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This review is intended to provide an overview of the design and fabrication of ionic liquid-based ionic electroactive polymer (IL-iEAP) transducers for advanced applications in biological and electronic fields. The iEAP is a class of smart materials that can perform sensing or actuating functions by controlling the movement of cations and anions in the active layer. This type of material can deform under low voltage stimulation and generate electrical signals when undergoing mechanical deformation because of ion redistribution. Numerous research attention has been focused on studying the deformation mechanisms and the potential for actuation, sensing, and energy harvesting applications. Compared to the traditional water-based iEAP, the non-volatile IL-iEAP delivers a wider electrochemical window and a more stable actuation performance. In this paper, the classification of iEAP with different actuation mechanisms is first outlined, followed by introducing various preparation methods including nanotechnology for IL-iEAPs, and discussing the key factors governing their actuation performance. In addition, the advanced functions of IL-iEAP in actuating and sensing, especially self-sensing in bionics and electromechanical equipment applications, are reviewed. Finally, novel nanotechnologies used for fabricating IL-iEAPs and the prospects of their microelectromechanical system (MEMS) applications are discussed.

Electroactive hydrogels have received increasing attention due to the possibility of being used in biomimetics, such as for soft robotics and artificial muscles. However, the applications are hindered by the poor mechanical properties and slow response time. To address these issues, in this study, supramolecular ionic polymer–carbon nanotube (SIPC) composite hydrogels were fabricated via in situ free radical polymerization. The polymer matrix consisted of carbon nanotubes (CNTs), styrene sulfonic sodium (SSNa), β-cyclodextrin (β-CD)-grafted acrylamide, and ferrocene (Fc)-grafted acrylamide, with the incorporation of SSNa serving as the ionic source. On applying an external voltage, the ions accumulate on one side of the matrix, leading to localized swelling and bending of the structure. Therefore, a controllable and reversible actuation can be achieved by changing the applied voltage. The tensile strength of the SIPC was improved by over 300%, from 12 to 49 kPa, due to the reinforcement effect of the CNTs and the supramolecular host–guest interactions between the β-CD and Fc moieties. The inclusion of CNTs not only improved the tensile properties but also enhanced the ion mobility, which lead to a faster electromechanical response. The presented electro-responsive composite hydrogel shows a high potential for the development of robotic devices and soft smart components for sensing and actuating applications.

Two-photon polymerization direct laser writing (TPP DLW) is an emerging technology for producing advanced functional devices with complex three-dimensional (3D) micro-structures. Tremendous efforts have been devoted to developing two-photon polymerizable photo-sensitive nanocomposites with tailored properties. Light-induced reconfigurable smart materials such as liquid crystalline elastomers (LCEs) are promising materials. However, due to the difficulties in designing two-photon polymerizable liquid crystal monomer (LCM) nanocomposite photoresists, it is challenging to fabricate true 3D LCE micro-structures. In this paper, we report the preparation of photo-sensitive LCE nanocomposites containing photothermal nanomaterials, including multiwalled carbon nanotubes, graphene oxide and gold nanorods (AuNRs), for TPP DLW. The printability of the LCE nanocomposites is assessed by the fidelity of the micro-structures under different laser writing conditions. DLW of GO/LCM photoresist has shown a vigorous bubble formation. This may be due to the excessive heat generation upon rapid energy absorption of 780 nm laser energy. Compared to pure LCM photoresists, AuNR/LCM photoresists have a lower laser intensity threshold and higher critical laser scanning speed, due to the high absorption of AuNRs at 780 nm, which enhanced the photo-sensitivity of the photoresist. Therefore, a shorter printing time can be achieved for the AuNR/LCM photoresist.

Iron oxide nanoparticle ([Fe.sub.3][O.sub.4]) has gained remarkable research interest for various applications, from environmental to biological, because of its superparamagnetic properties and good biocompatibility. In this work, the nucleation effect of [Fe.sub.3][O.sub.4] in a polylactide (PLA) matrix under an influence of an alternating magnetic field was studied. The nanocomposite films that is, containing different concentrations of [Fe.sub.3][O.sub.4] (~8 nm) which were uniformly dispersed in the PLA matrix, were prepared via a solution casting method. The amplitude and frequency of the magnetic field impose great effects on the morphology and nucleation rate of PLA crystallization. Thermogravimetric analysis was used to study the thermal stability of [Fe.sub.3][O.sub.4]/ PLA and it showed that the thermal stability of [Fe.sub.3][O.sub.4]/PLA was affected by the [Fe.sub.3][O.sub.4] content. Fourier transform infrared spectroscopy and X-ray diffractometry indicated that [Fe.sub.3][O.sub.4] shows impeding effect to the crystallization of PLA. Based on the differential scanning calorimetry results, composite with 1% of [Fe.sub.3][O.sub.4] content could promote the crystallization of PLA but it would become an obstacle when 3% of [Fe.sub.3][O.sub.4] was added. The result of polarized optical microscopy also showed a good agreement that the incorporation of [Fe.sub.3][O.sub.4] could act as an effective nucleation regent to the composite film., INTRODUCTION In recent years, magnetic nanoparticles ([Fe.sub.3][O.sub.4], [gamma]-[Fe.sub.2][O.sub.3], Pt, Ni, Co), which are sensitive to a change of external magnetic field, have drawn much research attention. [Fe.sub.3][O.sub.4] nanoparticles possesses certain [...]

Aggregation‐induced emission luminogens (AIEgens) as a new class of optical probes for two‐photon imaging (2PI) have attracted extensive attention in the research community. However, their non‐radiative energy dissipation plays a non‐negligible role in energy consumption, thereby weakening their performance in 2PI. Exploration of a facile and general approach to control the energy relaxation pathways is thus a fascinating yet significantly challenging task. To address this concern, an organic doping method is proposed herein by using TPE‐Br as the doping AIEgen and MeOTTMN as the functional AIEgen. With increased amount of doping molecules, a steadily strengthened brightness (up to 29‐fold of quantum yield) is observed at the expense of reactive oxygen species production. Remarkably, an ultradeep imaging depth of 1000 µm in a mouse brain is realized via 2PI using the heavily organic‐doped AIEgen(ODA) nanoparticles (NPs). Such result is far superior to the imaging depth of 156 µm enabled by MeOTTMN NPs. The safe use of ODA NPs is further evaluated by in vitro and in vivo toxicity assessment. This study thus provides an attractive paradigm to control the energy relaxation of AIEgen NPs and maximize their performance in 2PI while circumventing the difficulties in molecular engineering. [ABSTRACT FROM AUTHOR]