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One of the practical applications in the field of soft robotics involves the development of soft robotic wearable devices. These devices make use of their intrinsically compliant structures to interact safely and harmoniously with the human body. While soft wearable robots demonstrate their utility in lower‐limb applications for locomotion, the upper‐limb domain offers significant prospects in a wide range of applications that soft robotic technology can address. In this review, the current state of technology in the field of soft wearable upper limbs is systematically analyzed and categorized. Categorizations are made based on their applications in rehabilitation, activities of daily living support, and human augmentation. Furthermore, in this study, also contemporary technological aspects, encompassing sensing technology and control systems, are explored. Despite exciting potential in this domain, several limitations from existing devices inherently impede widespread adoption and thus hinder further progress in the field. In this study, also an overview of the different facets of the domain is provided and key considerations for the advancement of soft wearable robotic devices intended for upper‐limb applications are prescribed. [ABSTRACT FROM AUTHOR]

Flexible robotic systems (FRSs) and wearable user interfaces (WUIs) have been widely used in medical fields, offering lower infection risk and shorter recovery, and supporting amiable human–machine interactions (HMIs). Recently, soft electric, thermal, magnetic, and fluidic actuators with enhanced safety and compliance have innovatively boosted the use of FRSs and WUIs across many sectors. Among them, soft hydraulic actuators offer great speed, low noise, and high force density. However, they currently require bulky electric motors/pumps, pistons, valves, rigid accessories, and complex controllers, which inherently result in high cost, low adaptation, and complex setups. This paper introduces a novel soft fibrous syringe architecture (SFSA) consisting of two or more hydraulically connected soft artificial muscles that enable electricity‐free actuation, motorless control, and built‐in sensing ability for use in FRSs and WUIs. Its capabilities are experimentally demonstrated with various robotic applications including teleoperated flexible catheters, cable‐driven continuum robotic arms, and WUIs. In addition, its sensing abilities to detect passive and active touch, surface texture, and object stiffness are also proven. These excellent results demonstrate a high feasibility of using a current‐free and motor‐less control approach for the FRSs and WUIs, enabling new methods of sensing and actuation across the robotic field. [ABSTRACT FROM AUTHOR]

The heart's intricate myocardial architecture has been called the Gordian knot of anatomy, an impossible tangle of intricate muscle fibers. This complexity dictates equally complex cardiac motions that are difficult to mimic in physical systems. If these motions could be generated by a robotic system, then cardiac device testing, cardiovascular disease studies, and surgical procedure training could reduce their reliance on animal models, saving time, costs, and lives. This work introduces a bioinspired soft robotic left ventricle simulator capable of reproducing the minutiae of cardiac motion while providing physiological pressures. This device uses thin-filament artificial muscles to mimic the multilayered myocardial architecture. To demonstrate the device's ability to follow the cardiac motions observed in the literature, we used canine myocardial strain data as input signals that were subsequently applied to each artificial myocardial layer. The device's ability to reproduce physiological volume and pressure under healthy and heart failure conditions, as well as effective simulation of a cardiac support device, were experimentally demonstrated in a left-sided mock circulation loop. This work also has the potential to deliver faithful simulated cardiac motion for preclinical device and surgical procedure testing, with the potential to simulate patient-specific myocardial architecture and motion. Editor's summary: Cardiac devices and interventions are often dependent on the use of animal models and ex vivo tissue for testing and development. Moreover, surgical training for procedure-specific skills also relies on animal tissue. Davies et al. have developed a soft robotic device that can mimic the left ventricle of the heart and reproduce cardiac motion as well as physiological hemodynamic conditions. They demonstrated the ability to simulate conditions of healthy and diseased heart states, with the potential to counter the need for animal models to develop cardiac devices. —Amos Matsiko [ABSTRACT FROM AUTHOR]

Textiles are promising candidates for use in soft robots and wearable devices due to their inherent compliance, high versatility, and skin comfort. Planar fluidic textile‐based actuators exhibit low profile and high conformability, and can seamlessly integrate additional components (e.g., soft sensors or variable stiffness structures [VSSs]) to create advanced, multifunctional smart textile actuators. In this article, a new class of programmable, fluidic soft textile muscles (STMs) that incorporate multilayered silicone sheets with embedded fluidic channels is introduced. The STMs are scalable and fabricated by apparel engineering techniques, offering a fabrication approach able to create large‐scaled multilayered structures that can be challenging for current microfluidic bonding methods. They are also highly automation compatible due to no manual insertion of elastic tubes/bladders into textile structures. Liquid metal is employed for creating fluidic channels. It is not only used for actuation but also used as channels for additional features such as soft piezoresistive sensors with enhanced sensitivity to STMs' pressure‐induced elongation, or VSSs of either low‐melting‐point alloys or a new thermo‐responsive epoxy with low viscosity and transition temperature. The STMs hold promising prospects for soft robotic and wearable applications, which is demonstrated by an example of a textile‐based wearable 3D skin‐stretch haptic interface. [ABSTRACT FROM AUTHOR]

Palpation is a simple but effective method to distinguish tumors from healthy tissues. The development of miniaturized tactile sensors embedded on endoscopic or robotic devices is key to achieving precise palpation diagnosis and subsequent timely treatment. This paper reports on the fabrication and characterization of a novel tactile sensor with mechanical flexibility and optical transparency that can be easily mounted on soft surgical endoscopes and robotics. By utilizing the pneumatic sensing mechanism, the sensor offers a high sensitivity of 1.25 mbar and negligible hysteresis, enabling the detection of phantom tissues with different stiffnesses ranging from 0 to 2.5 MPa. Our configuration, combining pneumatic sensing and hydraulic actuating, also eliminates electrical wiring from the functional elements located at the robot end-effector, thereby enhancing the system safety. The optical transparency path in the sensors together with its mechanical sensing capability open interesting possibilities in the early detection of solid tumor as well as in the development of all-in-one soft surgical robots that can perform visual/mechanical feedback and optical therapy. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) bioprinting technology offers great potential in the treatment of tissue and organ damage. Conventional approaches generally rely on a large form factor desktop bioprinter to create in vitro 3D living constructs before introducing them into the patient's body, which poses several drawbacks such as surface mismatches, structure damage, and high contamination along with tissue injury due to transport and large open‐field surgery. In situ bioprinting inside a living body is a potentially transformational solution as the body serves as an excellent bioreactor. This work introduces a multifunctional and flexible in situ 3D bioprinter (F3DB), which features a high degree of freedom soft printing head integrated into a flexible robotic arm to deliver multilayered biomaterials to internal organs/tissues. The device has a master‐slave architecture and is operated by a kinematic inversion model and learning‐based controllers. The 3D printing capabilities with different patterns, surfaces, and on a colon phantom are also tested with different composite hydrogels and biomaterials. The F3DB capability to perform endoscopic surgery is further demonstrated with fresh porcine tissue. The new system is expected to bridge a gap in the field of in situ bioprinting and support the future development of advanced endoscopic surgical robots. [ABSTRACT FROM AUTHOR]

Taking a leaf out of evolutionary biology, soft robots have begun to utilize compliant materials and structures for improved interactions with humans and complex environments. However, these advances have not been followed closely by sensing mechanisms. Biology has had a head start on the development of advanced sensing systems. The human body and its skeletal muscles can tune their morphologies to interact with the surrounding environment. Inspired by such biological systems, this paper introduces a novel hydraulic soft filament sensor (SFS) with tunable sensitivity. The SFS is a type of hydraulic pressure‐based tubular strain sensor, which has a sensing core made of a soft and stretchable micro‐sized filament filled with incompressible fluid where its inner hydraulic pressure is changed with strain. The SFS can be customized to form a wide range of configurations such as a long fiber or a skin‐like structure. To demonstrate the SFS capability, different configurations for the SFS are fabricated and experimentally validated. The scalable and tunable nature of the SFS makes it suitable for a wide range of wearable and medical applications. [ABSTRACT FROM AUTHOR]

The marriage of textiles with artificial muscles to create smart textiles is attracting great attention from the scientific community and industry. Smart textiles offer many benefits including adaptive comfort and high conformity to objects while providing active actuation for desired motion and force. This paper introduces a new class of programmable smart textiles created from different methods of knitting, weaving, and sticking fluid-driven artificial muscle fibers. Mathematical models are developed to describe the elongation-force relationship of the knitting and weaving textile sheets, followed by experiments to validate the model effectiveness. The new smart textiles are highly flexible, conformable, and mechanically programmable, enabling multimodal motions and shape-shifting abilities for use in broader applications. Different prototypes of the smart textiles are created with experimental validations including various shape-changing instances such as elongation (up to 65%), area expansion (108%), radial expansion (25%), and bending motion. The concept of reconfiguring passive conventional fabrics into active structures for bio-inspired shape-morphing structures is also explored. The proposed smart textiles are expected to contribute to the progression of smart wearable devices, haptic systems, bio-inspired soft robotics, and wearable electronics. [ABSTRACT FROM AUTHOR]

Wound closure with surgical sutures is a critical challenge for flexible endoscopic surgeries. Substantial efforts have been introduced to develop functional and smart surgical sutures to either monitor wound conditions or ease the complexity of knot tying. Although research interests in smart sutures by soft robotic technologies have emerged for years, it is challenging to develop a soft robotic structure that possesses a similar physical structure as conventional sutures while offering a self-tightening knot or anchor to close the wound. This paper introduces a new concept of smart sutures that can be programmed to achieve desired and uniform tension distribution while offering self-tightening knots or automatically deploying secured anchors. The core technology is a soft hydraulic artificial muscle that can be elongated and contracted under applied fluid pressure. Each suture is equipped with a pressure locking mechanism to hold its temporary elongated state and to induce self-shrinking ability. The puncturing and holding force for the smart sutures with anchors are examined. Ex-vivo experiments on fresh porcine stomach and colon demonstrate the usefulness of the new smart sutures. The new approaches are expected to pave the way for the further development of smart sutures that will benefit research, training, and commercialization in the surgical field. [ABSTRACT FROM AUTHOR]

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 thermally activated variable stiffness structure (VSS) for high load capacity that can complete a softening‐stiffening cycle within 24 s, which is among the fastest results reported so far. In addition, a highly stretchable liquid metal‐based soft sensor with an enhanced sensing sensitivity (15 times more sensitive compared to conventional designs) is embedded into the gripper to provide real‐time touch sensing. The gripper successfully grasped various objects of different geometries and weights (up to 220 times of its mass) and retrieved them from confined hollow spaces. Its excellent performance and versatility make it an ideal candidate for various domains, including industry, exploration, rescue, and other applications in confined and hazardous environments such as gas/oil or drainage sectors. [ABSTRACT FROM AUTHOR]

Soft actuators (SAs) have been used in many compliant robotic structure and wearable devices, due to their safe interaction with the wearers. Despite advances, the capability of current SAs is limited by scalability, high hysteresis, and slow responses. In this paper, a new class of soft, scalable, and high-aspect ratio fiber-reinforced hydraulic SAs is introduced. The new SA uses a simple fabrication process of insertion where a hollow elastic rubber tube is directly inserted into a constrained hollow coil, eliminating the need for the manual wrapping of an inextensible fiber around a long elastic structure. To provide high adaptation to the user skin for wearable applications, the new SAs are integrated into flexible fabrics to form a wearable fabric sleeve. To monitor the SA elongation, a soft liquid metal-based fabric piezoresistive sensor is also developed. To capture the nonlinear hysteresis of the SA, a novel asymmetric hysteresis model which only requires five model parameters in its structure is developed and experimentally validated. The new SAs-driven wearable robotic sleeve is scalable, highly flexible, and lightweight. It can also produce a large amount of force of around 23 N per muscle at around 30% elongation, to provide useful assistance to the human upper limbs. Experimental results show that the soft fabric sleeve can augment a user's performance when working against a load, evidenced by a significant reduction on the muscular effort, as monitored by electromyogram (EMG) signals. The performance of the developed SAs, soft fabric sleeve, soft liquid metal fabric sensor, and nonlinear hysteresis model reveal that they can effectively modulate the level of assistance for the wearer. The new technologies obtained from this work can be potentially implemented in emerging assistive applications, such as rehabilitation, defense, and industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • A soft fabric gripper comprising fabric bending actuators is fabricated by facile and scalable process of apparel engineering. • The sheet actuators integrate gecko adhesion and variable stiffness filament to achieve high payload-to-weight ratio. • The thermo-responsive VSF features a relatively fast cooling speed of 51 s by ambient cooling. • The sheet actuators allow the integration of soft conductive fabric sensors made from a new liquid-metal-based composite. • Experimental validations of the fabric gripper with gecko adhesion, variable stiffness, and soft sensor are carried out. Fluid-driven soft grippers possess conformable grasping characteristics that differ from their rigid counterparts. Despite advances, their inherent low-stiffness due to constituent materials causes them to be inferior in many high-load applications. Existing fabrication methods of soft grippers that mostly rely on molding silicone elastomers, despite being simple, are not easily scalable. This article presents the design of a soft robotic fabric gripper that can be fabricated by a facile and highly scalable process of apparel engineering. The proposed robotic gripper features a multi-fingered design that comprises hydraulic-driven, sheet-shaped fabric bending actuators. Its performance is enhanced by incorporating a bio-inspired gecko adhesive and a thermo-responsive variable stiffness filament. Experimental studies demonstrate that adding the variable stiffness filament and gecko adhesive improves the holding force of the gripper up to 655 % and 507 % in the gripping and pull-out configurations, respectively. The variable stiffness filament features a relatively good cooling speed of only 31 s by ambient cooling. A simple analytical model was also developed to characterize the deformation of the fabric bending actuators. To monitor the gripper bending motion, a new soft fabric sensor comprising a conductive composite of liquid metal and carbon particles was developed. The sensor was configured in a sheet-like shape and can be easily integrated into the gripper, which has been usually absent for other fabric grippers. The materials employed by this gripper design are commercially available for a reasonable budget, enabling the gripper to be both cost-effective and have potential applications where both gentle grasping and high load capacity are required. [ABSTRACT FROM AUTHOR]

Soft robotics-based teleoperated robotic catheter systems hold great promise for improving the safety and efficacy of vascular interventional surgery (VIS). Despite advances, current robotic catheter systems actuated via cables have low stability, high force loss, lack of force sensing, and low stability when working against the dynamic cardiothoracic environment, all of which significantly reduce their effectiveness in clinical settings. Therefore, it is essential to equip the robotic catheters with a stabilizing mechanism (SM), a real-time force sensor, and the ability to expand the workspace without moving its body. This work introduces a new concept of a miniaturized soft robotic catheter (MSRC) for the VIS. The system consists of a soft manipulator for navigation and bending motion, a variable stiffness stabilizing mechanism (VSSM), and a soft force sensor for monitoring tool-tissue contact. By employing soft hydraulic filament artificial muscles (HFAMs), the flexible manipulator has an omnidirectional and extendable workspace and can generate a force of 0.375 N, which is monitored by a new HFAM-based sensor with a high sensitivity of about 10.7 KPa/N. The new VSSM can be deployed as a lantern form with a wide diameter range from 6 mm to 25 mm, potentially enhancing the catheter tip's stability at various blood vessels (e.g., the inferior vena cava IVC) to perform VIS. The VSSM has a controllable deploying force and is capable of withstanding highly compressed forces with little deflection. The system feasibility to perform cardiac ablation is demonstrated with a simulated heart's right atrium (RA), potentially offering a reliable tool for the treatment of atrial fibrillation (AF). The design, modelling, and fabrication of the device are also presented and followed by experimental characterizations, and ex-vivo tests. [Display omitted] • A novel soft robotic catheter with integrated bending and extending, stabilizing, and sensing ability is developed. • An omnidirectional manipulator with extendable workspace for bending and extending motion is fabricated and characterized. • A stabilizing mechanism with a unique characteristic of variable stiffness is proposed to use for stabilizing the catheter. • A new and low-cost soft force sensor with high sensitivity for monitoring tool-tissue contacts is proposed. • Ex-vivo experiments of the system performing ablation in the heart's right atrium (RA) are conducted. [ABSTRACT FROM AUTHOR]

Soft robotics, soft artificial muscles and smart textiles are on the rise to compete with their rigid counterparts in the fields of wearable technologies and medical applications owing largely to their improved compliance characteristics. This paper introduces a smart textile created by weaving a hydraulic artificial muscle for a wearable application. To capture the inherent nonlinear hysteresis of the developed smart woven textile, we propose a simple hysteresis model and implement a feedforward compensation scheme and an adaptive controller. Both control strategies significantly reduced the output elongation tracking errors, demonstrating up to 90% improvement in the case of adaptive control compared to the uncompensated system. We also present the development of a portable smart compression device to overcome the shortcomings of current compression devices to provide treatment for people with venous disease or compromised peripheral blood flow. While current compression devices are passive, difficult to put on/take off, slow to compress or noisy and bulky, our smart compression device is easy to wear, compact and portable, with low energy consumption and can be easily controlled with a smartphone application via Bluetooth connection. The smart compression device operated at 18% strain and took 5 s to complete each compression cycle. We also demonstrate the proof-of-concept of incorporating a soft contact force sensor and other electronic components into the smart textile structure for extra functionality. This work contributes to the advancement of soft robotic technologies, wearable electronics and smart wearables for medical applications. [Display omitted] • Woven hydraulic artificial muscle or smart textile for wearable device. • Tracking output by nonlinear hysteresis model, feedforward and adaptive controllers. • Compact and portable smart compression device for compression therapy. • Users can control the smart compression device with a smartphone via Bluetooth. • Smart textile is capable of incorporating electronics for extra functionality. [ABSTRACT FROM AUTHOR]