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International Journal of Molecular... Jan 2022Self-healing materials have been attracting the attention of the scientists over the past few decades because of their effectiveness in detecting damage and their... (Review)
Review
Self-healing materials have been attracting the attention of the scientists over the past few decades because of their effectiveness in detecting damage and their autonomic healing response. Self-healing materials are an evolving and intriguing field of study that could lead to a substantial increase in the lifespan of materials, improve the reliability of materials, increase product safety, and lower product replacement costs. Within the past few years, various autonomic and non-autonomic self-healing systems have been developed using various approaches for a variety of applications. The inclusion of appropriate functionalities into these materials by various chemistries has enhanced their repair mechanisms activated by crack formation. This review article summarizes various self-healing techniques that are currently being explored and the associated chemistries that are involved in the preparation of self-healing composite materials. This paper further surveys the electronic applications of self-healing materials in the fields of energy harvesting devices, energy storage devices, and sensors. We expect this article to provide the reader with a far deeper understanding of self-healing materials and their healing mechanisms in various electronics applications.
Topics: Cycloaddition Reaction; Elastomers; Electronics; Hydrogen Bonding; Polymers
PubMed: 35054803
DOI: 10.3390/ijms23020622 -
Advanced Science (Weinheim,... May 2022Biodegradable electronics are considered as an important bio-friendly solution for electronic waste (e-waste) management, sustainable development, and emerging... (Review)
Review
Biodegradable electronics are considered as an important bio-friendly solution for electronic waste (e-waste) management, sustainable development, and emerging implantable devices. Elastic electronics with higher imitative mechanical characteristics of human tissues, have become crucial for human-related applications. The convergence of biodegradability and elasticity has emerged a new paradigm of next-generation electronics especially for wearable and implantable electronics. The corresponding biodegradable elastic materials are recognized as a key to drive this field toward the practical applications. The review first clarifies the relevant concepts including biodegradable and elastic electronics along with their general design principles. Subsequently, the crucial mechanisms of the degradation in polymeric materials are discussed in depth. The diverse types of biodegradable elastomers and gels for electronics are then summarized. Their molecular design, modification, processing, and device fabrication especially the structure-properties relationship as well as recent advanced are reviewed in detail. Finally, the current challenges and the future directions are proposed. The critical insights of biodegradability and elastic characteristics in the elastomers and gel allows them to be tailored and designed more effectively for electronic applications.
Topics: Elastomers; Electronics; Gels; Humans; Polymers; Wearable Electronic Devices
PubMed: 35212474
DOI: 10.1002/advs.202105146 -
Nature Communications Jan 2022Concepts that draw inspiration from soft biological tissues have enabled significant advances in creating artificial materials for a range of applications, such as dry...
Concepts that draw inspiration from soft biological tissues have enabled significant advances in creating artificial materials for a range of applications, such as dry adhesives, tissue engineering, biointegrated electronics, artificial muscles, and soft robots. Many biological tissues, represented by muscles, exhibit directionally dependent mechanical and electrical properties. However, equipping synthetic materials with tissue-like mechanical and electrical anisotropies remains challenging. Here, we present the bioinspired concepts, design principles, numerical modeling, and experimental demonstrations of soft elastomer composites with programmed mechanical and electrical anisotropies, as well as their integrations with active functionalities. Mechanically assembled, 3D structures of polyimide serve as skeletons to offer anisotropic, nonlinear mechanical properties, and crumpled conductive surfaces provide anisotropic electrical properties, which can be used to construct bioelectronic devices. Finite element analyses quantitatively capture the key aspects that govern mechanical anisotropies of elastomer composites, providing a powerful design tool. Incorporation of 3D skeletons of thermally responsive polycaprolactone into elastomer composites allows development of an active artificial material that can mimic adaptive mechanical behaviors of skeleton muscles at relaxation and contraction states. Furthermore, the fabrication process of anisotropic elastomer composites is compatible with dielectric elastomer actuators, indicating potential applications in humanoid artificial muscles and soft robots.
Topics: Anisotropy; Biomimetic Materials; Elastomers; Electric Conductivity; Electricity; Finite Element Analysis; Muscle, Skeletal; Robotics
PubMed: 35082331
DOI: 10.1038/s41467-022-28185-z -
Molecules (Basel, Switzerland) Jul 2022Liquid crystal elastomers (LCEs) are programmable deformable materials that can respond to physical fields such as light, heat, and electricity. Photothermal-driven LCE... (Review)
Review
Liquid crystal elastomers (LCEs) are programmable deformable materials that can respond to physical fields such as light, heat, and electricity. Photothermal-driven LCE has the advantages of accuracy and remote control and avoids the requirement of high photon energy for photochemistry. In this review, we discuss recent advances in photothermal LCE materials and investigate methods for mechanical alignment, external field alignment, and surface-induced alignment. Advances in the synthesis and orientation of LCEs have enabled liquid crystal elastomers to meet applications in optics, robotics, and more. The review concludes with a discussion of current challenges and research opportunities.
Topics: Elastomers; Electricity; Liquid Crystals; Optics and Photonics
PubMed: 35889204
DOI: 10.3390/molecules27144330 -
Nature Communications Apr 2022Ligaments are flexible and stiff tissues around joints to support body movements, showing superior toughness and fatigue-resistance. Such a combination of mechanical...
Ligaments are flexible and stiff tissues around joints to support body movements, showing superior toughness and fatigue-resistance. Such a combination of mechanical properties is rarely seen in synthetic elastomers because stretchability, stiffness, toughness, and fatigue resistance are seemingly incompatible in materials design. Here we resolve this long-standing mismatch through a hierarchical crosslinking design. The obtained elastomer can endure 30,000% stretch and exhibit a Young's modulus of 18 MPa and toughness of 228 MJ m, outperforming all the reported synthetic elastomers. Furthermore, the fatigue threshold is as high as 2,682 J m, the same order of magnitude as the ligaments (~1,000 J m). We reveal that the dynamic double-crosslinking network composed of Li-O interactions and PMMA nanoaggregates allows for a hierarchical energy dissipation, enabling the elastomers as artificial ligaments in soft robotics.
Topics: Chemical Phenomena; Elastic Modulus; Elastomers; Ligaments
PubMed: 35477583
DOI: 10.1038/s41467-022-30021-3 -
Chemical Reviews Mar 2022This Review presents and discusses the current state of the art in "exchangeable liquid crystalline elastomers", that is, LCE materials utilizing dynamically... (Review)
Review
This Review presents and discusses the current state of the art in "exchangeable liquid crystalline elastomers", that is, LCE materials utilizing dynamically cross-linked networks capable of reprocessing, reprogramming, and recycling. The focus here is on the chemistry and the specific reaction mechanisms that enable the dynamic bond exchange, of which there is a variety. We compare and contrast these different chemical mechanisms and the key properties of their resulting elastomers. In the conclusion, we discuss the most promising applications that are enabled by dynamic cross-linking and present a summary table: a library of currently available materials and their main characteristics.
Topics: Elastomers; Liquid Crystals
PubMed: 33596647
DOI: 10.1021/acs.chemrev.0c01057 -
Polimery W Medycynie 2016Heart assisting devices have become a standard element in clinical practice and provide support for the traditional methods of treating heart disease. Regardless of the... (Review)
Review
Heart assisting devices have become a standard element in clinical practice and provide support for the traditional methods of treating heart disease. Regardless of the construction of VAD (ventricular assist devices), there are crucial requirements that have to be met by the construction materials: high purity, desired physical, chemical and mechanical properties, easy fabrication and high stability and susceptibility to sterilization. They must not cause thrombosis, destroy cellular elements, alter plasma protein, destroy enzymes, deplete electrolytes, cause immune response and cancer, and must not produce toxic and allergic reactions, when they are applied in direct contact with biological tissues and fluids. This paper provides an overview of the polymeric materials as construction materials for cardiovascular support systems, focusing on the group of thermoplastic elastomers, mainly polyurethane and polyester based ones. It also highlights the advantages and disadvantages of currently used materials and the progress in the design of new materials with potential application in the biomedical field.
Topics: Biocompatible Materials; Elastomers; Heart-Assist Devices; Humans; Polyesters; Polyurethanes
PubMed: 28397422
DOI: 10.17219/pim/65099 -
Macromolecular Rapid Communications Mar 2016Silicone elastomers are promising materials for dielectric elastomer transducers (DETs) due to their superior properties such as high efficiency, reliability and fast... (Review)
Review
Silicone elastomers are promising materials for dielectric elastomer transducers (DETs) due to their superior properties such as high efficiency, reliability and fast response times. DETs consist of thin elastomer films sandwiched between compliant electrodes, and they constitute an interesting class of transducer due to their inherent lightweight and potentially large strains. For the field to progress towards industrial implementation, a leap in material development is required, specifically targeting longer lifetime and higher energy densities to provide more efficient transduction at lower driving voltages. In this review, the current state of silicone elastomers for DETs is summarised and critically discussed, including commercial elastomers, composites, polymer blends, grafted elastomers and complex network structures. For future developments in the field it is essential that all aspects of the elastomer are taken into account, namely dielectric losses, lifetime and the very often ignored polymer network integrity and stability.
Topics: Dimethylpolysiloxanes; Electric Conductivity; Electric Power Supplies; Electrodes; Silicone Elastomers
PubMed: 26773231
DOI: 10.1002/marc.201500576 -
ACS Applied Materials & Interfaces Dec 2020Elastomers and, in particular, polydimethylsiloxane (PDMS) are widely adopted as biocompatible mechanically compliant substrates for soft and flexible micro-nanosystems...
Elastomers and, in particular, polydimethylsiloxane (PDMS) are widely adopted as biocompatible mechanically compliant substrates for soft and flexible micro-nanosystems in medicine, biology, and engineering. However, several applications require such low thicknesses (., <100 μm) that make peeling-off critical because very thin elastomers become delicate and tend to exhibit strong adhesion with carriers. Moreover, microfabrication techniques such as photolithography use solvents which swell PDMS, introducing complexity and possible contamination, thus limiting industrial scalability and preventing many biomedical applications. Here, we combine low-adhesion and rectangular carrier substrates, adhesive Kapton frames, micromilling-defined shadow masks, and adhesive-neutralizing paper frames for enabling fast, easy, green, contaminant-free, and scalable manufacturing of thin elastomer devices, with both simplified peeling and handling. The accurate alignment between the frame and shadow masks can be further facilitated by micromilled marking lines on the back side of the low-adhesion carrier. As a proof of concept, we show epidermal sensors on a 50 μm-thick PDMS substrate for measuring strain, the skin bioimpedance and the heart rate. The proposed approach paves the way to a straightforward, green, and scalable fabrication of contaminant-free thin devices on elastomers for a wide variety of applications.
Topics: Biocompatible Materials; Dimethylpolysiloxanes; Elastomers; Electric Impedance; Electrocardiography; Electrodes; Electronics; Epidermis; Humans
PubMed: 33252224
DOI: 10.1021/acsami.0c16312 -
Sensors (Basel, Switzerland) Jan 2022Dielectric elastomer (DE) sensors have been widely used in a wide variety of applications, such as in robotic hands, wearable sensors, rehabilitation devices, etc. A...
Dielectric elastomer (DE) sensors have been widely used in a wide variety of applications, such as in robotic hands, wearable sensors, rehabilitation devices, etc. A unique dielectric elastomer-based multimodal capacitive sensor has been developed to quantify the pressure and the location of any touch simultaneously. This multimodal sensor is a soft, flexible, and stretchable dielectric elastomer (DE) capacitive pressure mat that is composed of a multi-layer soft and stretchy DE sensor. The top layer measures the applied pressure, while the underlying sensor array enables location identification. The sensor is placed on a passive elastomeric substrate in order to increase deformation and optimize the sensor's sensitivity. This DE multimodal capacitive sensor, with pressure and localization capability, paves the way for further development with potential applications in bio-mechatronics technology and other humanoid devices. The sensor design could be useful for robotic and other applications, such as fruit picking or as a bio-instrument for the diabetic insole.
Topics: Elastomers; Hand; Robotics; Touch; Wearable Electronic Devices
PubMed: 35062583
DOI: 10.3390/s22020622