Search

A precise measurement of soil potassium (K) concentration is crucial for enhancing agricultural productivity and promoting sustainable land management. The efficiency of real-time soil quality monitoring is hampered by the time-consuming laboratory analysis that is commonly associated with conventional methods. The present research introduces an innovative approach utilizing a field-effect transistor (FET) structure coated with reduced graphene oxide-decorated valinomycin (rGO-v) for the detection of potassium ions in soil samples. The sensor exploits the distinctive electrical properties of reduced graphene oxide (rGO) and the specific affinity of valinomycin for potassium ions. To construct the device, we applied rGO-v onto an FET substrate. The conductance of the FET can be modified by the interaction between valinomycin and potassium ions, enabling the detection of potassium ions. Some of the advantages of this technology are its high sensitivity, fast response time, and potential for miniaturization. In addition, the device is tuned to demonstrate an enhanced sensitivity of 0.98 μA/(kg/ha) below the threshold voltage. The sensor exhibits a response time of 40 s and demonstrates exceptional stability in the face of unfavorable conditions, specifically humidity. Therefore, valinomycin-decorated reduced graphene oxide, when subjected to appropriate gate bias, demonstrates promising results as a versatile, cost-effective, and easy-to-use potassium ion sensor.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has triggered an ongoing global pandemic, necessitating rapid and accurate diagnostic tools to monitor emerging variants and preparedness for the next outbreak. This study introduces a multidisciplinary approach combining Fourier Transform Infrared (FTIR) microspectroscopy and Machine learning to comprehensively characterize and strain-type SARS-CoV-2 variants. FTIR analysis of pharyngeal swabs from different pandemic waves revealed distinct vibrational profiles, particularly in nucleic acid and protein vibrations. The spectral wavenumber range between 1150 and 1240 cm–1was identified as the classification marker, distinguishing Healthy (noninfected) and infected samples. Machine learning algorithms, with neural networks exhibiting superior performance, successfully classified SARS-CoV-2 variants with a remarkable accuracy of 98.6%. Neural networks were also able to identify and differentiate a small cohort infected with influenza A variants, H1N1 and H3N2, from SARS-CoV-2-infected and Healthy samples. FTIR measurements further show distinct red shifts in vibrational energy and secondary structural alterations in the spike proteins of more transmissible forms of SARS-CoV-2 variants, providing experimental validation of the computational data. This integrated approach presents a promising avenue for rapid and reliable SARS-CoV-2 variant identification, enhancing our understanding of viral evolution and aiding in diagnostic advancements, particularly for an infectious disease with unknown etiology.

In this study, we have systematically investigated the impact of intrinsic device parameters on the performance of beta gallium oxide ( $\beta $ -Ga2O3) nanomembrane metal–semiconductor field effect transistors (NM-MESFETs). The ON- and OFF-state performances of these devices were analyzed using a well-calibrated technology computer-aided design (TCAD) simulator, focusing on breakdown voltage ${(} {V}_{\text {BR}} {)}$ , ON-resistance ( ${R}_{\text {ON}}{)}$ , threshold voltage ${(} {V}_{\text {th}} {)}$ , maximum drain current ${(} {I}_{\text {D},\text {max}} {)}$ , and power figure of merit ${(} \text {PFOM} {)}$ . Two distinct breakdown mechanisms are identified, significantly affecting ${V}_{\text {BR}}$ of these NM-MESFETs. Interestingly, when studying the effect of individual device parameters on ${V}_{\text {BR}}$ , we observed an initial increasing trend up to a critical value, followed by a sharp fall and a subsequent decreasing trend. Through simulations, an empirical model is developed that facilitates the selection of appropriate device parameters to achieve MESFETs with high ${V}_{\text {BR}}$ . In addition, an analytical model of ${V}_{\text {th}}$ of the MESFET in terms of its device parameters is also proposed and validated with simulation results. The performance of the NM devices is also benchmarked against reported Ga2O3 devices.

The demand to detect toxic arsenic ions in water is increasing due to uncontrolled industrial and human activities. Conventional detection methods are found to be very complex, cumbersome, and nonportable. Here, we propose a novel reduced graphene oxide (RGO)–Fe3O4–leucine-based device with high sensitivity and stability for selective detection of arsenic ions in water. The operating voltage of the device is 2 V, which ensures low power consumption. Fe3O4 and leucine impart a high degree of selectivity toward arsenic ions, and RGO ensures a high surface-to-volume ratio for adsorption. The device is tested against eight metal ions, which are common water contaminants and found to be highly sensitive toward arsenic. The sensitivity of the RGO–Fe3O4–leucine-based device toward arsenic is found to be 140 nA/ppb, which is very high compared to the other ions. The sensor device exhibits a response time of 21 s and is highly stable against adverse humid conditions. The sensor shows high resilience in the degradation of sensing performance for 40 days. Therefore, the RGO–Fe3O4–leucine-based device shows promising results to be used in future portable, low cost, and user-friendly arsenic ion detector systems.

The impediments confronted by flexible batteries for fabrication methodologies and lower specific power for real-time applications ameliorate the stand of flexible supercapacitors as a novel impartial executor in the storage of energy. The commendable attributes of specific energy, long-cycle stability, and rapid ion transport make supercapacitors a crucial candidate in the devices of storage of energy. Eying on these recompenses of supercapacitors, Ni4CuO5-mw-CNT and rGO-FeVO3are fabricated for higher energy asymmetric solid-state supercapacitors through a facile solvothermal procedure delineated. The typical morphology of bimetallic oxides with crystallinity variation depicts a high surface area that grossly supersedes the sites of redox-active, which influences the diffusion of electrolyte ions and the variable-valence redox reaction with ion embolism. The synthesized oxide is investigated using X-ray diffraction, X-ray photoelectron, and Raman spectroscopy to affirm the phase and inspected by electron microscopy for structural features with BET. The Hirshfeld surface simulation analysis assists in grasping the electronic interaction to explicate the experimental consequences. An asymmetric supercapacitor (ASC) device comprising Ni4CuO5-mw-CNT as a cathode and rGO-FeVO3as an anode is assembled. The electrochemical response of Ni4CuO5-mw-CNT and rGO-FeVO3electrodes exhibits higher specific capacitances of ∼778.8 and ∼478 F/g at a current density of 0.4 A/g, respectively, superior long-cycle stabilities, and rate capabilities. Moreover, the convened ASC device achieves a maximum specific energy of ∼29.2 Wh/kg and a specific power density of ∼3201.6 W/kg, along with a retention of the capacitance of ∼82.6% after 10,000 cycles. The associated porous morphology network affords instantaneous accessibility of the electrolytic ions that utterly revamp the proficiency of the electrodes in the field of energy storage.

We report an ultra-low level of Lead ion (Pb2+) detection technique using solution-processed Bovine Serum Albumin (BSA) conjugated ZnO nanoparticle (BCZ) networks. Drop of the BCZ solution casting was performed in-between photolithography patterned two Au electrodes for sensor device. BCZ formation was confirmed by UV-Visible spectroscopy (UV-Vis spectroscopy) and Transmission Electron Microscopy (TEM) prior to device fabrication. The working principle of the sensor device depends on the variation of conductance with Pb2+concentration. The limit of detection (LOD) of this fabricated device was determined as 0.1 pM (S/N > 3).

Here, the synthesis of MoS2 nanosheet was performed by a novel approach “liquid-phase sonication technique” from MoS2 bulk powder to conjugate with ZnO nanoparticle and bovine serum albumin (BSA). This 2-D nano–bio composite MoS2–BSA–ZnO (MBZ) shows a tremendous potential to detect ultralow-level Hg $^{{2}+}$ ions. An extensive study was employed on the synthesis of MoS2 and their nano–bio composite to investigate the effect of Hg $^{{2}+}$ ions for sensing applications. The required characterization of the MBZ was carried out by XRD, field-emission scanning electron microscopy (FESEM), UV–Vis, and fluorescence (FL) spectroscopic technique prior to sensor fabrication. Absorbance spectra were studied and a Tauc plot was prepared to determine the bandgap of MoS2, ZnO, and MBZ, and also, the FL spectra were studied for the quenching effect for detection of Hg $^{{2}+}$ . A facile drop casting technique was used to develop a highly sensitive Hg $^{{2}+}$ detection scheme. The operating principle of the MBZ device for Hg $^{{2}+}$ detection depends on the current/conductance variation with various concentrations of Hg $^{{2}+}$ . Moreover, an electronic detection scheme based on MBZ was developed for ultralow-level sensing Hg $^{{2}+}$ with limit of detection (LOD) 1 pM ( ${S}/\!{N} >3$ ).

This article demonstrates the potential of silk film as gate dielectric in FET-based gas sensor. L-ascorbic acid (LAA) reduced graphene oxide (rGO) was used as semiconducting channel which acts as the sensing layer of the FET-based sensor. The morphology and capacitance of silk film were investigated to introspect two seldomly explored quantities: porosity and dielectric constant. The measured dielectric constant of silk film lies in the range of 32–13 in the low-frequency regime (40–100 Hz). Silk film also exhibited uniform, nonporous, smooth morphology. The Silk-FET device exhibited selective response toward formaldehyde (HCHO) among seven volatile organic compounds (VOCs), and rGO ensured room temperature sensing. During the adsorption of formaldehyde, electrons’ transfer takes place from formaldehyde to rGO, reducing the hole concentration of the channel. This leads to reduction in output current, revealing p-type characteristics of the device. The transfer and output characteristics also exhibited similar p-type nature. Device’s threshold voltage shift is also prominent with the exposure to formaldehyde. The gate bias played a pivotal role in improving the device performance. At 1.15-V gate voltage, the response was enhanced by 2.8 times for 45-ppm formaldehyde. The device exhibited maximum response at a gate voltage of 1.15 V, ensuring low-power operation of the FET device. The device’s response and recovery time were calculated as 97 and 280 s, respectively, at 180-ppm formaldehyde. The sensing behavior of the system was also reaffirmed through the TCAD SILVACO simulations. The energy band diagram revealed the depletion of carriers at rGO with adsorption of formaldehyde.

Integrating an energy harvester and energy storage into a single unit, without connecting any external source, has gathered substantial attention for its ability to convert and store energy in a single device. This study introduces an innovative, self-sustaining power cell called the self-power supercapacitor (SPSC). The SPSC consists of two triboelectric nanogenerators (TENG) and a carbon based supercapacitor cell sandwiched between two TENGs. The SPSC utilizes the energy produced by two TENGs and stores it directly in the supercapacitor, bypassing the requirement of power management circuits. This energy storage process is achieved using tribo-electrochemical methodology. The supercapacitor consists of activated porous carbon obtained from natural biowaste, infused with an ionic liquid electrolyte gel. Each TENG is constructed using a blend of naturally abundant Silk with PVA and PVDF as triboelectric components and exhibit a maximum voltage of 800 V with an instantaneous output power density of 598 mW/cm2. In addition, the self-power supercapacitor effectively gets charged to a voltage of 0.8 V after continuous tapping of 100 s Due to the huge active surface area of the activated carbon electrodes, the device attains a specific capacitance of 43.75 mF/cm2. The assessed specific energy and specific power of the assembled SPSC device were 3.89 mWh/cm2and 666.67 mW/cm2, respectively when subjected to tapping operations. The self-power supercapacitor cell also has the ability to power a range of portable electronics, such as LED. This research evidences the competence of charging the supercapacitor of SPSC system using TENGs without the need for an external parameter.

A mammoth effort has been levied to alleviate the specific energy of supercapacitors and the asymmetric cell formation that delineates a broader potential window. The α-Fe2O3is a potential candidate for the negative electrode in supercapacitor storage for possessing widespread operating potential, economic, higher redox activity, and eco-friendliness. The significance of the synergistic effects compared on the supercapacitive responses in accordance to the specific energy, specific capacitance, specific power, long cycle stability, and rate capability are emphasized along with the cathodic vanadium oxide PANI CNT composite. The flakes fashioned vanadium dioxide (V2O5) with the assimilation of mw-CNT and polyaniline (PANI) originate by a facile synthesis methodology to antagonize the barrier possessed by vanadium-based oxides in the advancement of supercapacitor. As a result of mw-CNT and PANI integration with V2O5, the established organic-inorganic electrode depicts a higher specific capacitance. Those iron and vanadium oxide composite delineates specific energy of ∼78.72 Wh kg−1and ∼49.31 Wh kg−1, along with retention of the capacitance of ∼91.1% and ∼80.9% each after 10,000 cycles. These inimitable amalgam systems of the combination of inorganic-organic can accomplish the compulsion for the growth of novel functional materials for the applications of energy storage.

In a thin film, p-i-n solar cell the front contact interface loss due to high band bending between TCO front contact and p-type window layer can be minimized by inserting a wind band gap hydrogenated amorphous silicon oxide interlayer at the TCO/p interface. In this paper, a simulation and experimental investigation on the performance of p-i-n solar cell by inserting the intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H) at the TCO/p interface has been carried out. A device quality wide bandgap i-a-SiO:H interlayer was prepared at 230 °C substrate temperature by using radio frequency plasma-enhanced chemical vapor deposition (13.56 MHz RF-PECVD) technique. The experimental results in this study showed that the integration of interlayer at the TCO/p interface reduces the barrier height from 0.513 to 0.472 eV resulting the power conversion efficiency (η) of 9.38% and fill factor (FF) of 74.8% for a single-junction p-i-n solar cell with an active area of 1.0 cm2. In addition, the electrically and optically calibrated simulations also confirm that the application of interlayer at the TCO/p interface reduces the barrier height. As a result, the electric filed over the frontal region has decreased, which aided to minimize the recombination of photogenerated holes with back diffusing electrons at the front contact. The spectral response of the solar cell with interlayer has also improved significantly in the lower wavelength region (350-600 nm) in comparison to the cell without an interlayer at the TCO/p interface.

The dual metal oxides anticipated prospective substitution of the transition of cathodic energy materials. The prominent attributes like higher specific energy, specific power, and long cycle stability are crucial to a supercapacitor device's energy storage. In this acclaimed research, the novel MnV2O7composite is fabricated by microwave process and tailed by a hydrothermal method where dimethyl formamide, ethylene glycol, and water are used as solvents separately. The bimetallic oxide's distinctive morphology with crystallinity variation realizes by the solvent. It delineates a higher active surface area that grossly supersedes redox-active sites, which eases diffusion of electrolyte ions and multi-valence redox reaction with ions intercalation. The lignocellulosic bio-waste-derived activated carbon materials are worked as anodic material. The synthesized oxide is investigated using diversified characterization tools to confirm the phase formation and investigated by electron microscopy for structural characteristics. The Hirshfeld surface, EPR and theoretical generalized gradient approximations simulation assist in comprehending the electronic interaction to elucidate the experimental consequences. The MnV2O7oxide depicts improved capacitance is 402 Fg−1at 2 mVs−1scan rate and 364 Fg−1at 2 mAcm−2current for dimethyl formamide as solvent compared to rest. Also, composites delineate 96 % long cycle stability up to 10,000 cycles at 40mAcm−2current with a maximum specific energy of 51.8 Whkg−1and specific power of 2500 Wkg−1. The integration of augmented energy storage of the composite leads to a perfect candidate to apprehend the urge of novel advanced materials engineering for applications of energy storage.

Rapid development of intelligent transportation demands accurate methods for monitoring vehicle overload information. This paper reports a detail analysis on the viability of triboelectric nanogenerator (TENG) as a smart traffic monitoring system. PVDF and silk film were exploited for TENG fabrication for their strong penchant of gaining and loosing electrons. The objective of this paper is two fold. Initially the electrical performance of the fabricated prototype was measured and reported. The prototype exhibited a maximum open circuit voltage of 648 V and an instantaneous power density of 24 mW/mm2. It was also capable to light up 75 commercial green LEDs. Furthermore, a TENG based traffic monitoring system was introduced for monitoring the traffic overload information and for counting the number of vehicles rolled on it. The TENG was used to convert the mechanical energy from the rolling of vehicles into electric pulses. The pulses that were generated by the TENG was incorporated into an interfacing circuit to anticipate the number of vehicles passed by it. The amplitude of those pulses also give a valuable information regarding the weight of vehicles as the generated voltage is proportional to the input force. Different output voltages of 207 V, 367 V and 558 V were produced for different types of vehicles like bicycle, motorbike and four wheeler passenger vehicle respectively depending on their mass. Output voltage was also varied depending on the load carried by vehicles and showed an increasing trend with load. In consequence, the proposed system can substantially be implemented at various automotive toll plazas to corroborate the paid tax and the actual tax that is supposed to be paid on the basis of laden weight of the vehicle.

Molybdenum diselenide (MoSe2), an in-organic analog of graphene, is considered a rising star in the family of transition-metal dichalcogenides (TMDs) because of its stable covalent Mo–Se bond, good catalytic properties, huge specific surface area, higher electrical, multivalent oxidation states of transition metal ions, and its ability to be intercalated with suitably-sized metal atoms or organic molecules to modify their physical properties with a distinguishing layered structure. It is being projected as the next-generation 2D layered nano-material for many energy storage-conversion applications. This review covers the properties, functionalization of MoSe2, and their applications in supercapacitors, discussing the current developments of MoSe2and its nano-composites-based supercapacitors, providing emphasis to the capacitive performances which comprise of specific capacitance/ capacity, cyclic lifespan, energy density, power density, rate capability, and their practicality in the real environments. Fundamental charge-storage mechanisms are also discussed to provide better insight into how MoSe2is ascribed to each supercapacitor. Wherever applicable, limitations of the existing approaches and future outlook are also described.

•Synthesis of activated porous carbon from bio waste.•Symmetric super capacitor based on the activated porous carbon attributes excellent electrochemical performance.•The symmetric super capacitor device and the carbon itself evinced excellent long cycle stability and high cell voltage.•High specific energy and specific power are realized in super capacitor analysis.•The system potential is calculated by utilizing the upper limit of the capacitive potential value.