Plasticized polyvinyl chloride (PVC) gels have shown increasing potential for developing integrated actuation and sensing devices in soft robotics and wearable electronics. Notably, the flexible electrodes in PVC gel-based devices are crucial to their overall performance. However, traditional carbon grease electrodes substantially limit the functionality and stability of such devices, primarily due to their uneven distribution and inherent durability. To address these limitations, we propose a novel PVC/carbon nanotubes (CNTs) gel electrode (GE) for constructing dual-mode actuation-sensing devices with high performance and stability. We investigated the effects of three representative fillers-carbon black, graphene, and CNTs on the formation of molecular networks of the gel. Owing to its intrinsic one-dimensional geometry, CNTs facilitate the formation of a 3D percolating network, enabling PVC/CNTs GE (PCGE) to achieve an unprecedented charge carrier density of 3.31 x 10 (1) (7) cm(-)(3) . The PCGE demonstrates a high electrical conductivity of 79.9 mS/cm (4.2 times higher than carbon grease), an ultralow 30-day impedance growth rate of 8.4 % (a 70-fold reduction), and a minimal 10,000-cycle drift of 1.25 %(a 51-fold improvement), surpassing carbon grease in both conductivity and durability for flexible electronic applications. The PCGE-based bending actuators exhibited remarkable performance (182 degrees at 3 V/mu m) and a fast response (2 Hz). Moreover, the PCGE-based sensors achieved high sensitivity (GF>35), precise resolution (0.06 %), and ideal dynamic response (0.5-4 Hz), addressing the durability limitations of carbon grease. Additionally, the actuators achieve biomimetic applications in robotics, demonstrating their potential as artificial muscles. In contrast, the sensors enable motion tracking, showcasing broad applicability in intelligent sensing systems.

Resting hand tremor, a prevalent neurological disorder, significantly compromises patients' quality of life without being directly life-threatening. Conventional pharmacological and surgical interventions are often costly and carry potential complications, thereby generating considerable interest in non-invasive wearable assistive devices. However, existing exoskeleton-based tremor suppression devices, which predominantly rely on conventional motor-driven mechanisms, are frequently hampered by issues such as large size, substantial weight, and significant obtrusiveness. These limitations readily induce muscle fatigue, severely restricting their clinical utility and patient compliance. To address these challenges, this study pioneers the application of multilayer polyvinyl chloride (PVC) gel actuators for hand tremor suppression. Aiming to develop a practical suppression device, we first identified the optimal parameter set by investigating the force/displacement characteristics of the actuator under varying plasticizer contents and stacking layers. This established a high-performance gel actuator configuration suitable for tremor suppression, upon which a modular encapsulation structure with adjustable pre-tension was designed. Subsequently, guided by the principles of active vibration control, a dedicated control system was developed, incorporating tremor signal frequency/phase detection and a voltage-source switching control strategy. Finally, a hand tremor simulation test platform was constructed for validation. Experimental results demonstrated that the multilayer PVC gel actuator achieved a suppression efficiency of up to 49%. The encapsulated actuator exhibited outstanding comprehensive performance, including low power dissipation (5.2%), rapid response (similar to 50 ms), high operational bandwidth (10 Hz), and lightweight (33 g), thereby fully validating its application potential in physiological tremor suppression.

The development of electroactive polymers (EAPs) affords novel integrated actuation and sensing technologies for intelligent flexible systems, enabling them to achieve remarkable flexibility and intelligence. Among EAPs, plasticized polyvinyl chloride (PVC) gel stands out as an ideal candidate for next-generation intelligent flexible applications due to its combination of exceptional actuation and sensing properties. This paper presents a comprehensive overview of recent advances in PVC gel actuators and sensors, including fabrication, properties, modeling, and applications. In particular, the outstanding actuation and sensing properties of PVC gel are thoroughly analyzed to exhibit its immense potential for application in smart flexible devices. Furthermore, the inherent relationships between the properties and materials of PVC gel are further revealed. Moreover, recent modification techniques to enhance the actuation and sensing properties of PVC gel are summarized, offering guidance for improving its properties. The current challenges and promising perspectives for enhancing performance and facilitating applications are finally discussed. We believe this paper will inspire the development of high-performance flexible devices employing PVC gel, as well as other EAPs, thereby paving the way for their practical applications.

Fiber-constrained PVC gel actuators have shown promising potential for applications in soft robotics. However, their applications have been hindered by issues such as poor interfacial compatibility, significant manual manufacturing deviations, and limited reliability. To overcome these challenges, this study proposes a fabrication approach for stiffness-varying PVC gel structures using direct ink writing (DIW) 3D printing. By optimizing the ink's rheology and printing parameters, we successfully produced gel fibers and membranes with tailored dimensions, enabling the fabrication of unidirectionally actuating planar actuators. The actuator demonstrated a maximum strain of 12%, with the integrated gel fibers effectively suppressing bending deformation, confirming the feasibility of the proposed strategy. This work presents a novel approach and technological foundation for advancing high-performance and customizable flexible actuators.

Plasticized polyvinyl chloride (PVC) gels have garnered significant attention in the field of electroactive materials due to their unique actuation properties. However, the conventional flat-electrode-structured PVCꞏgel bending actuator (fes-PGBA) suffers from limitations such as restricted bending angles and slow response speeds, making it challenging to meet the demands of high-performance bending actuation. Herein, we propose a novel annular-electrode-structured PVC gel bending actuator (aes-PGBA) using eco-friendly PVC (eco-PVC) gel with a structure-guiding mechanism. This mechanism utilizes the geometric curvature of the anode to actively control and significantly enhance the deformation behavior of the PVC gel. By adjusting the content of the environmentally benign acetyl tributyl citrate (ATBC) plasticizer and optimizing the anode's structural parameters, the proposed aes-PGBA achieved a 14.8-fold greater bending angle (270°) than the fes-PGBA. Besides, the mechanism of key structural parameters (thickness and width) on the output force was analyzed. Accordingly, the optimized actuator exhibited a bending angle of 229.54° under 1 kPa stress (at 4.5 V/μm). Finally, the Venus flytrap-inspired soft robot based on aesPGBA was developed. It exhibited the capability to close rapidly (2.07 s) and recover efficiently (1.17 s), showing its potential for biomimetic applications.

The 3D model of the perivascular-endosteal multi-microenvironment (PVM-EM) is crucial for studying early stage breast cancer (BrCa) bone metastasis. However, existing models struggle to accurately represent the composition and spatial intricacies of multi-microenvironments, limiting their ability to support cellular functional expression within these systems. Here, the nested aqueous two-phase system emulsion as a template to develop a novel type of core-shell microsphere for establishing the PVM-EM 3D model is utilized. This model enables precise control over the chemical composition, macroporous structure, and cell localization. By adjusting these parameters in each microenvironment, it is successfully reconstructed the PVM with precise compartmentalized cell distribution in the microsphere core and a functional EM in the microsphere shell in one step. The outcomes indicate that the porous architecture and cell localization significantly enhance cell activity and function within the microenvironment. Importantly, this multi-microenvironment model effectively encapsulates the key biological processes associated with bone colonization in early BrCa bone metastasis, including elevated cytokine expression, extensive angiogenesis within PVM, and significant inhibition of alkaline phosphatase expression within EM. This method paves the way for efficient and precise control of physiologically relevant PVM-EM models, facilitating future preclinical research and drug screening for BrCa bone metastasis.

Resting tremor suppression stands as a major problem in rehabilitation engineering. Traditional techniques, like pharmacological therapies and invasive surgical operations, typically bring about severe side effects, variable efficacy, and financial pressures. Notably, stiffness-based exoskeleton systems fabricated for tremor attenuation tend to feature large mass and low integration with natural biomechanical movement. To subdue these limitations, this research assesses the viability of polyvinyl chloride (PVC) gel as a high-performance electroactive polymer for tremor suppression. Via the systematic experimental testing of the material's mechanical properties, displacement aspects, capability of output-force production, and dynamic response, the study brings forward some positive features: short response time, light weight, compact shape, and high energy efficiency. Notably, the response bandwidth has a cutoff at 9 Hz that fully covers the standard 4-6 Hz range of human resting tremor. Notably, the response bandwidth has a 9 Hz cutoff that fully spans the normal 4-6 Hz range of human resting tremor.

To achieve rapid balance recovery of humanoid robots under external shocks, a bionic bipedal balance control approach based on control priority and target attitude adjustment was developed. In order to successfully restore equilibrium, the system first automatically modifies the control priority based on the impact magnitude and stability margin. This means that when the center of mass approaches the support border, it receives a higher attitude control priority. Second, the discriminating mechanism for the shock confrontation and balance recovery stages was designed, and the target attitude of the robot's centroid of mass was modified appropriately for each stage. The optimum three-dimensional force at the foot end was then obtained by combining MPC's state prediction in the future time domain with a quadratic programming solution, allowing the robot to quickly restore its equilibrium after being disturbed by the external environment. External force striking test were conducted on flat and irregular ground while the robot was standing bipedally. The results suggest that the proposed strategy can improve the robot's ability to withstand stronger external shocks and swiftly recover balance following external hits.

Plasticized Poly (vinyl chloride) (PVC) gel actuators, a type of electroactive soft actuator, have recently attracted increasing interest in soft robotics. Herein, we report a novel planar PVC gel actuator with flexible electrodes and a fiber-constrained structure for electroactive artificial muscles. PET adhesive fibers were evenly affixed on both sides of the unidirectional pre-stretched PVC gel membranes in one direction, resulting in a human-muscle-like unidirectional contraction and expansion movement. The fibers can constrain the bending motion of the PVC gel membranes, and the unidirectional pre-stretch in the direction of the attached fibers further makes the membrane anisotropic, leading to easy and fast actuation in the direction normal to the pre-stretch. The developed fiber-constrained plasticized PVC gel actuator (FCPPGA) unit exhibited high strain (>40%) and stress (>0.5 MPa) with a fast response time of about 0.1 s under a relatively low driving DC field (<15 V/mu m). The simulated data were in good agreement with the experimental results. Furthermore, the designed FCPPGA was successfully used to demonstrate the mimicry of lower jaw motions in a skeleton model.

The humanoid robot head plays an important role in the emotional expression of human-robot interaction (HRI). They are emerging in industrial manufacturing, business reception, entertainment, teaching assistance, and tour guides. In recent years, significant progress has been made in the field of humanoid robots. Nevertheless, there is still a lack of humanoid robots that can interact with humans naturally and comfortably. This review comprises a comprehensive survey of state-of-the-art technologies for humanoid robot heads over the last three decades, which covers the aspects of mechanical structures, actuators and sensors, anthropomorphic behavior control, emotional expression, and human-robot interaction. Finally, the current challenges and possible future directions are discussed.

In recent years, plasticized poly (vinyl chloride) (PVC) gel has attracted increasing attention in soft robotics. However, there is scarce research on the deformation mechanism and modeling of PVC gel actuators. In this study, to investigate the deformation mechanism of fiber-constrained planar PVC gel actuators, we propose a complex nonlinear model based on traditional thermodynamic electroactive polymer (EAP) multi-field coupling theory. The proposed model can reveal the dielectric breakdown strength of PVC gels and predict the deformation of planar PVC gel actuators with varying levels of pre-stretching. The theoretical results were in good agreement with the experimental results, indicating the feasibility of the proposed model.

Recently, the increasing interest in underwater exploration motivates the development of aquatic unmanned vehicles. To execute hazardous tasks in an unknown or even hostile environment, researchers have directed on developing biomimetic robots inspired by the extraordinary maneuverability, cruising speed, and propulsion efficiency of fish. Nevertheless, the performance of current prototypes still has gaps compared with that of real fishes. In this review, recent approaches in structure designs, actuators, and sensors are presented. In addition, the theoretical methods for modeling the robotic fishes are consolidated, and the control strategies are offered. Finally, the current challenges are summarized, and possible future directions are deeply discussed. It is expected that the emergence of new engineering and biological technologies will enhance the field of robotic fish for further advancement.

The clinical utility of 7-ethyl-10-hydroxycamptothecin (SN-38) is hampered by its low water solubility and reduced bioactivity at neutral or alkaline conditions. The rational design of an effective drug delivery system that can significantly enhance the therapeutic index of SN-38 and achieve complete tumor regression still remains a challenge. Herein, chitosan-based hybrid nanoparticles system co-loading with chemotherapeutic drug SN-38 and gold nanorods (AuNRs) was engineered for effective combinational photothermal-chemotherapy. To increase the solubility of SN-38, soluble polymeric prodrug poly (L-glutamic acid)-SN38 (L-PGA-SN38) was firstly synthesized and then complexed with chitosan to form stable nanomedicine via a mild and facile way without using any organic solvent or surfactant. Upon introducing AuNRs into chitosan-based nanomedicine by coordination interaction between the amine group of chitosan and AuNRs, the hybrid nanoparticles exhibited distinct synergistic therapeutic effect compared with single chemotherapy or photothermal treatment in vitro and in vivo. Almost complete tumor regression was achieved after 21-day treatment of the developed hybrid nanoparticles and showed no recurrence for at least 60 days.

Soft grippers take an important role in picking up and manipulating objects for adaptive machines and facilities to achieve near-human operations. The technology of soft actuators should be one of the key issues for developing such grippers. In this study, we proposed a novel two-figure gripper using polyvinyl chloride (PVC) gel-based multilayered soft actuators. We used the contraction-expansion movement and generation force of the actuators to realize the gripper movement. A prototype gripper and a testing platform were designed, fabricated and the basic characteristics were evaluated for the pilot study. And a preliminary clamping experiment was conducted to verify the reasonability of the proposed gripper. The results show that the gripper can steadily grasp various small, lightweight, fragile, and irregular objects which demonstrated the feasibility of the practical use of the gripper.

7-Ethyl-10-hydroxycamptothecin (SN-38) as a potent anti-tumor candidate, suffers the constraints from its poor water solubility, pH-dependent lactone ring stability and the lack of efficient delivery system without losing its activity. Herein, biocompatible superparamagnetic chitosan-based nanocomplexes complexing with water-soluble polymeric prodrug poly(L-glutamic acid)-SN-38 (PGA-SN-38) was engineered for efficient delivery of SN-38. The manufacturing process of colloidal complexes was green, expeditious and facile, with one-shot addition of PGA-SN-38 into chitosan solution without using any organic solvent or surfactant. Upon introducing ultra-small-size superparamagnetic nanoparticles (~10 nm), the developed magnetic nanocomplexes exhibited significantly boosted tumor-targeted accumulation and efficient cellular internalization under a local magnetic field. Notably, the magnetic nanocomplexes achieved distinctly superior targeting and anti-tumor efficacy in the established xenograft colorectal cancer model of mice, with high tumor suppression rate up to 81%. Therefore, this superparamagnetic chitosan-based nanocomplex system could provide a promising platform for the targeted delivery of SN-38 in colorectal cancer therapy.

The development of smart size-tunable drug delivery nanoplatform enables the solving of the paradox of inconsistent size-dependence of high tumor accumulation and deep penetration during its delivery process, thus achieving superior cancer treatment efficacy. Herein, we report a size-shrinkable nanomicelle complex system with an initial size of 101 nm enabling effective retention around the tumor periphery and could destruct to ultrasmall nanomicelles triggered by a near-infrared (NIR) laser to realize the deep tumor penetration. The nanomicelle system is consisted of an upper critical solution temperature (UCST)-type block copolymer poly(acrylamide-acrylonitrile)-polyethylene glycol-lipoic acid (p(AAm-co-AN)-g-PEG-LA) encapsulating gold nanorods. Upon the irradiation of the NIR laser at the tumor site, gold nanorods could convert the light energy to heat energy, realizing the photothermal ablation of superficial tumor tissue. Concurrently, the large micelles split into a cascade of ultrasmall micelles (∼7 nm), which could easily penetrate into the deep site of the tumor and achieve the in situ "on-demand" release of the loaded drug to exert superior combined photothermal-chemotherapy of cancer. By the precise manipulation of laser, the micelle complex system realized the hierarchical killing from the superficial-to-deep tumor and achieved almost complete tumor growth inhibition on the established xenograft liver tumor mice model.

Plasticized poly (vinyl chloride) (PVC) gel is a promising electroactive polymer material for soft actuators and sensors, and it has attracted extensive attention and interest in multi-disciplinary fields. Chlorinated polyvinyl chloride (CPVC) has enhanced mechanical and chemical properties and shows a promising potential for fabricating gel materials for electroactive polymer gel actuators. Thus, we proposed a novel soft actuator based on CPVC gels. We studied the properties of CPVC gels with various technologies, such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) analysis, thermogravimetric analysis (TGA), etc. Furthermore, CPVC gel actuators were fabricated and the influence of membrane thickness and plasticizer content on the basic characteristics was investigated. The experimental results show that the CPVC gel actuator with a higher content of DBA has a better strain than that of the actuator with lower amount of DBA despite the membrane thickness. With the same ratio of DBA, the CPVC gel actuator has a better performance than the traditional PVC gel actuator under a low applied load. The maximum strain and stress of the CPVC gel (CPVC : DBA = 1 : 2.5) actuator are 9% and 0.12 MPa respectively at 400 V, which reaches the same level of the PVC gel actuator with higher content of DBA (PVC : DBA = 1 : 4). These results demonstrate a good potential of the proposed CPVC gel soft actuator for practical application.

Conventional chemotherapy is effective for metastatic tumors widely present in colorectal cancer patients; however, chemotherapy may cause severe systemic toxicity due to a lack of specificity towards cancer cells. Effective delivery systems that can enhance targeted drug delivery to the desired tumor site and simultaneously protect the activity of drugs are in high demand. To that end, this study developed chitosan-based polyelectrolyte complexes (PECs) with the orientation of superparamagnetic nanoparticles, which enables the targeting delivery of the first-line model drug irinotecan (IRT) to the tumor area under a magnetic field. Colloidal PECs were mildly and facilely fabricated with chitosan and poly(glutamic acid) (PGA) via an all-in-water process, excluding the use of any potentially toxic chemicals. Iso-dispersed superparamagnetic Fe3O4 nanoparticles with relatively small particle diameters (~10 nm) were embedded into the IRT-loaded nano-PECs. The optimized nano-PECs showed high drug encapsulation capacity and improved anti-colon cancer cell efficacy compared with the free drug. Furthermore, the magnetic nano-PECs exhibited effective internalization by colon tumor cells, and favorable tumor-targeting ability was demonstrated via in vivo biodistribution study. Therefore, this magnetic targeted drug delivery nano-PECs system provides a promising platform to overcome the side effects of conventional chemotherapy for colorectal cancer.

Sports rehabilitation is an important branch of rehabilitation medicine and the most widely received project in the social security system. In the process of continuous improvement of rehabilitation services, the sports rehabilitation aids industry is developing towards product, industrialization and individuation. With the increasing number of rehabilitation patients and the development trend of the Internet, Traditional therapist-assisted training has been difficult to meet patients’ rehabilitation needs, and more rehabilitation training equipment and service design are needed to meet modern technology and user experience. Modern rehabilitation training equipment has greatly improved the rehabilitation efficiency and curative effect than traditional methods, but it lacks the psychological and emotional satisfaction to the rehabilitation patients. This is also an important problem to be solved in the focus of rehabilitation auxiliary man-machine interface. Through the investigation and analysis of sports rehabilitation field, rehabilitation accessories industry and products, this paper clarifies the subject direction. The process of designing and developing rehabilitation accessory products based on user research is discussed in this paper. Under the guidance of the design concept, the design and development of rehabilitation accessory products and more humanized rehabilitation treatment service flow were carried out.

•Parameters impacting the formation of chitosan-based colloidal polyelectrolyte complexes (PECs) are reviewed.•Chitosan-based nanoPECs towards the mucosal delivery, cancer therapy, gene delivery and anti-HIV therapy are highlighted.•Challenges and future perspectives on the applications of chitosan-based nanoPECs are emphasized and co mmented.