Terahertz (THz) spectroscopy has recently gained significant attention as a powerful tool for biomacromolecule detection due to its exceptional sensitivity in capturing molecular fingerprints, attributed to its unique wavelength range. THz biosensing platforms offer distinct advantages in identifying molecular rotational and vibrational states, making them effective for high-sensitivity, high-precision biomacromolecule analysis. This review highlights recent advancements in THz biosensing platforms, focusing on their spectroscopy interpretation and practical applications. We begin by introducing commonly used THz equipment and various metamaterials, followed by an overview of the key spectroscopy interpretation strategies for THz spectral analysis, including refractive index sensing and molecular fingerprint recognition. We also summarize the machine learning (ML) methods applied to enhance spectral analysis in THz biosensing platforms. Lastly, we provide an integrated perspective on the spectroscopy interpretation, clinical applications, and recent technological advancements in THz biosensing platforms, with an emphasis on how to construct a standardized THz-based biosensing workflow. We believe THz biosensing platforms hold immense potential to revolutionize molecular detection by enabling precise, label-free, and highly sensitive analysis of biomacromolecule interactions, paving the way for breakthroughs in medical diagnostics, environmental monitoring, and biochemical research.

This study demonstrates active control of terahertz (THz) transmission by exploiting the humidity-driven swelling of a submicron poly(vinyl alcohol) (PVA) film integrated with metallic nanoresonators. Conventional THz modulators typically require bulk-like membranes tens of micrometers thick to compensate for weak light-matter interaction, which inevitably results in slow, diffusion-limited response times. In contrast, our approach utilizes field confinement near nanometer gaps to achieve high modulation depth with an ultrathin layer, offering a potential route to high-speed operation. Under 90% relative humidity, the 193 nm PVA film swells to 380 nm, exhibiting a rapid response time of 373 ms─nearly three times faster than 1.25 μm films. The hybrid structure achieves a 13.6% transmission modulation, driven by a localized dielectric transition at electric-field hot-spots. These findings provide a robust strategy for high-performance THz metasurfaces that bypass the traditional trade-off between modulation depth and response speed.

Synergistic graphene-aptamer coating on a flexible metasurface enables on-apple terahertz sensing of pesticides.

Terahertz (THz) imaging technology is widely used in applications such as security screening, radar detection, and biomedical applications. Nevertheless, due to the inherent limitations of imaging conditions, THz images often exhibit low contrast, blurred contours, and reduced feature information under partial occlusion, which significantly compromises recognition accuracy. To address these challenges, we proposed an Enhanced and Occlusion-aware Focus YOLOv5(EOF-YOLOv5), an improved architecture based on YOLOv5. In this study, image enhancement preprocessing was applied to raw THz image datasets acquired from a THz active array imaging system to improve target contrast and contour clarity. An Occlusion Aware Context Attention (OCA) mechanism was integrated into the neck network of YOLOv5. This mechanism dynamically adjusts attention weights and enhances feature responses in visible areas by capturing spatial occlusion patterns via 1 × 1 convolution and modeling inter-channel dependencies. Additionally, the original Complete Intersection over Union (CIoU) loss function was replaced with the Focal-Efficient Intersection over Union (Focal-EIoU) loss function to reduce excessive focus on simple samples and improve the learning performance for challenging samples. Experimental results demonstrate that image enhancement preprocessing significantly improves both visual quality and structural information, thereby boosting the network's recognition accuracy. On the same preprocessed dataset, the EOF-YOLOv5 algorithm outperforms the baseline YOLOv5 model, elevating precision (P) from 66.7 to 79.3%, recall (R) from 73.1 to 80.6%, and mean average precision (mAP50) from 75.5 to 83.7%. The proposed model effectively identifies targets under blurry and occluded conditions, providing an innovative solution for terahertz image detection.

Excitons serve as the primary energy carriers for many organic semiconductor devices and chemical systems; however, understanding how these bound electron-hole pairs dissociate into free carriers on an ultrafast time scale remains challenging. Here, we demonstrate a contact-free approach using intense, single-cycle terahertz (THz) pulses to promote the dissociation of excitons via a field-induced charge hopping process. Applying this method to a prototypical organic semiconductor, we observe a photocurrent enhancement exceeding 100% under THz excitation. Time-resolved measurements reveal that hot excitons (formed immediately after above-bandgap photoexcitation) are particularly susceptible to dissociation. These findings establish a nonequilibrium, field-driven route for engineering exciton dissociation in a wide range of optoelectronic materials, providing a broadly applicable strategy to enhance photovoltaic performance as well as potential electrophotocatalytic applications through strong-field light-matter interactions.

Generating pre-designed vectorial beams via on-chip devices can yield many fascinating applications, but traditional diffraction-based devices are bulky and inefficient. While plasmonic metasurfaces exhibit ultra-compact sizes and deep-subwavelength resolutions, their working efficiencies are limited by metallic losses. Here, we propose a generic design for highly efficient, ultra-compact dielectric metasurfaces that generate tailored vectorial beams under surface-wave (SW) excitations, experimentally validated in the terahertz (THz) regime. We first experimentally characterize the basic dielectric meta-atom, and then demonstrate a benchmark meta-device that, under the SW excitation, can generate a circularly polarized focused beam. We next realize two dielectric meta-devices, each consisting of two subsets of meta-atoms responsible for generating two pre-designed circularly polarized beams with opposite helicity, with their interference forming the target vectorial beams. Our experiments show that these two meta-devices can generate an azimuthally polarized Bessel beam and a vectorial multifocal holographic image, respectively. We experimentally show that the present dielectric meta-system exhibits significant improvement in the relevant frequency band compared to its metallic counterpart, and numerically demonstrate that it exhibits an absolute working efficiency as high as 92%. Our study paves the way to realize many on-chip applications with high efficiencies, such as biological sensing, displays, image multiplexing, and beyond.

Terahertz (THz) radiation provides an effective means to probe and manipulate collective molecular dynamics in confined water. In this work, nonequilibrium molecular dynamics simulations are employed to investigate the frequency-dependent thermal response and microscopic structure of water confined in armchair-type double-walled carbon nanotubes (DWCNTs). Water encapsulated in (3, 3)@(13, 13), (3, 3)@(18, 18), and (3, 3)@(23, 23) DWCNTs is subjected to linearly polarized THz electric fields applied either parallel or perpendicular to the nanotube axis, and the resulting temperature jump, ΔT, is analyzed over a broad THz frequency range. In comparison with bulk water, confined water exhibits substantially enhanced and highly frequency-selective heating, with a pronounced dependence on field polarization. Under axial polarization, water confined in the narrowest (3, 3)@(13, 13) DWCNT shows a strong resonant response, yielding a maximum temperature increase of ΔT ∼ 370 K, approximately 3.3 times that of bulk water. This enhancement weakens systematically with increasing outer nanotube diameter and higher initial temperature. Analyses of oxygen-oxygen radial distribution functions and transverse density profiles reveal that nanoscale confinement induces pronounced molecular ordering and spatial localization, characterized by ring-like density distributions within the nanotube cross section. These confinement-induced structural features indicate a strong coupling between collective molecular motions and external THz fields, demonstrating that geometric confinement and field polarization jointly regulate resonant energy absorption in nanoscale aqueous systems.

Antibiotic abuse-induced residues pose a severe threat to human health, yet traditional detection methods suffer from large sample consumption and complicated pretreatment, which fail to meet practical needs. Terahertz (THz) spectroscopy, with its molecular fingerprinting capability, holds great promise for drug detection. Here, we propose a THz metasurface for accurate qualitative and quantitative analysis of antibiotics. First, quantum chemical calculations reveal the spectral response of antibiotics in the THz band and the formation mechanism of characteristic fingerprint peaks. Then, leveraging the metasurface resonance spectral dip induced by molecular fingerprint peaks, we extract the specific information via spectral inversion. After that, a joint feature space is constructed by combining resonant frequency shift and differential absorption intensity, and the characteristic frequency is further integrated to form a multidimensional detection system. As a proof of concept, the metasurface realizes qualitative and quantitative detection of two antibiotics with a limit of detection as low as 1.11 μg/mm2 and effectively identifies trace norfloxacin in complex mouse blood matrices. Combined with machine learning, the metasurface efficiently identifies multiple antibiotics on our experimental dataset. This work presents a label-free approach enabling direct qualitative and quantitative detection of trace antibiotics via a single THz metasurface, offering new insight for trace identification of drug molecules, with potential application prospects in biomedical detection applications.

The biosensors based on metasurfaces have attracted significant attention for biological detection in the terahertz (THz) band due to the characteristics of rapid, label-free, and nondestructive. Benefiting from the low-loss characteristics of the electromagnetically induced transparency (EIT), we propose two single-band EIT meta-biosensors and a dual-band EIT meta-biosensor through various combinations of three designed T-shaped resonators that act as bright modes. By utilizing the excellent biocompatibility of gold nanoparticles (AuNPs), the proposed meta-biosensors modified with carcinoembryonic antigen (CEA) antibody-conjugated AuNPs achieve the specific detection of CEA within mixed tumor markers in the THz band, which indicates that the frequency shifts of the transparent peaks increase only with increasing CEA concentration, as the CEA antibody-conjugated AuNPs specifically capture the target antigens. Furthermore, we employ a mutual information feature extraction algorithm integrated with a support vector machine (SVM) to verify the discrimination of transmission spectra samples with different CEA concentrations, and the classification results show high intraclass consistency and clear interclass distinction. This work paves the way for the development of novel meta-biosensors with high sensitivity and specific target antigen recognition, which would provide technical support for cancer screening and disease diagnosis.

Various external and internal factors constantly induce DNA damage, with DNA double-strand breaks (DSBs) being the most severe form of damage. DSBs must be repaired rapidly, and failure to repair leads to the development of cancer and other diseases. Here, we show that terahertz (THz) irradiation decreases the amount of DSBs in a frequency-dependent manner. Furthermore, DSBs were increased when samples were heated, indicating that the decrease in DSBs by THz irradiation is a nonthermal effect. The modulation of DNA damage repair by THz irradiation provides a noninvasive method with potential medical applications, such as the prevention and suppression of diseases caused by genomic instability.

To address the limitations of traditional absorbers, which are typically restricted to either broadband or narrowband single-function performance, this work introduces a dual-functional metamaterial stacked absorber using vanadium dioxide (VO2) and a three-dimensional bulk Dirac semimetal (BDS). The study designs a terahertz (THz) absorber with adjustable absorption modes and a simple structure. This absorber demonstrates a broadband absorption bandwidth of 44.73 THz, achieving an average absorption rate of 97.4%. Additionally, when configured for narrowband performance, it exhibits seven absorption peaks with a maximum sensitivity of 1474 GHz per RIU. The potential applications of this absorber include THz thermal imaging and stealth technology.

Tin (Sn) was incorporated into Ge2Sb2Te5 (GST) thin films to create a tunable platform for terahertz (THz) sensing. The films were prepared by DC magnetron cosputtering and examined using energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to analyze composition and phase evolution. Results show that Sn modifies the crystallization pathway of GST, forming mixed SnTe and SnSb phases that enable phase transformation at a lower thermal energy. THz time-domain spectroscopy (THz-TDS) revealed a pronounced dielectric contrast between amorphous and crystalline states, with Sn incorporation enhancing phase transition. The measured optical parameters were implemented in simulations of split-ring resonator (SRR) metasurfaces containing a GST underlayer. Phase switching in pure GST produced a resonance shift of about 0.16 THz; however, the Sn-incorporated GST sample could improve modulation efficiency with reduced thermal input. These findings identify Sn-incorporated GST as a promising material for reconfigurable, energy-efficient THz device platforms.

Compact and programmable wavefront control is a central task for advancing terahertz (THz) wave spectroscopy, imaging, and wireless communications. Although electrically programmable metasurfaces have exhibited remarkable versatility and significantly promoted THz dynamic device development, realizing two-dimensional (2D), nonvolatile, broadband, and high-resolution wavefront control remains a critical objective. Here, we present an optically programmable metasurface method that potentially overcomes these difficulties by leveraging the reversible phase change of the chalcogenide material Ge2Sb2Te5 (GST). The core innovation lies in the use of selective optical excitation to locally address and induce phase changes in constituent GST patches, enabling reconfigurable and nonvolatile reversal of the meta-atom symmetry. This unique mechanism yields a robust and broadband 0/π phase-switching capability at the meta-atom level, operating with subwavelength resolution and without the need for complex integrated electrodes. By employing spatially patterned optical pumping with predesigned masks as examples, we experimentally demonstrate two distinct 2D coded functionalities: controllable beam steering and tunable beam focusing. Our method establishes a new paradigm for programmable THz metasurfaces, offering a promising pathway for active and flexible THz wavefront engineering critical for systems requiring long-term, stable functionalities.

Ultrafast control of lattice motion in metals is a central challenge for high-frequency strain engineering and spintronic applications. Coherent strain control at terahertz (THz) frequencies in metals has remained elusive because free electrons are expected to delocalize energy beyond the optical penetration depth, preventing rapid and efficient stress generation. Here we show that robust and cost-effective metal–metal superlattices (SLs), where periodic repetitions of bilayers — each layer a few atoms thick — are deposited by sputtering, constitute thermoacoustic metamaterials that overcome this limitation. We combine femtosecond X-ray diffraction with mode-resolved density-functional theory and two-temperature modeling to show that electron pressure, rather than phonon stress, drives a large-amplitude coherent terahertz (1 THz) lattice oscillation in sputtered Pt/Cu superlattices. We establish electron pressure as an engineerable, dominant actuation mechanism in metallic metamaterials which can be tailored by the pitch and the constituent materials of the sputtered SL structure, enabling applications such as ultrafast strain-mediated antiferromagnetic spintronic devices.

Background and Objectives: Breast cancer remains one of the most common malignancies worldwide, and early detection plays a crucial role in improving treatment outcomes and reducing mortality. Several experimental studies using animal models of breast cancer have explored the potential of terahertz-based technologies in this field. However, their preclinical evidence base in breast cancer remains heterogeneous and has not been systematically synthesized with a focus on experimental models, imaging protocols, and barriers to translation. Methods: We conducted a descriptive systematic review, according to PRISMA guidelines, of 10 articles selected from a total of 372 identified across four databases-PubMed, Embase, Web of Science, and Cochrane-regarding the diagnostic performance of terahertz (THz) imaging in breast cancer animal models. We included studies that used rodent models diagnosed with breast cancer, subsequently confirmed through histological examination, and extracted relevant data. Results: The results were synthesized using a narrative approach. Most studies used C57BL/6J mice with E0771 cell line-induced breast tumors, with histopathology as the reference standard. In the reflection mode, at frequencies between 0.1 and 4 THz, the identification of tumoral, fibrous, fat, and muscle tissues was possible. Conclusions: Overall, the available preclinical evidence supports THz imaging as a promising proof-of-concept approach for breast tissue characterization, but not yet as a standardized or clinically translatable diagnostic platform. Future studies should use harmonized animal models, standardized acquisition and specimen-handling protocols, transparent reporting of classification workflows, and consistent outcome metrics to enable comparison across studies and to clarify the biological and biophysical determinants of THz contrast in breast cancer.

Terahertz (THz) communication is considered as a key technology enabler for realizing Sixth Generation (6G) network. THz band communication offers several promising advantages, but numerous challenges are expected due to the inherent limitations of propagation at THz frequencies in the 6G network, such as path loss, interference, human and wall blockages, etc. In retrospect, THz band communication finds its use in indoor network deployments. In this paper, a framework is developed to analyze the impact of the uplink performance of a single-tier THz network, incorporating the impact of wall and human blockages in the indoor environment. To model a practical system, 3D antenna model have been employed, which accounts for both horizontal and vertical radiation patterns, whose performance have been benchmarked against 2D antenna model that accounts only for horizontal direction. This evaluation has enabled us to highlight the impact of practical antenna models on THz communication performance. Using the developed system model, generalized expressions for uplink mean interference, uplink coverage probability, and area spectral efficiency have been derived. The impact of THz uplink network performance has been analyzed using an antenna model with varying user equipment heights and different main lobe beam widths, as well as considering different path loss exponents for Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) conditions. The analytical results obtained against different network conditions have been compared and validated against Monte Carlo simulations and both have been found in agreement.

Graphene Josephson junctions (JJs) are promising platforms for broadband quantum sensing because graphene combines frequency-independent absorption, ultralow electronic heat capacity, and weak electron-phonon coupling. While previous studies focused on microwave and infrared regimes, the terahertz (THz) range─where highly sensitive quantum detectors remain scarce─has largely remained unexplored. Here, we demonstrate a gate-tunable THz photoresponse in graphene JJs. Low-intensity THz illumination strongly suppresses the critical current, generating a pronounced photovoltage under current bias. From photovoltage measurements and independent electron thermometry, we extract a responsivity of 88 kV W-1 and a noise-equivalent power of 45 aW Hz-1/2 at 1.7 K. In addition, the hysteretic regime that persists up to 0.9 K suggests a possible route toward single-photon THz detection above millikelvin temperatures. Our results establish graphene JJs as promising candidates for cryogenic THz quantum sensing.

High-precision, non-destructive thickness measurement is essential for lithium-ion battery (LIB) manufacturing. Existing approaches, such as X-rays, acoustic waves, and optical lasers, are limited by speed, resolution, or penetration into conductive materials. Here, we demonstrate nanometre-precision thickness measurements of LIB electrodes using terahertz (THz) Fabry-Pérot (FP) interferometry referenced to a photonic frequency comb. Combining the comb's SI-traceable frequency accuracy with THz radiation's immunity to scattering and absorption, our system directly detects FP modes with sub-10 MHz precision at sweep rates exceeding 12 THz/s, while spectral analysis simultaneously yields the complex refractive index. Electrode thicknesses of 50-150 μm are measured with nanometre precision: 70.1 nm (anode) and 465.5 nm (cathode) at 0.2 s, improving to 7.8 nm and 25.2 nm at 25.6 s, representing a one-to-two orders of magnitude improvement over temporal-analysis methods. The system further supports 3D profiling and dynamic thickness monitoring, enabling a unified, calibration-free platform for next-generation LIB metrology.

Understanding the photoinduced terahertz (THz) conductivity in transition metal dichalcogenides (TMDs) is essential for their envisioned applications in optoelectronics. Recent studies of photoinduced terahertz conductivity in TMDs have revealed strong non-Drude behavior, empirically fitted by the Drude-Lorentz or Drude-Smith models, without adequate physical understanding of the parameters employed. Here, we report the photoexcited spectral response of the nonequilibrium carriers in WS2(1-x)Se2x (x = 0, 0.5, and 1) laminates consisting of few-layer flakes, using optical pump terahertz probe (OPTP) spectroscopy, and model the data using the Boltzmann transport equation (BTE) with energy-dependent scattering mechanisms. We demonstrate that by incorporating electron-electron (e-e) scattering mechanism into the Boltzmann transport framework, alongside impurity and phonon scattering, the terahertz photoconductivity can be quantitatively understood. Our analysis reveals that e-e scattering is a critical mechanism to understand the fluence-dependent blueshift of the zero-crossing frequency of the imaginary part of the photoinduced terahertz conductivity Δσim(ω), without any empirical fitting parameters. Drawing parallels with the hydrodynamic transport regime observed in graphene's Dirac fluid, we show that e-e interactions play a significant role in the carrier dynamics, leading to non-Drude terahertz photoconductivity response. The insight from this study highlights the indispensable role of e-e scattering in describing the nonequilibrium carrier dynamics in TMDs and offers insights for future optoelectronic device design.

Smart Optical Biosensor for Edible Oil Detection with Machine Learning Integration.