Accepted Manuscripts
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Recent advances in the design, fabrication, actuation mechanisms and applications of liquid crystal elastomers
Review Article |Published on: 29 Mar 2023 -
Recent progress in thermal management for flexible/wearable devices
Research Article |Published on: 22 Mar 2023
Articles
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Portable green energy out of the blue: hydrogel-based energy conversion devices
Soft Sci 2023;3:10. DOI: 10.20517/ss.2022.32AbstractTo alleviate the escalating global demands for electricity with a low carbon footprint, we can ... MORETo alleviate the escalating global demands for electricity with a low carbon footprint, we can resort to a green energy source that is conveyed by tiny temperature or moisture gradients. A tremendous source of low-grade energy scatters around us and remains unutilized, which is why thermoelectric and hydrovoltaic devices were invented. Our review focuses on a growing trend of implementing hydrogel-based ionic thermoelectric systems and hydrovoltaic devices as they hold the promise of electric outputs that are several times higher than conventional solid-state inorganic counterparts. This is due to the molecular-level tailorable features of hydrogel polymers and their interactions with water and other functional additives, which provide an ideal platform for low-grade heat and water energy harvesting from fundamental and practical perspectives. This review is divided into three sections. We present working principles, engineering concepts, state-of-art designs, and urgent challenges for hydrogel-based (i) ionic thermoelectric systems; (ii) hydrovoltaic devices; and (iii) their hybrids. LESS Full articleReview Article|Published on: 23 Mar 2023 -
A comprehensive survey of ionic polymer metal composite transducers: preparation, performance optimization and applications
Soft Sci 2023;3:9. DOI: 10.20517/ss.2023.01AbstractIonic polymer metal composite (IPMC) transducers, as one of the typical electroactive polymers with excellent ... MOREIonic polymer metal composite (IPMC) transducers, as one of the typical electroactive polymers with excellent electromechanical coupling properties, have tremendous potential to achieve high-performance actuators and sensors for flexible electronic and soft robotics. In this survey, after briefly describing the energy conversion mechanism of IPMC, we divided the history of IPMC into three stages based on the published papers, and then introduced the preparation technologies of IPMC in detail, which mainly include the selection of ionomer membrane and formation of electrodes. From the point of view of optimization, we summarized and analyzed the performance improvement methods of IPMC and the problems when it is used as actuators and sensors, respectively. The latest and typical applications of IPMC are widely presented as actuators and sensors, such as actuation in robots, grippers, medical and wearable devices, underwater perception and energy harvesting. Moreover, the challenges and opportunities of IPMC were envisioned for future prosperity. This survey will provide an overall general outline for the categorization, mechanism, precursors, and preparation methods of IPMC, which is helpful in facilitating the rapid development and application of IPMC. LESS Full articleReview Article|Published on: 20 Mar 2023 -
Progress on flexible tactile sensors in robotic applications on objects properties recognition, manipulation and human-machine interactions
Soft Sci 2023;3:8. DOI: 10.20517/ss.2022.34AbstractThe robotic with integrated tactile sensors can accurately perceive contact force, pressure, vibration, temperature and ... MOREThe robotic with integrated tactile sensors can accurately perceive contact force, pressure, vibration, temperature and other tactile stimuli. Flexible tactile sensing technologies have been widely utilized in intelligent robotics for stable grasping, dexterous manipulation, object recognition and human-machine interaction. This review presents promising flexible tactile sensing technologies and their potential applications in robotics. The significance of robotic sensing and tactile sensing performance requirements are first described. The commonly used six types of sensing mechanisms of tactile sensors are briefly illustrated, followed by the progress of novel structural design and performance characteristics of several promising tactile sensors, such as highly sensitive pressure and tri-axis force sensor, flexible distributed sensor array, and multi-modal tactile sensor. Then, the applications of using tactile sensors in robotics such as object properties recognition, grasping and manipulation, and human-machine interactions are thoroughly discussed. Finally, the challenges and future prospects of robotic tactile sensing technologies are discussed. In summary, this review will be conducive to the novel design of flexible tactile sensors and is a heuristic for developing the next generation of intelligent robotics with advanced tactile sensing functions in the future. LESS Full articleReview Article|Published on: 14 Mar 2023 -
Organic biodegradable piezoelectric materials and their potential applications as bioelectronics
Soft Sci 2023;3:7. DOI: 10.20517/ss.2022.30AbstractBiodegradable piezoelectrics represent an intriguing category of electroactive materials combining the mechanical-electrical coupling characteristics with ... MOREBiodegradable piezoelectrics represent an intriguing category of electroactive materials combining the mechanical-electrical coupling characteristics with a unique biodegradable feature that eliminates unnecessary materials retention and minimize associated infection risks. Here, we review the piezoelectric properties of representative organic biodegradable piezoelectric materials including amino acids, peptides, proteins, synthetic polymers and polysaccharides. Strategies to promote the piezoelectric activity are summarized, and recent progress in the utilization of biodegradable piezoelectric materials for bioelectronics is discussed, with perspectives and challenges provided at the end to enlighten possible future directions. LESS Full articleReview Article|Published on: 24 Feb 2023 -
Wearable plasmonic biofluid sensors as your photonic skin
Soft Sci 2023;3:6. DOI: 10.20517/ss.2022.31AbstractNoninvasive monitoring of markers in biofluids is of paramount significance for health and welfare, which ... MORENoninvasive monitoring of markers in biofluids is of paramount significance for health and welfare, which is being integrated into the next-generation consumable wearables. Movement-free sweat extraction and continuous monitoring of fresh sweat are two major challenges for wearable plasmonic sweat sensors. In this perspective, we highlight recent approaches that integrated an electronic sweat extraction system and a microfluidic system with plasmonic sensors to address the challenge. The future directions of systematic integration and miniaturization are discussed. LESS Full articlePerspective|Published on: 10 Feb 2023 -
Shape memory behaviors of 3D printed liquid crystal elastomers
Soft Sci 2023;3:5. DOI: 10.20517/ss.2022.28AbstractAs soft active materials, shape-memory polymers (SMPs) and liquid crystal elastomers (LCEs) have attracted considerable ... MOREAs soft active materials, shape-memory polymers (SMPs) and liquid crystal elastomers (LCEs) have attracted considerable research interest due to their potential applications in various areas. SMPs refer to polymeric materials that can return to their permanent shape in response to external stimuli, such as heat, light, and solvent. In this sense, LCEs can exhibit intrinsic shape-memory behaviors since LCEs can switch between two shapes with temperature change due to the order-disorder transition of liquid crystals. In this work, we fabricate both the polydomain and monodomain nematic LCEs through direct ink writing 3D printing. With increasing the temperature of the substrates, the printed LCEs change from the monodomain state to the polydomain state. For polydomain LCEs, a reversible shape change can occur upon constant loading, while the monodomain can switch the shape with temperature in the stress-free state. This two-way shape-memory behavior is caused by the nematic-isotropic phase transition. We further show that the printed LCEs exhibit a good one-way shape-memory effect due to glass transition. The shape recovery region increases with the programming temperature, which is a typical temperature memory effect. Finally, it is demonstrated that complex shape-memory performance can be designed by combining one-way and two-way shape-memory effects. Specifically, for the monodomain LCEs, with increasing temperature, the programmed shape first recovers, and a second shape change can further occur due to the nematic-isotropic transition. LESS Full articleResearch Article|Published on: 2 Feb 2023
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Recent progress in flexible tactile sensor systems: from design to application
Soft Sci 2021;1:3. DOI: 10.20517/ss.2021.02AbstractWith the rapid development of artificial intelligence, human-machine interaction, and healthcare systems, flexible tactile sensors ... MOREWith the rapid development of artificial intelligence, human-machine interaction, and healthcare systems, flexible tactile sensors have huge market potentials and research needs, so that both fundamental research and application demonstrations are evolving rapidly to push the potential to reality. In this review, we briefly summarize the recent progress of the flexible tactile sensor system, including the common sensing mechanisms, the important performance evaluation parameters, the device design trend, and the main applications. Moreover, the current device design trend towards flexible tactile sensor systems is discussed, including novel structures for outstanding performance, sensor arrays for large-area information acquisition, multi-mode information acquisition, and integration of tactile sensors with transistors. Various emerging applications enabled with these sensors are also exemplified in this review to show the potentials of the tactile sensors. Finally, we also discuss the technical demands and the future perspectives of flexible tactile sensor systems. LESS Full articleReview Article|Published on: 9 Jul 2021 -
Sodium nanofluid for efficient oil recovery in heavy oil and oil sand reservoirs
Soft Sci 2021;1:8. DOI: 10.20517/ss.2021.08AbstractNanomaterials exhibit unique chemical and physical properties in comparison with their bulk-phase counterparts, attracting significant ... MORENanomaterials exhibit unique chemical and physical properties in comparison with their bulk-phase counterparts, attracting significant attention from the oil and gas industry in the hope of solving challenging issues. Current heavy oil extraction methods are costly and have unsatisfactory efficiency, and facing environmental restrictions increasingly. Our recent introduction of sodium (Na) nanofluid provides a promising method for heavy oil extraction since it shows improved oil recovery without burning carbon-containing fuels. Here, we conducted core-flooding tests to further evaluate the effect of this Na nanofluid on recovering oil from different formations, which had not been previously demonstrated, as well as to deepen our understanding of the underlying mechanisms. The Na nanofluid exhibited excellent oil-extraction efficiency for both types of heavy oil tested. The recovery mechanisms were found to be complicated. We also found that post-injection soaking and using the proper solvent to disperse the sodium nanoparticles are important for further boosting oil recovery. LESS Full articleResearch Article|Published on: 8 Sep 2021 -
Uncovering isolated resonant responses in antagonistic pure-shear dielectric elastomer actuators
Soft Sci 2021;1:1. DOI: 10.20517/ss.2021.01AbstractThe dielectric elastomer actuator (DEA) is one type of emerging soft actuator that has the ... MOREThe dielectric elastomer actuator (DEA) is one type of emerging soft actuator that has the attractive features of large actuation strains, high energy density, and inherent compliance, which is desirable for novel bio-inspired and soft robotic applications. Due to their inherent elasticity, when stimulated by an alternating current voltage with a frequency matching the natural frequency of the DEA system, the DEAs can exhibit resonant responses which maximize the oscillation amplitude. Silicone elastomers are widely utilized for resonant actuation applications for their reduced viscous damping hence better dynamic performance compared to VHB elastomers. However, the low pre-stretch ratios adopted by silicone elastomers could induce loss-of-tension of the mem-branes in high amplitude oscillations, yet its effects on the dynamic responses of a DEA are not fully understood. By using a numerical dynamic model, this work studies the effects of the loss-of-tension on the frequency response of the antagonistic pure-shear DEAs. A subharmonic frequency response curve isolated from the main response branch is uncovered for the first time in a parametrically forced DEA system, which causes a sudden jump in the oscillation amplitude and serves as a severe threat to the dynamic stability and controllability of the DEA system. By using a global analysis method, the evolution of the isolated response curve against the excitation components and system physical parameters is also investigated numerically. LESS Full articleResearch Article|Published on: 21 May 2021 -
Tattoo-like epidermal electronics as skin sensors for human-machine interfaces
Soft Sci 2021;1:10. DOI: 10.20517/ss.2021.09AbstractFlexible electronic skin (e-skin) has been successfully utilized in diverse applications, including prosthesis sensing, body-motion ... MOREFlexible electronic skin (e-skin) has been successfully utilized in diverse applications, including prosthesis sensing, body-motion monitoring and human-machine interfaces, due to its excellent mechanical properties and electrical characteristics. However, current e-skins are still relatively thick (> 10 µm) and uncomfortable for long-term usage on the human body. Herein, an ultrathin skin-integrated strain sensor with miniaturized dimensions, based on the piezoresistive effect, with excellent stability and robustness, is introduced. The fractal curve-shaped Au electrode in a serpentine format, which is the dominant component of the strain sensor, is sensitive to ambient strain variations and can turn the mechanical motion into a stable electrical signal output. With the advanced design of metallic electrodes, the device presents good operational stability and excellent mechanical tolerance towards bending, stretching and twisting. The stain sensor allows intimate mounting onto the human epidermal surface for the detection of body motion. By adopting a liquid bandage as an encapsulation layer, the device exhibits an ultrathin thickness (6.2 µm), high sensitivity towards mechanical deformations and capability for the clear detection of motion, such as walking, finger bending and the human pulse rate with identifiable electrical signals. Furthermore, the tattoo-like strain sensor is applied in robotic control by tracing finger bending motion and results in the smooth control of a robotic hand nearly without any detention. This e-skin design exhibits excellent potential for wearable electronics and human-machine interfaces. LESS Full articleResearch Article|Published on: 13 Oct 2021 -
Insights into fluidic endogenous magnetism and magnetic monopoles from a liquid metal droplet machine
Soft Sci 2021;1:15. DOI: 10.20517/ss.2021.16AbstractMagnetism and magnetic monopoles are among the most classical issues in physics. Conventional magnets are ... MOREMagnetism and magnetic monopoles are among the most classical issues in physics. Conventional magnets are generally composed of rigid materials and may face challenges in extreme situations. Here, as an alternative to rigid magnets, we propose, for the first time, the generation of fluidic endogenous magnetism and construct a magnetic monopole through tuning with a liquid metal machine. Based on theoretical interpretation and conceptual experimental observations, we illustrate that when liquid metals, such as gallium alloy, in a solution rotate under electrical actuation, they form an endogenous magnetic field inside. This explains the phenomenon where two such discrete metal droplets can easily fuse together, indicating their reciprocal attraction via the N and S poles. Furthermore, we reveal that a self-fueled liquid metal motor also runs as an endogenous fluidic magnet owing to the electromagnetic homology. When aluminum is added to liquid gallium in solution, it forms a spin motor and dynamically variable charge distribution that produces endogenous magnetism inside. This explains the common phenomena where reflective collision and attractive fusion between running liquid metal motors occur, which are partially caused by the dynamic adjustment of their N and S polarities, respectively. On this basis, more experimental approaches capable of generating dynamic electrical fields also work for the same target. Finally, we propose that such a fluidic endogenous magnet could lead to a magnetic monopole and four technical routes to realize this are suggested. The first involves matching the interior flow of liquid metal machines. The second is the superposition between an external electric effect and the magnetic field. The third route involves composite construction between magnetic particles and a liquid metal spin motor. Finally, chemical methods, such as via galvanic cell reactions, are proposed. Overall, the present theory and identified experimental evidence illustrate the role of a liquid metal machine as a fluidic endogenous magnet and highlight promising methods for the realization of magnetic monopoles. A group of unconventional magnetoelectric devices and applications could therefore be possible in the near future. LESS Full articleResearch Article|Published on: 16 Dec 2021
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Wearable electronics for skin wound monitoring and healing
Review Article|Published on: 30 Jun 2022 -
PEDOT:PSS-based intrinsically soft and stretchable bioelectronics
Perspective|Published on: 14 Jun 2022 -
Biocompatible composite thin-film wearable piezoelectric pressure sensor for monitoring of physiological and muscle motions
Research Article|Published on: 26 Jun 2022 -
A brief review of mechanical designs for additive manufactured soft materials
Review Article|Published on: 14 Feb 2022 -
Biomedical DNA hydrogels
Perspective|Published on: 25 Feb 2022
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Progress on flexible tactile sensors in robotic applications on objects properties recognition, manipulation and human-machine interactions
Review Article|Published on: 14 Mar 2023 -
Wearable plasmonic biofluid sensors as your photonic skin
Perspective|Published on: 10 Feb 2023 -
Applications of flexible polyimide: barrier material, sensor material, and functional material
Review Article|Published on: 11 Jan 2023 -
Shape memory behaviors of 3D printed liquid crystal elastomers
Research Article|Published on: 2 Feb 2023 -
Electro-assisted assembly of conductive polymer and soft hydrogel into core-shell hybrids
Research Article|Published on: 17 Jan 2023
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About The Journal
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ISSN
2769-5441 (Online)
Publisher
OAE Publishing Inc.
Article Processing Charges
$1200
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Editor-in-Chief
Zhifeng Ren
Publishing Model
Gold Open Access
Copyright
Copyright is retained by author(s)
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Publication Frequency
Quarterly
Indexing
Open Archives
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Portico
All published articles will be preserved here permanently:
https://www.portico.org/