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Poly(vinylidene fluoride‐co‐trifluoroethylene) (P(VDF‐co‐TrFE)) is an electroactive polymer with growing interest for applications in biomedical materials and flexible electronics. In this study, a solvent‐free additive manufacturing technique called melt electrowriting (MEW) has been utilized to fabricate well‐defined microperiodic structures of the copolymer (P(VDF‐co‐TrFE)). MEW of the highly viscous polymer melt was initiated using a heated collector at temperatures above 120 °C and required remarkably slow collector speeds below 100 mm min−1. The fiber surface morphology was affected by the collector speed and an increase in β‐phase was observed for scaffolds compared to the unprocessed powder. Videography shows vibrations of the P(VDF‐co‐TrFE) jet previously unseen during MEW, probably due to repeated charge buildup and discharge. Furthermore, piezo‐force microscopy measurements demonstrated the electromechanical response of MEW‐fabricated fibers. This research therefore achieves the melt electrohydrodynamic processing of fibers with micrometer resolution into defined structures with an important electroactive polymer. © 2021 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Lasers based on biological materials are attracting an increasing interest in view of their use in integrated and transient photonics. Deoxyribonucleic acid (DNA) as optical biopolymer in combination with highly emissive dyes has been reported to have excellent potential in this respect. However, achieving miniaturized lasing systems based on solid‐state DNA shaped in different geometries to confine and enhance emission is still a challenge, and the physicochemical mechanisms originating fluorescence enhancement are not fully understood. Herein, a class of wavelength‐tunable lasers based on DNA nanofibers is demonstrated, for which optical properties are highly controlled through the system morphology. A synergistic effect is highlighted at the basis of lasing action. Through a quantum chemical investigation, it is shown that the interaction of DNA with the encapsulated dye leads to hindered twisting and suppressed channels for the nonradiative decay. This is combined with effective waveguiding, optical gain, and tailored mode confinement to promote morphologically controlled lasing in DNA‐based nanofibers. The results establish design rules for the development of bright and tunable nanolasers and optical networks based on DNA nanostructures. [ABSTRACT FROM AUTHOR]

Combined dry–wet transient materials and devices are introduced, which are based on water‐dissolvable dye‐doped polymers layered onto nonpolar cyclic hydrocarbon sublimating substrates. Light‐emitting heterostructures showing amplified spontaneous emission are obtained on transient elements and used as illumination sources for speckle‐free, full‐field imaging, and transient optical labels are realized that incorporate QR‐codes with stably encoded information. The transient behavior is also studied at the microscopic scale, highlighting the real‐time evolution of material domains in the sublimating compound. Finally, the exhausted components are fully soluble in water thus being naturally degradable. This technology opens new and versatile routes for environmental sensing, storage conditions monitoring, and organic photonics. [ABSTRACT FROM AUTHOR]

ABSTRACT: Technologies for energy harvesting from objects in motion are gaining a continuously increasing interest to directly power wearable electronics, sensors, and wireless transmitters. New networks where things will be uniquely identified and interconnected will require key enabling technologies, particularly cheap, flexible generators of renewable energy, conformable to any solid surface, to power independently individual objects and data transmission. Polymer‐based nanogenerators (PNGs), capable of converting mechanical energy into electricity, have exact features to fulfill these requirements. This article highlights advances in PNGs with focus on material chemistries and geometrical features, device design strategies, and performances. Representative examples of applications which show large‐scale capability are reported. Concluding sections summarize the key challenges and the commercialization perspectives of PNGs for use in real life applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45674. [ABSTRACT FROM AUTHOR]

Chemical sensors have been essential components in recent years due to the gathering attention in environmental monitoring and healthcare. In this review, the authors comprehensively highlight recent progresses on the 1D chemiresistive-type sensors based on semiconductor metal oxides (SMOs) and optical-type sensors, which are prepared by electrospinning technique. In the part of chemiresistive-type sensors, diverse synthesis techniques for 1D SMO nanofibrous structure are presented with controlled microstructure and surface morphology. In addition, unique functionalization routes of emerging nanocatalysts encapsulated by bio-inspired templates are described for the next generation catalyst on the 1D SMO nanofibers (NFs). For the optical-type sensors, new classes of 1D NFs employing specific absorption and emission properties are introduced. In particular, diverse 1D NF-based colorimetric and fluorescence sensors as well as Raman and surface-enhanced Raman scattering sensors are covered in the view point of material preparation and optical sensing properties. Finally, the authors prospect future research directions to overcome current limitations and challenges to achieve high performance chemical sensors. [ABSTRACT FROM AUTHOR]

The recent emergence of materials for electronic systems that are capable of programmable self-destruction and/or bio/eco-resorption creates the potential for important classes of devices that cannot be easily addressed using conventional technologies, ranging from temporary biomedical implants to enviromentally benign environmental monitors to hardware secure data systems. Although most previous demonstrations rely on wet chemistry to initiate transient processes of degradation/decomposition, options in 'dry transient electronic systems' could expand the range of possible uses. The work presented here introduces materials and composite systems in which sublimation under ambient conditions leads to mechanical fragmentation and disintegration of active devices upon disappearance of a supporting substrate, encapsulation layer, interlayer dielectric and/or gate dielectric. Examples span arrays of transistors based on silicon nanomembranes with specialized device designs to solar cells adapted from commercial components. [ABSTRACT FROM AUTHOR]

The processing, properties, and applications of electrospun light-emitting nanofibers are reviewed. The different experimental approaches for electrospinning conjugated polymers and light-emitting compounds are presented. The characterization of the optoelectronic properties of electrospun conjugated polymer nanofibers evidences intriguing features, such as polarized emission, self-waveguiding, enhanced energy transfer, and charge transport. The applications of such nanostructured materials include polarized light sources for lab-on-chip devices, nanoscale organic light-emitting diodes and optically pumped lasers, field-effect transistors, and high-performance optical sensors. Future challenges and perspectives of electrospun light-emitting nanofibers are also discussed. [ABSTRACT FROM AUTHOR]

Electrospun nanofibers are extensively studied and their potential applications are largely demonstrated. Today, electrospinning equipment and technological solutions, and electrospun materials are rapidly moving to commercialization. Dedicated companies supply laboratory and industrial-scale components and apparatus for electrospinning, and others commercialize electrospun products. This paper focuses on relevant technological approaches developed by research, which show perspectives for scaling-up and for fulfilling requirements of industrial production in terms of throughput, accuracy, and functionality of the realized nanofibers. A critical analysis is provided about technological weakness and strength points in combination with expected challenges from the market. [ABSTRACT FROM AUTHOR]

The potentialities of miniaturized laser sources are still far from being fully developed. Unprecedented opportunities are generated in this field by organic nanowires and nanofibers, which can be used as building blocks of micro‐ and nanolasers in which they combine optical gain, waveguiding, and very high versatility to create nanophotonic networks. The progress in laser devices and network architectures based on optically pumped organic light‐emitting nanowires and nanofibers is here presented, with emphasis on developed active materials, fabrication technologies, lasing mechanisms, and cavity geometries, and on achieved device performance in terms of spectral tunability, excitation threshold, and resonator quality factors. Recent examples of optical coupling of different miniaturized lasers, of their application in optical sensing, and of network lasers are presented. Future directions for research are also outlined, which include the exploration of new classes of active organic or hybrid materials within nanowires, the more in‐depth characterization of the fundamental properties of these lasers, and the use of topologically defined organic nanophotonics in network science, computing, and diagnostics. [ABSTRACT FROM AUTHOR]

Controlling the differentiation to certain lineages is the main goal of current stem cell research, which might exploit new routes based on the interaction of cells with nanomaterials. Here it is shown that primary neurospheres from dental pulp stem cells grown on combinatorial surfaces with different fibrous morphology and graphene oxide functionalization exhibit different differentiation propensity. The developed materials strongly influence the stem cell fate, as highlighted by morphological, immunofluorescence, molecular biology, and functional analyses. Instructive cues lead to the increased expression of markers that are characteristic of selective differentiation into osteoblasts, glial cells, fibroblasts, and neurons even in basal medium conditions, and randomly oriented fibers are found to revert neuronal precommitment and to trigger osteoblastic differentiation. Graphene oxide coatings lead instead to the relatively enhanced expression of genes typical of either glial or neuronal commitment, depending on the underlying nanofibrous morphology. The mechanisms addressing cell fate are investigated, highlighting the correlation of wetting anisotropy and protein adsorption capacity of different surfaces, ultimate cell conformational changes reflected by skeletal and nuclear elongation, and directed cell commitment. Cues from the different surfaces are therefore lineage‐specific, unveiling remarkable potentialities for cellular programming by means of nanomaterials. Fibrous surfaces with different morphology and graphene oxide functionalization selectively direct the differentiation of primary neurospheres from stem cells. These scaffolds drive the differentiation toward glial cells and neurons, or are able to revert neuronal precommitment, inducing fibroblast and osteoblast differentiation. [ABSTRACT FROM AUTHOR]

The combination of materials with targeted optical properties and of complex, 3D architectures, which can be nowadays obtained by additive manufacturing, opens unprecedented opportunities for developing new integrated systems in photonics and optoelectronics. The recent progress in additive technologies for processing optical materials is here presented, with emphasis on accessible geometries, achievable spatial resolution, and requirements for printable optical materials. Relevant examples of photonic and optoelectronic devices fabricated by 3D printing are shown, which include light‐emitting diodes, lasers, waveguides, optical sensors, photonic crystals and metamaterials, and micro‐optical components. The potential of additive manufacturing applied to photonics and optoelectronics is enormous, and the field is still in its infancy. Future directions for research include the development of fully printable optical and architected materials, of effective and versatile platforms for multimaterial processing, and of high‐throughput 3D printing technologies that can concomitantly reach high resolution and large working volumes. 3D printing technologies are opening new routes for photonics and optoelectronics, enabling devices with 3D architecture and with unprecedented level of integration. Here, the authors review the recent advances in additive manufacturing of optical materials, highlighting achievable spatial resolution, requirements for printable systems, and relevant examples of photonic and optoelectronic devices fabricated by 3D printing. [ABSTRACT FROM AUTHOR]

Front Cover: The feature describes two different types of chemical sensors, i.e., chemiresistive type sensors and optical sensors. For the chemiresistive type sensors, electrical signals are modulated during the reaction with chemical gas species. On the other hand, distinctive color changes are occurred in the case of optical sensors after the reaction with chemical analytes. The feature is designed for the review paper about one‐dimensional nanofibrous sensing structures for chemiresistive type sensors and optical sensors. This is reported by Seon‐Jin Choi, Luana Persano, Andrea Camposeo, Ji‐Soo Jang, Won‐Tae Koo, Sang‐Joon Kim, Hee‐Jin Cho, Il‐Doo Kim and Dario Pisignano, in article number 1600569. [ABSTRACT FROM AUTHOR]

By using subliming materials, Bong Hoon Kim, John A. Rogers, and co‐workers successfully design dry electronic systems that undergo timed self‐destruction. As described in article number 1606008, sublimation causes mechanical fragmentation and disintegration of the devices. The concept is promising for such diverse fields as biomedical implants, environmental monitoring, and secure data systems. [ABSTRACT FROM AUTHOR]