Affective computing depends on biosensors capable of detecting physiological signals associated with human emotions. Chitosan, a naturally occurring cationic polysaccharide derived from chitin, has emerged as a promising platform for such devices due to its renewability, biodegradability, biocompatibility, and ease of chemical modification. Its abundant amino and hydroxyl groups provide versatile sites for derivatization, enabling tailored solubility, mechanical performance, and functional responsiveness. These attributes make chitosan well suited for wearable and implantable emotion-sensing systems; however, challenges remain, including environmental stability, signal drift under large deformation, and maintaining long-term skin comfort. This review provides an interdisciplinary overview of chitosan’s structural, solution, and interfacial properties, demonstrating how these characteristics can enhance biosensor performance in affective computing applications. Advances in chemical modification are evaluated for their roles in improving solubility, conductivity, selectivity, and mechanical robustness. Persistent challenges, including reproducibility, durability, and biocompatibility under real-world conditions, are discussed. Finally, future perspectives are outlined, focusing on greener production methods, multi-modal sensor integration, and the expansion of chitosan-based technologies into new emotion-aware application domains.

The development of a highly responsive and selective gas sensor for volatile organic compounds, such as hydrogen sulfide and acetone, is still required. In this study, FeWO₄ hollow spheres modified with Pd nanoparticles were synthesized using ammonium phosphotungstate hydrate dodecahedra as sacrificial templates followed by liquid-phase reduction. The morphologies, microstructures, and gas-sensing characteristics of as-prepared sensing nanomaterials have been investigated. The tiny Pd nanoparticles are well anchored on the FeWO₄ hollow spheres. At the working temperature of 280 °C, the 3 wt.% Pd/FeWO₄ hollow sphere sensor exhibits higher sensitivity to acetone and ethanol gasses than unmodified FeWO₄ hollow spheres, as well as good repeatability and fast response. Meanwhile, the 3-Pd/FeWO₄ hollow sphere sensor at a low operation temperature of 25 °C exhibits a high response of 2.3–10 ppm hydrogen sulfide with excellent selectivity, which is much stronger than that of the FeWO₄ sensor. The outstanding performance of the 3-Pd/FeWO₄ hollow sphere sensor is attributable to its exceptional hollow microstructure with a high specific surface area and the catalytic properties of Pd nanoparticles.

Hydrogel materials possess unique physicochemical properties, including high water absorption, strong moisture retention, biocompatibility, tunable mechanical properties, environmental responsiveness, biodegradability, and a three-dimensional network structure. These characteristics endow them with significant practical value and broad application prospects in fields such as tissue engineering and biomedicine. Based on recent advances in both domestic and international research, this review focuses on the applications of biomedical hydrogels in emerging areas such as tissue engineering, drug delivery systems, and wound dressings. The materials covered include natural polymer hydrogels, synthetic hydrogels, ceramic‒polymer composites, and stimuli-responsive hydrogels. Additionally, this paper introduces hydrogel fabrication technologies and reviews commercially available hydrogel-based products in the medical field. As part of the progress in tissue engineering applications, this review aims to provide a reference for further clinical development and application.

Semiconductor electrodes offer powerful routes to engineer electrochemical function, yet predicting surface confined charge transfer remains challenging because crystallography and doping reshape interfacial structure, band bending, and potential distribution. Here we map these coupled effects using ferrocene (Fc) monolayers grafted onto hydrogen-terminated p- and n-type Si(100), Si(110), and Si(111). Successful functionalization was confirmed by X-ray photoelectron spectroscopy and cyclic voltammetry. The Fc surface coverage (Γ) is strongly facet dependent and, in particular, doping reverses the facet selectivity: p-type follows (100) > (110) > (111), whereas n-type follows (111) > (110) > (100). In contrast, the Fc/Fc⁺ mid-point potential shows a consistent orientation hierarchy for both dopings ((100) > (110) > (111)) with an additional ~20–40 mV positive shift on n-type relative to p-type, indicating robust redox energetics with doping-controlled offsets. Peak widths exceed the ideal surface-confined limit and, together with impedance responses, point to non-ideal behavior dominated by interfacial electrostatics rather than ohmic artifacts. This facet-by-doping map clarifies how the silicon surface structure and electronic boundary conditions partition their influence across the monolayer formation and redox energetics, providing guidance for silicon-based molecular electrochemical interfaces in sensing and molecular electronics.

With the continuous advancement of the new energy sector, direct methanol fuel cells (DMFCs) have attracted significant research interest. However, the development of DMFCs is hindered by the reliance on platinum-based anode catalysts, which suffer from high cost, intermediate-induced poisoning, and rapid performance degradation. Herein, this study develops a low-cost NiO/CuO composite for efficient methanol oxidation reaction (MOR) through defect engineering and heterojunction strategy. The NiO/CuO composite exhibits higher concentration of oxygen vacancies and interface lattice distortion compared to their individual counterparts. The NiO/CuO composite exhibits exceptional photoelectrochemical MOR activity and stability. The enhanced performance is attributed to the synergistic effect of the NiO/CuO heterojunction and the high concentration of oxygen vacancies, which together improve light absorption, increase the electrochemically active surface area, provide more active sites, and accelerate charge transfer kinetics. This work presents a promising strategy for designing cost-effective, high-performance photo-assisted anode catalysts for DMFCs.

Lead is a highly toxic and persistent heavy metal that poses serious risks to human health. The detection of lead ions in water is therefore essential not only for balancing economic and environmental priorities, improving public services, and ensuring agricultural safety, but also for preventing lead poisoning, promoting health equity, and safeguarding international trade in the context of global health. Conventional detection methods are often limited by expensive instrumentation and complex procedures, whereas surface-enhanced Raman scattering (SERS) has emerged as a promising alternative due to its high sensitivity and operational simplicity. In this study, we developed an ultrasensitive SERS-based method for the Pb²⁺ detection using L-cysteine-functionalized bismuth nanoparticles as probes. L-cysteine binds Pb²⁺ through its −COOH and −NH₂ groups, inducing nanoparticle aggregations and generating Raman hotspots that enhance the signal of 4-aminothiophenol (4-ATP). Additionally, an electrodeposited bismuth substrate further amplifies the SERS response. This method achieves a detection limit as low as 0.005 nmol·L⁻¹ (1.04 × 10⁻³ μg·L⁻¹), demonstrating 2‒5 orders of magnitude greater sensitivity compared to conventional lead ion detection techniques.

Helical carbon nanotubes (HCNTs) offer unique geometrical characteristics and capabilities; however, their properties, functionalization, and applications have not been sufficiently explored, compared to the straight CNTs that have different crystallinity and structural characteristics. The coil-shaped geometries of HCNTs can substantially increase their mechanical entanglement/interlocking with solidified host-resins and the microfiber-reinforcements in fiber-reinforced composites. As a result, it can considerably improve the mechanical, thermal, electrical, and magnetic properties of the composites. To further improve their effectiveness, HCNTs should be chemically treated to promote their molecular interactions and bonding-effectiveness with the resin molecules, as well as to enhance their dispersion-uniformity and suspension-stability in the host-resin. In this study, a reflux method was deployed to chemically functionalize HCNTs with a low-molarity nitric acid-solution and then effects of reflux time and temperature on surface-modification and dispersion-homogeneity of the functionalized HCNTs (FHCNTs) were investigated. The results from SEM, FTIR, XRD, Raman spectroscopy, and visual dispersion-test showed that changes in reflux time and temperature were mostly effective in atomic scale structural alteration of the HCNTs. Except for the FHCNTs that were treated at higher temperatures for a longer time, the rest showed improvements in their dispersion, an increase in I_D/I_G Raman ratios, and changes in FTIR spectra.

The conversion of low-grade waste heat into valuable chemicals is a promising route toward energy conservation and carbon neutrality. Herein, we demonstrate that La-substituted SrTiO₃ serves as an efficient thermoelectrocatalytic material for the simultaneous H₂O₂ production via H₂O oxidation and O₂ reduction. Under a mild temperature gradient of 130 °C, the system achieves a notable H₂O₂ production rate of 412 μmol·L⁻¹·g⁻¹·h⁻¹. This work offers a potential strategy for sustainable chemical synthesis by utilizing ubiquitous low-grade thermal energy.