 1.25 kg.

To address the application bottlenecks of organic phase change materials characterized by low thermal conductivity and susceptibility to liquid leakage, this study utilized natural poplar wood as a raw material to construct a three-dimensional carbon/silver heterogeneous porous skeleton via delignification, gradient carbonization, and in situ electroless silver plating. Polyethylene glycol (PEG) was then vacuum-encapsulated within this structure to prepare form-stable composite phase change materials (CPCMs). The regulatory effects of carbonization temperature and metal interface modification on the microscopic morphology and thermophysical properties of the materials were systematically investigated. The results indicate that the skeleton carbonized at 800 °C achieves an optimal balance between pore distribution and skeleton rigidity, ensuring the uniform conformal growth of silver nanoparticles and endowing the material with excellent anti-leakage performance. The thermal conductivity of the optimal sample reaches as high as 0.683 W/(m·K), with the melting latent heat maintained at 133.9 J/g, while also demonstrating an agile and stable photothermal conversion response. Non-equilibrium molecular dynamics (NEMD) simulations further confirm that the silver nanoparticle modification layer smooths the phonon vibration frequency mismatch between the carbon substrate and organic segments, significantly reducing the interfacial thermal resistance. This research provides an important reference for the structural design and microscopic heat transfer mechanism analysis of high-performance phase change energy storage materials.