In the current work, cuprous oxide (Cu2O) nanoparticles coated with Tween 80 were successfully synthesized via the chemical reduction method. Nanocomposites composed of low-density polyethylene (LDPE) and different ratios of Cu2O nanoparticles were fabricated by the melt mixing process. 10% of ethyl vinyl acetate (EVA) as a compatibilizing agent was added to the molten LDPE matrix and the mixing process continued until homogenous nanocomposites were fabricated. To study the influence of ionizing radiation on the fabricated samples, the prepared species were exposed to 50 and 100 kGy of gamma rays. The synthesized Cu2O nanoparticles were investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). XRD and TEM analysis illustrated the successful formation of spherical Cu2O nanoparticles with an average size of 16.8 nm. The as-prepared LDPE/Cu2O nanocomposites were characterized via different techniques such as mechanical, thermal, morphological, XRD, and FTIR. Electromagnetic interference shielding (EMI) of the different nanocomposite formulations was performed as a promising application for these materials in practical life. The electromagnetic shielding effectiveness (SE) of the produced samples was measured in the X-band of the radio frequency range from 8 to 12 GHz using the vector network analyzer (VNA) and a proper waveguide. All the samples were studied before and after gamma-ray irradiation under the same conditions of pressure and temperature. The shielding effectiveness increased significantly from 25 dB for unirradiated samples to 35 dB with samples irradiated with 100 kGy, which reflects 40% enhancement in the effectiveness of the shielding.

This work introduces the design, analysis, simulation, and a standard MEMS fabrication process for a three-dimensional micro-coil with a magnetic core and a digital switch configuration using a completely integrated, fully MEMS-compatible process to achieve a digitally controlled inductance. The proposed design can also be utilized as a micro-transformer. The proposed design consists of five identical 3D coils and their corresponding MEMS switches. These coils are digitally controlled to achieve a variable inductor ranging from one-fifth of the coil inductance up to five times the coil inductance. A standard five-layer Polymumps process is proposed to fabricate the micro-coils and the integrated switches. Each micro coil is anchored directly on-chip, which is connected to the input signal from one side, and the other is connected to the switch. The Ni-based magnetic core improves the coil’s response by confining and guiding the magnetic field in the magnetic device compared to Si core based by more than five times. The presented coil has the number of windings limited by the designed length and the minimum spacing that can be realized by standard optical lithography. The coil’s diameter is also restricted by the limits defined by optical lithography, whereas the maximum height realizable by the Polymumps process limits the height of the magnetic core and accordingly results in lower inductor performance. Based on this technique, we present coils ranging from 100 μm length and ten winding up to 1000 μm length and 100 windings. The new monolithically integrated MEMS switches act as selectors to achieve a variable inductance with digital control to allow the selection among n(n + 1)/2 inductance steps, where n is the number of coils.

Conductive polymer nanocomposites for electromagnetic interference (EMI) shielding are important materials that can be combat the increasingly dangerous radiation pollution arising from electronic equipment and our surrounding environment. In this work, we have synthesized polyaniline-copper nanoparticles (PANI-Cu NPs) by the copper salt based oxidative polymerization method at room temperature and then added with different concentration (0, 1, 3 and 5 wt%) in polystyrene polymer forming PS/ PANI-Cu nanocomposites films by means of the traditional solution casting technique. The formed PANI-Cu NPs were investigated by UV/Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and SEM/EDX elemental mapping techniques. On the other hand, the prepared PS/PANI-Cu nanocomposites films were evaluated by UV and SEM, the mechanical properties of the nanocomposites films were evaluated and showed an improvement by added PANI-Cu NPs up to 3 wt% and 50 kGy gamma exposure dose. The PS/PANI-Cu nanocomposites films were examined as electromagnetic interference shielding material. Electromagnetic shielding effectiveness of the produced nanocomposites were tested in the X-band of the radio frequency range namely from 8 to 12 GHz using the vector network analyzer (VNA) and a proper wave guide. All samples were studied before and after 50 kGy gamma-ray irradiation under the same condition of pressure and temperature. The results showed that the nanocomposites have improved shielding properties.

This study introduces the synthesis of graphite-carbon nitrite (g-C3N4) using thermal treatment of urea. The prepared powder is treated to generate nanoparticles. The structure and grain size of the g-C3N4 have been obtained via X-ray diffraction (XRD) technique and transmission electron microscope. The graphite-carbon nitride on Polyvinyl Chloride (PVC/g-C3N4) nanocomposite films were produced by mixing different concentrations (0, 3, 5, 7, 10 and 20 wt%) of nanoparticles with Polyvinyl Chloride (PVC) solutions. The structure and elemental composition of the prepared nanocomposites films PVC/g-C3N4 were studied by using XRD, scanning electron microscope (SEM), (EDX), infrared spectroscopy (IR) and electron spin resonance (ESR). Also, spectral distribution of the optical absorbance for the PVC/g-C3N4 nanocomposites films was studied in the wavelength range from 190 to 1100 nm. Thermal stability of the investigated nanocomposites films was investigated by thermal gravimetric analysis technique (TGA). The effect of various concentrations of the g-C3N4 and different doses of gamma-rays on the polymeric matrix and electrical properties of PVC film also has been investigated. The g-C3N4 additives on PVC influenced the crystal structure and optical properties of the nanocomposites films. The nanocomposite film with 10% g-C3N4 achieved higher values of the refractive index and optical conductivity compared with the other films. With different doses of gamma-ray irradiation, the crystal structure and optical properties of PVC/g-C3N4 nanocomposite films were changed in accordance to the cross-linking process within the PVC polymeric chains where a structural rearrangement can be occurred as a result of gamma irradiation. The elemental composition and morphological study of PVC/g-C3N4 nanocomposite films have been checked by the scanning electron microscopy which indicated the homogeneous dispersion of g-C3N4 nanoparticles within PVC network. Finally, electrical properties of PVC/g-C3N4 nanocomposite films with different ratios and distinct gamma doses also have been studied.

Carbon nanotubes (CNTs) have established wide attention as strengthened fillers because of their excellent several characters. Nano polymers based on thermoplastic elastomer composed of waste polyethylene (WPE)/Waste ethylene propylene diene monomer (WEPDM) blended equally 50/50 wt. % and strengthened with different concentrations of CNT (0.1, 0.3, and 0.5%) were fabricated via melt mixing. The prepared specimens were exposed to various gamma radiation doses, namely 50 and 100 kGy to evaluate the impact of radiation on the Nano polymers structure. FTIR and XRD were used to track the structure and crystallinity changes of thermoplastic elastomer with CNT filling. Mechanical features including tensile strength (TS), elongation at break (E%), modulus of elasticity (EM) and hardness (Shore D) of the unirradiated and irradiated samples were evaluated. Furthermore, the dynamic mechanical properties named storage (E′) and loss modulus as well as tan delta (δ) of the fabricated specimens were measured. TGA and also DSC monitored the thermal decomposition and the melting point alterations caused by CNT reinforcement. Electromagnetic Interference (EMI) was studied for all fabricated samples as an application of shielding for radio frequency signals. In general, all the studied parameters revealed improvements of thermoplastic elastomer properties via CNT interference. Subsequent reinforcement of CNT concentrations into WPE/WEPDM produced higher shielding for radio frequency signals. Furthermore, applied gamma radiation doses improved the shielding properties of the fabricated nanocomposites.

Wood plastic composites (WPCs) consisting of high-density polyethylene (HDPE) reinforced with alkali-treated sugarcane bagasse fibers (BF) in a concentration of 30 parts per hundred parts of plastic (php) were fabri-cated using the melt-blending technique. The carbon black (CB) was added at a concentration of 10 php while the graphene oxide nanoparticles (GO) were added in different concentrations (0.25, 0.5, 0.75, and 1 php). The influence of these additives and electron beam irradiation at different doses (100 and 200 kGy) on the flexural properties, electrical conductivity (sigma dc), and electromagnetic interference (EMI) shielding efficiency of the HDPE/BF composite were investigated. The samples were examined under microwave signals in the range from 0.8 GHz to 3.5 GHz to study the shielding effectiveness. The maximum flexural strength (29 MPa) was recorded for the HDPE/BF/CB composite, which contains 1 php of GO and was irradiated at 100 kGy with an improvement percentage of 56.6% in comparison with that of the unirradiated HDPE/BF composite. The addition of GO improved the electrical conductivity and EMI shielding efficiency of the prepared composite. It was observed that at frequency 3 GHz, the increase of GO up to 1 php enhanced the shielding effectiveness by a factor of 17.35% and 16.94% at 0 and 200 kGy, respectively. Furthermore, increasing the irradiation dose increased shielding effectiveness by about 4.92%.

In the radiation sensing community, it's very important to detect gamma-ray radiation using remote sensing like IoT platforms. In this paper, high efficient low cost gamma-ray radiation sensor is designed to monitor and early detect radioactive materials that are present in the environment, and this is to be achieved based on IoT platform. Such platform provides a safer monitoring technique that helps avoiding the direct exposure to radiation and allows the exploration of inaccessible places. This paper conducts a deep informed study of N-channel (NMOS) and P-channel (PMOS) MOSFETs to be used as a dosimeter and sensor for gamma-ray radiation. The proposed technique herein uses the active load configuration of MOSFETs to detect the output current or the channel on resistance. MOSFET drain current and channel resistance values are changed based on variations of threshold voltage (VT) that are affected directly by the dose of absorbed gamma-ray radiation. For the purpose of sensing the ionizing radiation, the change ratios of output current or channel resistance values; due to threshold voltage shifting, are measured. A complete prototype of the proposed gamma-ray radiation IoT monitoring solution has been built and tested in a real gamma radiation environment over a dose range from 10 Gy up to 40 Gy. The highest current sensitivity of the proposed dosimeter was 0.579 mA/Gy and 0.529 mA/Gy for NMOS and PMOS respectively. The practical results show that the IoT monitoring radiation system is able to efficiently detect the gamma radiation remotely using low cost MOSFET transistors.

In this paper, a theoretical analysis of a Vertical Cavity Surface Emitting Laser (VCSEL) excited by a rectangular pulse signal is developed. The analytical model is based on the transfer function of the laser characteristic equation. The transient behavior of the device under investigation at different widths of input rectangular pulse signals is studied, the output derivative of the optical output power as a measure of the device speed is also analyzed. All interesting parameters are taken into account. In addition, the effect of the width of the input pulse signal and the resonance frequency are also considered. The results show that higher resonant frequency makes the device to arrive to a saturated definite value very faster than the lower resonant frequency. Also, the increased resonance frequency makes the device to change its case from high current state to low current state faster than the lower resonant frequency. This type of device reached the steady state at very short time; it can be exploited in different applications of very high speed optical systems.

In this manuscript, Cobalt (Co)-doped to Zinc Oxide (ZnO) samples prepared as thin films.These samples were obtained by utilizing spray pyrolysis have different concentrations of Cobalt.For investigating the effect of Co concentration on the thin films samples' physical properties, Different experimental techniques are employed.Such as Scanning Electron Microscope (SEM), X-ray diffraction, and optical spectroscopy.The grain size has been obtained using Scherrer's equation.From the obtained results, one can notice that the grain size behavior is non-linearly with the Co-concentration level.Electron Spin Resonance (ESR) is involved to observe the resonance absorption of microwave radiation of these thin films.It measures the spins of an electron of a molecule or an atom in a magnetic field.The study is performed before and after irradiation doses of 1 KGy and 3 KGy.The ESR signal shows the ferromagnetic response at room temperature which is improved after irradiation with Gamma-ray.The optical band gap of pure ZnO film was found to be 3.25 eV and the minimum bandgap is 3.11 for 1wt%.The existence of Co in the obtained film was confirmed by Energy Dispersive X-Ray (EDX) data.From the obtained results, the percentage of Co is increasing from 1.9% to 5.4% when the wt% is raising.In addition, the effect of the ionizing radiation doses; 1KGy and 3 KGy, on the magnetic and structural properties are investigated.As a result, Magnetic measurements for all prepared samples show a Room Temperature Ferromagnetic (RTFM) behaviour.Finally, increasing Co concentration and Gammaray irradiation dose will have a notified change on the ESR signal.

This paper proposes a new graphene gamma- and beta-radiation sensor with a backend RF ring oscillator transducer employed to convert the change in the graphene resistivity due to ionizing irradiation into a frequency output. The sensor consists of a CVD monolayer of graphene grown on a copper substrate, with an RF ring oscillator readout circuit in which the percentage change in frequency is captured versus the change in radiation dose. The novel integration of the RF oscillator transducer with the graphene monolayer results in high average sensitivity to gamma irradiation up to 3.82 kΩ/kGy, which corresponds to a percentage change in frequency of 7.86% kGy−1 in response to cumulative gamma irradiation ranging from 0 to 1 kGy. The new approach helps to minimize background environmental effects (e.g., due to light and temperature), leading to an insignificant error in the output change in frequency of the order of 0.46% when operated in light versus dark conditions. The uncertainty in readings due to background light was analyzed, and the error in the resistance was found to be of the order of 1.34 Ω, which confirms the high stability and selectivity of the proposed sensor under different background effects. Furthermore, the evolution of the graphene’s lattice defect density due to radiation was observed using Raman spectroscopy and SEM, indicating a lattice defect density of up to 1.780 × 1011/cm2 at 1 kGy gamma radiation, confirming the increase in the graphene resistance and proving the graphene’s sensitivity. In contrast, the graphene’s defect density in response to beta radiation was 0.683 × 1011/cm2 at 3 kGy beta radiation, which is significantly lower than the gamma effects. This can be attributed to the lower p-doping effect caused by beta irradiation in ambient conditions, compared with that caused by gamma irradiation. Morphological analysis was used to verify the evolution of the microstructural defects caused by ionizing irradiation. The proposed sensor monitors the low-to-medium cumulative range of ionizing radiations ranging from 0 to 1 kGy for gamma radiation and 0 to 9 kGy for beta radiation, with high resolution and selectivity, filling the research gap in the study of graphene-based radiation sensors at low-to-medium ionizing radiation doses. This range is essential for the pharmaceutical and food industries, as it spans the minimum range for affecting human health, causing cancer and DNA damage.

This work presents a variable RF MEMS capacitor based on five cantilever shunt switches for the first time. Conceptually, the proposed varactor design comprises five identical cantilever shunt switches, which allow the creation of 32 discrete capacitance values ranging from 0.091 to 6.04 pF. The latter translates to a tuning range of around 67. The overall varactor’s size is 400 μm × 850 μm. As verified by finite element simulations, the proposed beam configuration reduces sensitivity to in-plane residual stresses, which alleviates the pull-in voltage effect. The pull-in voltage and switching time were 24.18 V and 2.39 μs, respectively. It was found that the pull-in voltage of 24.18 V is less affected by the residual stresses. The high capacitance ratio of the varactor is achieved by the new design of a fixed and different capacitor with asymmetric design as the base structure of the varactor. The minimum capacitance (Cmin) is minimized by selecting the minimum overlap capacitor area. Moreover, the selection of fixed plate capacitors minimized the stresses. A thin layer of 0.5 μm was deposited on specified regions to avoid contact between the drive electrodes and the beam structure, thus improving the device's reliability. Furthermore, investigated and verified in-plane residual stress (induced by the fabrication process) and stress gradient's effects on spring constant and the beam's displacement profile. It was verified that the beam's behavior is minimally affected by the in-plane residual stresses, attributed to 3.2 GPa. The proposed RF-MEMS varactor provides a good solution for wireless multi-standard communication systems, such as phase shifters and reconfigurable filters as RF MEMS switching and varactors can be fabricated in a small package with low cost, low insertion loss, high linearity, high isolation, and low power consumption.

Graphene-based RF ring oscillator sensor was demonstrated as a high gauge factor (GF) strain sensor. CVD-grown graphene monolayer on a flexible Cu layer was integrated on a five-stage RF ring oscillator platform and utilized to measure elastic strain. The main features of the proposed technique are high sensitivity (i.e., high gauge factor), low power, and high signal-to-noise-ratio due to the digital operation, which leads to noise suppression. Strains in the range of $8\times 10^{-4}$ to $2.5\times 10^{-2}$ were measured with the detected change in surface resistance in the order of $1.6-1.8\ \Omega/$ , and average gauge factor, $\text{GF}\approx 64.36$ . The main advantage of the proposed approach with frequency change detection as compared to the widely investigated graphene on PDMS strain gauges are higher sensitivity due to higher conductivity of the graphene layer, and lower noise due to the overall low resistance of the circuit and better CMOS integration as compared to the conventional resistive change sensing platforms.

This research article focuses on investigating the relation between carbon nanotube network (CANET) parameter adoption and data flow, then encoding. The phase angle and angle division play an important role for encoding the data between the transmitter (source) and the destination (drain) of the CANETs [field effect transistor (FET)]. In addition, the length and radius of the carbon nanotubes (CNT) and the space between them affect the overall CANET behavior. For this, a theoretical study is undertaken to determine how to enhance the data flow and encoding process. One can see that peaks can be recognized at a specified phase angle and angle division, adjacent distance and adjacent distance deviation for certain CNT specifications. As a result, the data can be extracted at these peaks at specified CANET parameters, as they give the highest conductance value, 30 KΩ−1, and lowest charge mobility. Therefore, the theoretical model presented here can be utilized to assign peaks corresponding to any CANET specification. The data flow is controlled not only by the phase angle and angle division, but by the CNT length and radius as well. Finally, the effect of CNT mobility on CANET behavior is studied. From the results obtained, the FET mobility values (−13 cm2/Vs to 16 cm2/Vs), under considered conditions, enable us to fabricate CNTs in nano-dimension practical phase processes.

Gamma irradiation method has been used to change the electrical properties of CdS thin film. A specific dose of γ-irradiation increases the activation energy of CdS thin film. In addition, γ-irradiation was used to change the sign of Hall coefficient, RH, of CdS thin film from negative to positive irrespective of temperature. The Hall mobility mechanism shows noticeable change after γ-irradiation from decreasing to increasing with raising the temperature. In depth, analysis was done using capacitance-voltage measurement in order to realize the modification in the CdS/Si junction band gap after γ-irradiation. Several parameters were also studied such as charge carrier concentration, ND, and flat band potential, Vfb. The γ-irradiation was found to increase the concentration of the deep traps within the band gap of the CdS/Si heterojunction.

In the present work undoped arid Mn doped ZnO nanoparLicles (ZnO:Mn), diluted magnetic semiconductors, were successfully synthesized by the sol-gel method at room temperature. The morphology of ZnO nanoparticles constituted by flower-like structures with hexagonal morphologies that changed significantly after the incorporation of Mn. Rietveld refinements results showed that Mn ions are successfully doped into ZnO matrix without altering its wurtzite phase. Meanwhile, Raman spectroscopy analyses confirm the wurtzite structure of undoped ZnO and ZnO:Mn nanoparticles. The lattice parameters increase with increasing Mn content due to the large ionic radius of Mn2+ compared to that of Zn2+. Electron spin resonance measurements were performed to gain information about oxidation state and site occupancy of the magnetic Mn ions in the ZnO lattice. Moreover, UV-vis absorption spectra have been utilized to calculate the optical band gap of the uncloped ZnO and ZnO:Mn nanoparticles before and after different gamma-irradiation doses. The band gap of ZnO:Mn (2%) is 2.62 eV which is noticeably smaller than the 326 eV of undoped ZnO. The thermal decomposition properties of the prepared nanoparticle samples were also studied using simultaneous Thermogravimetric analysis in temperature range from 30 to 500 degrees C. (C) 2015 Elsevier B.V. All rights reserved.

We present a key idea of using the graphene-based Schottky junction to achieve high sensitivity and wide detection range radiation sensors. Nanostructured Schottky junction is formed at the interface between a graphene, metal electrode, and a semiconductor. The current flowing through the junction is mainly controlled by the barrier's height and width. Therefore, the detection principle is based on Schottky barrier height (SBH) modulation in response to different materials and stimuli. We have illustrated the concept for gamma (gamma) radiation sensors. It's demonstrated that the integration of graphene leads to a great enhancement in sensitivity of up to 11 times coupled with 5 times increase in the sensing range as compared to conventional Schottky junctions. Furthermore, it was demonstrated that for proposed sensors, that the change in SBH could be fairly linearized as a function in the radiation dose unlike the SBH of comparable conventional junctions. The new concept opens the door for a novel class of minitivarized, low biased, nanoscale radiation sensors for wireless sensor networks. The devices are based on new nanostructured Schottky junctions made by growing graphene on ultrathin platinum catalytic layer grown on different silicon substrates. Graphene high uniformity film with small flakes size embedded with platinum particles was synthesized using two deposition steps. The integration of graphene layers on regular M-S junctions was only possible by using an ALD grown platinum thin film (10-40 nm) and then growing graphene in PECVD at temperatures lower than platinum suicide formation temperature. The radiation sensing behaviors were investigated using two different substrate types. The first substrate type is a moderately doped n-type (n approximate to 12 x 10(15) cm(-3)) silicon substrate in which a Schottky rectifier response with different threshold voltages was observed. A device that is based on Pt/n-Si conventional Schottky junction was used as a reference. The various devices were exposed to a range of gamma-irradiations (2-120 kGy) using Co-60 source, and a change in terminal voltages before and after radiation were measured accordingly. A sensitivity of 3.259 mu A/kGy cm(2) at 1 V bias over a wide detection range has been realized. The charge transport mechanisms are interpreted on the basis of testing the detectors at elevated temperatures and theoretical models, both of which both verified tunneling as the dominant charge transport in the device. Tunneling allowed the operation of the detectors at low bias voltages with good sensitivity. The detector's realized sensitivity at low bias voltage is a significant advantage, allowing the sensor to operate on a small battery or an energy-harvesting source. This is ideal for low-cost wireless sensor networks.The obtained responses, increase in sensitivity, and increase in detection range, were explained by studying the band diagrams of the graphene-Schottky junction in comparison to that of the conventional junction. Further, the fact that graphene layer was grown on the M-S junction adds to the uniqueness of this research since exfoliated graphene will result in increased contact resistance and lower carrier mobility which might not yield the desired sensing response. (C) 2015 Elsevier B.V. All rights reserved.

Nano-structured CdS thin film was deposited onto a glass substrate by an electron beam evaporation technique at room temperature from a powder prepared by a hydrothermal method. The morphology and structural properties of the as-deposited film were characterized using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The AFM morphology study confirms that the CdS thin film has nano-sized grains and a dense morphology. The mean particle size that resulted from XRD analyses was 8.4nm. Also, the XRD patterns show that CdS powder and thin film have hexagonal wurtzite type structure with a preferred c-axis orientation along (002) plane. The refractive index and the film thickness were obtained using the Swanepoel method from transmission spectrum. The optical band gap was calculated from the absorption spectrum, and was found to be 2.41eV corresponding to direct optical transition. The dispersion of the refractive index was explained using a single oscillator model. The dielectric relaxation time and the optical conductivity were determined and studied with photon energy.

This paper reports on a new fabricated sensor for rapid and ultrahigh sensing of gamma-ray (Y-ray) radiation based on a new nanostructure of columnar graphene oxide grown on Platinum/n-type Silicon (Pt/n-Si) substrate which gives a Schottky rectifier response with different threshold voltages. The diodes were exposed to a range of Y-ray irradiations (5 − 35 KG) and a change in terminal voltages before and after radiation were measured accordingly. The sensitivity was predicted to be (2mA/KG) over a wide detection range, which is higher than the state-of-the-art radiation sensor devices. Moreover, the proposed sensor operates on low power, isotropic (i.e., independent of the radiation exposure angle), easy to fabricate, can operate wirelessly, and can be seamlessly integrated in wearable detection devices for ultrahigh sensitivity online monitoring of Y-ray radiations.

Abstract In this paper, we aim to demonstrate a novel scheme for integration of nanostructured semiconductor Graphene Oxide (GO) shottky diodes on flexible substrate for a wide range of sensing applications. The platform introduces a novel flexible GO/Pt/n-Si and GO/Pt/SiN composite structures which provides excellent optical and electrical properties, while maintaining an acceptable mechanical, biocompatibility, and return loss performance. The new structure was investigated for glucose, radiation, and infrared sensing. The sensors results showed ultrahigh sensitivity and high linearity in the targeted regions of interest. Moreover, the use of nanostructured materials allows for the development of a new generation of modern printed circuit antennas and will enable wide range of applications merging both technologies for a wide range of wearable and implantable sensing devices.