Shape‐programmable soft materials that exhibit integrated multifunctional shape manipulations, including reprogrammable, untethered, fast, and reversible shape transformation and locking, are highly ...desirable for a plethora of applications, including soft robotics, morphing structures, and biomedical devices. Despite recent progress, it remains challenging to achieve multiple shape manipulations in one material system. Here, a novel magnetic shape memory polymer composite is reported to achieve this. The composite consists of two types of magnetic particles in an amorphous shape memory polymer matrix. The matrix softens via magnetic inductive heating of low‐coercivity particles, and high‐remanence particles with reprogrammable magnetization profiles drive the rapid and reversible shape change under actuation magnetic fields. Once cooled, the actuated shape can be locked. Additionally, varying the particle loadings for heating enables sequential actuation. The integrated multifunctional shape manipulations are further exploited for applications including soft magnetic grippers with large grabbing force, reconfigurable antennas, and sequential logic for computing.
A novel magnetic shape‐memory polymer, which is a composite consisting of two types of magnetic particles in an amorphous shape‐memory polymer matrix, integrates multiple shape‐manipulation functions, including untethered rapid reversible shape change, sequential actuation, reprogrammability, and shape locking. Applications including soft magnetic grippers with large grabbing force, sequential logic for computing, and reconfigurable antennas are exploited.
Magnetoactive soft materials (MSMs) are soft polymeric composites filled with magnetic particles that are an emerging class of smart and multifunctional materials with immense potentials to be used ...in various applications including but not limited to artificial muscles, soft robotics, controlled drug delivery, minimally invasive surgery, and metamaterials. Advantages of MSMs include remote contactless actuation with multiple actuation modes, high actuation strain and strain rate, self-sensing, and fast response etc. Having broad functional behaviours offered by the magnetic fillers embedded within non-magnetic matrices, MSMs are undoubtedly one of the most promising materials in applications where shape-morphing, dynamic locomotion, and reconfigurable structures are highly required. This review article provides a comprehensive picture of the MSMs focusing on the materials, manufacturing processes, programming and actuation techniques, behaviours, experimental characterisations, and device-related achievements with the current state-of-the-art and discusses future perspectives. Overall, this article not only provides a comprehensive overview of MSMs’ research and development but also functions as a systematic guideline towards the development of multifunctional, shape-morphing, and sophisticated magnetoactive devices.
Magnetically responsive soft materials are soft composites where magnetic fillers are embedded into soft polymeric matrices. These active materials have attracted extensive research and industrial ...interest due to their ability to realize fast and programmable shape changes through remote and untethered control under the application of magnetic fields. They would have many high-impact potential applications in soft robotics/devices, metamaterials, and biomedical devices. With a broad range of functional magnetic fillers, polymeric matrices, and advanced fabrication techniques, the material properties can be programmed for integrated functions, including programmable shape morphing, dynamic shape deformation-based locomotion, object manipulation and assembly, remote heat generation, as well as reconfigurable electronics. In this review, an overview of state-of-the-art developments and future perspectives in the multifunctional magnetically responsive soft materials is presented.
Metals are excellent choices for electrical- and thermal-current conducting. However, either the stiffness of solid metals or the fluidity of liquid metals could be troublesome when flexibility and ...formability are both desired. To address this problem, a reliable two-stage route to improve the functionalities of gallium-based liquid metals is proposed. A series of stable semiliquid/semisolid gallium-based liquid metal amalgams with well-controlled particle packing ratios, which we call TransM2ixes, are prepared and characterized. Through effectively packing the liquid metal with copper particles (which are found to turn into intermetallic compound, CuGa2, after dispersing), remarkable enhancements in electrical conductivity (6 × 106 S m–1, ∼80% increase) and thermal conductivity (50 W m–1 K–1, ∼100% increase) are obtained, making the TransM2ixes stand out from current conductive soft materials. The TransM2ixes also exhibit appealing semiliquid/semisolid mechanical behaviors such as excellent adhesion, tunable formability, and self-healing ability. As a class of highly conductive yet editable metallic mixtures, the TransM2ixes demonstrate potential applications in fields like printed and/or flexible electronics and thermal interface materials, as well as other circumstances where the flexibility and conductivity of interfaces and connections are crucial.
The development of science and technology of advanced materials using nanoscale units can be conducted by a novel concept involving combination of nanotechnology methodology with various research ...disciplines, especially supramolecular chemistry. The novel concept is called 'nanoarchitectonics' where self-assembly processes are crucial in many cases involving a wide range of component materials. This review of self-assembly processes re-examines recent progress in materials nanoarchitectonics. It is composed of three main sections: (1) the first short section describes typical examples of self-assembly research to outline the matters discussed in this review; (2) the second section summarizes self-assemblies at interfaces from general viewpoints; and (3) the final section is focused on self-assembly processes at interfaces. The examples presented demonstrate the strikingly wide range of possibilities and future potential of self-assembly processes and their important contribution to materials nanoarchitectonics. The research examples described in this review cover variously structured objects including molecular machines, molecular receptors, molecular pliers, molecular rotors, nanoparticles, nanosheets, nanotubes, nanowires, nanoflakes, nanocubes, nanodisks, nanoring, block copolymers, hyperbranched polymers, supramolecular polymers, supramolecular gels, liquid crystals, Langmuir monolayers, Langmuir-Blodgett films, self-assembled monolayers, thin films, layer-by-layer structures, breath figure motif structures, two-dimensional molecular patterns, fullerene crystals, metal-organic frameworks, coordination polymers, coordination capsules, porous carbon spheres, mesoporous materials, polynuclear catalysts, DNA origamis, transmembrane channels, peptide conjugates, and vesicles, as well as functional materials for sensing, surface-enhanced Raman spectroscopy, photovoltaics, charge transport, excitation energy transfer, light-harvesting, photocatalysts, field effect transistors, logic gates, organic semiconductors, thin-film-based devices, drug delivery, cell culture, supramolecular differentiation, molecular recognition, molecular tuning, and hand-operating (hand-operated) nanotechnology.
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•Synthesize of soft acrylate-based stretchable OCAs.•High adhesion strength and close storage and loss moduli to commercial OCAs.•High optical transparency, low Tg, and rapid strain ...reversibility.•Large strain strategy leads to achieve the realistic mechanical results.•Fatigue results (10,000 cycles), shows the great potential use of 70 %EHA (49.7 kPa) in electronic applications.
Touchscreen panels and foldable smartphones rely heavily on optically clear adhesives (OCAs) to function effectively. Therefore, these applications have created a demand for OCAs that are flexible, bendable, or stretchable with high transparency. Developing highly viscoelastic, and optically clear adhesives is crucial for flexible electronics to become commercially viable. This study focuses on synthesizing UV-curable soft acrylate-based OCAs using 2-ethylhexyl acrylate (EHA) and 2-hydroxyethyl acrylate (HEA) as functional monomers without any solvent or crosslinker. To make the OCAs stronger under various mechanical loading types, liquid OCAs with primary and final curing under pressure were used to endure high shear stress and strain. Based on the dynamic mechanical analysis results, the shear stresses of samples at room temperature and 65 °C increased from 9.41 ± 0.6 and 2.91 ± 0.31 (90 wt% EHA, cohesive failure) to 97.5 ± 8.54, and 57.81 ± 1.52 kPa (70 wt% EHA, not failed), respectively. Besides, it should be noted that the OCA hyper-viscoelasticity properties were studied in all of the mechanical experiments, and 500 % large strain was applied to match the actual strain loading in the foldable screens. In this condition, the OCA layer's large deformation behavior and other mechanical properties are more relevant for real-world applications. The fabricated OCAs in this study exhibit competitiveness comparable to commercial OCAs, such as TMS and V0, in terms of performance and quality. Moreover, the potential utilization of 70 wt% EHA (49.7 kPa) in various applications, including stretchable displays, wearable electronic devices, and foldable smartphones, is demonstrated through 3-point tests (100 cycles), wrist bending tests (100–120 cycles), and fatigue tests for up to 10,000 cycles.
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•A versatile sweat-enhanced adhesive hydrogel-based motion sensor (VDBA).•Human sweat pH serves as a trigger for self-adhesive protection-deprotection.•VDBA exhibits integration of ...exceptional mechanical and anti-freezing properties.•Remarkable sensing and counting performances in sports training.
PVA-based wearable hydrogels have emerged as promising candidate for motion sensors due to their skin-like softness and unique biocompatibility. However, an open question is whether and how the strain-sensitive hydrogel designing can prevent adhesive performance loss caused by sweat between devices and human-skin and reduce interfacial failure. Herein, a versatile sweat-enhanced adhesive hydrogel-based motion sensor (VDBA) paradigm is engineered consisting of sweat sensitivity and self-adhesive function components. Taking advantage of catechol chemistry inspired mussel, the VDBA hydrogel enhances substrate adhesion behavior. The borate ions (B(OH)4−) are found to efficient condensation form borate ester groups with phenolic hydroxyl. Interestingly, human sweat pH serves as a trigger for borate ester bonds protection-deprotection, whereby partial catechol primarily functions in non-sweating states and significantly activates during sweating. The VDBA hydrogel achieves a maximum adhesive strength of 13.45 kPa on skin at non-sweat, however, the maximum bonding strength increases to 24.0 kPa when sweating. The resultant VDBA hydrogel exhibits integration of exceptional mechanical properties and anti-freezing properties. Also, desirable conductivity appears in the hydrogel, allowing outputting accurate and repeatable signals for body motion sensing in various scenarios. Furthermore, VDBA hydrogel is demonstrated for use as a sports training times counter, which can achieve sensitive statistics for stretching and bending movements. This work provides a great hydrogel candidate for various motion sensor applications, particularly beneficial for people with sweaty skin and athletes.
In article number 1906657, H. Jerry Qi, Ruike Zhao, and co‐workers present a novel magnetic shape memory polymer that uses the embedded magnetic particles to regulate the material stiffness and ...induce actuation. This enables integrated shape‐manipulation functions, including untethered rapid reversible shape change, sequential actuation, shape locking, and reprogrammability. The integrated functions permit applications such as soft grippers with large grabbing force, morphing electronics, and minimally invasive biomedical devices.
Humans rely increasingly on sensors to address grand challenges and to improve quality of life in the era of digitalization and big data. For ubiquitous sensing, flexible sensors are developed to ...overcome the limitations of conventional rigid counterparts. Despite rapid advancement in bench-side research over the last decade, the market adoption of flexible sensors remains limited. To ease and to expedite their deployment, here, we identify bottlenecks hindering the maturation of flexible sensors and propose promising solutions. We first analyze challenges in achieving satisfactory sensing performance for real-world applications and then summarize issues in compatible sensor-biology interfaces, followed by brief discussions on powering and connecting sensor networks. Issues en route to commercialization and for sustainable growth of the sector are also analyzed, highlighting environmental concerns and emphasizing nontechnical issues such as business, regulatory, and ethical considerations. Additionally, we look at future intelligent flexible sensors. In proposing a comprehensive roadmap, we hope to steer research efforts towards common goals and to guide coordinated development strategies from disparate communities. Through such collaborative efforts, scientific breakthroughs can be made sooner and capitalized for the betterment of humanity.
Soft dielectric materials typically exhibit poor heat transfer properties due to the dynamics of phonon transport, which constrain thermal conductivity (k) to decrease monotonically with decreasing ...elastic modulus (E). This thermal–mechanical trade-off is limiting for wearable computing, soft robotics, and other emerging applications that require materials with both high thermal conductivity and low mechanical stiffness. Here, we overcome this constraint with an electrically insulating composite that exhibits an unprecedented combination of metal-like thermal conductivity, an elastic compliance similar to soft biological tissue (Young’s modulus < 100 kPa), and the capability to undergo extreme deformations (>600% strain). By incorporating liquid metal (LM) microdroplets into a soft elastomer, we achieve a ∼25× increase in thermal conductivity (4.7 ± 0.2 W·m−1·K−1) over the base polymer (0.20 ± 0.01 W·m−1·K−1) under stress-free conditions and a ∼50× increase (9.8 ± 0.8 W·m−1·K−1) when strained. This exceptional combination of thermal and mechanical properties is enabled by a unique thermal–mechanical coupling that exploits the deformability of the LM inclusions to create thermally conductive pathways in situ. Moreover, these materials offer possibilities for passive heat exchange in stretchable electronics and bioinspired robotics, which we demonstrate through the rapid heat dissipation of an elastomer-mounted extreme high-power LED lamp and a swimming soft robot.
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