A novel multiband terahertz (THz) refractive index-based carcinoma sensor is designed and investigated in this paper. The proposed THz sensor is constructed using meandered sectoral stubs enclosed in a square loop. The proposed sensor has a footprint of 1.019 λeff× 1.019 λeff and operates at three distinct frequencies, viz. 1.095 THz, 2.865 THz, and 4.065 THz. The absorption characteristics of the sensor are analyzed to estimate the performance of the proposed sensor. The free space absorptivity is estimated as 99.6%, 99.1% and 99.2% at the said three resonant frequencies. The peak Q factor of 22.58 is realized at 4.065 THz under free space unloaded condition. Further, a study on different design parameters on absorption peaks and polarization independency is conducted and the results are presented. Followed by these, the sensitivity performance of the proposed carcinoma THz sensor is analyzed for healthy and cancerous cells of blood, skin and breast based on their unique refractive index profile. The peak sensitivity of 514.28 GHz/RIU at 2.865 THz, 476.35 GHz/RIU at 4.065 THz, and 476.91 GHz/RIU at 4.065 THz is theoretically observed for blood, skin and breast cancer cells respectively. Similarly, the high Q factor of 21.85, 18.06, 19.21 at 4.065 THz with FoM of 2.8, 2.38 and 2.384 are also observed for blood, skin and breast cancer respectively. Furthermore, the influence of the sample thickness on the THz sensor performance is analyzed. Thus, the proposed THz sensor is a promising entity for the detection and early diagnosis of cancer cells using THz radiation.

In this paper, a graphene-based THz metamaterial has been designed and characterized for use in sensing various refractive index profiles. The proposed single-band THz sensor was constructed using a graphene-metal hybridized periodic metamaterial wherein the unit cell had a footprint of 1.395λ_eff × 1.395λ_eff and resonated at 4.4754 THz. The realized peak absorption was 98.88% at 4.4754 THz. The sensitivity of the proposed metamaterial sensor was estimated using the absorption characteristics of the unit cell. The performance of the sensor was analyzed under two different categories, viz. the random dielectric loading and chemical analytes, based on the refractive index. The proposed THz sensor offered a peak sensitivity of 22.75 GHz/Refractive Index Unit (RIU) for the various sample loadings. In addition, the effect of the sample thickness on the sensor performance was analyzed and the results were presented. From the results, it can be inferred that the proposed metamaterial THz sensor that was based on a refractive index is suitable for THz sensing applications.

This study describes the design and characterization of a highly sensitive THz refractive index-based metamaterial sensor for the detection of biological samples. The proposed ultra-miniaturized THz sensor is constructed using a fan-shaped resonator enclosed within a square loop. The proposed sensor has a footprint of 0.353 $\lambda$ _eff × 0.353 $\lambda$ _eff where $\lambda$ _eff is the wavelength calculated at the operating frequency of 4.87 THz. The sensitivity of the THz sensor is estimated using the absorption characteristics of the metamaterial. The estimated free space absorptivity is 99.9%. The proposed sensor is polarization insensitive due to the rotational symmetry and it is angularly stable up to 60°. The performance of the sensor is evaluated for different materials and biomedical samples. The results indicate that the proposed sensor has an average sensitivity of 1936 GHz/ Refractive Index Unit (RIU). Furthermore, the influence of the sample thickness is analysed, and the results are presented. From the results, it is inferred that the proposed THz sensor has a good Figure of Merit (FoM) and is suitable for chemical sensing, including the nucleic acids and other components present in the biological samples.

A novel miniaturized and highly sensitive terahertz (THz) sensor is designed and analyzed in this article. For material sensing applications, a unique resonator, consisting of spokes and a hexagonal rim, is proposed. The footprint of the designed resonator is 0.67 $\lambda_{\text{eff}}$ $\times$ 0.67 $\lambda_{\text{eff}}$ , where $\lambda_{\text{eff}}$ represents the effective wavelength calculated at 7.16 THz. The sensitivity of the proposed metamaterial unit cell sensor is determined by analyzing its absorption characteristics. The proposed sensor demonstrates 99.9% absorptivity in free space and remains insensitive to polarization variations due to its geometry, which has rotational symmetry. The sensor is found to be angularly stable for oblique incidences up to 60 $^{\circ}$ . Various analytes with different refractive indices are used to study the sensing performance, and the mean sensitivity is estimated to be 1.37 THz/refractive index unit (RIU). Furthermore, the impact of thickness of the analyte is examined, and the average deviation is estimated to be 59 GHz/ $\mu$ m. From the achieved results, it can be concluded that the proposed THz metamaterial unit cell is well suited for material sensing applications.

This paper discusses the design, characterization and analysis of an ultra-miniaturized and highly sensitive metamaterial THz sensor for material sense. A novel spin-shaped resonator integrated with hexagonal is designed as an absorber to perform material sensing operations. The footprint of the proposed sensor is 0.67λeff × 0.67λ_eff where λ_eff is the effective wavelength calculated at 7.16 THz. The proposed THz sensor is analyzed based on the absorption characteristics by estimating the sensitivity of the metamaterial sensor. The proposed sensor offers 99.9% absorptivity under free-space conditions. The proposed THz sensor exhibits rotational symmetry and hence it is insensitive to polarization changes. Furthermore, the proposed sensor is angularly stable for oblique incidences up to 60˚. The sensor performance is estimated for different refractive indices of various analytes and the average sensitivity is estimated as 1.37 THz/Refractive Index Unit (RIU). The impact of the thickness of the analyte is analyzed and the average deviation of 59 GHz/µm is reported. Thus, it is concluded that the proposed metamaterial THz sensor is best suitable for different material sensing applications.