The advent of graphene has opened new avenues for the design of high-performance metamaterial devices, particularly in the realm of electromagnetic absorption applications. This paper introduces a novel design for a broadband tunable graphene metamaterial absorber (GMMA) utilizing graphene. Through numerical simulations, our proposed GMMA demonstrates a absorption bandwidth of 3 THz (1.14 – 4.14 THz) with absorptivity exceeding 90% for both transverse magnetic (TM) and transverse electric (TE) modes. A comprehensive numerical analysis, using a transmission line equivalent circuit model, is conducted to find out the impedance components of all the corresponding layers, which can be significant to determine the impedance matching. The absorber exhibits wideband tunability, polarization insensitivity, and robust tolerance to structural variations, making it a promising candidate for diverse applications in the terahertz (THz) band especially in the antenna regime. Our proposed GMMA antenna can achieve a gain of 37.48 dB, a directivity of 32.81 dB, a return loss of -34 dB, and an efficiency of 99.96%. This research provides a valuable contribution to the development of tunable broadband GMMAs for THz frequencies, addressing the increasing demand for high-speed and efficient devices in the modern era of science and technology.

In this article, we present an innovative plasmonic lab-on-chip (LoC) sensor featuring three ports, utilizing a 1 × 2 demultiplexer to detect two separate samples without cross-contamination. The performance of the sensor is numerically investigated using the finite element method, yielding a maximum sensitivity of 865.9 nm per refractive index unit (RIU) and a figure of merit (FOM) of 58.4 in the 700-920 nm range. The proposed metal–insulator–metal (MIM) structure, incorporating a diamond-shaped silicon nanodot array with a perimeter of less than 100 nm, serves as a sensing surface, detecting changes in the refractive index (RI) of the surrounding medium. Our suggested sensor demonstrates an extraordinary transmission coefficient of around -18 dB, it surpasses classical optics predictions, and its nanoscale light confinement enhances interaction with analytes. Our LoC sensor, based on the MIM structure, achieves high accuracy and precision in measuring small RI changes, making it portable and suitable for on-site applications, and settings with limited resources. This sensor streamlines medical processes by rapidly detecting blood groups and diabetes levels with minimal sample volume, potentially improving patient care efficiency.

Recently, metamaterials and metasurface have gained rapidly increasing attention from researchers due to their extraordinary optical and electrical properties. Metamaterials are described as artificially defined periodic structures exhibiting negative permittivity and permeability simultaneously. Whereas metasurfaces are the 2D analogue of metamaterials in the sense that they have a small but not insignificant depth. Because of their high optical confinement and adjustable optical resonances, these artificially engineered materials appear as a viable photonic platform for biosensing applications. This review paper discusses the recent development of metamaterial and metasurface in biosensing applications based on the gigahertz, terahertz, and optical frequency domains encompassing the whole electromagnetic spectrum. Overlapping features such as material selection, structure, and physical mechanisms were considered during the classification of our biosensing applications. Metamaterials and metasurfaces working in the GHz range provide prospects for better sensing of biological samples, THz frequencies, falling between GHz and optical frequencies, provide unique characteristics for biosensing permitting the exact characterization of molecular vibrations, with an emphasis on molecular identification, label-free analysis, and imaging of biological materials. Optical frequencies on the other hand cover the visible and near-infrared regions, allowing fine regulation of light-matter interactions enabling metamaterials and metasurfaces to offer excellent sensitivity and specificity in biosensing. The outcome of the sensor's sensitivity to an electric or magnetic field and the resonance frequency are, in theory, determined by the frequency domain and features. Finally, the challenges and possible future perspectives in biosensing application areas have been presented that use metamaterials and metasurfaces across diverse frequency domains to improve sensitivity, specificity, and selectivity in biosensing applications.

This article presents a novel transition metal nitride (TMN)–based plasmonic pressure sensor (PPS) that utilizes a TMN-Insulator-TMN structure. Our proposed sensor is built with Zirconium Nitride (ZrN), an alternative plasmonic material that provides several benefits over conventional plasmonic metals like silver and gold. Notably, ZrN is compatible with standard Complementary Metal Oxide Semiconductor (CMOS) technology and it offers tunability of optical properties. The sensor demonstrates a maximum pressure sensitivity of 177.56 nm/MPa with a resolution of 5.63 × 10 ^-6 MPa. Furthermore, the incorporation of TMN endows the PPS with several beneficial characteristics, such as exceptional hardness, high-temperature thermal stability, optical tunability, and lower electrical resistivity which are typically absent in conventional plasmonic noble metals, limiting their practical application in plasmonic devices. Consequently, our proposed configuration outperforms the conventional noble material-based Metal-Insulator-Metal (MIM) configuration, which removes the barriers to wide-scale adaptations of plasmonic devices by paving the way for the research and development of efficient, robust, and long-lasting sensors at subwavelength scales, thereby forging a link between nanoelectronics and plasmonics.

In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electron-beam lithography (EBL), and show that this structure could be used for multilayered optical storage media capable of continuous-wave (cw) laser readout. The gold nanorods fabricated using the EBL method are aligned perfectly and homogeneous in size and shape, allowing the polarization response of surface plasmon resonance (SPR) to be observed through ensemble array. This property in turn permits polarization detuned SPR readout possible and other manipulations such as progressively twisted arrays through the multilayers to make cw readout possible through deeper layers without too much extinction loss. The layered gold nanorod arrays are separated by thick spacer layer to enable the optical resolving of individual layers. Using this method, we demonstrated four-fold reduction in extinction loss for cw readout in three-layer structure. The current technique of multilayer fabrication and readout can be useful in 3-dimensional fabrication of plasmonic circuits and structures.