compliance of constituent materials enables soft grippers to safely work with flexible, fragile, and delicate objects. A great number of actuation methods have been investigated, including cable-driven mechanisms, [19] fluid elastomer actuators (FEA), [20,21] dielectric elastomer actuators, [22,23] magnetic actuators, [24-26] and shape memory materials including metal alloys [27,28] and polymers. [29] Among these actuation methods, FEA is one of the oldest and the most widespread technologies employed for soft robotic grippers owing to a number of advantages such as lightweight, high power-to-weight ratio, large stroke and force production, ease of fabrication, robustness, and low-cost materials. [30,31] FEA-based soft grippers have been mostly developed based on claws or human-like structures consisting of multiple inward-bending fingers. This design is suitable for gripping objects spanning a wide range of sizes. However, existing FEA-based grippers are ill-suited for applications that require high conformability or high-load sustainability. The integration of electro-adhesion, [23,32] gecko adhesion, [33,34] or variable stiffness structures (VSSs) can help improve the load capacity. Several studies also address both the issues by designing robotic fingers that can adjust their effective length via the use of segments of VSS. [21] Two main types of VSSs for soft grippers include vacuum-driven jamming of granules [35,36] or layers, [6] and phase-change materials such as thermoplastics, [12,37] shape memory polymers (SMPs), [20,21,38] and low-melting-point alloys (LMPAs). [22,39,40] In another approach, grippers with closed structures have been investigated in an attempt to improve both conformability and load capacity. [23,24,38-40] However, grippers with closed structures are not able to grip objects that are either smaller or larger than the opening orifice of the gripper. Another approach that has also been investigated involves the use of helical winding to enclose objects. This gripping strategy was inspired by natural instances such as elephant trunks, python body constriction, or cephalopod tentacles that use a continuum finger to helically grasp around the objects, thereby increasing the area of contact and stability between the gripper and objects. [41] Continuum, helical grippers that are not constrained by any host have the advantage of being free to wrap around objects and adapt to a wide range of object sizes, shapes, and orientations. There are many instances in nature where continuum, helical manipulators are used to efficiently grasp different objects with various shapes and sizes. Inspired by nature, this paper introduces a continuum, flat, scalable, helical soft-fabric robotic gripper that is thin and lightweight with stiffness tunability and sensory feedback. The gripper is fabricated by a facile method of simple insertion using a computerized technique from apparel engineering and controlled by a miniature hydraulic source to grasp different objects at different scales and weights. It uses a ...

Surgical robots have had clinical use since the mid‐1990s. Robot‐assisted surgeries offer many benefits over the conventional approach including lower risk of infection and blood loss, shorter recovery, and an overall safer procedure for patients. The past few decades have shown many emerging surgical robotic platforms that can work in complex and confined channels of the internal human organs and improve the cognitive and physical skills of the surgeons during the operation. Advanced technologies for sensing, actuation, and intelligent control have enabled multiple surgical devices to simultaneously operate within the human body at low cost and with more efficiency. Despite advances, current surgical intervention systems are not able to execute autonomous tasks and make cognitive decisions that are analogous to those of humans. Herein, the historical development of surgery from conventional open to robotic‐assisted approaches with discussion on the capabilities of advanced intelligent systems and devices that are currently implemented in existing surgical robotic systems is reviewed. Also, available autonomous surgical platforms are comprehensively discussed with comments on the essential technologies, existing challenges, and suggestions for the future development of intelligent robotic‐assisted surgical systems toward the achievement of fully autonomous operation.

The use of soft artificial muscles (SAMs) is rapidly increasing in various domains such as haptics, robotics, and medicine. There is a huge need for a SAM that is highly compliant and facile to fabricate with performance characteristics similar to human muscles. This paper introduces bio-inspired soft hydraulic filament artificial muscles (HFAMs) that can be extended and contracted under fluid pressures. The HFAMs, which have a high aspect ratio of at least 5000, use a simple and low-cost fabrication method of insertion, enabling scalability and mass-production while increasing its generated force via a stiff constrained helical layer and an adjustable stretch ratio of their inner silicone microtube. The developed muscles can produce a high elongation of 246.8% and a high energy efficiency of 62.7%. In addition, the HFAMs can generate a higher contraction force compared to existing state-of-the-art devices via their constrained hollow layer and the adjustable stretch ratio of the inner microtube, enabling a tunable force capability. Experiments are carried out to validate the HFAM performance including durability, lifting, frequency response and energy efficiency tests. The HFAM capabilities are demonstrated via various experiments, offering a potential substitute for the conventional tendon-driven mechanisms with less friction loss and stable energy efficiency while working against long and tortuous paths. A HFAMs-driven soft exoskeleton glove that could assist in grasping multiple objects is developed and evaluated. The new muscles open great opportunities for research and commercial sectors including emerging applications such as soft wearable devices and flexible surgical robots.INDEX TERMS fluid-driven artificial muscles, soft actuators, soft exoskeletons, soft robotics, tendondriven mechanisms, wearable devices.

In the real world, people heavily rely on haptic or touch to manipulate objects. In emerging systems such as assistive devices, remote surgery, self-driving cars and the guidance of human movements, visual or auditory feedback can be slow, unintuitive and increase the cognitive load. Skin stretch devices (SSDs) that apply tangential force to the skin via a tactor can encode a far richer haptic space, not being limited to force, motion, direction, stiffness, indentation and surface geometry. This paper introduces novel hand-worn hydraulic SSDs that can induce 3-axis tangential forces to the skin via a tactor. The developed SSDs are controlled by new soft microtubule muscles (SMMs) which are driven by hydraulic pressure via custom miniature syringes and DC micromotors. An analytical model is developed to characterize the responses of SMM output in terms of force and elongation. A kinematic model for the motion of the 3-axis SSD is also developed. We evaluate the capability of the tactor head to track circular reference trajectories within different working spaces using an optical tracking system. Experimental results show that the developed SSDs have good durability, high-speed, and can generate omnidirectional shear forces and desired displacement up to 1.8 N and 4.5 mm, respectively. The developed SMMs and SSDs created in this paper will enable new forms of haptic communication to augment human performance during daily activities such as tactile textual language, motion guidance and navigational assistance, remote surgical systems, rehabilitation, education, training, entertainment, or virtual and augmented reality.

In this work, we present a new method of creating fibre-metal composites to effectively modulate the in-plane fracture behaviour of brittle conductive thin metal films on stretchable PDMS substrates via insertion of a toughening interlayer of CNFs.

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Current stretchable strain sensors possess limited linear working ranges and it is still a formidable challenge to develop sensors that concurrently possess high gauge factors and high stretchability (ε ~...