MXenes and their derivatives have attracted tremendous attention over the past few decades, and several reviews have already been dedicated to their synthesis, properties, device functionalities, and performances. Nitrogen (i.e., N), as an important non-metal element, has been widely reported as an external dopant to improve the properties of MXenes. Herein, we review the recent advances of NMXenes, with a significant concern on the impact of N-doping on the structural and photo-/electrochemical properties of bulk MXenes, and their emerging applications. The different types of recently reported N-MXenes and the associations between the N-doping and the structural characteristics (e.g., the change of atomic lattice and the number and type of active sites, as well as the removal of detrimental functional groups) of MXenes are systematically summarized and discussed, with the aim to highlight the resulting improvements in response to the photo-/electrochemical and electronic stimuli. Applications of the N-MXenes in the fields of electrochemistry, photo-/electrocatalysis, and photosensing are then described. Finally, we summarize this review, and disclose our perspectives on the future opportunities of the N-MXenes and the potential development challenges of this research branch.

In conjunction with the advancement of digital healthcare, the field of wearable biosensors has experienced rapid growth in recent years and is projected to expand further in the coming years. As wearable biosensors enter their next phase, emphasis is increasingly placed on developing comfortable, breathable, washable, and lightweight intelligent fibers and textiles as key components. This review examines the contributions of both natural and synthetic fibers and textiles to wearable biosensors. The structure and preparation process of intelligent fibers and textiles are systematically elucidated, including the development of the conductive layer. Additionally, key micro–nano technologies that have emerged in this domain are highlighted such as built-in power supplies, wireless data transmission, precise data analysis driven by artificial intelligence, and machine learning. Furthermore, advanced functionalities integrated into recent biosensing systems, such as heat management, real-time displays, and human–machine interaction are summarized. Moreover, the applications of fiber-based wearable biosensors for monitoring biophysical and biochemical signals are presented. Finally, the challenges faced by the community working on wearable sensors based on intelligent fibers and textiles are discussed alongside promising future directions.

Photoalignment technology is serving as an emerging technology for programming liquid crystalline polymer (LCP) materials due to its advantages including noncontact, high resolution, spatial control, programmability, and high efficiency. In this review, we report the research progress in implementing polarized light to design the anisotropy of LCPs, which is categorized based on the photoalignment mechanisms. The alignment approaches and the different stimulus-responsive behaviors of the materials after photoalignment are discussed. Additionally, we have summarized the applications of photoaligned LCPs such as liquid crystal displays, optical components, intelligent soft actuators, and beyond. Finally, the challenges and future directions of the technology are outlined.

Responsive polymers can react to surrounding environments by changing their physical and/or chemical properties. Among them, liquid crystal elastomers (LCEs) have emerged as one of the important branches in the field of applied polymer science due to their significant advantages in flexible mechanics and shape memory. Manufacturing LCE fibers with a large specific surface area and functional fillers has become a research hotspot in recent years. This type of LCEcontained fibrous composite (LCEF) exhibits not only extremely high response sensitivity but also excellent axial mechanical strength and a high degree of deformation freedom. In this paper, we provide a bird’s eye view of recent developments in LCEF, including structural designs, synthesis and forming methods, mechanical response principles and modes. Furthermore, we discuss recent advances of LCEF in artificial muscles, smart textiles, biomimetic systems, intelligent soft machines, followed by challenges and possible routes in fabrications and applications of LCEF. At the end, we aim to provide a perspective for an emerging field of stimulus-responsive polymeric fiber composites.

Enabling soft shape memory polyurethane (SMPU) with self-healing is an effective strategy to extend its service life; however, the tradeoff between high mechanical strength and rapid self-healing to meet the practical applications remains a challenge. Herein, we prepared a polyurethane (PU) with polycarbonate diol as a soft segment, incorporating urea bonds and dynamic disulfide bonds through chain extenders. This material, denoted as PU-NSS75, exhibited a remarkable tensile strength of 51.4 MPa, attributed to the synergistic energy dissipation effect of urea hydrogen bonding and dynamic disulfide bonds during stretching, leading to enhanced mechanical properties of the PU. The dynamic nature of the bonds, including hydrogen bonding and disulfide bonds, endowed the PU with exceptional self-healing capabilities. Furthermore, leveraging the reversible mechanism of disulfide bonds under UV irradiation at room temperature, PU-NSS75 achieved complete self-healing within 1 min. This photoinduced dynamic chemical bonding also facilitated rapid reconfigure the original shape of the soft SMPU at room temperature, thus broadening its potential applications. This study offers a design approach to enhance soft shape memory polyurethane materials, while the rapid self-healing and shape reconfiguration provide new avenues for expanding the applications of shape memory polyurethanes.

Tunable plasmonics has shown a wide range of applications in (bio)chemical sensing, displays, actuators, photonic chips, biomedicine, etc. in the last 2 decades. This review focuses on their recent development from the device perspective, which involves the understanding of fundamental principles and specific applications with desired functionality and compatibility. We classify these active plasmonic devices based on the nature of their structures and working environment as colloidal-based, chip-based, and colloidal chip-based to further elaborate their performance and functions. We also highlight recent progress on tunable surfaceenhanced Raman spectroscopy, metasurfaces, and chiroptics to show the emerging applications of tunable plasmonic systems. We conclude this review with a general perception of the research trend in this field and challenges for their practical applications.

Magnetic microparticles (MPs) and nanoparticles (NPs) have long been used as ideal miniaturized delivery and detection platforms. Their use as micro- and nanorobots (MNRs) is also emerging in the recent years with the help of more dedicated external magnetic field manipulations. In this review, we summarize the research progress on magnetic micro- and nanoparticle (MNP)-based MNRs. First, the fabrication of micro- and nanorobots from either template-assisted NP doping methods or directly synthesized MPs is summarized. The external driving torque sources for both types of MNRs are analyzed, and their propulsion control under low Reynolds number flows is discussed by evaluating symmetry breaking mechanisms and interparticle interactions. Subsequently, the use of these MNRs as scientific models, bioimaging agents, active delivery, and treatment platforms (drug and cell delivery, and sterilization), and biomedical diagnostics has also been reviewed. Finally, the perspective of MNPs-based MNRs was outlined, including challenges and future directions.

Production of electrical energy in an environmental-friendly manner is important for meeting the increasing demand of electricity in smart vehicles and energy devices. Benefitted from its moderate working temperatures and high conversion efficiency , proton exchange membrane fuel cell (PEMFC) has received broad attention and commercialized rapidly in the past decades. Herein, we comprehensively review the advanced types of electrolytes and their underlying working mechanisms to offer a considerate guidance to develop novel electrolytes with high proton conductivity and wide working temperature window. Moreover, to rationally design cost-effective and robust electrodes, the well-developed anode and cathode and their fundamental working principles are elaborately reviewed and discussed. Furthermore, from the viewpoint of overall structure, fabricating approaches of functional components of PEMFC and their corresponding influencing factors are minutely reviewed and analyzed with the aim of tuning cell performance and preparing PEMFC in a high-throughput way. Lastly, we highlight the conclusions of this review and present the penitential developing directions.