Engineered Optical Fibers for Deep‐Tissue Applications

Organic single crystals quickly emerge as dense yet light and nearly defect‐free media for emissive elements. Integration of functionalities and control over the emissive properties is currently being explored for a wide range of these materials to benchmark their performance against organic emissive materials diluted in powders or films. Here, we report mechanically flexible emissive chiral organic crystals capable of an unprecedented combination of fast, reversible, and low‐fatigue responses. UV‐excited single crystals of both enantiomers of the material, 4‐chloro‐2‐(((1‐phenylidene)imino)methyl)phenol, exhibit a drastic yet reversible change in the emission color from green to orange‐yellow within a second and can be cycled at least 2000 times. The photoresponse was found to depend strongly on the excitation intensity and temperature. Combining chirality, mechanical compliance, rapid emission switching, multiple responses, and writability by UV light, this material provides a unique and versatile platform for developing organic crystal‐based materials for on‐demand signal transfer, information storage, and cryptography.

Imaging through scattering media holds significant application potential in remote sensing, biomedical diagnostics, and industrial detection. However, conventional imaging systems fail to maintain robustness and generalization across diverse environments. Here, we demonstrate a photon-level single-pixel imaging system that exploits data-domain alignment to overcome this limitation. By coupling a physical preprocessing module with a deep neural network, the system translates scattering-induced degradations from different scattering media into a unified data domain, preserving the essential structure of the optical information. Under natural fog and rain conditions, the proposed method clearly reconstructs the fine target details at a distance of 150 m, demonstrating strong robustness across the scattering medium. With 0.088 photons per pattern per pixel in a single measurement, the 256×256 dynamic imaging is well reconstructed. These results establish a generalizable framework for photon-level imaging in diverse scattering media and highlight its promise for robust optical imaging under extreme atmospheric conditions.

This review explores the transformative potential of graphene-based, non-invasive biochemical sensors in the context of real-time health monitoring and personalised medicine. Traditional diagnostic methods often involve invasive procedures that can be uncomfortable, pose risks, and limit the frequency of monitoring. In contrast, wearable sensors incorporating graphene offer a compelling alternative by enabling continuous, real-time tracking of physiological and biochemical signals with minimal intrusion. Graphene’s exceptional electrical conductivity, mechanical flexibility, biocompatibility, and high surface-area-to-volume ratio make it ideally suited for integration into skin-conformal sensor platforms. These properties not only enhance sensitivity and signal fidelity but also promote user comfort and long-term wearability, critical factors for the adoption of wearable health technologies. The discussion evaluates current developments in the design and deployment of graphene-based biosensors, with particular attention given to their role in managing chronic conditions, supporting preventative healthcare, and facilitating decentralised diagnostics. By bridging materials science and biomedical engineering, this review positions graphene as a key enabler in the shift towards more proactive, patient-centred healthcare models. The text also identifies ongoing challenges and future directions in sensor design, aiming to inform researchers working at the intersection of advanced materials and medical technology.

Innovative approaches to sustainable civil and structural engineering are essential for addressing the challenges of climate change, resource scarcity, and urbanization.This paper explores the integration of resilient design, advanced material science, and smart technologies to enhance the sustainability and performance of infrastructure.Resilient design focuses on creating structures that can withstand and recover from extreme events, while advanced materialssuch as high-performance concrete and composite materials-offer improved durability and strength.Smart technologies, including real-time monitoring systems and adaptive materials, provide dynamic responses to environmental changes and structural stress.By combining these elements, engineers can develop infrastructure that not only meets current demands but also anticipates future challenges.This holistic approach supports the creation of more adaptable, efficient, and long-lasting structures, ultimately contributing to more sustainable built environments.

Rationale: Mesenchymal stem cell (MSC) therapy may be a novel approach to improve interstitial cystitis/bladder pain syndrome (IC/BPS), an intractable disease characterized by severe pelvic pain and urinary frequency. Unfortunately, the properties of transplanted stem cells have not been directly analyzed in vivo, which hampers elucidation of the therapeutic mechanisms of these cells and optimization of transplantation protocols. Here, we monitored the behaviors of multipotent stem cells (M-MSCs) derived from human embryonic stem cells (hESCs) in real time using a novel combination of in vivo confocal endoscopic and microscopic imaging and demonstrated their improved therapeutic potency in a chronic IC/BPS animal model.Methods: Ten-week-old female Sprague-Dawley rats were instilled with 10 mg of protamine sulfate followed by 750 μg of lipopolysaccharide weekly for 5 weeks. The sham group was instilled with phosphate-buffered saline (PBS). Thereafter, the indicated dose (0.1, 0.25, 0.5, and 1×106 cells) of M-MSCs or PBS was injected once into the outer layer of the bladder. The distribution, perivascular integration, and therapeutic effects of M-MSCs were monitored by in vivo endoscopic and confocal microscopic imaging, awake cystometry, and histological and gene expression analyses.Results: A novel combination of longitudinal intravital confocal fluorescence imaging and microcystoscopy in living animals, together with immunofluorescence analysis of bladder tissues, demonstrated that transplanted M-MSCs engrafted following differentiation into multiple cell types and gradually integrated into a perivascular-like structure until 30 days after transplantation. The beneficial effects of transplanted M-MSCs on bladder voiding function and the pathological characteristics of the bladder were efficient and long-lasting due to the stable engraftment of these cells.Conclusion: This longitudinal bioimaging study of transplanted hESC-derived M-MSCs in living animals reveals their long-term functional integration, which underlies the improved therapeutic effects of these cells on IC/BPS.

The rapid advancement of optoelectronic devices has intensified the demand for materials that are not only functional but also mechanically adaptable to human-centric applications. Conventional transparent conductors, such as indium tin oxide, offer excellent conductivity and optical transparency but fail under mechanical strain, limiting their use in flexible and stretchable systems. This limitation has motivated the development of intrinsically stretchable and transparent conductors capable of maintaining electrical and optical performance under large, repeated deformations. These conductors are typically fabricated by embedding conducting fillers within elastomeric matrices, providing skin-like mechanical compliance without the need for complex geometric patterning and enabling seamless integration with soft, irregular surfaces. Intrinsically stretchable and transparent conductors can be divided into metallic and non-metallic conductors. Each category offers distinct advantages but also presents trade-offs among conductivity, transparency, stretchability, and environmental stability. Therefore, careful material selection and design optimization are essential to balance these competing properties. This review summarizes recent progress in intrinsically stretchable and transparent conductors, with a focus on materials and design strategies for optimizing electrical, optical, and mechanical performance. We further highlight their integration into optoelectronic devices and discuss remaining challenges and potential solutions to advance next-generation soft optoelectronic technologies.

Improvements in graded-index multimode optical fiber sensor performance caused by an on-axis dip in the parabolic index of refraction profile of the fiber are considered. The effects of such a dip on fiber multimode propagation are first reviewed.1 Effects on both the modulation mechanisms and the resulting sensitivities of intrinsic bend loss and extrinsic coupling sensors are then analyzed. Experimental measurements of both of these observables obtained using specimens having two different degrees of such a central refractive-index profile dip are compared with this analysis. Analytical and experimental results indicate that sensor sensitivities are increased by ~10% for the specific fiber profiles considered. It is shown that by further increasing the severity of the central dip from the nominal parabolic index profile, an additional sensitivity increase of 20% is attainable.

Multifunctional metamaterials have emerged as a transformative platform for controlling multi‐physical fields, promising applications in intelligent manufacturing, flexible electronics, thermal management, and energy conversion. However, conventional metamaterial designs typically prioritize optimizing single‐field responses, constraining their adaptability and functional integration potential in complex multi‐physics scenarios where coordinated regulation of multiple fields is required. Here, a V‐shaped 3D electrothermal dual‐function metamaterial (V‐ETDFM) architecture is proposed, enabling efficient and reconfigurable control of both electric and thermal transport. By expanding conduction pathways into 3D space, the proposed V‐shaped structure introduces additional degrees of freedom, enhancing its functional integration and adaptability. Through theoretical and numerical analysis, the feasibility of dynamically controlling cloak parameters, including size, shape, and spatial positioning, is demonstrated by reversibly stretching and compressing the V‐shaped framework based on transformation principles that maintain effective parameter invariance. Experimentally, a series of electrothermal cloaks with varying cloaked regions are fabricated to validate key design principles, confirming the static properties of the theoretical framework, while the implementation of real‐time dynamic tuning presents an avenue for future exploration. The work establishes a novel design strategy for electrothermal multifunctional metamaterials and provides a foundational theoretical framework for flexible and reconfigurable multi‐physics materials.

The effects of γ-irradiation on potassium dihydrogen phosphate crystals containing arsenic impurities are investigated with different optical diagnostics, including UV-VIS absorption spectroscopy, photo-thermal common-path interferometer and photoluminescence spectroscopy. The optical absorption spectra indicate that a new broad absorption band near 260 nm appears after γ-irradiation. It is found that the intensity of absorption band increases with the increasing irradiation dose and arsenic impurity concentration. The simulation of radiation defects show that this absorption is assigned to the formation of AsO₄⁴⁻ centers due to arsenic ions substituting for phosphorus ions. Laser-induced damage threshold test is conducted by using 355 nm nanosecond laser pulses. The correlations between arsenic impurity concentration and laser induced damage threshold are presented. The results indicate that the damage performance of the material decreases with the increasing arsenic impurity concentration. Possible mechanisms of the irradiation-induced defects formation under γ-irradiation of KDP crystals are discussed.

This study presents a comprehensive and multidisciplinary approach to the seismic performance assessment and restoration of the Erdi Baba (Abdal Yakup) Dervish Lodge complex, constructed in 1741 on Istanbul’s historic peninsula. The restoration process was carried out in four stages: (i) field and archival surveys to identify original architectural features, (ii) extensive laboratory analyses of collected materials, (iii) seismic performance evaluation using linear, nonlinear, and kinematic limit analyses, and (iv) development and implementation of context-specific restoration practices. Laboratory analyses revealed that the mortar samples generally exhibited low mechanical strength, with calcium carbonate content exceeding 50% in most cases, which indicates weak binding characteristics. SEM-EDX and petrographic examinations confirmed high calcium content and the presence of brick ballast, lime lumps, and flax fibers in the samples, consistent with traditional Ottoman construction materials. Seismic analyses were conducted using Midas Gen software in accordance with the Turkish Building Earthquake Code (TBEC-2018) and the Guideline for Seismic Risk Management of Cultural Heritage Buildings (SRMGHS-2017). This research presents a replicable methodology for the restoration of similar Ottoman-era religious complexes in seismic regions, providing a benchmark for future interdisciplinary studies that integrate historical architecture, materials science, and structural engineering.

Construction technology developed quickly during the first decades of the twentieth century. This influenced the construction of industrial buildings at the UN Educational, Scientific and Cultural Organization World Heritage site of Rjukan and Notodden in Norway. Behind the construction was Hydro, a company founded in 1905 to produce synthetic nitrogen fertiliser to increase the world’s food production. This industrial development demanded large structures such as hydropower stations and production facilities. Concrete was introduced for the first time during this period, and systems are characterised by heavy concrete bearing walls and mixed bearing walls where concrete and steel were combined. Such systems demanded significant material resources and resulted in the development of steel and concrete skeleton frames. The development of viable systems was achieved through research in materials science and structural engineering, in both the USA and Europe. This paper discusses how concrete influenced construction and building systems at this site. Similarities to industrial buildings and other building typologies are evident and connect the site to the international context of architecture and engineering history. Understanding the characteristics of individual buildings and presenting them in an order of a construction systems will support the work of architects and engineers in future conservation schemes.

Externally bonded fiber-reinforced polymer composites have been in use in civil infrastructure for decades, but their long-term performance is still difficult to predict due to many knowledge gaps in the understanding of degradation mechanisms. This paper summarizes critical durability issues associated with the application of fiber-reinforced polymer (FRP) composites for rehabilitation of concrete structures. A variety of factors that affect the longevity of FRP composites are discussed: installation, quality control, material selection, and environmental conditions. Critical review of design approaches currently used in various international design guidelines is presented to identify potential opportunities for refinement of design guidance with respect to durability. Interdisciplinary approaches that combine materials science and structural engineering are recognized as having potential to develop composites with improved durability.

The service life prediction of inorganic materials is, at present, primarily deduced from studies on mechanical and chemical performance in given environments. Selected models of the behaviour of concrete structures are presented. They are either structural engineering models or materials science models. They can predict mechanical properties, frost resistance or behaviour regarding carbonation. The barriers to service life prediction are related to the complexity of multicomponent systems, to little known degradation mechanisms, to unsatisfactory accelerated tests and to insufficient preventive measures. Examples of chemical deterioration of concrete are given. They emphasize the need for more research in materials science and a closer collaboration between structural engineers and materials scientists.

The trade-off between lateral resolution and depth of focus (DOF) severely limits the capability of endoscopic optical coherence tomography (OCT) for high-resolution deep-tissue imaging. To address this issue, we developed a novel miniature all-fiber axicon OCT probe by inserting a segment of gradient-index (GRIN) fiber between a piece of single-mode fiber (SMF) and an axicon polished from a no-core fiber. The GRIN lens served as a beam expander extending the probe DOF by 5.2 times while maintaining a high lateral resolution of 2 μm. The DOF extension was experimentally verified by measuring the axial profile of the probe output beam and further by imaging multilayered polymer tapes and onion samples. The designed probe with a tight focus over a large DOF holds great potential in endoscopic OCT imaging of deep tissues at the cellular level.

Bioelectronics for healthcare that monitor the health information on users in real time have stepped into the limelight as crucial electronic devices for the future due to the increased demand for "point-of-care" testing, which is defined as medical diagnostic testing at the time and place of patient care. In contrast to traditional diagnostic testing, which is generally conducted at medical institutions with diagnostic instruments and requires a long time for specimen analysis, point-of-care testing can be accomplished personally at the bedside, and health information on users can be monitored in real time. Advances in materials science and device technology have enabled next-generation electronics, including flexible, stretchable, and biocompatible electronic devices, bringing the commercialization of personalized healthcare devices increasingly within reach, e.g., wearable bioelectronics attached to the body that monitor the health information on users in real time. Additionally, the monitoring of harmful factors in the environment surrounding the user, such as air pollutants, chemicals, and ultraviolet light, is also important for health maintenance because such factors can have short- and long-term detrimental effects on the human body. The precise detection of chemical species from both the human body and the surrounding environment is crucial for personal health care because of the abundant information that such factors can provide when determining a person's health condition. In this respect, sensor applications based on an organic-transistor platform have various advantages, including signal amplification, molecular design capability, low cost, and mechanical robustness (e.g., flexibility and stretchability). This Account covers recent progress in organic transistor-based chemical sensors that detect various chemical species in the human body or the surrounding environment, which will be the core elements of wearable electronic devices. There has been considerable effort to develop high-performance chemical sensors based on organic-transistor platforms through material design and device engineering. Various experimental approaches have been adopted to develop chemical sensors with high sensitivity, selectivity, and stability, including the synthesis of new materials, structural engineering, surface functionalization, and device engineering. In this Account, we first provide a brief introduction to the operating principles of transistor-based chemical sensors. Then we summarize the progress in the fabrication of transistor-based chemical sensors that detect chemical species from the human body (e.g., molecules in sweat, saliva, urine, tears, etc.). We then highlight examples of chemical sensors for detecting harmful chemicals in the environment surrounding the user (e.g., nitrogen oxides, sulfur dioxide, volatile organic compounds, liquid-phase organic solvents, and heavy metal ions). Finally, we conclude this Account with a perspective on the wearable bioelectronics, especially focusing on organic electronic materials and devices.