Soft actuators using pressurized air are being widely used due to their inherent compliance, conformability, and customizability. These actuators are powered and controlled by pneumatic supply systems (PSSs) consisting of components such as compressors, valves, tubing, and reservoirs. Regardless of the choice of actuator, the PSS critically affects overall performance of soft robots because it governs

Liquid–vapor phase change materials (PCMs), capable of significant volume change, are emerging as attractive actuating components in forming advanced soft composites for robotic applications. However, the novel and functional design of these PCM composites is significantly limited due to the lacking of the fundamental understanding of the mechanical properties, which further inhibits the broad applications

To advance the field of soft robotics, a unified database of material constitutive models and experimental characterizations is of paramount importance. This will facilitate the use of finite element analysis to simulate their behavior and optimize the design of soft-bodied robots. Samples from seventeen elastomers, namely Body Double™ SILK, Dragon Skin™ 10 MEDIUM, Dragon Skin 20, Dragon Skin 30, Dragon

Stiffness transition of a soft continuum body is an essential feature for dexterous interaction with an unstructured environment. Softness ensures safe interaction, whereas rigidness generates high force for movement or manipulation. Vacuum-based granular jamming is a widely used technique for on-line stiffness transition because of its high reconfigurability and intuitive driving method. However,

Various actuators (e.g., pneumatics, cables, dielectric elastomers, etc.) have been utilized to actuate soft robots. Besides widely used actuators, a relatively new artificial muscle—twisted-and-coiled actuators (TCAs)—is promising for actuating centimeter-scale soft robots because they are low cost, have a large work density, and can be driven by electricity. However, existing works on TCA-actuated

The human stomach breaks down and transports food by coordinated radial contractions of the gastric walls. The radial contractions periodically propagate through the stomach and constitute the peristaltic contractions, also called the gastric motility. The force, amplitude, and frequency of peristaltic contractions are relevant to massaging and transporting the food contents in the gastric lumen. However

Worldwide, over 50 million people suffer from persistent hand impairments after stroke or spinal cord injury (SCI). This results in major loss of independence and quality of life. Robotic hand exoskeletons can compensate for lost motor function and assist in grasping tasks performed in everyday activities. Several recent prototypes can partially provide this assistance. However, it remains challenging

Introducing functional synthetic biomaterials to the literature became quite essential in biomedical technologies. For the growth of novel biomedical engineering approaches, progressive functional properties as well as the robustness of the manufacturing processes are essential. By using acid-induced epoxide ring-opening polymerizations through catalysts, a wide variety of biodegradable and functionalized

Soft robotics requires new actuators and artificial muscles that are lighter, less expensive, and more effective than current technologies. Recently developed bubble artificial muscles (BAMs) are lightweight, flexible, inexpensive, pneumatic actuators with the capability of being scalable, contracting at a low pressure, and generating sufficient tension and contraction for assisting human mobility

Given that mobile soft robots are adaptable to the environment, they are always tethered with slow locomotion speed. Compared with other types of mobile robots, mobile soft robots may be more suitable for rescuing tasks, accompanying elderly people, and being used as a safe toy for children. However, the infinite freedom of soft robots increases the difficulty of precision control. In addition, the

Many mammals use their vibrissae (whiskers) to tactually explore their surrounding environment. Vibrissae are thin tapered structures that transmit mechanical signals to a wealth of mechanical receptors (sensors) located in a follicle at each vibrissal base. A recent study has shown that—provided that the whisker is tapered—three mechanical signals at the base are sufficient to determine the three-dimensional

Soft robotic devices can be used to demonstrate mechanics, robotics, and health care devices in classrooms. The complexity of soft robotic actuator fabrication has limited its classroom use. We propose a single-mold method of fabricating soluble insert actuators (SIAs) to simplify existing actuator fabrication methods using common accessible materials. This was accomplished by embedding molded soluble

Dielectric elastomer actuators (DEAs) have been shown to produce electrically induced strains beyond 500%. The ability to undergo large deformation allows the DEA to store large amounts of elastic energy by electrical actuation; it also allows the DEA to perform flexibly in a diverse range of motions. Existing studies used different methods to maximize actuation strain for soft robotic applications

Soft spherical tensegrity robots are novel steerable mobile robotic platforms that are compliant, lightweight, and robust. The geometry of these robots is suitable for rolling locomotion, and they achieve this motion by properly deforming their structures using carefully chosen actuation strategies. The objective of this work is to consolidate and add to our research to date on methods for realizing

Variable-stiffness artificial muscles are important in many applications including running and hopping robots, human–robot interaction, and active suspension systems. Previously used technologies include pneumatic muscles, layer and granular jamming, series elastic actuators, and shape memory polymers. All these are limited in terms of cost, complexity, the need for fluid power supplies, or controllability

Soft hands based only on an actuator system using a motor, air compressor, or smart material show obvious shortcomings due to the characteristics of each actuator. In this article, to overcome the weaknesses of each actuator system, a novel soft hand with a hybrid actuator system is presented to improve the grasping capacity and complete complex tasks, as the individual actuators can complement each

Soft robots leverage deformable bodies to achieve different types of locomotion, improve transportability, and safely navigate cluttered environments. In this context, variable-stiffness structures provide soft robots with additional properties, such as the ability to increase forces transmitted to the environment, to lock into different body configurations, and to reduce the number of actuators required

Soft robots have applications in safe human–robot interactions, manipulation of fragile objects, and locomotion in challenging and unstructured environments. In this article, we present a computational method for augmenting soft robots with proprioceptive sensing capabilities. Our method automatically computes a minimal stretch-receptive sensor network to user-provided soft robotic designs, which is

This article describes the performance of a flexible resistive sensor network to track shoulder motion. This system monitors every gesture of the human shoulder in its range of motion except rotations around the longitudinal axis of the arm. In this regard, the design considers the movement of the glenohumeral, acromioclavicular, sternoclavicular, and scapulothoracic joints. The solution presented

This article describes a novel design of bioinspired soft robotic fingers based upon hybrid jamming principle—integrated layer jamming and particle jamming. The finger combines a fiber-reinforced soft pneumatic actuator with a hybrid jamming substrate. Taking advantage of different characteristics of layer jamming and particle jamming, the substrate is designed with three chambers filled with layers

This work described a bioinspired soft robotic finger with variable bending length to conform objects with different sizes by means of selectively varying the structural stiffness of its segments. The basic design is a shape memory alloy-based soft actuator with embedded stiffness-varying structures serving as modifiable endoskeletons. The stiffness-varying structure is composed of shape memory polymer

Human skins are active, smart, and stretchable. Artificial skins that can replicate these properties are promising materials and technologies that will enable lightweight, cost-effective, portable, and deployable soft devices and robots. We show an active, stretchable, and portable artificial skin (ElectroSkin) that combines dielectric elastomer actuators (DEAs) and soft electroadhesives (EAs) in a

Fabric muscle is important for wearable robots that are soft, compliant, and silent with high contractility and high force. This study presents a novel shape memory alloy (SMA) spring-based fabric muscle (SFM). The SFM is manufactured by bundling SMA springs with proven performance as artificial muscle. The SFM generates high contractility and high force, and is soft, flexible, and light because it

Soft pneumatic actuators (SPAs) are widely studied and applied in the field of soft robotics. To expand their applications, the SPAs should be purpose-built to generate application-specific complex motions with multiple degrees of freedom. This article describes a new SPA consisting of a series of internal chambers with the same helix angle arranged in a row, which could generate bending and twisting

Changing the shape and the stiffness of a device in a dynamic and controlled way enables important advancements in the field of robotics and wearable robotics. Variable stiffness materials and technologies can be used to address this challenge. In particular, layer jamming actuation is a very promising technology, featured by high efficiency and low cost. In this article, a stiffness- and shape-changing

Wearable devices developed with flexible electronics have great potential applications for human health monitoring and motion sensing. Although material softness and structural flexibility provide a deformable human–machine interface to adapt to joint bending or tissue stretching/compression, flexible sensors are inconvenient in practical uses as they usually require calibration every time they are

This article presents a frog-inspired swimming soft robot whose joints are articulated pneumatic soft actuators. The soft actuator is designed and prepared by studying the biological structure and limb movement characteristics of frogs. A schematic limb motion diagram of the robot is established based on the kinematic model, and the design scheme is determined by a combined control system. The torso

Recently, there has been active research in finding robotized solutions for the treatment of atrial fibrillation (AF) by augmenting catheter systems through the integration of force sensors at the tip. However, limited research has been aimed at providing automatic force control by also integrating actuation of the catheter tip, which can significantly enhance safety in such procedures. This article

Soft wearable actuators can help connect machines and humans, providing a personalized, ergonomic, and cooperative physical interface between people and their world. Until now, the torque of these interfaces has been limited, restricting their ability to assist the completely paralyzed. This article presents a method for realizing a soft structure that stably and comfortably applies a knee extension

Current additive manufacturing, including three-dimensional (3D) and so-called four-dimensional printing, of soft robotic devices is limited to millimeter sizes. In this study, we present additive manufacturing of soft microactuators and microrobots to fabricate even smaller structures in the micrometer domain. Using a custom-built extrusion 3D printer, microactuators are scaled down to a size of 300 × 1000 μm2

Recent advances in robotic systems have increased the need for various kinds of robots in many fields, such as aerospace and medical. Utilizing hard robots in such fields can cause irrecoverable damages; therefore, scientists have taken inspiration from nature to build robots with soft bodies. In this article, a soft pneumatic actuator that reshapes in the x–y plane is controlled. This continuous soft

Fluid actuated soft robots, or fluidic elastomer actuators, have shown great potential in robotic applications where large compliance and safe interaction are dominant concerns. They have been widely studied in wearable robotics, prosthetics, and rehabilitations in recent years. However, such soft robots and actuators are tethered to a bulky pump and controlled by various valves, limiting their applications

Mimicking the locomotive abilities of living organisms on the microscale, where the downsizing of rigid parts and circuitry presents inherent problems, is a complex feat. In nature, many soft-bodied organisms (inchworm, leech) have evolved simple, yet efficient locomotion strategies in which reciprocal actuation cycles synchronize with spatiotemporal modulation of friction between their bodies and

To control and navigate micro air vehicles (MAVs) efficiently, there is a need for small, lightweight, durable, sensitive, fast, and low-power airspeed sensors. When designing sensors to meet these requirements, soft materials are promising alternatives to more traditional materials due to the large deformations they can withstand. In this article, a new concept of a soft material flow sensor is presented

Grasping is an important characteristic of robots in interacting with humans and the environment. Due to the inherent compliance of soft grippers, they can easily adapt to novel objects and operate safely in a human-centered environment. However, soft hands suffer from poor grasping robustness and operation durability, especially for heavy objects or objects with sharp spikes, mainly due to their fragile

This study presents an optimal design procedure, including topology and geometry optimization methods to design a compliant constant-force mechanism, which can generate a nearly constant output force over a range of input displacements. The proposed constant-force mechanism is a passive force regulation device that can be used in various applications such as precision manipulation and overload protection

In this study, we introduce a haptic communication method using two-dimensional (2D) arrayed thermal haptic module. The 2D thermal haptic module delivers real-time information to user through the thermoception of the user's skin. Such 2D thermal haptic module could be realized using flexible thermoelectric (TE) device and independent temperature control of individual unit cell that are arranged in

Robotic self-assembly of deformable materials holds potential for the automatic construction of complex robots. Current manipulation for deformable manipulation mainly focuses on a soft robot. It still remains a great challenge for morphology manipulation of a swarm of particles. Chladni patterns have raised great interest in the field of self-assembly for different materials. The formation of Chladni

Tunable-impedance mechanisms can improve the adaptivity, robustness, and efficiency of a vast array of engineering systems and soft robots. In this study, we introduce a tunable-stiffness mechanism called a “sandwich jamming structure,” which fuses the exceptional stiffness range of state-of-the-art laminar jamming structures (also known as layer jamming structures) with the high stiffness-to-mass

Soft actuators producing large motion in a short time are mostly based on stretchable polymers actuated by pneumatic pressure; they consist of bulky components, including a motor, pump/compressor, tubes, and valves. In this study, we develop a fast-responding large-amplitude soft actuator, based on a liquid–gas phase transition, which produces a compact system. The required pressure is generated solely

One of the many secrets to the success and prevalence of insects is their versatile, robust, and complex exoskeleton morphology. A fundamental challenge in insect-inspired robotics has been the fabrication of robotic exoskeletons that can match the complexity of exoskeleton structural mechanics. Hybrid robots composed of rigid and soft elements have previously required access to expensive multi-material

Robots made of soft materials are demonstrating to be well suited in applications where dexterity and intrinsic safety are necessary. However, one of the most challenging goals of soft robotics remains the ability to change the stiffness of body parts to guarantee stability and to produce significant forces. Among soft actuation technologies reported in literature, the jamming phenomenon is now achieving

A theoretical model is built in this study for analyzing and predicting the deformation of a bending-type soft pneumatic actuator used for bionic robotic fish. The actuator is composed of two symmetrically distributed silicone rubber blocks (Ecoflex0030 from Smooth-on Co., Ltd.). Between the two rubber blocks, an ABS plate is fixed to work as a neutral layer. When one side of the actuator is inflated

We present a manufacturing process for creating centimeter-scale multichambered inflatable robots and structures that can include both soft and rigid components. Our process uses a thermoplastic polyurethane (TPU) adhesive film to bond together layers of textiles, plastics, or other materials. The structures are heated and compressed a few layers at a time with a heat press machine or bonded in an

Conformable robotic systems are attractive for applications in which they may actuate structures with large surface areas, provide forces through wearable garments, or enable autonomous robotic systems. We present a new family of soft actuators that we refer to as Fluidic Fabric Muscle Sheets (FFMS). They are composite fabric structures that integrate fluidic transmissions based on arrays of elastic

In the field of marine biology-inspired robotics, anguilliform locomotion, as one of the most common underwater propulsion types, has been widely studied and implemented in many robot prototypes. Most of these robots consisted of rigid parts, and they were able to generate smooth sine waves along the robot body using a great number of rigid segments, electric motors, and complicated control. To simplify

A leading concept in soft robotics actuation, as well as in microfluidics applications such as valves in lab-on-a-chip devices, is applying pressurized flow in cavities embedded within elastic bodies. Generating complex deformation patterns typically requires control of several inputs, which greatly complicates the system's operation. In this study, we present a novel method for single-input control

This study presents a novel idea of rebraiding thin McKibben muscles to overcome their limitation of contraction. The thin McKibben muscles, presented in the authors' previous work, have the flexibility that allows them to be braided. According to the experimental results of our previous research, the original single muscles have a contracting ratio of 28%, and the corresponding value for the muscles

Mechanoreception, the ability of robots to detect mechanical stimuli from the internal and external environments, contributes significantly to improving safety and task performance during the operation of robots in unstructured environments. Various approaches have been proposed to endow robot systems with mechanoreception. In the case of soft robots, the state-of-the-art mechanosensory solutions typically

Due to their high deformability, lightness, and safe interaction with the surrounding environment, flexible actuators are key ingredients in soft robotics technologies. Among these, electro-thermal actuators (ETAs), based on carbon nanotubes (CNTs), are used to generate agile movements when current is applied. The extent of movement is determined mostly by the coefficient of thermal expansion (CTE)

This article deals with a novel active bending soft body that uses metamaterials and combines soft behavior, integrated actuation, low complexity, and a high density of producible forces and moments. The presented concept consists of a tube-like structure with tailored, unconventional material properties, which enable the generation of a bending deformation and/or moment when circumferential stress

This article presents the system integration, sensing, and control of a novel modular soft-rigid pneumatic exoskeleton for lower limb. The proposed exoskeleton consists of three soft hinges (to drive the hip, knee, and ankle joints) and four rigid links (aligned with the waist, thigh, crus, and foot). Each soft hinge is made of and actuated by a customized bidirectional curl pneumatic artificial muscle

Soft actuators and robotics have been widely researched in recent years mainly due to their compliance to environments and safe interaction with humans. However, the need of tether and low energy efficiency of such actuators/robots has limited their practical applications. This article presents a novel tendon-driven soft actuator concept that has the property of self-pumping, called soft self-pumping

The recent discovery of electroactive polymers has shown great promises in the field of soft robotics and was logically followed by experimental, numerical, and theoretical developments. Most of these studies were concerned with systems entirely covered by electrodes. However, there is a growing interest for partially active polymers, in which the electrode covers only one part of the membrane. Indeed

Wireless power transfer (WPT) has the significant potential for soft-bodied continuum robots to extend the operational time limitlessly and reduce weight. However, rigid power receiver coils, widely used in WPT, hinder the continuum deformation of the robot, and as a result, the function realization using the continuum deformation (e.g., locomotion) is impaired. Therefore, this article introduces that

By designing an actuator composed of thin layers with different coefficients of thermal expansion (CTE) together with an electrically conductive layer, the CTE mismatch can be utilized to produce soft electrothermal actuators (ETAs). These actuators have been typically implemented using only two layers, commonly relying on Timoshenko's analytic model that correlates the temperature to the actuator's

The field of self-healing soft robots was initiated a few years ago. A healing ability can be integrated in soft robots by manufacturing their soft membranes out of synthetic self-healing polymers, more specifically elastomeric Diels–Alder (DA) networks. As such they can recover completely from macroscopic damage, including scratches, cuts, and ruptures. Before this research, these robots were manufactured

Pneumatic artificial muscles (PAMs) are an extensively investigated type of soft actuator. However, the PAM motions have been limited somewhat to uniaxial contraction and extension, restraining the development of PAMs. Given the current strong interest in soft robotics, PAMs have been gaining renewed attention due to their excellent compliance and ease of fabrication. Herein, under the inspiration

Soft continuum robots are getting more popular in areas such as minimally invasive surgery, search and rescue, and inspection due to their inherent compliance and flexibility. However, most of the conventional continuum robots still lack the ability to significantly change size and length. Growth as a means of robotic locomotion is a novel actuation method that can be used to overcome this disadvantage