The innovative terahertz biosensor described in this article is based on perfect metamaterial absorption. Because the terahertz (THz) electromagnetic (EM) wave is extremely sensitive to polar elements, including water, and reacts clearly to polar materials, it was recommended that terahertz (THz) wave electromagnetic (EM) imaging be used to diagnose basal cell carcinomas (BCCs). The proposed biosensor structure is totally capable of absorbing energy in two separate bands, 0.78 THz and 0.904 THz, respectively. The design demonstrated two significant absorption peaks with greater than 99.5% absorption. The proposed biosensor’s polarization angle, electric and magnetic field distributions, surface current distribution, and power flow have all been thoroughly studied to ensure sensitivity in discriminating between healthy skin and non-melanoma skin cancer. The electric field, magnetic field, and magnetic energy density were all thoroughly investigated as a result of utilizing microwave imaging techniques.

non-melanoma skin cancer (NMSC) is among the most prevalent forms of cancer originating in the top layer of the skin, with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) being its primary categories. While both types are highly treatable, the success of treatment hinges on early diagnosis. Early-stage NMSC detection can be achieved through clinical examination, typically involving visual inspection. An alternative, albeit invasive, method is a skin biopsy. Microwave imaging has gained prominence for non-invasive early detection of various cancers, leveraging distinct dielectric properties of healthy and malignant tissues to discriminate tumors and categorize them as benign or malignant. Recent studies demonstrate the potential of terahertz (THz) spectroscopy for detecting biomarkers by aligning electromagnetic wave frequencies in the low THz range (0.1 to 10 THz) with resonant frequencies of biomolecules, such as proteins. This study proposes an innovative microscale biosensor designed to operate in the THz range for the high-sensitivity and efficient diagnosis of non-melanoma skin cancer. By incorporating meticulously designed metamaterial layers, the sensor's absorption properties can be controlled, a critical aspect for discriminating between normal and NMSC-affected skin. In particular, the interaction between skin and THz waves, influenced by dielectric properties and unique vibrational resonances of molecules within tissue, is crucial for wave propagation and scattering. Extensive numerical studies showcased the suitability of the proposed biosensor for NMSC diagnosis, illustrated through specific case studies. These findings hold the potential to pave the way for further development of non-invasive microwave-imaging-based techniques for detecting NMSC and other types of skin cancer.

This study proposes an innovative geometry of a microstrip sensor for high-resolution microwave imaging (MWI). The main intended application of the sensor is early detection of breast, lung, and brain cancer. The proposed design consists of a microstrip patch antenna fed by a coplanar waveguide with a metamaterial (MTM) layer-based lens implemented on the back side, and an artificial magnetic conductor (AMC) realized on as a separate layer. The analysis of the AMC’s permeability and permittivity demonstrate that the structure exhibits negative epsilon (ENG) qualities near the antenna resonance point. In addition, reflectivity, transmittance, and absorption are also studied. The sensor prototype has been manufactures using the FR4 laminate. Excellent electrical and field characteristics of the structure are confirmed through experimental validation. At the resonance frequency of 4.56 GHz, the realized gain reaches 8.5 dBi, with 3.8 dBi gain enhancement contributed by the AMC. The suitability of the presented sensor for detecting brain tumors, lung cancer, and breast cancer has been corroborated through extensive simulation-based experiments performed using the MWI system model, which employs four copies of the proposed sensor, as well as the breast, lung, and brain phantoms. As demonstrated, the directional radiation pattern and enhanced gain of the sensor enable precise tumor size discrimination. The proposed sensor offers competitive performance in comparison the state-of-the-art sensors described in the recent literature, especially with respect to as gain, pattern directivity, and impedance matching, all being critical for MWI.

This research introduces an innovative design for a metamaterial-based compact multi-band biosensor aimed at early-stage cervical cancer detection. The device operates within the terahertz (THz) frequency range, specifically from zero to six THz. The proposed sensor architecture features a metamaterial layer composed of a patterned aluminum structure deposited on a polyimide substrate. The primary design objective is to optimize the geometry parameters to achieve near-perfect absorption of electromagnetic waves across the entire operating bandwidth. The design process utilizes full-wave electromagnetic simulation tools. The paper details all intermediate steps in the sensor’s topology development, guided by an investigation of the absorption characteristics of successive architectural variations. It also analyzes the effects of the substrate and resonator material. The suitability of the proposed sensor for early-stage cancer diagnosis is demonstrated using a microwave imaging (MWI) system that incorporates the device. Extensive simulation studies confirm the sensor’s capability to distinguish between healthy and cancerous cervical tissue. For further validation, comprehensive benchmarking is conducted against numerous state-of-the-art sensor designs reported in recent literature. These comparative studies indicate that the proposed sensor offers superior performance in terms of absorbance levels and the width of the operating bandwidth, both of which enhance the sensitivity of cancer detection.

This study highlights the potential of employing terahertz metamaterial structures as dual-band biosensors for the early detection of cancerous biological tissue. The fundamental principle leveraged here is the alteration of the effective dielectric constant of biological tissue by cancerous cells. The change in the dielectric constant, in turn, induces a shift in the resonance frequency of the metamaterial sensor. One notable advantage of the terahertz metamaterial sensor is its relatively compact size compared to other sensor types, as its dimensions are independent of the wavelength. This property translates into a requirement for a much smaller biopsy sample, facilitating less invasive testing procedures. Beyond the size advantage, the proposed biosensor demonstrates efficacy in detecting abnormalities within biological tissue.

Cancer remains one of the leading causes of mortality worldwide, with breast cancer being a particularly prevalent form. Projections estimate nearly 20 million new cases globally over the next two decades. Early detection is critical for effective treatment; however, conventional diagnostic techniques often lack the necessary sensitivity and specificity, with some methods being invasive and labor-intensive. Recent advancements in microwave imaging (MWI) have shown significant potential as efficient, non-invasive tools for monitoring various cancer types. MWI operating in the terahertz (THz) range has emerged as a promising approach for bio-sensing, offering the precision needed to differentiate between healthy and cancerous tissues by analyzing small-scale biological features. Among the methods for breast cancer detection, the identification and analysis of MCF-7 breast cancer cells are particularly significant. THz waves interact uniquely with the intrinsic properties of MCF-7 cells, making THz-based biosensors ideal candidates for diagnostic tools. However, many existing sensors are limited in key performance areas, including operating bandwidth and absorption efficiency. This study introduces a novel multi-band metamaterial (MTM)-based biosensor specifically designed for the detection of MCF-7 breast cancer cells. The sensor features a compact geometry composed of multiple resonators made from 200-nm-thick aluminum (Al) layers on a 50-μm-thick polyethylene terephthalate (PET) substrate. With dimensions of only 198 × 198 μm², the proposed device is exceptionally compact. It operates in the 0.5 THz to 1.6 THz frequency range and achieves near-perfect absorption rates (>99%) across multiple bandwidths. These results are achieved through precise tuning of the sensor's geometry and architectural optimization, significantly enhancing its sensitivity for cancer detection. Comprehensive validation of the sensor is performed using full-wave electromagnetic analysis, which includes evaluating electric and magnetic field distributions, surface currents, and scattering parameters. Extensive benchmarking demonstrates the device’s superior performance compared to state-of-the-art biosensors, excelling in metrics such as quality-factor, figure of merit (FOM), and absorption efficiency. Additionally, the proposed sensor has been integrated into an MWI system to evaluate its practical application. The device successfully discriminated against subtle changes in the refractive index of biological tissues, confirming its ability to detect MCF-7 cells effectively. These findings highlight the sensor's suitability as a non-invasive, early-stage diagnostic tool for breast cancer.