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Smart materials respond to environmental signals by changing their microstructure and physical properties. Programming multiple behaviors and functions into a single material could increase its utility and adaptability to ever‐changing environmental conditions. A swellable and stretchable metamaterial hydrogel or "metasponge" engineered to morph into customized sizes and shapes that dynamically tune its physical properties and functions is reported. Multiple case studies that take advantage of the morphing properties of the metasponge, including robotic actuation, light guidance, optical and sonic invisibility ("cloaking"), adaptation of propulsion mode, sampling, and multiple biomedical applications, are illustrated. Developing multifunctional smart materials in which logic is programmed into the materials rather than electronic components could pave a new path to autonomy and dynamic responses in soft robots, sensors, and actuators. [ABSTRACT FROM AUTHOR]

Smart materials that respond to external stimuli are the top choice as actuators. Herein, inspired by the natural plants, a smart dual-response actuator with Janus structure was fabricated from natural cellulose. Two cellulose derivatives with controllable chemical structure acted as the responsive elements, including ethanol-responsive cellulose 3,5-di-tert-butyl-4-hydroxybenzoate (CBH) and water-responsive carboxymethyl cellulose (CMC). Via changing the degree of substitution of 3,5-di-tert-butyl-4-hydroxybenzoate, the solubility, swellable property and swellable ratio of CBH in ethanol were precisely adjusted. After transforming the partial carboxylate group into the carboxylic acid, water-swellable CMC was obtained. Combining the ethanol-swellable CBH with water-swellable CMC by two-step blade-coating process, a Janus film was fabricated with dual-driven motility and complete biodegradability. This eco-friendly dual-responsive film can predict the concentration of ethanol/water mixture according to the different deformation angle. Moreover, it can be acted as a dual-responsive single-pole double-throw switch, indicating a huge potential in practical eco-friendly actuator. [ABSTRACT FROM AUTHOR]

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The development of robust bioanalytical devices and biosensors for infectious pathogens is progressing well with the advent of new materials, concepts, and technology. The progress is also stepping towards developing high throughput screening technologies that can quickly identify, differentiate, and determine the concentration of harmful pathogens, facilitating the decision-making process for their elimination and therapeutic interventions in large-scale operations. Recently, much effort has been focused on upgrading these analytical devices to an intelligent technological platform by integrating them with modern communication systems, such as the internet of things (IoT) and machine learning (ML), to expand their application horizon. This review outlines the recent development and applications of bioanalytical devices and biosensors to detect pathogenic microbes in environmental samples. First, the nature of the recent outbreaks of pathogenic microbes such as foodborne, waterborne, and airborne pathogens and microbial toxins are discussed to understand the severity of the problems. Next, the discussion focuses on the detection systems chronologically, starting with the conventional methods, advanced techniques, and emerging technologies, such as biosensors and other portable devices and detection platforms for pathogens. Finally, the progress on multiplex assays, wearable devices, and integration of smartphone technologies to facilitate pathogen detection systems for wider applications are highlighted. [ABSTRACT FROM AUTHOR]

Origami, a paper folding art, has inspired engineering applications in various fields for decades. It provides a simple approach to realize the transformation between simple 2D composite sheets and complex 3D functional structures. By integrating the origami concept with smart materials, a number of advanced origami robots have been developed with self-deploying and programming capacities to respond to external environment stimuli. At present, miniaturized origami robots have demonstrated advantages in many-profile applications, including bio-inspired robotics, biomedical engineering, and environment monitoring. However, how to properly drive origami robots is a big challenge. In this paper, the investigation and analyses of the previous literature focus on the various actuations of miniaturized origami robots, including the magnetic, light, electric, swelling, motors, thermal, and other actuation methods. Finally, the article investigates applications of actuation methods for miniaturized origami robots with various functions, and discusses the challenges and opportunities in future applications. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: Stimuli‐responsive molecules are highly desirable in different scenario such as smart materials, bio‐imaging, and environment monitoring. Herein, a series of hetero polycycles which show optical response toward chemical stimuli are synthesized from trithiasumanene (TTS). The TTS is transformed into ortho‐quinone form, which then undergoes three‐component Debus‐Radziszewski reaction with aldehydes and ammonia to give oxazole‐fused TTS (2—6). The thiophene rings on 3—5 are selectively oxidized to thiophene‐S,S‐dioxides, affording 3‐3O2—5‐3O2. It is found that the electronic structures of these compounds are governed by the substituents on oxazole moiety and oxidation state of thiophene ring. Moreover, these hetero polycycles exhibit optical response toward different chemical stimuli. Particularly, compounds 6 and 3‐3O2 can serve as fluorescence detectors for harmful chemicals sulfide ions (S2–/HS–) and aniline, respectively. This work indicates that TTS is a promising precursor for the creation of responsive materials. [ABSTRACT FROM AUTHOR]

The development of robust bioanalytical devices and biosensors for infectious pathogens is progressing well with the advent of new materials, concepts, and technology. The progress is also stepping towards developing high throughput screening technologies that can quickly identify, differentiate, and determine the concentration of harmful pathogens, facilitating the decision-making process for their elimination and therapeutic interventions in large-scale operations. Recently, much effort has been focused on upgrading these analytical devices to an intelligent technological platform by integrating them with modern communication systems, such as the internet of things (IoT) and machine learning (ML), to expand their application horizon. This review outlines the recent development and applications of bioanalytical devices and biosensors to detect pathogenic microbes in environmental samples. First, the nature of the recent outbreaks of pathogenic microbes such as foodborne, waterborne, and airborne pathogens and microbial toxins are discussed to understand the severity of the problems. Next, the discussion focuses on the detection systems chronologically, starting with the conventional methods, advanced techniques, and emerging technologies, such as biosensors and other portable devices and detection platforms for pathogens. Finally, the progress on multiplex assays, wearable devices, and integration of smartphone technologies to facilitate pathogen detection systems for wider applications are highlighted.

Supramolecular functional materials featuring self‐healing properties are a fascinating class of materials that are currently attracting great interest. In this respect, use of dynamic metal–ligand bonds has received much less attention than other reversible interactions – either covalent bonds or noncovalent interactions. Nonetheless, systems and materials with enhanced and special functionalities might arise from the synergic combination of labile coordination bonds and the physicochemical properties – optical, magnetic, electrical, catalytic, and so on – associated with the presence of judiciously chosen metal ions or organic ligands. Here, advances in the field of healing and multi‐functional materials based on the reversible formation of metal‐ligand bonds are highlighted through a selection of key examples, including bioinspired ones. [ABSTRACT FROM AUTHOR]

The structure of certain nonliving tissues determines their self-shaping and self-folding capabilities in response to a stimulus. Predetermined movements are realized according to changes in the environmental conditions due to the generated stresses of the multilayer anisotropic structure. In this study, we present bioinspired responsive anisotropic multilayer films and their fabrication process which comprises low-cost techniques. The anisotropic multilayer materials are capable of deforming their geometry caused by small temperature changes (

In recent decades, the design and construction of smart materials capable of switching into a polyzwitterionic state by an external trigger have been intensively pursued. Polyzwitterionic states have unique antifouling and surface properties and external triggers, such as pH, light, ions, electric field and CO2, cause significant changes in materials with regard to overall charge, ionic strength and wettability. This survey highlights current progress in the irreversible as well as the reversible switching process involving polyzwitterionic moieties, which can, in turn, be applied to studying the interaction of various interfaces with biological species as protein, DNA, bacteria or platelets and also for advanced use. [ABSTRACT FROM AUTHOR]

Natural materials possess many distinctive "living" attributes, such as self-growth, self-healing, environmental responsiveness, and evolvability, that are beyond the reach of many existing synthetic materials. The emerging field of engineered living materials (ELMs) takes inspiration from nature and harnesses engineered living systems to produce dynamic and responsive materials with genetically programmable functionalities. Here, we identify and review two main directions for the rational design of ELMs: first, engineering of living materials with enhanced performances by incorporating functional material modules, including engineered biological building blocks (proteins, polysaccharides, and nucleic acids) or well-defined artificial materials; second, engineering of smart ELMs that can sense and respond to their surroundings by programming dynamic cellular behaviors regulated via cell–cell or cell–environment interactions. We next discuss the strengths and challenges of current ELMs and conclude by providing a perspective of future directions in this promising area. Existing strategies for the design of engineered living materials (ELMs). Various chassis cells (bacterial, yeast, mammalian, and fungal cells) can be developed into ELMs through two design principles: functional module incorporation and dynamic behavior regulation. Functional module incorporation refers not only to the functional modification of endogenous biological building blocks (proteins, polysaccharides, and nucleic acids), but also to the combination of functional exogenous artificial materials (e.g., hydrogels, conductive materials, and nanoparticles) with living systems. Dynamic behavior regulation exploits the capacity of living systems to regulate their own behavior in response to cues from other cells or from the external environment, aiming at manufacturing advanced responsive and self-patterning living materials. [Display omitted] • Introduction of endogenous or exogenous functional modules endows ELMs with emerging properties. • Programming cell–cell or cell–environment interactions enables dynamic living materials. • ELMs composed of multicellular consortia exhibit intrinsic advantages including resource sharing and division of labor. • Machine learning techniques accelerate the design of functional modules and genetic circuits for ELMs. [ABSTRACT FROM AUTHOR]

In this review, current activities in the development of active biomaterials related to bio‐interfacial design as well as novel concepts for smart polymer systems are highlighted. For instance, advanced biomedical coatings, including vapor‐based polymer coatings for the controlled attachment of biomolecules, and temperature‐responsive coatings for tissue engineering are outlined. Moreover, recent trends with the fabrication of “smart,” switchable surfaces, such as conformationally switching monolayers, will be reviewed. Specific focus will further be given to multi‐functionalized biomaterials including shape‐memory polymers that undergo specific changes in shape in response to stimuli like heat or light. This novel class of intelligent materials highlights a recent trend in biomaterial development targeting is the extension of this concept to multi‐functionalization. In particular, the combination of biodegradability and shape‐memory effects opens a range of opportunities for biomedical applications including intelligent sutures or stents. [ABSTRACT FROM AUTHOR]

The present manuscript offers an overview of the current state of affairs within the research field of adaptive and environmentally sensitive polymer surfaces designed to respond to external stimuli in a controlled and predictable manner. Intensive study in the field of the adaptive/responsive surfaces began several decades ago in an attempt to understand relationships between bulk properties/composition of pristine polymeric materials and their surface characteristics. With time, the focus of the research has moved to the design of materials with ‘smart’ or ‘intelligent’ surface behavior. This review describes a number of approaches that has been employed to fabricate such materials, which include but not limited to (a) synthesis of functional polymers with specific composition and architecture; (b) blending of a virgin polymer material with small amounts of (macro)molecular additive; (c) surface modification by various chemical/physical treatment. [Copyright &y& Elsevier]

The advancement of smart materials has substantially affected the sample preparation techniques. Recently, different smart materials like carbon-based materials, magnetic nanoparticles, and ferrofluids have been used to separate analytes from different matrices. Among these, ferrofluids have attracted considerable attention due to their liquidity and magnetic controllability, facilitating their recovery during the extraction process. Ferrofluids are dispersions of magnetic powders in a carrier liquid with a great magnetic response. Ferrofluid can be moved with the help of positioning and strength of a magnetic field. So, the fluid can be positioned at the desired point very precisely. This review offers a comprehensive discussion of the modern trends in ferrofluid-based microextraction techniques from the introduction of ferrofluids as an extractant (2010) to 2020. Also, the challenges faced by each method have been investigated. This review details the essential factors in the synthesis of ferrofluids. Finally, the challenges and outlooks of ferrofluids are outlined. [Display omitted] • Ferrofluid based microextraction techniques were discussed. • The synthesis of different ferrofluids was reviewed. • The application of ferrofluids in the microextraction techniques was summarized. • The advantages and disadvantages of each microextraction method were examined. • The future research direction of ferrofluids was identified. [ABSTRACT FROM AUTHOR]

A smart window that dynamically modulates light transmittance is crucial for building energy efficiently, and promising for on‐demand optical devices. The rapid development of technology brings out different categories that have fundamentally different transmittance modulation mechanisms, including the electro‐, thermo‐, mechano‐, and photochromic smart windows. In this review, recent progress in smart windows of each category is overviewed. The strategies for each smart window are outlined with particular focus on functional materials, device design, and performance enhancement. The advantages and disadvantages of each category are summarized, followed by a discussion of emerging technologies such as dual stimuli triggered smart window and integrated devices toward multifunctionality. These multifunctional devices combine smart window technology with, for example, solar cells, triboelectric nanogenerators, actuators, energy storage devices, and electrothermal devices. Lastly, a perspective is provided on the future development of smart windows. [ABSTRACT FROM AUTHOR]

Smart materials with coupled optical and mechanical responsiveness to external stimuli, as inspired by nature, are of interest for the biomimetic design of the next generation of soft machines and wearable electronics. A tough polymer that shows adaptable and switchable mechanical and fluorescent properties is designed using a fluorescent lanthanide, europium (Eu). The dynamic Eu‐iminodiacetate (IDA) coordination is incorporated to build up the physical cross‐linking network in the polymer film consisting of two interpenetrated networks. Reversible disruption and reformation of Eu‐IDA complexation endow high stiffness, toughness, and stretchability to the polymer elastomer through energy dissipation of dynamic coordination. Water that binds to Eu3+ ions shows an interesting impact simultaneously on the mechanical strength and fluorescent emission of the Eu‐containing polymer elastomer. The mechanical states of the polymer, along with the visually optical response through the emission color change of the polymer film, are reversibly switchable with moisture as a stimulus. The coupled response in the mechanical strength and emissive color in one single material is potentially applicable for smart materials requiring an optical readout of their mechanical properties. [ABSTRACT FROM AUTHOR]

Joining two materials with an adhesive is an extremely common activity, but is most often irreversible. However, emerging and current applications ranging from consumer and medical products to soft robotics and wearable bio‐monitoring devices demand strong adhesives which can be easily removed on‐demand and subsequently reused. This requires new paradigms in adhesive science and engineering, resulting in the emergence of new classes of multifunctional switchable adhesives. Here summarized is the current state of the art in switchable adhesive systems, focusing on how devices fit into the basic science of adhesion while providing performance metrics for comparison across current approaches. Using fracture mechanics as a guide, systems are classified as functioning under one of three basic mechanisms: near‐interface, contact area, or mechanical. These mechanisms must be initiated or "triggered" by a specific input, which can include mechanical, electromagnetic, fluidic, or thermal stimuli. Triggers and adhesion switching performance are compared through the use of a "switching ratio," the interfacial energy release rate, and an estimate of mechanism timing. Finally, it is discussed that how the fundamental mechanisms relate to challenges and opportunities for switchable interfaces in future applications and adhesive systems. [ABSTRACT FROM AUTHOR]