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  1. Hossain A, Islam R, Islam MT, Kirawanich P, Soliman MS
    Comput Biol Med, 2024 Dec;183:109316.
    PMID: 39489108 DOI: 10.1016/j.compbiomed.2024.109316
    The microwave brain imaging (MBI) system is an emerging technology used to detect brain tumors in their early stages. Multi-class microwave-based brain tumor (MBT) identification and classification are crucial due to the tumor's patterns and shape. Manual identification and categorization of the tumors from the images by physicians is a challenging task and consumes more time. Recently, to overcome these issues, the deep transfer learning (DTL) technique has been used to classify brain tumors efficiently. This paper proposes a Fine-tuned Feature Extracted Deep Transfer Learning Model called FT-FEDTL for multi-class MBT classification purposes. The main objective of this work is to suggest a better pathway for brain tumor diagnosis by designing an efficient DTL model that automatically identifies and categorizes the MBT images. The InceptionV3 architecture is utilized as a base for feature extraction in the proposed FT-FEDTL model. Thereafter, a fine-tuning method is applied to the additional five layers with hyperparameters. The fine-tuned layers are attached to the base model to enhance classification performance. The MBT data are collected from two sources and balanced by augmentation techniques to create a total of 4200 balanced datasets. Later, 80 % images are used for training, 20 % images are utilized for validation, and 80 samples of each class are used for testing the FT-FEDTL model for classifying tumors into six classes. We evaluated and compared the FT-FEDTL model with the three traditional non-CNN and seven pretrained models by applying an imbalanced and balanced dataset. The proposed model showed superior classification performance compared to other models for the balanced dataset. It attained an overall accuracy, recall, precision, specificity, and Fscore of 99.65 %, 99.16 %, 99.48 %, 99.10 %, and 99.23 %, respectively. The experimental outcomes ensure that the proposed model can be employed in biomedical applications to assist radiologists for multi-class MBT image classification purposes. The Anaconda distribution platform with Python 3.7 on the Windows 11 OS is used to implement the models.
  2. Hakim ML, Alam T, Soliman MS, Sahar NM, Baharuddin MH, Almalki SHA, et al.
    Sci Rep, 2022 Jan 10;12(1):479.
    PMID: 35013437 DOI: 10.1038/s41598-021-04236-1
    Metamaterial absorber (MMA) is now attracting significant interest due to its attractive applications, such as thermal detection, sound absorption, detection for explosive, military radar, wavelength detector, underwater sound absorption, and various sensor applications that are the vital part of the internet of things. This article proposes a modified square split ring resonator MMA for Ku-band sensing application, where the metamaterial structure is designed on FR-4 substrate material with a dielectric constant of 4.3 and loss tangent of 0.025. Perfect absorption is realized at 14.62 GHz and 16.30 GHz frequency bands, where peak absorption is about 99.99% for both frequency bands. The proposed structure shows 70% of the average absorption bandwidth of 420 MHz (14.42-14.84 GHz) and 480 MHz (16.06-16.54 GHz). The metamaterial property of the proposed structure is investigated for transverse electromagnetic mode (TEM) and achieved negative permittivity, permeability, and refractive index property for each absorption frequency band at 0°, 45°, and 90° polarization angles. Interference theory is also investigated to verify the absorption properties. Moreover, the permittivity sensor application is investigated to verify the sensor performance of the proposed structure. Finally, a comparison with recent works is performed, which shows that the proposed MMA can be a good candidate for Ku-band perfect absorber and sensing applications.
  3. Hossain A, Islam MT, Beng GK, Kashem SBA, Soliman MS, Misran N, et al.
    Sci Rep, 2022 Oct 01;12(1):16478.
    PMID: 36183039 DOI: 10.1038/s41598-022-20944-8
    In this paper, proposes a microwave brain imaging system to detect brain tumors using a metamaterial (MTM) loaded three-dimensional (3D) stacked wideband antenna array. The antenna is comprised of metamaterial-loaded with three substrate layers, including two air gaps. One 1 × 4 MTM array element is used in the top layer and middle layer, and one 3 × 2 MTM array element is used in the bottom layer. The MTM array elements in layers are utilized to enhance the performance concerning antenna's efficiency, bandwidth, realized gain, radiation directionality in free space and near the head model. The antenna is fabricated on cost-effective Rogers RT5880 and RO4350B substrate, and the optimized dimension of the antenna is 50 × 40 × 8.66 mm3. The measured results show that the antenna has a fractional bandwidth of 79.20% (1.37-3.16 GHz), 93% radiation efficiency, 98% high fidelity factor, 6.67 dBi gain, and adequate field penetration in the head tissue with a maximum of 0.0018 W/kg specific absorption rate. In addition, a 3D realistic tissue-mimicking head phantom is fabricated and measured to verify the performance of the antenna. Later, a nine-antenna array-based microwave brain imaging (MBI) system is implemented and investigated by using phantom model. After that, the scattering parameters are collected, analyzed, and then processed by the Iteratively Corrected delay-multiply-and-sum algorithm to detect and reconstruct the brain tumor images. The imaging results demonstrated that the implemented MBI system can successfully detect the target benign and malignant tumors with their locations inside the brain.
  4. Islam MR, Islam MT, Soliman MS, Baharuddin MH, Mat K, Moubark AM, et al.
    Sci Rep, 2021 Nov 05;11(1):21782.
    PMID: 34741089 DOI: 10.1038/s41598-021-01275-6
    In this research paper, an inverse double V loaded complementary square split ring resonator based double negative (DNG) metamaterial has been developed and examined numerically and experimentally. The electromagnetic (EM) properties of the proposed inverse double V-structure were calculated using computer simulation technology (CST-2019) and the finite integration technique (FIT). The designed metamaterial provides three resonance frequencies are 2.86, 5, and 8.30 GHz, covering S-, C-, and X-bands. The total size of the recommended unit cell is 8 [Formula: see text] 8 [Formula: see text] 1.524 mm3, and a high effective medium ratio (EMR) value of 13.11 was found from it. The - 10 dB bandwidths of this structure are 2.80 to 2.91, 4.76 to 5.17, and 8.05 to 8.42 GHz. The proposed structure's novelty is its small size, simple resonator structure, which provides double negative characteristics, high EMR, maximum coverage band, and required resonance frequencies. Wi-Fi network speeds are generally faster when frequencies in the 5 GHz band are used. Since the proposed structure provides a 5 GHz frequency band, hence the suggested metamaterial can be used in Wi-Fi for high bandwidth and high-speed applications. The marine radars operate in X-band, and weather radar works in S-band. Since the designed cell provides two more resonance frequencies, i.e., 2.86 GHz (S-band) and 8.30 GHz (X-band), the proposed metamaterial could be used in weather radar and marine radar. The design process and various parametric studies have been analyzed in this article. The equivalent circuit is authenticated using the advanced design system (ADS) software compared with CST simulated result. The surface current, E-field, and H-field distributions have also been analyzed. Different types of array structure, i.e., 1 [Formula: see text] 2, 2 [Formula: see text] 2, 3 [Formula: see text] 3, 4 [Formula: see text] 4, and 20 [Formula: see text] 25 is examined and validated by the measured result. The simulated and measured outcome is an excellent agreement for the inverse double V loaded CSSRR unit cell and array. We showed the overall performance of the suggested structure is better than the other structures mentioned in the paper. Since the recommended metamaterial unit cell size is small, provides desired resonance frequency, gives a large frequency band and high EMR value; hence the suggested metamaterial can be highly applicable for Radar and Wi-Fi.
  5. Jain P, Chhabra H, Chauhan U, Prakash K, Gupta A, Soliman MS, et al.
    Sci Rep, 2023 Jan 31;13(1):1792.
    PMID: 36720922 DOI: 10.1038/s41598-023-29024-x
    A hepta-band terahertz metamaterial absorber (MMA) with modified dual T-shaped resonators deposited on polyimide is presented for sensing applications. The proposed polarization sensitive MMA is ultra-thin (0.061 λ) and compact (0.21 λ) at its lowest operational frequency, with multiple absorption peaks at 1.89, 4.15, 5.32, 5.84, 7.04, 8.02, and 8.13 THz. The impedance matching theory and electric field distribution are investigated to understand the physical mechanism of hepta-band absorption. The sensing functionality is evaluated using a surrounding medium with a refractive index between 1 and 1.1, resulting in good Quality factor (Q) value of 117. The proposed sensor has the highest sensitivity of 4.72 THz/RIU for glucose detection. Extreme randomized tree (ERT) model is utilized to predict absorptivities for intermediate frequencies with unit cell dimensions, substrate thickness, angle variation, and refractive index values to reduce simulation time. The effectiveness of the ERT model in predicting absorption values is evaluated using the Adjusted R2 score, which is close to 1.0 for nmin = 2, demonstrating the prediction efficiency in various test cases. The experimental results show that 60% of simulation time and resources can be saved by simulating absorber design using the ERT model. The proposed MMA sensor with an ERT model has potential applications in biomedical fields such as bacterial infections, malaria, and other diseases.
  6. Khalil MA, Yong WH, Islam MT, Hoque A, Islam MS, Leei CC, et al.
    Sci Rep, 2023 May 05;13(1):7373.
    PMID: 37147337 DOI: 10.1038/s41598-023-34514-z
    Metamaterials have gained much attention due to their exciting characteristics and potential uses in constructing valuable technologies. This paper presents a double negative square resonator shape metamaterial sensor to detect the material and its thickness. An innovative double-negative metamaterial sensor for microwave sensing applications is described in this paper. It has a highly sensitive Q-factor and has good absorption characteristics approximately equal to one. For the metamaterial sensor, the recommended measurement is 20 by 20 mm. Computer simulation technology (C.S.T.) microwave studios are used to design the metamaterial structure and figure out its reflection coefficient. Various parametric analyses have been performed to optimize the design and size of the structure. The experimental and theoretical results are shown for a metamaterial sensor that is attached to five different materials such as, Polyimide, Rogers RO3010, Rogers RO4350, Rogers RT5880, and FR-4. A sensor's performance is evaluated using three different thicknesses of FR-4. There is a remarkable similarity between the measured and simulated outcomes. The sensitivity values for 2.88 GHz and 3.5 GHz are 0.66% and 0.19%, respectively, the absorption values for both frequencies are 99.9% and 98.9%, respectively, and the q-factor values are 1413.29 and 1140.16, respectively. In addition, the figure of merit (FOM) is analyzed, and its value is 934.18. Furthermore, the proposed structure has been tested against absorption sensor applications for the purpose of verifying the sensor's performance. With a high sense of sensitivity, absorption, and Q-factor, the recommended sensor can distinguish between thicknesses and materials in various applications.
  7. Moniruzzaman M, Islam MT, Hossain I, Soliman MS, Samsuzzaman M, Almalki SHA
    Sci Rep, 2021 Nov 08;11(1):21842.
    PMID: 34750440 DOI: 10.1038/s41598-021-01266-7
    In this paper, a tuned metamaterial (MTM) consisting of a symmetric split ring resonator is presented that exhibits epsilon negative (ENG), near zero permeability and refractive index properties for multiband microwave applications. The proposed metamaterial is constituted on a Rogers (RT-5880) substrate with 1.57 mm thickness and the electrical dimension of 0.14λ × 0.14λ, where wavelength, λ is calculated at 4.2 GHz. The symmetric resonating patch is subdivided into four equal and similar quartiles with two interconnecting split rings in each quartile. The quartiles are connected at the center of the substrate with a square metal strip with which four tuning metal strips are attached. These tuning metal strips are acted as spacers between four quartiles of the resonator patch. Numerical simulation of the proposed design is executed in CST microwave studio. The proposed MTM provides four resonances of transmission coefficient (S21) at 4.20 GHz, 10.14 GHz, 13.15 GHz, and 17.1 GHz covering C, X and Ku bands with negative permittivity, near zero permeability and refractive index. The calculated effective medium ratio (EMR) is 7.14 at 4.2 GHz indicates its compactness. The resonance frequencies are selective in nature which can be easily tuned by varying the length of the tuning metal stubs. The equivalent circuit of the proposed MTM is modelled in Advanced Design Software (ADS) that exhibits a similar S21 compared with CST simulation. Surface current, electric and magnetic fields are analyzed to explain the frequency tuning property and other performances of the MTM. Compact size, ENG with near zero permeability and refractive index along with frequency selectivity through tuning provides flexibility for frequency selective applications of this MTM in wireless communications.
  8. Ullah N, Islam MS, Hoque A, Alzamil A, Soliman MS, Islam MT
    Sci Rep, 2024 Aug 16;14(1):19000.
    PMID: 39152247 DOI: 10.1038/s41598-024-69976-2
    This article presents a compact, wide-angle, polarization-insensitive metamaterial harvester that can efficiently harvest electromagnetic (EM) energy in the S, C, X, and Ku bands. The harvester's unit cell consists of a split ring resonator, two strip lines, and two split strip lines, giving it a total size of (10 × 10) mm2. Each split gap is filled with a 50 Ω resistive load. The input impedance of the harvester is precisely designed to match that of free space, allowing for efficient absorption of EM power and appropriate redirection towards the resistive loads. The harvester's performance is also evaluated for various polarization and incident angles, considering the Transverse Electric and Transverse Magnetic modes. The simulation results reveal that the proposed harvester exhibits a notably greater conversion efficiency of around > 95%. The simulation outcomes were carefully validated through experimental tests conducted in an anechoic chamber using a 3 × 3 cell array of the proposed design. This ensured the accuracy and reliability of the results. The strong correlation between the experimental data and the full-wave simulations strongly supports the effectiveness of the proposed harvester. Therefore, the demonstrated efficiency and compact size make it a perfect fit for energy harvesting systems in wireless sensor networks.
  9. Mahmud S, Chowdhury AR, Hannan S, Tariqul Islam M, Alshammari AS, Soliman MS
    Heliyon, 2024 Dec 15;10(23):e40102.
    PMID: 39669167 DOI: 10.1016/j.heliyon.2024.e40102
    In this paper, we present an unprecedented metamaterial absorber design exhibiting exceptional characteristics in electromagnetic wave absorption. The proposed bent Y-shaped structure, fabricated on an FR-4 substrate with copper patches, showcases remarkable performance across a diverse frequency spectrum. Through exhaustive simulations in CST, this design manifests eight distinct resonant frequencies, achieving absorption rates exceeding 90 % at each resonance. The resonances, strategically spanning from L-band (3.728 GHz) through S-band, C-band, X-band, Ku-band, and K-band up to 22.664 GHz, signify unparalleled versatility and efficacy in mitigating electromagnetic radiation. It investigates the equivalent circuit parameters of a proposed metamaterial absorber design, focusing on inductance (L), capacitance (C), and resistance (R). This paper investigates the applications of UWB devices at 3.728 GHz and Doppler navigation aids at the 13.4 GHz frequency as regulated by the Federal Communications Commission. It includes a discussion on near-zero refractive Index Metamaterials (NZRIM), highlighting their potential utilization in achieving extraordinary control over wave behaviour. Notably, the absorber's inherent polarization insensitivity fortifies its adaptability in various applications. Additionally, the metamaterial exhibits near-zero or negative permittivity, altering electric response, while simultaneously demonstrating permeability absolute zero throughout all frequency bands sparking new avenues for exploration and challenging conventional electromagnetic theories.
  10. Mohammed SH, Singh MSJ, Al-Jumaily A, Islam MT, Islam MS, Alenezi AM, et al.
    PLoS One, 2025;20(1):e0316536.
    PMID: 39869576 DOI: 10.1371/journal.pone.0316536
    Modernizing power systems into smart grids has introduced numerous benefits, including enhanced efficiency, reliability, and integration of renewable energy sources. However, this advancement has also increased vulnerability to cyber threats, particularly False Data Injection Attacks (FDIAs). Traditional Intrusion Detection Systems (IDS) often fall short in identifying sophisticated FDIAs due to their reliance on predefined rules and signatures. This paper addresses this gap by proposing a novel IDS that utilizes hybrid feature selection and deep learning classifiers to detect FDIAs in smart grids. The main objective is to enhance the accuracy and robustness of IDS in smart grids. The proposed methodology combines Particle Swarm Optimization (PSO) and Grey Wolf Optimization (GWO) for hybrid feature selection, ensuring the selection of the most relevant features for detecting FDIAs. Additionally, the IDS employs a hybrid deep learning classifier that integrates Convolutional Neural Networks (CNN) and Long Short-Term Memory (LSTM) networks to capture the smart grid data's spatial and temporal features. The dataset used for evaluation, the Industrial Control System (ICS) Cyber Attack Dataset (Power System Dataset) consists of various FDIA scenarios simulated in a smart grid environment. Experimental results demonstrate that the proposed IDS framework significantly outperforms traditional methods. The hybrid feature selection effectively reduces the dimensionality of the dataset, improving computational efficiency and detection performance. The hybrid deep learning classifier performs better in key metrics, including accuracy, recall, precision, and F-measure. Precisely, the proposed approach attains higher accuracy by accurately identifying true positives and minimizing false negatives, ensuring the reliable operation of smart grids. Recall is enhanced by capturing critical features relevant to all attack types, while precision is improved by reducing false positives, leading to fewer unnecessary interventions. The F-measure balances recall and precision, indicating a robust and reliable detection system. This study presents a practical dual-hybrid IDS framework for detecting FDIAs in smart grids, addressing the limitations of existing IDS techniques. Future research should focus on integrating real-world smart grid data for validation, developing adaptive learning mechanisms, exploring other bio-inspired optimization algorithms, and addressing real-time processing and scalability challenges in large-scale deployments.
  11. Hasan MM, Islam MT, Samsuzzaman M, Baharuddin MH, Soliman MS, Alzamil A, et al.
    Sci Rep, 2022 Jun 08;12(1):9433.
    PMID: 35676407 DOI: 10.1038/s41598-022-13522-5
    This work proposes a compact metasurface (MS)-integrated wideband multiple-input multiple-output (MIMO) antenna for fifth generation (5G) sub-6 GHz wireless communication systems. The perceptible novelty of the proposed MIMO system is its wide operating bandwidth, high gain, lower interelement gap, and excellent isolation within the MIMO components. The radiating patch of the antenna is truncated diagonally with a partially ground plane, and a metasurface has been employed for enhancing the antenna performance. The suggested MS integrated single antenna prototype has a miniature dimension of 0.58λ × 0.58λ × 0.02λ. The simulated and measured findings demonstrate a wideband characteristic starting from 3.11 to 7.67 GHz including a high realized gain of 8 dBi. The four-element MIMO system has been designed by rendering each single antenna orthogonally to one another while retaining compact size and wideband properties between 3.2 and 7.6 GHz. The suggested MIMO prototype has been designed and fabricated on a low loss Rogers RT5880 substrate with a miniature dimension of 1.05λ × 1.05λ × 0.02λ and its performance is evaluated using a suggested 10 × 10 array of a square enclosed circular split ring resonators within the same substrate material. The inclusion of the proposed metasurface with a backplane significantly reduces antenna backward radiation and manipulates the electromagnetic field, thus improving the bandwidth, gain and isolation of MIMO components. The suggested 4-port MIMO antenna offers a high realized gain of 8.3 dBi compared to existing MIMO antennas with an excellent average total efficiency of 82% in the 5G sub-6 GHz spectrum and is in good accordance with measured results. Furthermore, the developed MIMO antenna exhibits outstanding diversity characteristics in respect of envelope correlation coefficient (ECC) less than 0.004, diversity gain (DG) close to 10 dB (> 9.98 dB) and high isolation between MIMO components (> 15.5 dB). Therefore, the proposed MS-inspired MIMO antenna substantiates its applicability for 5G sub-6 GHz communication networks.
  12. Hasan MM, Islam MT, Rahim SKA, Alam T, Rmili H, Alzamil A, et al.
    Materials (Basel), 2023 Feb 20;16(4).
    PMID: 36837381 DOI: 10.3390/ma16041751
    This article demonstrates a compact wideband four-port multiple-input-multiple-output (MIMO) antenna system integrated with a wideband metamaterial (MM) to reach high gain for sub-6 GHz new radio (NR) 5G communication. The four antennas of the proposed MIMO system are orthogonally positioned to the adjacent antennas with a short interelement edge-to-edge distance (0.19λmin at 3.25 GHz), confirming compact size and wideband characteristics 55.2% (3.25-5.6 GHz). Each MIMO system component consists of a fractal slotted unique patch with a transmission feed line and a metal post-encased defected ground structure (DGS). The designed MIMO system is realized on a low-cost FR-4 printed material with a miniature size of 0.65λmin × 0.65λmin × 0.02λmin. A 6 × 6 array of double U-shaped resonator-based unique mu-near-zero (MNZ) wideband metamaterial reflector (MMR) is employed below the MIMO antenna with a 0.14λmin air gap, improving the gain by 2.8 dBi and manipulating the MIMO beam direction by 60°. The designed petite MIMO system with a MM reflector proposes a high peak gain of 7.1 dBi in comparison to recent relevant antennas with high isolation of 35 dB in the n77/n78/n79 bands. In addition, the proposed wideband MMR improves the MIMO diversity and radiation characteristics with an average total efficiency of 68% over the desired bands. The stated MIMO antenna system has an outstanding envelope correlation coefficient (ECC) of <0.045, a greater diversity gain (DG) of near 10 dB (>9.96 dB), a low channel capacity loss (CCL) of <0.35 b/s/Hz and excellent multiplexing efficiency (ME) of higher than -1.4 dB. The proposed MIMO concept is confirmed by fabricating and testing the developed MIMO structure. In contrast to the recent relevant works, the proposed antenna is compact in size, while maintaining high gain and wideband characteristics, with strong MIMO performance. Thus, the proposed concept could be a potential approach to the 5G MIMO antenna system.
  13. Sakib S, Hoque A, Rahim SKBA, Singh M, Sahar NM, Islam MS, et al.
    Materials (Basel), 2023 Jan 30;16(3).
    PMID: 36770180 DOI: 10.3390/ma16031172
    This paper reports a central spiral split-rectangular-shaped metamaterial absorber surrounded by a polarization-insensitive ring resonator for s-band applications. The rated absorption is 99.9% at 3.1 GHz when using a three-layer structure where the top and ground are made of copper and the center dielectric material is a commonly used FR-4 substrate. The central split gaps have an impact on the unit cell by increasing high absorption, and an adequate electric field is apparent in the outer split ring gap. At 3.1 GHz, the permittivity and permeability are negative and positive, respectively, so the proposed unit cell acts as an epsilon negative (ENG) metamaterial absorber. In a further analysis, Roger4450B was used as a substrate and obtained excellent absorption rates of 99.382%, 99.383%, 99.91%, and 95.17% at 1.44, 3.96, 4.205, and 5.025 GHz, respectively, in the S- and C-band regions. This unit cell acts as a single negative metamaterial (SNG) absorber at all resonance frequencies. The S11 and S21 parameters for FR-4 and Rogers4450B were simulated while keeping the polarization angle (θ and φ) at 15, 30, 45, 60, 75, and 90 degrees to measure, permittivity, permeability, reflective index, absorption, and reflection. The values of the reflective index are near zero. Near-zero reflective indexes (NZRI) are widely used in antenna gain propagation. The unit cell fabricated for the FR-4 substrate attained 99.9% absorption. S-band values in the range of (2-4) GHz can be applied for low-frequency radar detection.
  14. Rahman AAM, Islam MT, Moniruzzaman M, Rahim SKA, Singh M, Misran N, et al.
    Sci Rep, 2023 Sep 24;13(1):15943.
    PMID: 37743360 DOI: 10.1038/s41598-023-43182-y
    In this article, a unique metamaterial (MTM) structure is presented that exhibits four resonances of transmission coefficient (S21) that fall into S, X, and Ku bands. The MTM design is initiated on a Rogers (RT5880) substrate with an electrical dimension of 0.088 λ × 0.088 λ (λ is calculated at 3.424 GHz). The resonating patch contains four quartiles connected by a central metallic strip. The placement of each quartile is such that the whole resonator is mirror symmetric about the vertical axis. Two H-shaped modifiers connect two quartiles of each vertical half of the resonator. These H-shaped modifiers form the resonance cavity in its vicinity, and thus help significantly to orient the overall resonances of the proposed MTM at 3.424 GHz, 10 GHz, 14.816 GHz, and 16.848 GHz. The resonance phenomena are examined through equivalent circuit modeling and verified in Advanced Design Software (ADS). Metamaterial properties of the proposed MTM are extracted and it exhibits negative permittivity, permeability, and refractive index. The prototype of the MTM is fabricated and measurement is taken. The measured S21 shows a close similarity with the simulated result. Moreover, effective medium ratio (EMR) is calculated for the proposed MTM and a high EMR of 10.95 is obtained that expresses its compactness. This compact MTM with negative permittivity, permittivity, and refractive index can be important component for improving the performance of the miniaturized devices for multi-band wireless communication systems.
  15. Bansal S, Jain A, Kumar S, Kumar A, Kumar PR, Prakash K, et al.
    Sci Rep, 2024 Nov 15;14(1):28230.
    PMID: 39548271 DOI: 10.1038/s41598-024-79727-y
    This research explores the design of an infrared (IR) photodetector using mercury cadmium telluride (Hg1-xCdxTe). It proposes two- and three-dimensional homojunction models based on p+-Hg0.7783Cd0.2217Te/n--Hg0.7783Cd0.2217Te, focusing on applications in the long-wavelength infrared range. The photodetector's performance is analyzed using Silvaco ATLAS TCAD software and compared with analytical calculations based on drift-diffusion, tunneling, and Chu's approximation techniques. Optimized for operation at 10.6 μm wavelength under liquid nitrogen temperature, the proposed photodetector demonstrates promising optoelectronic characteristics including the dark current density of 0.20 mA/cm2, photocurrent density of 4.98 A/cm2, and photocurrent density-to-dark current density ratio of 2.46 × 104, a 3-dB cut-off frequency of 104 GHz, a rise time of 0.8 ps, quantum efficiency of 58.30 %, peak photocurrent responsivity of 4.98 A/W, specific detectivity of 3.96 × 1011 cmHz1/2/W, and noise equivalent power of 2.52 × 10-16 W/Hz1/2 indicating its potential for low-noise, high-frequency and fast-switching applications. The study also incorporates machine learning regression models to validate simulation results and provide a predictive framework for performance optimization, evaluating these models using various statistical metrics. This comprehensive approach demonstrates the synergy between advanced materials science and computational techniques in developing next-generation optoelectronic devices. By combining theoretical modeling, simulation, and machine learning, the research highlights the potential to accelerate progress in IR detection technology and enhance device performance and efficiency. This multidisciplinary methodology could serve as a model for future studies in optoelectronics, illustrating how advanced materials and computational methods can be utilized to enhance device capabilities.
  16. Khalil MA, Yong WH, Batool T, Hoque A, Chiong LY, Goh HH, et al.
    Sci Rep, 2025 Jan 17;15(1):2283.
    PMID: 39825064 DOI: 10.1038/s41598-025-85800-x
    This research presents the design and analysis of a compact metamaterial (MTM)-based star-shaped split-ring resonator (SRR) enclosed in a square, constructed on a cost-effective substrate for liquid chemical sensing applications. The designed structure has dimensions of 10 × 10 mm2 and is optimized for detecting adulteration in edible oils. When the sample holder is filled with different percentages of oil samples, the resonance frequency of the MTM-based SRR sensor shift significantly. The measured results demonstrate that the proposed SRR sensor is superior in terms of sensitivity and quality factor compared to studies in the literature. The proposed sensor shows superior performance in sensitivity and quality factor (Q-factor) compared to existing sensors in the literature. It exhibits a remarkable sensitivity of 0.92 with a frequency shift of 760 MHz for adulteration detection, which is higher than sensors with shifts ranging from 140 to 600 MHz reported in previous studies. Additionally, the design has a high Q-factor of 149, indicating its efficiency in determining adulteration in edible oils. Additionally, the error rate in detecting adulteration is minimal at 3.1%, a significant improvement over prior sensors, which have error rates as high as 8%. These enhancements highlight the sensor's potential in applications requiring precise, efficient, and cost-effective detection of edible oil adulteration, thus offering a significant advancement in both performance and practical utility over traditional methods.
  17. Soliman MM, Islam MT, Chowdhury MEH, Alqahtani A, Musharavati F, Alam T, et al.
    J Mater Chem B, 2023 Nov 15;11(44):10507-10537.
    PMID: 37873807 DOI: 10.1039/d3tb01469j
    The UK's National Joint Registry (NJR) and the American Joint Replacement Registry (AJRR) of 2022 revealed that total hip replacement (THR) is the most common orthopaedic joint procedure. The NJR also noted that 10-20% of hip implants require revision within 1 to 10 years. Most of these revisions are a result of aseptic loosening, dislocation, implant wear, implant fracture, and joint incompatibility, which are all caused by implant geometry disparity. The primary purpose of this review article is to analyze and evaluate the mechanics and performance factors of advancement in hip implants with novel geometries. The existing hip implants can be categorized based on two parts: the hip stem and the joint of the implant. Insufficient stress distribution from implants to the femur can cause stress shielding, bone loss, excessive micromotion, and ultimately, implant aseptic loosening due to inflammation. Researchers are designing hip implants with a porous lattice and functionally graded material (FGM) stems, femur resurfacing, short-stem, and collared stems, all aimed at achieving uniform stress distribution and promoting adequate bone remodeling. Designing hip implants with a porous lattice FGM structure requires maintaining stiffness, strength, isotropy, and bone development potential. Mechanical stability is still an issue with hip implants, femur resurfacing, collared stems, and short stems. Hip implants are being developed with a variety of joint geometries to decrease wear, improve an angular range of motion, and strengthen mechanical stability at the joint interface. Dual mobility and reverse femoral head-liner hip implants reduce the hip joint's dislocation limits. In addition, researchers reveal that femoral headliner joints with unidirectional motion have a lower wear rate than traditional ball-and-socket joints. Based on research findings and gaps, a hypothesis is formulated by the authors proposing a hip implant with a collared stem and porous lattice FGM structure to address stress shielding and micromotion issues. A hypothesis is also formulated by the authors suggesting that the utilization of a spiral or gear-shaped thread with a matched contact point at the tapered joint of a hip implant could be a viable option for reducing wear and enhancing stability. The literature analysis underscores substantial research opportunities in developing a hip implant joint that addresses both dislocation and increased wear rates. Finally, this review explores potential solutions to existing obstacles in developing a better hip implant system.
  18. Soliman MM, Islam MT, Alam T, Misran N, Abdul Rahim SK, Alzamil A, et al.
    Nanoscale, 2023 Aug 10;15(31):12972-12994.
    PMID: 37477438 DOI: 10.1039/d3nr01941a
    Developing a meta-structure with near-unity absorbance in the visible and infrared spectra for solar energy harvesting, photodetection, thermal imaging, photo-trapping, and optical communications is a long-term research challenge. This research presents a four-layered (insulator-metal-insulator-metal) meta-structure unit cell that showed a peak absorbance of 99.99% at 288-300 nm and the average absorbance of 99.18% over the 250-2000 nm wavelength range in TE and TM modes, respectively. The symmetric pattern of the resonator layer shows polarization insensitivity with an average absorption of 99.18% in both TE and TM modes. Furthermore, the proposed design shows a wide incident angle stability up to ≤60 degrees in both TE and TM modes. The proposed structure also exhibits negative index properties at 288-300 nm and 1000-2000 nm, respectively. The negative index properties of the proposed design generate an anti-parallel surface current flow in the ground and resonator layers, which induces magnetic and electric field resonance and increases absorption. The performance of the proposed design is further validated by the interference theory model and a zero value for the polarization conversion ratio (PCR). The electric field E, magnetic field H, and current distribution are analyzed to explain the absorption mechanism of the proposed meta-structure unit cell. It also exhibits the highest photo-thermal conversion efficiency of 99.11%, demonstrating the viability of the proposed design as a solar absorber. The proposed design promises potentially valuable applications such as solar energy harvesting, photodetection, thermal imaging, photo-trapping, and optical communications because of its decent performance.
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