Terahertz (THz) waves exhibit distinctive advantages for biomedical sensing, while metasurface technology offers an effective route toward high-performance THz sensors. A high-sensitivity THz metasurface absorber sensor for biological sample detection is proposed and numerically investigated. The sensor adopts a metal-insulator-metal (MIM) configuration, in which four centrosymmetrically arranged split metal rings form a multimode resonator. Copper is employed as the metallic layer, and PTFE is selected as the dielectric spacer. The electromagnetic response of the sensor is analyzed using CST Microwave Studio based on the FIT. Simulation results demonstrate that the proposed sensor supports two independent near-perfect absorption resonances at 3.1564 THz and 3.724 THz, with peak absorption rates of 99.75% and 99.84%, respectively. Owing to the strong localized field enhancement and multimode coupling effects, the resonant frequencies exhibit pronounced sensitivity to variations in the surrounding refractive index. Within the typical refractive-index range of biomedical samples, the maximum sensitivity reaches 241 GHz/RIU, accompanied by a maximum figure of merit (FOM) of 8.02. In addition, the absorption performance remains above 99% for polarization angles from 0° to 90°, with negligible resonance shift, indicating excellent polarization insensitivity. Benefiting from the use of low-dielectric-constant materials, the proposed sensor showed good material compatibility and portability. These results suggested that the designed metasurface absorber provided a promising platform for high-sensitivity terahertz biosensing applications.

Terahertz (THz) waves exhibit distinctive properties, such as high transmittance, pronounced absorption, and minimal photon energy, enabling a wide range of applications in biomedical diagnosis, non-destructive testing, and quality/safety monitoring of food and agricultural products. Consequently, THz-based sensors have garnered increasing attention. However, the design of traditional coupling structures fails to effectively match the high-frequency oscillation of THz waves, resulting in low signal energy transmission efficiency and limiting the performance of THz sensors, while microstructure technology can offer a solution by achieving localized enhancement of the electromagnetic field energy through precise matching of sub-wavelength resonance units with the high-frequency oscillation of THz waves, which significantly improves the sensitivity of THz sensors. This review summarizes the basic principles and research status of various THz sensors based on different microstructures, such as split-ring resonators (SRRs), photonic crystals, waveguide resonators, and surface plasmon resonance. Notably, the rapid development of artificial intelligence, especially deep learning, is increasingly influencing THz sensing technologies with its strengths in signal processing, pattern recognition accuracy, and inverse design. Integrating deep learning with THz sensor design enhances feature extraction from complex signals, improves target identification, and enables intelligent optimization of microstructure parameters for high-performance sensor design and performance prediction. This interdisciplinary approach provides a new pathway to overcome traditional design limitations and advance THz sensor performance.

Photodetectors (PDs) serve as a fundamental enabling technology and are indispensable in numerous applications. Recent advances in novel functional materials and metasurface technologies are paving the way for revolutionary improvements in PD performance, functionality, and integration. Functional materials, characterized by their unique band structures, broad spectral response, and high carrier mobility, can significantly improve detector sensitivity, response speed, and spectral selectivity. Similarly, metasurfaces empower precise electromagnetic wave manipulation and customized light-field control through subwavelength micro/nanostructures. The synergy between these two fields has overcome the constraints of traditional PD design. While numerous reviews have surveyed advances from the perspective of either materials or metasurfaces in isolation, a holistic approach that integrates both is increasingly critical in both research and practical applications, leading to significant breakthroughs. This review bridges this gap by providing a comprehensive overview of recent advances achieved through the synergistic optimization of PDs. Beginning with fundamental principles, we systematically elucidate the enhancement mechanisms of this composite system on core performance metrics, including temporal response, spectral response, and dark current suppression, and explore its potential for intelligent functional integration. This review concludes by discussing future challenges and opportunities from a manufacturability standpoint, offering guidance for innovative cross-disciplinary applications.

Perovskite solar cells (PSCs) incorporating 2D/3D heterostructures have exhibited remarkable improvements in both power conversion efficiency and operational stability. Nevertheless, the prevalent spin-coating fabrication technique presents formidable challenges for scalable manufacturing processes. Herein, we present a blade-coating compatible methodology for fabricating high-performance 2D/3D PSCs utilizing a low-volatility t-amyl alcohol (t-AmOH) -dimethylformamide (DMF) mixed solvent system. Through systematic materials characterization and comprehensive device performance analysis, we demonstrate that this approach facilitates uniform spatial distribution of butylammonium iodide (BAI) organic spacers, thereby promoting the formation of a high-quality 2D/3D perovskite architecture characterized by enhanced crystallinity and substantially reduced defect density. The optimized device achieves a champion power conversion efficiency of 22.25% while demonstrating exceptional operational stability, retaining 83% of its initial performance after prolonged exposure under ambient conditions (45% relative humidity) for 1000 h.