Application Of Smart Materials Research Articles

Energy Harvesting Materials and Structures for Smart Textile Applications: Recent Progress and Path Forward.

A major challenge with current wearable electronics and e-textiles, including sensors, is power supply. As an alternative to batteries, energy can be harvested from various sources using garments or other textile products as a substrate. Four different energy-harvesting mechanisms relevant to smart textiles are described in this review. Photovoltaic energy harvesting technologies relevant to textile applications include the use of high efficiency flexible inorganic films, printable organic films, dye-sensitized solar cells, and photovoltaic fibers and filaments. In terms of piezoelectric systems, this article covers polymers, composites/nanocomposites, and piezoelectric nanogenerators. The latest developments for textile triboelectric energy harvesting comprise films/coatings, fibers/textiles, and triboelectric nanogenerators. Finally, thermoelectric energy harvesting applied to textiles can rely on inorganic and organic thermoelectric modules. The article ends with perspectives on the current challenges and possible strategies for further progress.

Laser printing-based high-resolution metal patterns with customizable design and scalable fabrication of high-performance flexible planar micro energy storage devices

The ever-increasing demand for light, thin, flexible, and small-sized smart electronics has developed a market for planar micro energy storage devices with high performance, flexibility, and robust integration, that is not mature yet. Here, a high-resolution patterned platinum (Pt) layer that can be designed/shaped as required is prepared by printing sacrificial patterns (SPs) using a commercial laser printer. MnO2-based micro-supercapacitors (MSCs) are successfully prepared on commercial Polyethylene terephthalate (PET) via electrodeposition. Because of the large surface area and large number of active sites of the nano-branch-shaped MnO2, the MnO2/Pt MSCs exhibit excellent volumetric specific capacitance (615.14F cm−3) as well as an ultrahigh volumetric power density (11.677 Wh cm−3) and energy density (54.679 mWh cm−3). In addition, the MnO2/Pt MSCs possess excellent flexibility and integration, with capacitance retention when bend to 180° and can be designed to connect in series or parallel for delivering the desired output voltage and capacitance. Furthermore, planar Zn-MnO2 batteries are successfully prepared through step-by-step electrodeposition. Simultaneously, a flexible energy conversion storage system is constructed by connecting solar cells and electrical appliances with the fabricated MSCs, demonstrating that this straightforward strategy is extremely promising for future application in microcircuits and flexible wearable smart textiles.

Radical-Doped Crystalline Lanthanide-Based Photochromic Complexes: Self-Assembly Driven by Multiple Interactions and Photoswitchable Luminescence.

Stimuli-responsive functional materials, especially the light stimulation color change and tunable fluorescent materials, have received considerable attention because of their broad applications in smart materials. Herein, a series of lanthanide-based [Ln = Nd(III) (1), Sm(III) (2), Eu(III) (3), Gd(III) (4), Tb(III) (5), Yb(III) (6), and Lu(III) (7)] crystalline complexes were attained by simply adding the aqueous lanthanide nitrate solution to the water-soluble naphthalenediimide derivative. The obtained lanthanide-based crystalline materials not only show significant photochromism but also possess reactive organic radicals under ambient conditions. Intriguingly, photoswitchable near-infrared (NIR) fluorescence was realized in the crystalline complex 1. The structures of these crystalline materials were systematically studied to clarify the weak interaction-assisted charge-transfer process. The underlying multiple-interaction-assisted supramolecular self-assembly, the radical-doped nature, and the corresponding photochromic mechanism were thoroughly unearthed by single-crystal X-ray diffraction, in situ solid-state UV-vis diffuse reflectance, and electron paramagnetic resonance spectrometric analysis.

Smart materials in architecture for actuator and sensor applications: A review

Severe challenges such as depletion of natural resources, natural catastrophes, extreme weather conditions, or overpopulation require intelligent solutions especially in architecture. Built environments that are conceived from smart materials based on actuator and sensor functionality provide a promising approach in order to address this demand. The present paper reviews smart materials-based technologies which are currently applied or developed for application in civil structures, focusing on smart material applications for actuation or sensing. After giving a definition and categorization of smart materials, applications of the investigated materials (i.e. shape memory materials, electro- and magnetostrictive materials, piezoelectric materials, ionic polymer-metal composites, dielectrical elastomers, polyelectrolyte gels as well as magneto- and electrorheological fluids) are presented for the fields of architecture and civil engineering. While some materials are already highly advantageous in the application context, others still need further research in order to become applicable in real-world constructions. Nonetheless this review indicates their large innovation potential which should be consolidated by systematic research efforts in the near future.

Electroactive Smart Materials for Neural Tissue Regeneration.

Repair in the human nervous system is a complex and intertwined process that offers significant challenges to its study and comprehension. Taking advantage of the progress in fields such as tissue engineering and regenerative medicine, the scientific community has witnessed a strong increase of biomaterial-based approaches for neural tissue regenerative therapies. Electroactive materials, increasingly being used as sensors and actuators, also find application in neurosciences due to their ability to deliver electrical signals to the cells and tissues. The use of electrical signals for repairing impaired neural tissue therefore presents an interesting and innovative approach to bridge the gap between fundamental research and clinical applications in the next few years. In this review, first a general overview of electroactive materials, their historical origin, and characteristics are presented. Then a comprehensive view of the applications of electroactive smart materials for neural tissue regeneration is presented, with particular focus on the context of spinal cord injury and brain repair. Finally, the major challenges of the field are discussed and the main challenges for the near future presented. Overall, it is concluded that electroactive smart materials play an ever-increasing role in neural tissue regeneration, appearing as potentially valuable biomaterials for regenerative purposes.

Sustainability of Civil Structures through the Application of Smart Materials: A Review.

Every year, structural flaws or breakdowns cause thousands of people to be harmed and cost billions of dollars owing to the limitations of design methods and materials to withstand extreme earthquakes. Since earthquakes have a significant effect on sustainability factors, there is a contradiction between these constraints and the growing need for more sustainable structures. There has been a significant attempt to circumvent these constraints by developing various techniques and materials. One of these viable possibilities is the application of smart structures and materials such as shape memory and piezoelectric materials. Many scholars have examined the use of these materials and their structural characteristics up to this point, but the relationship between sustainability considerations and the deployment of smart materials has received little attention. Therefore, through a review of previous experimental, numerical, and conceptual studies, this paper attempts to draw a more significant relationship between smart materials and structural sustainability. First, the significant impact of seismic events on structural sustainability and its major aspects are described. It is then followed by an overview of the fundamentals of smart material’s behaviour and properties. Finally, after a comprehensive review of the most recent applications of smart materials in structures, the influence of their deployment on sustainability issues is discussed. The findings of this study are intended to assist researchers in properly addressing sustainability considerations in any research and implementation of smart materials by establishing a more explicit relationship between these two concepts.

Helical shape linen artificial muscles responsive to water

Artificial muscles, as the name suggests, can generate contractile force and movement from another source of energy in response to an external stimulus. Moisture-responsive artificial muscles can be manufactured from commodity natural fibers for smart textile applications taking advantage of the anisotropy, low cost and skin comfort of these fibers. Here we prepared water-driven artificial muscles by twisting linen yarns into spring-like cylindrical coils. Structural evolution, including increase in diameter and decrease in length of coils, is identified as a key factor to the actuation performances of the as-fabricated muscles. Artificial muscles with a single helical configuration can generate a large, reversible contraction stroke of about 22.5% and a high gravimetric work capacity during contraction of about 110 J kg−1 work capacity, which is many times greater than animal skeletal muscles and many synthetic fiber muscles. A torque-balanced double-helix muscle was constructed from the single helical muscle. The double helix showed good reversibility and high retention of contraction stroke (∼16.5%) in cyclic actuation tests. Finally, the as-fabricated water-responsive artificial muscles were used as manipulator arm of a miniature excavator.

Graphene oxide incorporated waste wool/PAN hybrid fibres

This work aims to evaluate the potential of using textile waste in smart textile applications in the form of a hybrid fibre with electrical properties. The bio-based electrically conductive fibres were fabricated from waste wool and polyacrylonitrile (PAN) via wet spinning with different wool content. The control PAN and hybrid fibre produced with the highest amount of wool content (25% w/v) were coated with graphene oxide (GO) using the "brushing and drying" technique. The GO nanosheets coated control PAN and wool/PAN hybrid fibres were chemically reduced through hydrazine vapour exposure. The Fourier transform infrared spectroscopy showed the presence of both protein and nitrile peaks in the wool/PAN hybrid fibres, although the amide I and amide A groups had disappeared, due to the dissolution of wool. The morphological and structural analysis revealed effective coating and reduction of the fibres through GO nanosheets and hydrazine, respectively. The hybrid fibre showed higher electrical conductivity (~ 180 S/cm) compared to the control PAN fibres (~ 95 S/cm), confirming an effective bonding between the hydroxyl and carboxylic groups of the GO sheets and the amino groups of wool evidenced by chemical analysis. Hence, the graphene oxide incorporated wool/PAN hybrid fibres may provide a promising solution for eco-friendly smart textile applications.

Coating of multi-wall carbon nanotubes (MWCNTs) on three-dimensional, bicomponent nonwovens as wearable and high-performance piezoresistive sensors

Wearable piezoresistive sensors have attracted increasing attention because of their important applications in wearable electronics, smart textiles and human–machine interaction. However, existing piezoresistive sensors still suffer from problems including expensive starting materials, weak bonding fastness between conductive substances and substrates, limited sensing range and poor comfort. Herein, we report a three-dimensional (3D) piezoresistive sensor based on a nonwoven substrate composed of highly crimped bicomponent fibers. The unique core-sheath structure of these fibers in combination with a thermally-assisted coating method ensures the swift and tight adhesion of multi-walled carbon nanotubes (MWCNTs) on fiber surface, and thus making the nonwoven conductive. With the multi-layered fibrous structure, the resultant sensor exhibits good flexibility, high sensitivity (5.57% and 0.113% kPa−1 in the range of 0–7 and 30–131.32 kPa, respectively), broad dynamic sensing range (0–131.32 kPa), fast response/relaxation (105/156 ms), as well excellent breathability and long-term reliability. Versatility of this sensor is proved by real-time detection of both small and large human motions (such as pulse, speech recognition and joint motion). A sensor network containing 16 sensors is further developed to precisely map and recognize the position, shape and local distribution of pressure. Moreover, the sensor is fabricated by using affordable materials and scalable methods. Taken together, we believe this work may open up a new perspective for the design of high-performance wearable piezoresistive sensors.

High Contrast and Bright Emission Piezochromic Fluorescence in Organic Crystals via Pressure Modulated Exciton Coupling Effect

AbstractWith its recent debut in various fields, piezochromic fluorescent (PCF) materials have attracted considerable attention due to their unique photophysical features with dynamically reversible emission wavelength and intensity. Herein, a novel luminogen DBCT is developed, which is sensitive to external pressure and displays dual color reversibly switched PCF fluorescence. The solid state emission can switch from bright orange (O) (λem = 586 nm, Φsolid = 0.47) to deep red (R) emission (λem = 646 nm, Φsolid = 0.34) with high contrast through pressing (0.6 MPa), heating and fuming processes. Single crystal X‐ray analysis and theoretical calculations verify that the reversible luminescence switching characteristic is highly related to the different molecular packing mode within O and R crystals, which amplifies the exciton coupling (EC) effect and results in good PCF performances with high Φsolid as well as distinguishable red‐shifted emission. With such multiple advantages that writable fluorescent inks are successfully fabricated with high contrast for security anti‐counterfeiting applications based on DBCT molecules. This research may offer an important guideline for molecular design of PCF materials and enrich the underlying mechanism of mechanochromic luminescence, which also broadens the real‐life applications of smart materials.

What Is Driving the Growth of Inorganic Glass in Smart Materials and Opto-Electronic Devices?

Inorganic glass is a transparent functional material and one of the few materials that keeps leading innovation. In the last decades, inorganic glass was integrated into opto-electronic devices such as optical fibers, semiconductors, solar cells, transparent photovoltaic devices, or photonic crystals and in smart materials applications such as environmental, pharmaceutical, and medical sensors, reinforcing its influence as an essential material and providing potential growth opportunities for the market. Moreover, inorganic glass is the only material that is 100% recyclable and can incorporate other industrial offscourings and/or residues to be used as raw materials. Over time, inorganic glass experienced an extensive range of fabrication techniques, from traditional melting-quenching (with an immense diversity of protocols) to chemical vapor deposition (CVD), physical vapor deposition (PVD), and wet chemistry routes as sol-gel and solvothermal processes. Additive manufacturing (AM) was recently added to the list. Bulks (3D), thin/thick films (2D), flexible glass (2D), powders (2D), fibers (1D), and nanoparticles (NPs) (0D) are examples of possible inorganic glass architectures able to integrate smart materials and opto-electronic devices, leading to added-value products in a wide range of markets. In this review, selected examples of inorganic glasses in areas such as: (i) magnetic glass materials, (ii) solar cells and transparent photovoltaic devices, (iii) photonic crystal, and (iv) smart materials are presented and discussed.

Radical-doped asymmetrical naphthalenediimides derivatives: Multiple stimuli chromism and their mechanical grinding toning with organic molecules

Realizing multiple stimuli responsiveness in organic molecular systems is very important and highly desirable to broaden their potential applications in smart materials. Such stimuli responsive materials are usually required in nontrivial multistep synthesis. In the present research, a series of asymmetrical naphthalene diimide derivatives (NDIs), which display interesting multiple external stimuli responsiveness including ultrafast photochromism and chemical stimulation chromism, with the generations of organic radical anions and charge transfer, were obtained by simple synthetic process. Importantly, the multicolored functionality was ingeniously achieved by mixing commercially available materials (guest molecules) and the readily-made asymmetrical NDIs through mechanical grinding under solvent-free conditions. Noteworthy the charge transfer processes, strongly depending on the distinctive structures of NDIs molecules as well as the weak intermolecular interactions, can be induced by external stimuli (i. e. light, chemical, or grinding). Subsequently, significant stimuli responsiveness as well as multicolored properties were realized and the underlying weak interactions-assisted charge transfer mechanism was thoroughly unearthed.

Rapid water-responsive shape memory films for smart resistive bending sensors

Development of multi-functional water-sensitive shape memory material is crucial for applications in smart textiles, artificial intelligence, and biomedical areas. However, it remains a great challenge to achieve good biocompatibility, rapid water response, and robust mechanical strength in one single material. In this respect, we report a green approach to produce a series of multi-functional water-sensitive memory films (named MCP films) from sisal cellulose microcrystals (MSF-g-COOH), peach gum polysaccharide (PGP), citric acid (CA), and graphene nanosheets (GN). After crosslinking with CA, MCP films exhibit excellent water-induced shape memory and rapid pH stimulus response. More importantly, MCP films can effectively amplify different external motion stimuli by converting them into independent electrical signals to achieve accurate and continuous perception of bending. A high-performance resistive bending sensor was further fabricated from the MCP films to mimic natural human skin. The resistive bending sensor exhibited excellent water-responsive shape memory, self-adhesion, and bending sensitivity, which can be used in electronic skin, human-machine interactions, intelligent wearable devices, personalized health monitoring and other applications. Our work successfully demonstrates the application of the water-sensitive shape memory films in electronic skin and health-monitoring components, and fills the gap between material design and high-performance devices.

Robust and rapid responsive organic-inorganic hybrid bilayer hydrogel actuators with silicon nanoparticles as the cross-linker

Hydrogel actuators belong to a type of smart soft materials which can take place anisotropic thrust and/or displacement under various environmental stimuli including thermal, light, pH, humidity etc. Robust strength and rapid response are of critical importance to high-performance hydrogel actuators. Here we report the syntheses and investigations of mechanical properties for series novel organic-inorganic hydrogels by using vinyl functionalized silicon nanoparticles (SiNPs) as the cross-linker. The doped SiNPs significantly enhance the mechanical strength of polyacrylamide (PAAm) hydrogels. Furthermore, the SiNPs composite poly-N-isopropylacrylamide (PNIPAm) hydrogels exhibit rapid response in deswelling and swelling behaviours. The excellent mechanical and responsive properties are attributed to the enhanced rigidity via SiNPs doping into the hydrogel network and the improved water diffusion through mPEG branch chains on the surface of nanoparticles, respectively. As a proof of concept, a bilayer PNIPAm@PAAm hydrogel actuator is facilely synthesized via an in-situ polymerization process. This composite hydrogel actuator shows extremely fast response rate of directional bending in hot water, about 6 times faster than the control without doping of SiNPs. This work demonstrates that these SiNPs composite hydrogels provide enhanced mechanical and responsive performances and may expand the future applications in smart hydrogel materials.

Electromechanical Manipulation of Topological Defects to Yield Giant Piezoelectric Response in Epitaxial Lead Zirconate Titanate Bilayers on Silicon

AbstractThe combination of topological defect mobility and exploitation of the boundary conditions in bilayer heterostructures presents an enormous opportunity for enhancing actuation responses from modest external stimuli in electromechanical applications. Tetragonal PbZr0.3Ti0.7O3 and underlying rhombohedral PbZr0.54Ti0.46O3 ferroelectric bilayers are epitaxially grown on silicon substrates. The topmost layer shows crystallographic symmetry lower than a typical tetragonal structure but is arranged in‐plane with a mosaic pattern of superdomains and ferroelastic a1/a2 nanodomains within. The domain pattern also shows a series of vortex/anti‐vortex pairs induced in the pseudo‐tetragonal film, which can be manipulated to either migrate across the film or annihilate one another in the presence of an external electrical bias. The mobility of defect pairs and domain walls, through reduced substrate clamping by the underlying rhombohedral film, is the driving force for endowing the bilayer with a ≈45% increased effective d33 response compared to a rhombohedral single layer on silicon. Furthermore, a square in‐plane polarization loop (≈32 µC cm–2) provides further evidence of the mobility and large‐scale polarization switching. An improvement of this magnitude demonstrates the opportunity to implement bilayer technology while exploiting a functional silicon substrate for enhanced, industry‐ready, smart material applications.

Thermo-mechanical response of the twisted and coiled polymer actuator (TCPA): a finite element analysis (FEA)

Twisted and coiled polymer actuators (TCPAs) are a recently discovered thermally driven artificial muscle, fabricated from a polymer fiber coiled into a helix. They produce axial contraction or torsion when heated above glass transition temperature and relaxes to their previous state when cooled back to their initial temperature. Studies have shown the actuator to produce enormous tensile strain (49%), power densities (27.12 kW kg−1), and specific work (2.48 kJ kg−1) [Haines (2014 Science 343 868–72)]. The remarkable capabilities of TCPAs have raised interest in the applications of smart materials, soft robotics, and artificial muscles. Recently, Yang et al investigated the physical phenomena of TCPA’s actuation through a top-down multiscale model, validated through experimental works [Yang and Li (2016 J. Mech. Phys. Solids 92 237–59)]. This paper extends Yang’s approach to a finite element analysis simulation for predicting the thermo-mechanical response of a TCPA, validated by experimental comparison. Currently, there are little to no studies done in the numerical simulation of TCPAs, which is an essential tool in all fields of engineering. A numerical simulation is imperative for increasing the model’s adaptability in real-life physical systems, where analytical solutions become too complex, and for predictive simulations for designing prototype robotic actuators. The equations developed by Yang et al are implement into a three-dimensional COMSOL Multiphysics model. The results of the numerical simulation displacement response show great accuracy when compared to the experimental data tested by a dynamic mechanical analyzer.

Application of smart materials in civil engineering: A review

Smart materials have played significant contribution towards the development of buildings. There are various smart materials which can change their properties and behavior under the influence of external catalyst or stimulus. Such materials are changing the face of traditional engineering materials. Smart materials can be utilized individually as well as it can be incorporated with existing materials to enhance their desirable properties. Smart materials are widespread across all the domains of human inventions due to its multidisciplinary applications. Some of these materials are relatively new while some are being used from a very long time. Hence it suffices to say that the recently developed smart materials still require research. The general classification of smart material is illustrated in this review paper. The paper intends to identify the various types of available smart materials and also illustrated the application of such materials in the various fields of civil engineering. Further, the potential benefits and downsides are also discussed along with their applicability under different conditions. Some innovative materials are also discussed which can bring potential revolution in the construction industry. The impact or the benefits related to sustainability also discussed in this review paper.

Efficient Optical Limiting in Carbon-Nanohorn Suspensions

Nonlinear optical properties of aqueous dispersions of single-wall carbon nanohorns (SWCNH) are investigated by a simple and original technique, relating nonlinear transmittance measurements with semi-empirical model fitting and allowing to identify the dominant nonlinear mechanism. The nanofluids shown a particularly strong optical limiting under irradiation by nanosecond laser pulses at 355, 532 and 1064 nm, much stronger than that previously reported in SWCNHs with smaller aggregate size. The effect is more relevant at 355 nm, where a nearly ideal optical limiting behavior with output energy practically independent on the input one is obtained, and it is attributed to the massive production of bubbles under the effect of light irradiation. This result opens interesting perspectives for the use of SWNCH-based suspensions for smart materials applications and green energy.

An Detailed review on Applications of Smart Materials in Structural Engineering

Smart structural materials are a fundamental aspect that requires critical analysis in in structural engineering. This research contribution considers two vital crystal structures: Martensite and Austenite with their characteristic variations under different temperatures. From this research, it is seen the smart materials presents two vital features, which are distinguished from typical steels. The first one is the memory shape and the second one is super-elasticity. All of these properties can suit various applications in structural engineering e.g. dual actuators, self-rehabilitation and pre-stress bars. This research is purposed at analyzing the applications of smart materials in the field of structural engineering through the focus of relevant literature reviews, typical collection of data and major mechanic elements of smart materials. In axial tension evaluation, the curve for force and extension and the strain and stress curves of super-elasticity and Shape Memory Alloy (SMA) materials have been considered. The beam experiment with the superelasticity materials considered as the bars for reinforcement has been considered as well. This contribution provides the initial step of evaluation of the wide-range application of smart materials in the field of structural engineering.

Smart textiles: A toolkit to fashion the future

Smart textiles are adaptive materials that use established textile methods to integrate multifunctionalities beyond apparels. Despite recent advancement, a significant gap exists between commercial needs and the academic state of the art. In this perspective, we aim to address the gap by (i) holistically investigating smart textile system operation, (ii) exploring production methods and materials for stimuli-responsive smart textiles, (iii) discussing key emerging application areas for stimuli-responsive textiles, and (iv) identifying markets, production techniques, and strategies for future development. Stimuli-responsive smart textiles rely on materials and processes to interact with the environment and wearer. Smart textile applications, such as assistive soft robotics, smart healing, and thermal comfort regulation, require textiles to meet the needs of form and function. Smart textile commercialization requires the identification of markets ready for adaptive textiles, wherein a smart phone or patch does not address the consumer needs. Interdisciplinary collaborations can focus efforts to the right applications, bridging the gap between academic research and product relevance, bringing smart textiles into the future.