Soft Technologies Research Articles

Liquid crystal-based actuators

Liquid crystal polymer networks (LCNs) have a great potential in soft actuator technologies. In contrast to other materials, LCNs offer a wide range of external stimuli which can trigger their actuation. These are for example based on changes of temperature, photo-induced orviathe application of electric fields. We here discuss the main LCN actuation mechanisms and classify them into several groups based on the used stimulus. Specific recent examples are provided for liquid crystal actuators and several general applications of such materials in connection to actuation mechanisms are exemplary outlined.

Soft Underwater Swimming Robots Based on Artificial Muscle

AbstractWith the increasing requirements of underwater missions and the rapid development of soft robotics technologies, soft underwater swimming robots have become a hot topic of research due to their low noise, high flexibility, and high environmental adaptability. In the past 10 years, research into soft underwater robots based on artificial muscle actuation has made considerable progress. Herein, a comprehensive survey on recent advances in soft underwater swimming robots based on different actuation methods is reviewed systematically, including pressure actuation, intelligent material actuation, and biomaterial actuation. First, for each type of actuation, the actuating principle, structural design, and swimming performance of soft underwater robots are introduced in detail. Then, according to the different swimming modes of underwater organisms, the aforementioned soft underwater robots are classified and compared. The results show that for different swimming tasks and application scenarios, the robot needs to realize the optimal design by reasonably selecting the actuating method and the swimming mode. This review summarizes the advanced information and critical technology in designing high‐performance soft underwater robots in the aspect of structural design, actuating methods, and swimming modes and offers an insightful outlook for the future development of soft robots.

RoboHeart: A Bi-Directional Zipping Actuator

Widespread adoption of soft robotic technologies is held back by the limitations of existing soft robotic actuators. One cause of the limited performance of soft actuators is their uni-polar stroke, which means only part of the work-cycle is powered. In this work, we introduce RoboHeart, a bi-directional compliant smart actuator. RoboHeart consists of two spring-steel strips covered with PVC insulation, pre-bent into a heart shape and is driven by dielectrophoretic zipping. Here, we perform isotonic and isometric characterisation of RoboHeart performance, demonstrating work output of 17 mJ (expansion) and 18 mJ (contraction) and power of 1.5 mW (expansion) and 2 mW (contraction). We then confirm the practical application of RoboHeart by demonstrating a 10-RoboHeart ring configuration capable of gripping a range of objects as they are lifted. We also demonstrate bidirectional control of actuation using three separate control channels. We believe that RoboHeart represents a step towards high-performance soft actuators and technologies.

Dielectric Elastomer Architectures with Strain‐Tunable Permittivity

AbstractFlexible hybrid electronic (FHE) materials and devices exploit the interaction of mechanical and electromagnetic properties to operate in new form factors and loading environments, which are key for advancing wearable sensors, flexible antennas, and soft robotic skin technologies. Dielectric elastomer (DE) architectures offer a novel substrate material for this application space as they are a class of strain‐tolerant and programmable metamaterials that derive their mechanical and dielectric properties from their architecture. Due to their hyperelasticity, dielectric elastomers can leverage reversible finite deformation to physically reconfigure their internal architecture to repeatedly tune their material behavior. Here a combined computational and experimental study of two dielectric elastomer architectures, based on square and hexagonal unit cell periodicities are presented. A shift in effective permittivity is observed due to the relative increase in matrix volume and the rearrangement of the electric field distribution in the cells. Additive fabrication allows rapid unit cell geometry customization for tuning the electromechanical response of the architectures. Effective permittivity shifts Δε2 > 0.7 under compressive strains of 35% are observed. The practical utility of this strain‐tunable permittivity is demonstrated in a microstrip patch antenna, which exhibits shifts in resonance frequency greater than 110 MHz when the dielectric elastomer substrate is compressed.

Preparing caregivers for dehospitalization of technology-dependent patients: perspective of Home Care professionals

Objective: to know how the preparation of caregivers of technology-dependent patients is conducted from the perspective of professionals from the Home Care Service. Methods: a qualitative study, conducted with nine professionals from the Home Care Service teams. The data was collected through semi-structured interviews and submitted to Content Analysis, thematic modality. Results: two categories emerged: Strategies and resources used in the preparation of caregivers for dehospitalization and Factors that influence the preparation of caregivers for dehospitalization, which show that this preparation involves the use of soft technologies, based on the interaction and valorization of learning, besides aspects related to the organization of the service in the intra-hospital and home contexts. Conclusion: the preparation of caregivers is permeated with concern for facilitating the acquisition of knowledge and skills for care at home; it involves the use of specific resources and strategies and is influenced positively by technologies and negatively by factors related to hospital structure and organization. Contributions to practice: the findings of the study can subsidize the practices of multiprofessional teams working in the home scenario, since they point out aspects that

Corporate social investment practices as ‘soft technology’: A case of selected Botswana firms

The study on which this article is based sought to examine the motives and patterns of corporate social investment practices using the experiences of eight Botswana Stock Exchange listed firms. It followed an exploratory sequential mixed-methods design utilizing a triangulation of documentary and archival records, and cross-sectional survey techniques. The study found out that although the motives for the practices were varied they were largely reactive and fragmented, and mostly driven by economic rather than business ethics imperatives. The article supports extant literature indicating the existence of growing publics' disillusionment with the apparent dissonance between corporates' historical institutional rhetoric and practice. Although the firms publicly portrayed themselves as good corporate citizens addressing wider societal challenges, in practice they engaged in the traditional ‘giving back to community’ donations. The article concludes that overall the practices served as ‘soft technologies’ for the (re)-figuration of corporate identities.

In-plane nonlinear vibration of circular dielectric elastomer membranes with extreme stretchability

This work investigates large in-plane stretches in thin circular membranes pre-stretched mechanically and dynamically excited by fluctuating voltages applied through their thicknesses. The nonlinear equation of motion is derived using Hamilton’s principle. Nonlinearity arises from the elastomer’s material behavior and electromechanical coupling from applied voltages. Primary and secondary resonances exhibit typical softening nonlinearity characterized by a range of frequencies where two coexisting vibrations, referred to as the upper branch and lower branch response, are possible. Our focus is the upper branch response, where extremely large dynamic stretches in the hundreds of percent are possible. These large stretches have not been fully investigated by prior research. The membrane’s upper branch vibrations can be found by decreasing frequency sweeps through resonance, and may not be captured if only increasing frequency sweeps are analyzed. Large-amplitude upper branch stretches occur when the membrane vibrates about both small-stretch and large-stretch equilibria. In addition to larger amplitudes, the upper branch dynamic stretches near secondary resonances have dominant frequencies different from the excitation frequency. Whether the dielectric elastomer membrane vibrates on the lower or upper branch depends on its initial conditions, and the initial conditions that result in each case are quantified. A technique is demonstrated to switch the membrane’s vibration from the lower to upper branch using impulse-like voltages superposed on the nominal sinusoidal component. The large-amplitude nonlinear dynamic stretches highlighted in this work, and the strategies we propose for accessing and controlling them, could be leveraged for improved performance in existing soft transducer technologies.

Design and Characterisation of a Muscle-Mimetic Dielectrophoretic Ratcheting Actuator

The high potential impact of soft robotics is hampered by a lack of actuators that combine high-force, high-work and high-power capabilities, limiting application in real-world problems. Typically, soft actuators are tuned to an application by gearing - for example, trading power for strain. An example of a recently developed soft-actuator which exploits such gearing is the dielectrophoretic liquid zipping (DLZ) actuator. DLZs can produce large strains ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&gt;\!99\%$</tex-math></inline-formula> ) and power densities comparable to biological muscles, but cannot achieve both in a single actuator. In this work, we introduce a muscle-mimetic DLZ ratcheting actuator (DLZ-R) that allows multiple DLZ-R heads to operate in parallel, thereby increasing force output without sacrificing stroke or power. We first characterise the effect of geometry on the performance of a 1-head DLZ-R, before demonstrating that the force, work, and power output of the DLZ-R scale linearly with the number of active DLZ heads. Next, we investigate the relationship between driving frequency and power output. Finally, we demonstrate a 12-head DLZ ratchet. We believe the DLZ-R represents a step towards soft actuators that can provide both high-work and high-power and the widespread use of soft technologies.

Microfluidic Tissue Engineering and Bio-Actuation.

Bio-hybrid technologies aim to replicate the unique capabilities of biological systems that could surpass advanced artificial technologies. Soft bio-hybrid robots consist of synthetic and living materials and have the potential to self-assemble, regenerate, work autonomously, and interact safely with other species and the environment. Cells require a sufficient exchange of nutrients and gases, which is guaranteed by convection and diffusive transport through liquid media. The functional development and long-term survival of biological tissues in vitro can be improved by dynamic flow culture, but only microfluidic flow control can develop tissue with fine structuring and regulation at the microscale. Full control of tissue growth at the microscale will eventually lead to functional macroscale constructs, which are needed as the biological component of soft bio-hybrid technologies. This review summarizes recent progress in microfluidic techniques to engineer biological tissues, focusing on the use of muscle cells for robotic bio-actuation. Moreover, the instances in which bio-actuation technologies greatly benefit from fusion with microfluidics are highlighted, which include: the microfabrication of matrices, biomimicry of cell microenvironments, tissue maturation, perfusion, and vascularization.

Comprehensive characterization of glycerol/ZnO green nanofluids for advances in multifunctional soft material technologies

Nanofluids (NFs) are increasingly used in most of the areas of soft condensed matter technologies, especially for heat transfer, energy harvesting, electrical insulation, and in the development of a variety of optoelectronic devices and controllable systems. Nowadays, green nanofluids are of considerable interest to researchers from an environmental safety point of view. Therefore, in this work, green nanofluids having biodegradable glycerol (GLY) as base fluid with homogeneous dispersion of eco-friendly zinc oxide (ZnO) nanoparticles (concentration range 0.01–1.00 wt%) were prepared and comprehensively characterized by employing various advanced techniques for exploring their promising multifunctional properties. The X-ray diffraction study of these GLY/ZnO green nanofluids, which is the first of its kind on nanofluids, confirmed the existence of monodispersed ZnO nanoparticles in the arranged 3D supramolecular structural network of the glycerol fluid. The ZnO nanoparticles having higher suspension stability in the GLY fluid were able to exhibit all the characteristic crystalline diffraction peaks for the concentration ≥ 0.30 wt%, at which the visible range photons absorption became almost saturated. The detailed analysis of the UV–Vis absorbance spectra of these nanofluids with increasing ZnO concentration explained substantial alterations in the electronic transition energy for the lone electron pairs of the hydroxyl oxygen atoms of glycerol molecules and also the valence band electrons of the ZnO nanomaterial. Dielectric and electrical spectra of these nanofluid materials are carried out in the harmonic field of 20 Hz to 1 MHz range, at 25 °C. A small change in the static dielectric permittivity of these GLY/ZnO nanofluids with the increase of ZnO concentration reveals some modifications in the parallel arranged dipolar ordering of the glycerol molecules. The conductivity relaxation process ruled the electrical conductivity of the GLY/ZnO nanofluids, but the low conductivity of these materials confirmed them as potential candidates for electric insulating nanodielectrics. The decreased viscosity and the increased thermal conductivity with some constructive changes in the acoustic parameters of these nanofluids were noted with the increase of ZnO concentration. The experimental results on the structural, optical, dielectric, electrical, and thermophysical properties of the GLY/ZnO nanofluids are technologically appealing and recognize these as innovative multifunctional soft materials.

Cybernetic governance of the Peruvian State: a proposal.

This paper aims to make a proposal to govern the Peruvian State under the umbrella of management cybernetics, following the paths of the viable system model (VSM), proposed by Prof. Stafford Beer, enriched with other soft and hard systemic methodologies and technologies, to cover the soft and hard issues that are part of the complex Peruvian reality at different levels of recursion. For doing this, four defined perspectives were adopted to understand the complexity of Peru: the sectoral view, the regions view, the river basins view and the macroregions view. Peru is seen as a system in focus, defining, for each of these four perspectives, the five systems that VSM has. The application of the VSM in each perspective serves to apply it in two modes: diagnosis and design, according to the respective perspective. Then an integrative analysis and reflection is done considering the four perspectives, to analyze the viability of the VSM approach in the governance of the Peruvian State to establish some conclusions and recommendations in relation to the proposal, appearing at the end of the paper.

Self-healing ionic gelatin/glycerol hydrogels for strain sensing applications

Soft sensing technologies have the potential to revolutionize wearable devices, haptic interfaces and robotic systems. However, there are numerous challenges in the deployment of these devices due to their poor resilience, high energy consumption, and omnidirectional strain responsivity. This work reports the development of a versatile ionic gelatin-glycerol hydrogel for soft sensing applications. The resulting sensing device is inexpensive and easy to manufacture, is self-healable at room temperature, can undergo strains of up to 454%, presents stability over long periods of time, and is biocompatible and biodegradable. This material is ideal for strain sensing applications, with a linear correlation coefficient R2 = 0.9971 and a pressure-insensitive conduction mechanism. The experimental results show the applicability of ionic hydrogels for wearable devices and soft robotic technologies for strain, humidity, and temperature sensing while being able to partially self-heal at room temperature.

Bioinspired bilayer hydrogel-based actuator with rapidly bidirectional actuation, programmable deformation and devisable functionality

Smart hydrogel actuators which respond to external stimuli have attracted great attention and shown good application prospects in many fields as their simplicity and reliability, while the challenges remain in terms of the relatively low driving force, responsive velocity and deformation amplitude considering the structure-dependent actuation behavior. Here, we propose a thermosensitive hydrogel-based actuator with bioinspired bilayer structure by applying a textured airlaid paper to induce the formation of heterogeneous construction. This nature-inspired design benefits the hydrogel-based actuator rapidly bidirectional actuation, realizing excellent bending velocity (140.6° s−1 within first 5 s) and bending amplitude (850.0° within 30 s) in hot water, powerful recovery in cool water and remarkable reproducibility upon external environmental stimulus by optimizing the texture orientation and mechanical property of airlaid paper. The excellent bonding between airlaid paper and hydrogel also endows the actuator satisfactory stability for circularly operation under water environment for weeks. The programmable deformation and devisable functionality are further realized by propagable and elaborate design for architecture and component of responsive hydrogel, favoring the hydrogel-based actuator alterable ethanol-sensitive ability, photothermal drivability and regenerability. This bilayer hydrogel-based actuator provides promising potentials for the applications in soft robots, smart actuators, artificial muscles, and intelligent human-machine technologies.

Soft, Wearable Robotics and Haptics: Technologies, Trends, and Emerging Applications

Recent advances in the rapidly growing field of soft robotics highlight the potential for innovations in wearable soft robotics to meet challenges and opportunities affecting individuals, society, and the economy. Some of the most promising application areas include wearable haptic interfaces, assistive robotics, and biomedical devices. Several attributes of soft robotic systems make them well-suited for use in human-wearable applications. Such systems can be designed to accommodate the complex morphology and movements of the human body, can afford sufficient compliance to ensure safe operation in intimate proximity with humans, and can provide context-appropriate haptic feedback or assistance to their wearers. Many soft robotic systems have been designed to resemble garments or wearables that are already widely used today. Such systems could one day become seamlessly integrated into a myriad of human activities and environments. Here, we review emerging advances in wearable soft robotic technologies and systems, including numerous examples from prior research. We discuss important considerations for the design of such systems based on functional concerns, wearability, and ergonomics. We describe an array of design strategies that have been adopted in prior research. We review wearable soft robotics applications in diverse domains, survey sensing and actuation technologies, materials, and fabrication methods. We conclude by discussing frontiers, challenges, and future prospects for soft, wearable robotics.

Soft Robotic Deployable Origami Actuators for Neurosurgical Brain Retraction.

Metallic tools such as graspers, forceps, spatulas, and clamps have been used in proximity to delicate neurological tissue and the risk of damage to this tissue is a primary concern for neurosurgeons. Novel soft robotic technologies have the opportunity to shift the design paradigm for these tools towards safer and more compliant, minimally invasive methods. Here, we present a pneumatically actuated, origami-inspired deployable brain retractor aimed at atraumatic surgical workspace generation inside the cranial cavity. We discuss clinical requirements, design, fabrication, analytical modeling, experimental characterization, and in-vitro validation of the proposed device on a brain model.

Modeling and analysis of effective factors in the outsourcing of R&amp;D projects by SEM and ISM approaches: A case study of "Iranian aviation industries organization"

Given that CoPSdevelopment projects are costly, failing to conduct them will ruin the organization. Therefore, the decision to out/insource them, is important. In this paper, the factors influencing this decision are discussed. Employingthe Fuzzy Delphi method, the indices are utilized to develop the SEM model. The results show three dimensions of the “projects characteristics”, “requirements” and “competency”. Hypothesesurge that projects characteristics have a significant effect on the requirements, which in turn have a similar effect on the competency. To compare, the ISM method was used. The results are quite similar to those of the SEM model. No sooner could organizations outsource such projects than they gain the technological, contractual, project control, integration, soft technologies, financial and communications strategies capability. The managers of organizations and companies developing CoPS such as airplanes power plants, express trains and ships can use the results and implications of this model.

Adaptable Poly-Articulated Bionic Hands EnhanceBoth Performance and User's Perception in Bilateral Amputation: A Case Study.

This article evaluates and compares the performance and perception of prosthetic devices based on different design principles, a traditional rigid gripper and an adaptable poly-articulated hand, in a pre- and post-training protocol with an individual with bilateral amputation. As a representative of the first class, we use commercial hands (Ottobock's MyoHand VariPlus Speed), which is a widely adopted model by prosthesis users worldwide. We compare these with two SoftHand Pro hands, which are experimental prototypes exhibiting 19 articulations actuated by one single motor, and are inspired by human hand motor control models. Results show that the individual with bilateral amputation, who was a non-expert myoelectric user, achieved better performance with adaptive poly-articulated hands. Furthermore, the acceptation, satisfaction and perceived functionality of the user were considerably higher for the SoftHand Pro. An observational analysis of the patient's behaviour by experienced therapists suggests that adaptable poly-articulated hands reduced compensatory movements and cognitive load. Using soft technologies may be especially advantageous for individuals with bilateral amputation, who present a very limited residual mobility and can largely benefit from the active use of their artificial arms in everyday life.

Fault Diagnosis of Power Transformer Based on SSA—MDS Pretreatment

Aiming at the problems of coupling between transformer input characteristics and low accuracy of transformer fault diagnosis, SSA-MDS and other soft technologies are used to analyze the key characteristics of transformer faults, so as to improve the accuracy of transformer fault diagnosis. The SSA algorithm cascade MDS algorithm to process the DGA data is proposed. Subsequently, the TSSA-RF model is introduced to classify the DGA data. The DGA data is first mapped to a high-dimensional space. Next, the optimal feature subset is encoded using the SSA algorithm to reduce irrelevant and redundant features. In this study, the correlation between the optimal feature dimension and the transformer fault diagnosis accuracy is investigated. the expression of the optimal feature subset is obtained by decompiling the SSA operator. The pre-processed data are classified using the RF model, and the TSSA -RF model for classifying the DGA data is found with the highest accuracy through the comparison of different optimization algorithms. After the RF model is optimized using the TSSA algorithm, its accuracy increases by 7.89%, and the accuracy of the TSSA -RF model is obtained as 92.11%. The example results show that compared with the original data, the proposed data processing algorithm improves the diagnostic accuracy of transformer by 11.97 % in the RF model. Compared with multiple preprocessing methods, SSA-MDS has the highest accuracy. Compared with the original data, the accuracy of TSSA-RF model increases by 11.64 %.

Analysis of Soft Soil Subgrade Treatment Technology in Road Construction

Soft soil subgrade is a special form in highway construction. The stability and operability of soft soil subgrade are poor, which is easy to affect the road construction quality and the whole road structure. In order to effectively improve the comprehensive performance of soft soil subgrade, effective treatment methods must be adopted. At present, highway construction technology is becoming more and more mature in the process of soft soil treatment, in which there are different treatment processes, each with its advantages and disadvantages. Based on this, this paper makes an extensive analysis on some soft foundation treatment technologies in highway construction, which has certain guiding significance for the construction of similar projects. Starting from the main influence of soft soil foundation, this paper focuses on the treatment technology of soft soil foundation, and puts forward the key points of construction engineering, in order to provide reference for similar road construction projects.

Health education: a booklet for colostomized people in use of the plug

To develop and validate a booklet on the use of the colostomy plug as a technological support for educational intervention. Methodological study focusing on the production of soft and hard technologies for colostomized people using a plug, developed in three stages: literature review; validation with 13 experts; and with seven colostomized persons. The content for the booklet was selected based on the analysis of the articles identified in Step 1. In Step 2, regarding the content, the number of pages and appearance obtained a Content Validity Index of 0.85 and 1.00 respectively. In Step 3, the minimum Content Validity Index was 0.71 in two items related to organization and 0.86 for the writing style. The other items obtained a Content Validity Index of 1.0. The booklet was validated among experts and colostomized persons, and the final version, containing 50 pages, was offered to health professionals and colostomized people in use of a plug.