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A double SAW resonator system was developed as a novel method for gas sensing applications. The proposed system was investigated for hydrogen sensing. Commercial Surface Acoustic Wave (SAW) resonators with resonance frequencies of 433.92 MHz and 433.42 MHz were employed in the double SAW resonator system configuration. The advantages of using this configuration include its ability for remote measurements, and insensitivity to vibrations and other external disturbances. The sensitive layer is composed of functionalized multiwalled carbon nanotubes and polyaniline nanofibers which were deposited on pre-patterned platinum metal electrodes fabricated on a piezoelectric substrate. This was mounted into the DSAWR circuit and connected in parallel. The sensor response was measured as the difference between the resonance frequencies of the SAW resonators, which is a measure of the gas concentration. The sensor showed good response towards hydrogen with a minimum detection limit of 1%. [ABSTRACT FROM AUTHOR]

The transmission mechanism of artificial flapping-wing drones generally needs low weight and the fewest interconnecting components, making their development challenging. The four-bar Linkage mechanism for flapping actuation has generally been used till now with complex and heavy connecting designs, but our proposed novel perpendicularly organized 3-cylindrical joint mechanism is designed to be unique and lighter weight with smooth functioning performance. The proposed prototype transforms the rotary motion of the motor into a specific angle of flapping movement, where the dimensions and specifications of the design components are proportional to the obtained flapping angle. Power consumption and flapping actuation can be monitored by adjusting the motor's rotational speed to control the individual wing in this mechanism. The proposed mechanism consists of a crank with three slightly slidable cylindrical joints perpendicularly arranged to each other with a specified distance in a well-organized pattern to produce a flapping movement at the other end. In order to examine the kinematic attributes, a mathematical process approach is formulated, and kinematic simulations are performed using SIMSCAPE multibody MATLAB, PYTHON programming and COMPMECH GIM software. The proposed invention's real-time test bench prototype model is designed, tested and analyzed for flapping validation. [ABSTRACT FROM AUTHOR]

This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator (SRR) for microwave sensors that operates at a resonance frequency around 5 GHz. The sensor consists of a microstrip transmission line loaded with two elements of rectangular SRR on both sides. The proposed metamaterial sensors were designed and fabricated on Rogers RT5880 substrate having dielectric constant of 2.2 and thickness of 0.787 mm. The final dimension of the proposed sensor was measured at 35 x 14 mm². Measured results show good agreement with simulated ones as well as exhibiting high Q-factor for use in sensing application. A remarkably shift of resonance frequency is observed upon introduction of several sample with different dielectric value. [ABSTRACT FROM AUTHOR]

A gas sensor array was developed in a 10 × 10 mm2 space using Screen Printing and Pulse Laser Ablation Deposition (PLAD) techniques. Heater, electrode, and an insulator interlayer were printed using the screen printing method on an alumina substrate, while tin oxide and platinum films, as sensing and catalyst layers, were deposited on the electrode at room temperature using the PLAD method, respectively. To ablate SnO2 and Pt targets, depositions were achieved by using a 1,064 nm Nd-YAG laser, with a power of 0.7 J/s, at different deposition times of 2, 5 and 10 min, in an atmosphere containing 0.04 mbar (4 kPa) of O2. A range of spectroscopic diffraction and real space imaging techniques, SEM, EDX, XRD, and AFM were used in order to characterize the surface morphology, structure, and composition of the films. Measurement on the array shows sensitivity to some solvent and wood smoke can be achieved with short response and recovery times. [ABSTRACT FROM AUTHOR]

Research into surface acoustic wave (SAW) devices began in the early 1970s and led to the development of high performance, small sizes and high reproducibility devices. Much research has now been done on the application of such devices to consumer electronics, process monitoring, and communication systems. The use of novel materials, such as gallium phosphate (GaPO4), extends the operating temperature of the elements. SAW devices based on this material operating at 434 MHz and up 800°C, can be used for passive wireless sensor applications. Interdigital transducer (IDT) devices with platinum/zirconium metallization and 1.4 μm finger-gap ratio of 1:1 have been fabricated using direct write e-beam lithography and a lift-off process. The performance and long-term stability of these devices has been studied, and the results are reported in this paper. [ABSTRACT FROM AUTHOR]

Research into surface acoustic wave (SAW) devices began in the early 1970s and led to the development of high performance, small sizes and high reproducibility devices. Much research has now been done on the application of such devices to consumer electronics, process monitoring, and communication systems. The use of novel materials, such as gallium phosphate (GaPO4), extends the operating temperature of the elements. SAW devices based on this material operating at 434 MHz and up 800°C, can be used for passive wireless sensor applications. Interdigital transducer (IDT) devices with platinum/zirconium metallization and 1.4 μm finger-gap ratio of 1:1 have been fabricated using direct write e-beam lithography and a lift-off process. The performance and long-term stability of these devices has been studied, and the results are reported in this paper. [ABSTRACT FROM AUTHOR]

Various doping materials, such as MWCNTs, graphene nanoflakes and MXene, have been doped into TiO 2 and the hydrogen sensing properties investigated. Using a similar volume, MWCNTs (5 wt.%) and graphene nanoflakes (5 wt.%) and MXene (10 wt.%) were added to TiO 2 and prepared in a paste form by mixing the sensing material with the organic binder. The sensing film was deposited on an alumina substrate using a screen-printing technique and annealed at 500 °C for 30 min in ambient air. The crystallinity of TiO 2 and the doped material in the sensing film after the annealing treatment were verified using FESEM, EDX, XRD and Raman Spectroscopy. By depositing an interdigitated electrode at the bottom of the sensing film, the thick film gas sensors (TiO 2 /MWCNT, TiO 2 /Gr, TiO 2 /MXene) were exposed to 100–1000 ppm of hydrogen at an operating temperature of 100–250 °C. The responses showed that the addition of MWCNTs and MXene to TiO 2 reduced the operating temperature of the TiO 2 gas sensor from 150 °C to 100 °C, while the addition of graphene nanoflakes did not affect the operating temperature of the TiO 2 gas sensor. The TiO 2 /MWCNT gas sensor showed linear sensitivity as hydrogen concentrations increased for operating temperatures of 100–250 °C. The optimal operating temperature for TiO 2 /MXene occurred at 100 °C, while the optimal operating temperature for the TiO 2 /Gr gas sensor occurred at 200 °C. The highest sensitivity for 100–500 ppm hydrogen was generated by the TiO 2 /MXene gas sensor, and for 600–1000 ppm hydrogen was generated by the TiO 2 /MWCNT gas sensor at an operating temperature of 250 °C. The TiO 2 /MWCNT gas sensor produced the highest sensitivity to hydrogen at the operating temperature of 250 °C with sensitivity values of approximately 6.36, 33.61, 67.64, 102.23 and 159.07 for 100, 300, 500, 700 ppm and 1000 ppm of hydrogen, respectively. • TiO 2 thick film gas sensors with the addition of MWCNTs/graphene nanoflakes/MXene were fabricated using screen-printing technology. • Addition of MWCNTs and MXene into TiO 2 gas sensor shown ability to operate at an operating temperature of 100 °C for 100–1000 ppm of hydrogen. • TiO 2 /MWCNT gas sensor produced the highest sensitivity to hydrogen at the operating temperature of 250 °C for 1000 ppm of hydrogen. [ABSTRACT FROM AUTHOR]

In the original article Norhafiz Azis's last name is spelled incorrectly. It is correct as reflected here. [ABSTRACT FROM AUTHOR]

There are many factors affecting oil extraction rate (OER) but a large contributor to high national OER is by processing good-quality fresh fruit bunches (FFB) at the mills. The current practice for grading oil palm fruit bunches in mills is using human graders for visual inspection, which can lead to repeated mistakes, inconsistent evaluation results, and many other related losses. This study aims to develop a fruit maturity sensor that can detect oil palm fruit maturity grade and send indication to the user whether to accept or reject the bunches. This study focuses on fruit battery principle and applying the charging concept to the fruit battery in order to generate significant load voltage readings of oil palm fruit battery. The charging process resulted in amplified load voltage readings, which were 4 times more sensitive to changes as compared to normal fruit battery without charging process. From the load voltage readings, the fruits can be characterized into their maturity grade based on moisture content. It was determined that fruits with moisture content less than 44% and average load voltage, Vavg, between 20 to 30 mV are considered ripe fruits. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSSCs) are considered to be one of the promising photovoltaic devices in terms of low cost, low toxicity, and versatility. However, the issue of low power conversion efficiency (PCE) is still a main issue of those devices, especially in low light harvesting and the issue of electron–hole recombination that hinders the PCE of the device. This study aims to enhance the PCE by maximizing the light-harvesting without sacrificing the electron–hole separation by a novel approach of the Stack Formation Framework (SFF) for multi-layered Titanium Dioxide (TiO 2) photoanodes in DSSCs by integrating bifacial illumination capabilities. The SFF method, leveraging both commercial and synthesized TiO 2 pastes, now considers light absorption from both the front and rear sides of the device, aiming to harness the full potential of ambient light sources. Comparative analyses under varying illumination conditions reveal the T/sp-P25-T/sp (TPT) configuration's superior efficiency (6.1%) and (3.8%) PCE in front and back respectively, with a notable increase in overall theoretical photocurrent (J s c) to (15.99 mA) and (9.32 mA) in front and back illumination respectively. When both sides are utilized using a reflective mirror, the PCE reaches (9.9%). This work underscores the potential of bifacial DSSCs in maximizing energy capture and conversion, setting a new benchmark for photoanode performance in photovoltaic applications. [Display omitted] • Introduced novel SFF to boost DSSCs efficiency via bifacial illumination. • Superior efficiency shown in T/sp-P25-T/sp under dual illumination. • Marked increase in J s c for bifacial illumination setups. • Set new benchmarks for photoanode performance in PV applications. • Highlighted bifacial DSSCs' potential in enhancing energy conversion. [ABSTRACT FROM AUTHOR]

The major limitation of carbon nanotubes (CNTs) is their poor solubility in the common solvents. Solving the solubility issue of CNTs is comprehended either by functionalizing the CNTs or using a dispersity agent. Agents such as ionic surfactant dramatically alter the suspension conductivity causing undesirable thermal flow in dielectrophoresis (DEP) mediums. In this study, the lack of CNTs solubility in common solvents was resolved by functionalizing multi-wall carbon nanotubes (MWCNTs) using a mild regulated procedure. The mild treatment was used to maintain the electrical conductivity of MWCNTs, since its essential for their dielectrophoretic response. Fourier-transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy were used to investigate the treatment quality. The ability of different solvents to dissolve MWCNT agglomerates after treatment was analyzed using ultraviolet-visible (UV-Vis) spectroscopy and dynamic light scattering (DLS) analysis. The characterization results indicate that the treated MWCNTs by the presented procedure contain hydroxylic and carboxylic functional groups and showed strong solubility in water, dimethylformamide (DMF) and acetone. This study provides a better solution to improve the processability of MWCNTs in common solvents without degrading their electrical conductivity. [ABSTRACT FROM AUTHOR]

The properties of nickel zinc ferrite (Ni 0·5 Zn 0·5 Fe 2 O 4) thick film with Ni 0·5 Zn 0·5 Fe 2 O 4 nanopowders as active powders and linseed oil as the organic vehicle is studied and investigated in this work. Ni 0.5 Zn 0.5 Fe 2 O 4 thick film paste samples have been prepared with various weight ratios to study the rheology properties of the pastes. Rheology results show that paste with 30% wt. Ni 0.5 Zn 0.5 Fe 2 O 4 has suitable rheological shear-thinning behavior, which is required for formulating screen printing pastes. Dielectric and magnetic properties of the thick film show values lower than bulk Ni 0·5 Zn 0·5 Fe 2 O 4 , which is relatable to the weight ratio of the ferrite in thick film and thickness of approximately 20 μm. With a low firing temperature of 200 °C, a screen printed microstrip patch antenna with a Ni 0·5 Zn 0·5 Fe 2 O 4 thick film layer as substrate overlay has an increase in return loss by 64.22% and also increase in bandwidth by 84.61%, which has shown great potential for microwave devices applications. [ABSTRACT FROM AUTHOR]

This paper describes the development of an integrated system using a dry film resistant (DFR) microfluidic channel consisting of pulsed field dielectrophoretic field-flow-fractionation (DEP-FFF) separation and optical detection. The prototype chip employs the pulse DEP-FFF concept to separate the cells (Escherichia coli and Saccharomyces cerevisiae) from a continuous flow, and the rate of release of the cells was measured. The separation experiments were conducted by changing the pulsing time over a pulsing time range of 2–24 s and a flow rate range of 1.2–9.6 μ L min − 1 . The frequency and voltage were set to a constant value of 1 M Hz and 14 V pk-pk, respectively. After cell sorting, the particles pass the optical fibre, and the incident light is scattered (or absorbed), thus, reducing the intensity of the transmitted light. The change in light level is measured by a spectrophotometer and recorded as an absorbance spectrum. The results revealed that, generally, the flow rate and pulsing time influenced the separation of E. coli and S. cerevisiae. It was found that E. coli had the highest rate of release, followed by S. cerevisiae. In this investigation, the developed integrated chip-in-a lab has enabled two microorganisms of different cell dielectric properties and particle size to be separated and subsequently detected using unique optical properties. Optimum separation between these two microorganisms could be obtained using a longer pulsing time of 12 s and a faster flow rate of 9.6 μ L min − 1 at a constant frequency, voltage, and a low conductivity. [ABSTRACT FROM AUTHOR]

High demand of semiconductor gas sensor works at low operating temperature to as low as 100 °C has led to the fabrication of gas sensor based on TiO2 nanoparticles. A sensing film of gas sensor was prepared by mixing the sensing material, TiO2 (P25) and glass powder, and B2O3 with organic binder. The sensing film was annealed at temperature of 500 °C in 30 min. The morphological and structural properties of the sensing film were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The gas sensor was exposed to hydrogen with concentration of 100–1000 ppm and was tested at different operating temperatures which are 100 °C, 200 °C, and 300 °C to find the optimum operating temperature for producing the highest sensitivity. The gas sensor exhibited p-type conductivity based on decreased current when exposed to hydrogen. The gas sensor showed capability in sensing low concentration of hydrogen to as low as 100 ppm at 100 °C. [ABSTRACT FROM AUTHOR]

This research focuses on developing a uniquely miniaturized 4×4 Butler Matrix Network integrated with a 1×4 linear array antenna, generating four beams with exceptional isolation and transmission coefficients. Extensive analyses evaluate the antenna's radiation characteristics, including gain, directivity, and beam-forming capabilities. Innovative design techniques achieve significant Butler matrix miniaturization without compromising performance, resulting in a compact final design measuring 23mm × 20.5mm. The integrated multi-beam antenna array demonstrates favorable outcomes, ensuring impedance matching at 50Ω, high gain, and four beams directed at angles of ±8º and ±33º. These results highlight the design's superiority over traditional counterparts, with gains of up to 11 dB. Detailed radiation patterns for all ports are presented. The paper also provides insights into the manufacturing process, materials used, and challenges faced. The results conclusively confirm the system's compliance with performance criteria, effectively operating within the 28 GHz frequency band. This research significantly contributes to downsizing antenna systems, facilitating more compact and efficient communication devices in the future. [ABSTRACT FROM AUTHOR]

This study addresses the challenge of separating bacteria with similar structures such as Escherichia coli and Aeromonas hydrophila. This approach employs pulsed field dielectrophoresis assisted by laminar flow fractionation in a lab-on-a-chip system with integrated optical detection. Bacterial cells passed through 30-µm microelectrodes subjected at 1 MHz and 14 V peak-to-peak in pulsed mode, while fluid flow carried bacteria towards the chamber's end. The on-and-off electric field at specific pulse intervals expose bacterial cells to diverse forces, including kinetics, dielectrophoresis, gravity, drag, and diffusion, resulting in a net force facilitating their movement. Variations of pulsing time, flow rates, and voltage were investigated to identify the optimal combination for efficient separation. Next, the bacteria were detected using an optical fibre based on their absorbance. Results demonstrated a 30% separation efficiency in 90 min at 9.6 μL min−1 flow rates, 4 s pulsing time, and 40 μS cm−1 medium conductivity. A. hydrophila aggregates experienced greater DEP force and retained at microelectrodes during electric field application compared to E. coli, which moved faster towards optical detection. The separation mechanism with and without electric field was different, and precise control of cell movement during field-off periods is important to minimize uncontrolled diffusion. While the optical detection part has been successful, longer time and separation length are recommended for better separation. A carefully tuned combination of pulsing time, flow rates, voltage, and microelectrode design is crucial for this integrated lab-on-chip system to be efficient for separating and detecting closely related microorganisms. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of multilayer graphene (MLG) growth on bimetallic Co-Ni oxide/ Al2O3 substrate using chemical vapour deposition (CVD) were investigated. The synthesis of MLG was performed at a temperature range of 700-900 °C. Characterization was carried out using TGA, XRD, FESEM, HRTEM, EDX, XPS, FTIR, and Raman spectroscopy. The MLG growth on the bimetallic substrate was confirmed by XRD, FESEM, and HRTEM analysis. TGA and Raman spectroscopy analyses indicate the formation of thermally stable and high-quality MLG. The kinetic growth of MLG was investigated by varying the reaction temperature and monitoring the partial pressure of the ethanol (C2H5OH) as well as that of hydrogen. The data obtained were fitted to the Langmuir-Hinshelwood kinetic model for the estimation of the reaction rate constants at different temperatures. The results showed that the reaction rate constant increased with temperature and the apparent activation energy of 13.72 kJ.mol-1 was obtained indicating a relatively fast rate of MLG growth. The parity plot obtained for the comparison of the predicted and observed rate of C2H5OH consumptions showed an excellent agreement. This study is important for understanding the growth kinetics of MLG in order to develop appropriate measures that can control the production of MLG thin films for use in the electronic industries. [ABSTRACT FROM AUTHOR]

Insect RoboFlyers are interesting and active focuses of study but producing high-quality flapping robots that replicate insect flight is challenging., due to the dual requirement of both a sophisticated transmission mechanism with light weight and minimal intervening connections. This innovative mechanism was created to address the need for a producible structure that is small in size, small in mass, and has reduced design linkages. The proposed Single Crank-Slotted Dual Lever (SC-SDL) mechanism transforms rotational motion into specific angular motion at different velocities for each of its two strokes, i.e., the forward stroke and the return stroke. The discovery of a lag between the left and right lever motions in our design mechanism-I leads us to the conclusion that the flapping is asymmetric. To eliminate the position lag, the design has been altered, and a new design mechanism-II has been developed. Comparative kinematic analysis of both design systems is performed using simulations. Two-dimensional analysis of the base ornithopter configuration using ANSYS FLUENT yielded deeper insights regarding the influence of varying flapping frequency on critical flow metrics regarding adequate lift and thrust. For a flapping frequency of 24 Hz, adequate lift generation was achieved with minimal flow disturbances and wake interactions. Averaged dual wing estimations were made as part of the CFD study, which showed similar agreements. To validate the estimations, experimental tests were performed over the design mechanism-II configuration. [ABSTRACT FROM AUTHOR]

Flying insects are interesting dipteras with an outstanding wing structure that makes their flight efficient. It is challenging to mimic flying insects and create effective artificial flapping drones that can imitate their flying techniques. The smaller insect-size drones have remarkable applications, but they need lightweight and minimal connecting structures for their transmission mechanism. Many operating methods, such as the traditional rotary actuation method and non-conventional oscillatory mechanisms with multiple transmission configurations, are popularly adopted. The classification and recent design innovations with flapping actuation mechanism challenges, particularly bio-inspired (biomimetics) and bio-morphic types of flapping-wing aerial vehicles from micro to pico-scale, are discussed in this review paper. For ease of understanding, we have attempted to depict the actuation mechanisms in the form of block diagrams. The ability of hybrid efficient mechanisms to improve the flapping frequency of wings and flapping actuation design process, including other parameters, such as flapping angle, lift generation, and hovering ability with current driving mechanisms, is also discussed. Depending on their endearing resemblance, we have segregated Flapping-Wing Micro Air Vehicle (FWMAV) design patterns like birds, small birds, nano hummingbirds, moths, bats, biomorphic types, flapping test bench models, and fully flyable models, which are characterized by their flight modes. Important flapping actuation systems that can be used to achieve hovering capability are highlighted. The actuation mechanisms' specifications and configurations are expanded by focusing on the need of flapping frequency and stroke angle controllability via the linkage mechanisms with insight into flapping patterns. Besides that, the requirements for the sustainability of flying patterns during manual and automatic launches were investigated. In addition, the different researchers' annual progress on their Flapping-wing models has been emphasized. The best performing prototypes with their flapping actuation mechanism contributions to achieving better lift and long-duration flight sustainability are articulated through ranking. An insight into some of the significant challenges and future work on flapping performance levels are also discussed. [ABSTRACT FROM AUTHOR]

A highly sensitive silicon nanowire (SiNW)-based sensor device was developed using electron beam lithography integrated with complementary metal oxide semiconductor (CMOS) technology. The top-down fabrication approach enables the rapid fabrication of device miniaturization with uniform and strictly controlled geometric and surface properties. This study demonstrates that SiNW devices are well-aligned with different widths and numbers for pH sensing. The device consists of a single nanowire with 60 nm width, exhibiting an ideal pH responsivity (18.26 × 106 Ω/pH), with a good linear relation between the electrical response and a pH level range of 4–10. The optimized SiNW device is employed to detect specific single-stranded deoxyribonucleic acid (ssDNA) molecules. To use the sensing area, the sensor surface was chemically modified using (3-aminopropyl) triethoxysilane and glutaraldehyde, yielding covalently linked nanowire ssDNA adducts. Detection of hybridized DNA works by detecting the changes in the electrical current of the ssDNA-functionalized SiNW sensor, interacting with the targeted ssDNA in a label-free way. The developed biosensor shows selectivity for the complementary target ssDNA with linear detection ranging from 1.0 × 10−12 M to 1.0 × 10−7 M and an attained detection limit of 4.131 × 10−13 M. This indicates that the use of SiNW devices is a promising approach for the applications of ion detection and biomolecules sensing and could serve as a novel biosensor for future biomedical diagnosis. [ABSTRACT FROM AUTHOR]

According to several research circles, it is predicted that future wireless systems that employ smart antenna techniques would be more effective at using available spectrum and at building new networks at lower cost, while also improving service quality and allowing for cross-technology operation. These systems require constant monitoring in order to function properly, allowing users to apply machine learning algorithms to analyse large amounts of data from various antenna settings. Machine learning is a technique in which a machine learns and improves on its own, based on past data. These techniques enable the smart antenna target to be learned in an efficient, reliable, and adaptive manner. In this paper, the antenna array and antenna developed for the Internet of Things applications were highlighted. In this paper, we review how machine learning techniques can handle these applications effectively and what the concept of adaptive antenna is and when it can be used in this day and age characterized by the rapid development of information technology. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) can be aligned along electric field lines between transparent electrodes to form a conductive network. In this work, MWCNTs were successfully deposited across indium tin oxide (ITO) electrodes using dielectrophoretic (DEP) force. For the first time, the deposition of MWCNTs across ITO electrodes separated by a distance of 50 μm is demonstrated to form an aligned network. The role of the AC signal amplitude, frequency, and duration is investigated experimentally. We found that the alignment was improved as the frequency increases (>105 Hz), while the minimum amplitude per the unit distance to deposit MWCNTs across ITO electrodes was 0.2 V/μm. The deposition process is observed in real-time using optical microscopy, and the aligned MWCNTs are observed with FeSEM spectroscopy. The study also investigates the resistivity, density and length of the aligned MWCNTs as a function of time. The deposition of MWCNTs across transparent electrodes using a room temperature method that requires a simple setup has potential use in future transparent electronics. [Display omitted] • MWCNTs were successfully assembled and aligned across IDE electrodes made of ITO. • The assembly is achieved using the DEP method, where the dispersed MWCNTs are polarized in a non-uniform E-field. • AC signal with a specific amplitude, frequency and duration is used to generate the E-field and control the assembly. • The density, length and resistance of the aligned MWCNTs were controlled by varying the signal parameters. [ABSTRACT FROM AUTHOR]

The effect of different particle size obtained by diverse milling time towards the microstructure and magnetic properties of gadolinium iron garnet (GdIG) at room temperature was reported in this research work. Gadolinium iron garnet (GdIG) has been mechanically alloyed at 3, 6, 9 and 12 h followed by sintering at 1200 °C. The samples were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM) and impedance analyser. All milled samples were in nanosized of 36.9, 27.2, 19.2 and 20.8 nm for 3, 6, 9 and 12 h, respectively. The single phase of gadolinium iron garnet (GdIG) with average grain size of 0.66, 0.67, 0.72 and 0.69 μm, respectively, showed low initial permeability and low magnetic loss when applied with low-frequency range. The effect of magnetic properties was proven to be dominantly contributed by sintering process. The result illustrated that the polycrystalline GdIG has the ability to be applied as potential patch antenna application. [ABSTRACT FROM AUTHOR]

This study investigates the optimization of multilayer graphene (MLG) growth on Co–Ni/Al2O3 substrate. The MLG synthesized by chemical vapor deposition technique (CVD) was characterized using various instrument techniques. The surface area and pore volume of the MLG were estimated as ~ 642 m2/g and ~ 2.7 cm3/g, respectively. The Raman spectrometric analysis showed evidence of MLG. The effects of parameters such as temperature, Co–Ni composition and ethanol flow rate were investigated using response surface methodology (RSM) and central composite design. The maximum MLG yield of 77% was attained at optimum conditions of 800 °C, Co–Ni composition of 0.3/0.7 and ethanol flow rate of 11 ml/min. The analysis of variance (ANOVA) results showed that the RSM quadratic model is significant with a p value < 0.0001. The coefficient of determination (R2) values of 0.9694 revealed the reliability of the RSM model. The potential of CVD as a technique to synthesize MLG growth of a highly ordered crystallinity structure has been demonstrated in this study. The resulting MLG films are promising materials for the use in improving graphene-based electronics, sensing and energy devices. [ABSTRACT FROM AUTHOR]

A strategy of a highly feasible method to achieve a broad bandwidth of radar absorbing materials (RAM) is reported. Herein the magnetic Sr-hexaferrite were prepared using a conventional sintering process at 900 °C and later hybridized with coiled carbon nanotubes (CNT) via a chemical vapour deposition (CVD) method. X-ray diffraction (XRD) detected two phases of compounds after sintering which were 36 % of SrFe 2 O 4 and 64 % of SrFe 12 O 19. Two groupings of nanoparticle size showed no significant effect on reflection loss (RL) performance. Interestingly after hybridization of coiled CNT with the magnetic materials, the permittivity was increased tremendously hence enhancing the RL. Multiple relaxations of dielectric and eddy current losses were responsible for the enhancement. The RL was increased as the thickness was increased from 1 mm to 3 mm. 6 % of coiled CNT/Sr-hexaferrite hybrid resulted in low RL of -19 dB with the broadest bandwidth of 3GHz over X-band frequency. The report is important for paving future work in obtaining a desired broad bandwidth RAM. [Display omitted] • Synthesis of Sr-hexaferrite via 900 °C sintering and CNT hybridization using CVD • Coiled CNT hybridization increased permittivity, improving relaxation-based RL. • Increasing from 1 mm to 3 mm enhanced RL performance, revealing optimal thickness. • 6 % composition yielded -19 dB RL and 3GHz bandwidth over X-band. [ABSTRACT FROM AUTHOR]

Haptic sensors are essential devices that facilitate human-like sensing systems such as implantable medical devices and humanoid robots. The availability of conducting thin films with haptic properties could lead to the development of tactile sensing systems that stretch reversibly, sense pressure (not just touch), and integrate with collapsible. In this study, a nanocomposite based hemispherical artificial fingertip fabricated to enhance the tactile sensing systems of humanoid robots. To validate the hypothesis, proposed method was used in the robot-like finger system to classify the ripe and unripe tomato by recording the metabolic growth of the tomato as a function of resistivity change during a controlled indention force. Prior to fabrication, a finite element modeling (FEM) was investigated for tomato to obtain the stress distribution and failure point of tomato by applying different external loads. Then, the extracted computational analysis information was utilized to design and fabricate nanocomposite based artificial fingertip to examine the maturity analysis of tomato. The obtained results demonstrate that the fabricated conformable and scalable artificial fingertip shows different electrical property for ripe and unripe tomato. The artificial fingertip is compatible with the development of brain-like systems for artificial skin by obtaining periodic response during an applied load. [ABSTRACT FROM AUTHOR]

• Sr 4 Mn 2- x Zn x Fe 36 O 60 sintered proved single phase confirmed by XRD analysis. • Magnetization increased with doping of MnZn up to 0.8 and decreased with X = 1.0. • MnZn inclusion in the crystal structure greatly influence the natural resonance frequency. • The RL was maximum when after the samples was dope with Mn and Zn with x = 0.8. In the present work, substitution of strontium U-type hexaferrite with the composition of Sr 4 Mn 2- x Zn x Fe 36 O 60 (x = 0.5,0.6,0.8, and 1.0) was prepared via high energy ball milling (HEBM) and sintered at 1100 °C. The phase, microstructure, magnetic, dielectric and electromagnetic wave absorbing properties of U-type strontium hexaferrite composites were measured using XRD, FESEM, and Vector Network Analyzer in the frequency range of 8–18 GHz (X-band and Ku-band). MnZn doping was found to shift the natural resonance of the materials by affecting its magnetocrystalline anisotropy. The reflection loss (RL) indicated that the composite possessed good microwave-absorbing properties with U-type strontium hexaferrite (Sr 4 Mn 2- x Zn x Fe 36 O 60) of x = 0.8 resulted in high minimum RL value for all thickness of 1 mm and two peaks at approximately − 32.50 and − 41.50 dB at 14.00 and 15.60 GHz, with bandwidth of 0.60 and 0.80 GHz for losses less than − 10 dB. [ABSTRACT FROM AUTHOR]

This paper investigates the influences of the electrode geometry in terms of shape, configuration, dimensions, overlapping, and extensions on the dielectrophoretic (DEP) assembly of multi-walled carbon nanotube (MWCNT) bundles. A computational model was employed to predict the motion, trajectory, and assembly location of MWCNT bundles. The density and shape of the assembled bundles were precisely controlled by optimizing the electrode dimensions and adjusting the AC signal parameters. Experimental work was conducted to validate the simulation results. MWCNT bundles were assembled and aligned across indium tin oxide (ITO) electrodes using an AC signal of 10 V and 1 kHz. [Display omitted] • Investigating the electric field and dielectrophoretic force across parallel pair and interdigitated electrodes structures. • The electrode dimensions were optimized and the motion, trajectory and deposition location of MWCNT bundles were predicted. • The density of the deposited MWCNT bundles was controlled by AC signal parameters, which is required in sensor fabrication. [ABSTRACT FROM AUTHOR]

Terahertz (THz) band antennas are becoming a more attractive field of research due to the wide range of applications and advantages in future communications. A design of a helical antenna for ultra-high-speed THz wireless applications over short-range communication is proposed. The proposed antenna provides ultra-wideband bandwidth, high directional gain, low-cost, and circular polarization features. The proposed antenna design shows interesting results with respect to a fractional bandwidth of 65.40% and impedance bandwidth of 0.50992 THz for VSWR ≤ 2. Simulation results also show that maximum directivity, its realized gain and radiation efficiency of the proposed antenna is 12.1 dBi, 11.8 dBi, and 95.31% at 1 THz, respectively. The proposed antenna is performed, simulated and analysed by using the commercial CST microwave studio software. The simulation results display noticeable improvements in terms of fractional bandwidth, directivity and gain compared with other related-works. The proposed antenna can be used for several THz wireless applications, mainly for ultra-high-speed THz wireless applications over a short-range communication, such as Wi-Fi, base station, and medical applications. • The proposed metal helical antenna is designed to achieve extremely wide bandwidth. • Certain design of THz metal helical antenna gives a good performance, by simulation. • The proposed antenna is intended for ultra-high-speed broadband THz applications. [ABSTRACT FROM AUTHOR]

• Antenna specifications for short-range ultra-high-speed THz wireless communication in the 6G technology. • Review of recent related-works of THz band antenna, fabrication and measurement with their open challenges. • Overall analysis and opportunity to develop any of THz band antenna studies for the 6G wireless communication system. • Other possible research directions are included for further studies. The Terahertz (THz) frequency band (0.1-10 THz) will be used in the 6G wireless communication system to support the user demand of higher data rates and ultra-high-speed communication for many future applications. In this paper, 6G antenna specifications for these applications are highlighted. An exhaustive review of recent related-works of THz band antenna, fabrication and measurement are presented. Challenges of the THz band antenna design, fabrication and measurement are addressed. Research directions of THz band antenna for 6G technology are included, for THz band in antenna design, manufacturing and testing. [ABSTRACT FROM AUTHOR]

Surfactants such as sodium dodecyl sulfate (SDS) are used to improve the dispersity of carbon nanotubes (CNTs) in aqueous solutions. The surfactant concentration in CNT solutions is a critical factor in the dielectrophoretic (DEP) manipulation of CNTs. A high surfactant concentration causes a rapid increase in the solution conductivity, while a low concentration results in undesirably large CNT bundles within the solution. The increase in the solution conductivity causes drag velocity that obstructs the CNT manipulation process due to the electrothermal forces induced by the electric field. The presence of large CNT bundles is undesirable since they degrade the device performance. In this work, mathematical modeling and experimental work were used to optimize the concentration of the SDS surfactant in multiwalled carbon nanotube (MWCNT) solutions. The solutions were characterized using dynamic light scattering (DLS) and ultraviolet-visible spectroscopy (UV-Vis) analysis. We found that the optimum SDS concentration in MWCNT solutions for the successful DEP manipulation of MWCNTs was between 0.1 and 0.01 wt %. A novel DEP configuration was then used to assemble MWCNTs across transparent electrodes. The configuration was based on ceiling deposition, where the electrodes were on top of a droplet. The newly proposed configuration reduced the drag velocity and prevented the assembly of large MWCNT bundles. MWCNTs were successfully assembled and aligned across interdigitated electrodes (IDEs). The assembly of MWCNTs from aqueous solutions across transparent electrodes has potential use in future transparent electronics and sensor devices., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The dielectrophoresis (DEP) method is used to fabricate sensor devices by assembling and aligning carbon nanotubes (CNTs) across electrode structures. The challenges of the method increase as the gap width between the electrodes increases. In this work, a novel DEP setup is proposed to reduce the resistance mismatch in manufacturing carbon nanotube-based sensors. The proposed setup utilizes hot airflow and thermal annealing to fabricate long-aligned multi-walled carbon nanotube (MWCNT) bridges across transparent electrodes with a gap width up to 75 μm. The best alignment results were obtained at airflow velocities between 1.5 m s -1 and 2.5 m s -1 . The minimum variation in the resistance of the aligned bridges was 1.81% observed at a MWCNT concentration of 0.005 wt% and deposition time of 10 min. Long MWCNT bridges have many contact points that link MWCNTs to each other, making the contact resistance a robust indicator of the variation in the ambient temperature. The characteristics of the MWCNT bridges as a temperature sensor, including the response, sensitivity, and recovery, were investigated., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A new approach through heat treatment has been attempted by establishing defects by the process of quenching towards electrical and magnetic properties in the nickel zinc ferrite (Ni 0.5 Zn 0.5 Fe 2 O 4 ) sample. The measured property values in permeability and hysteresis characteristic gave their recovery behaviour in which the values, after quenching were recovered after undergoing the annealing. Interestingly, a different trend observed in the permittivity value whereas the value was increased after quenching and subsequently recovered after annealing. The mechanisms which produced the changes is believed to be involved by defects in the form of vacancies, interstitials, microcracks and dislocations created during quenching which gave rise to changes in the values of the complex permeability and permittivity components and hysteresis behaviour., (© 2021. The Author(s).)

Humidity measurement is one of the most significant issues in various areas of applications such as instrumentation, automated systems, agriculture, climatology and GIS. Numerous sorts of humidity sensors fabricated and developed for industrial and laboratory applications are reviewed and presented in this article. The survey frequently concentrates on the RH sensors based upon their organic and inorganic functional materials, e.g., porous ceramics (semiconductors), polymers, ceramic/polymer and electrolytes, as well as conduction mechanism and fabrication technologies. A significant aim of this review is to provide a distinct categorization pursuant to state of the art humidity sensor types, principles of work, sensing substances, transduction mechanisms, and production technologies. Furthermore, performance characteristics of the different humidity sensors such as electrical and statistical data will be detailed and gives an added value to the report. By comparison of overall prospects of the sensors it was revealed that there are still drawbacks as to efficiency of sensing elements and conduction values. The flexibility offered by thick film and thin film processes either in the preparation of materials or in the choice of shape and size of the sensor structure provides advantages over other technologies. These ceramic sensors show faster response than other types.

This paper presents a new type diode connected MOS transistor to improve CMOS conventional rectifier's performance in RF energy harvester systems for wireless sensor networks in which the circuits are designed in 0.18  μm TSMC CMOS technology. The proposed diode connected MOS transistor uses a new bulk connection which leads to reduction in the threshold voltage and leakage current; therefore, it contributes to increment of the rectifier's output voltage, output current, and efficiency when it is well important in the conventional CMOS rectifiers. The design technique for the rectifiers is explained and a matching network has been proposed to increase the sensitivity of the proposed rectifier. Five-stage rectifier with a matching network is proposed based on the optimization. The simulation results shows 18.2% improvement in the efficiency of the rectifier circuit and increase in sensitivity of RF energy harvester circuit. All circuits are designed in 0.18 μm TSMC CMOS technology.

A gas sensor array was developed in a 10 × 10 mm(2) space using Screen Printing and Pulse Laser Ablation Deposition (PLAD) techniques. Heater, electrode, and an insulator interlayer were printed using the screen printing method on an alumina substrate, while tin oxide and platinum films, as sensing and catalyst layers, were deposited on the electrode at room temperature using the PLAD method, respectively. To ablate SnO(2) and Pt targets, depositions were achieved by using a 1,064 nm Nd-YAG laser, with a power of 0.7 J/s, at different deposition times of 2, 5 and 10 min, in an atmosphere containing 0.04 mbar (4 kPa) of O(2). A range of spectroscopic diffraction and real space imaging techniques, SEM, EDX, XRD, and AFM were used in order to characterize the surface morphology, structure, and composition of the films. Measurement on the array shows sensitivity to some solvent and wood smoke can be achieved with short response and recovery times.

Research into surface acoustic wave (SAW) devices began in the early 1970s and led to the development of high performance, small size, and high reproducibility devices. Much research has now been done on the application of such devices to consumer electronics, process monitoring, and communication systems. The use of novel materials, such as gallium phosphate (GaPO4), extends the operating temperature of the elements. SAW devices based on this material operating at 434 MHz and up 800 degrees C, can be used for passive wireless sensor applications. Interdigital transducer (IDT) devices with platinum/zirconium metallization and 1.4 microm finger-gap ratio of 1:1 have been fabricated using direct write e-beam lithography and a lift-off process. The performance and long-term stability of these devices has been studied, and the results are reported in this paper.