Effective monitoring of H2S gas is crucial, as inhaling H2S poses a significant risk to human health, potentially leading to grave harm or even death. Chemiresistive semiconducting metal oxides (SMOs) play a crucial role in detecting low concentrations of H2S, providing early cautioning and ensuring immediate action. To develop affordable chemiresistive gas sensors guaranteeing no trade-offs in sensitivity and selectivity, ongoing research continues to explore different SMOs, enhancing their performance. This study focuses on leveraging affordable carbon-based nanomaterials in CuCrO2 to improve H2S detection, highlighting the efficacy of candle soot (CS) as an effective carbon source for H2S gas. The CS (1.5 wt%) loaded CuCrO2 provides a large surface area, which results in a relative response of 66.4% and 31% toward 50 ppm and 100 ppb of H2S gas, respectively, at 100 degrees C. The 1.5_CS@ CuCrO2 gas sensor performs exceptionally well in a highly humid (RH 80%) atmosphere with a relative response of 65.9% for 50 ppm of H2S gas, despite the hydrophilic nature of candle soot. The first principle density functional theory (DFT) calculations indicate that the hybrid carbon system can detect H2S gas due to its high adsorption energy, charge transfer, and orbital interactions compared to the CuCrO2 system.

Hydrogen presents a promising clean alternative to fossil fuels; however, its high flammability necessitates the development of sensitive, selective, and robust detection strategies under ambient conditions. We report a hydrogen sensor based on Pd nanoparticle functionalized graphitic carbon nitride (g-C3N4) nanosheet integrated AlGaN/GaN high electron mobility transistor, operating at room temperature. The nitrogen-rich adsorption sites of g-C3N4 and the catalytic dissociation of H-2 on Pd imparts exceptional H-2 selectivity over common inquisitive gases (NO2, NH3, H2S, CO2, SO2, and VOCs). The device exhibits a wide dynamic range of 0.5-1000 ppm, a sensitivity of 0.67 mu A/ppm, and a rapid response/recovery time (similar to 28/40 s at 10 ppm) under dry air. Stability is retained under humidity up to 80 % RH, temperature between 25 and 85 degrees C, and multiple aging cycles, outdoing prior reports. Enabling smart sensing, the sensor was interfaced with an ESP32 microcontroller for wireless, real-time data transmission. Machine learning algorithms, including Gaussian Process Regression and Multilayer Perceptron, were applied to the transient response for accurate H-2 concentrations prediction. The MLP achieved RMSE approximate to 26 ppm, R-2 > 0.94, enabling real-time concentration tracking. The synergy of Pd/g-C3N4 catalytic layers, the AlGaN/GaN HEMT platform, IoT connectivity, and ML analytics delivers a scalable and energy-efficient approach for next-generation hydrogen safety infrastructure.

Hydrogen sulfide sensors are censoriously important for environmental monitoring, industrial safety, and biomedical applications due to the highly toxic and corrosive nature of H2S gas. We report indium sulfide (In2S3) flakes were grown via chemical vapor deposition (CVD) and functionalized with palladium (Pd) nanoparticles(NPs) to develop a high-performance chemiresistive H2S gas sensor. The pristine In2S3 flakes have a porous microstructure with abundance of active sites, however the addition of Pd NPs improves the gas sensing response through enhancing charge transfer interactions along with providing catalytic spillover sites. The Pd-functionalized In2S3 sensor demonstrated a increase in respone (1.4-fold) and selectivity towards H2S, attaining a sensing response of approximately 67.60% at 50 ppm concentration at 75 degrees C. The sensor demonstrated rapid kinetics with response and recovery times of 48 s and 260 s, respectively, and a remarkably low limit of detection of 59 ppb. Furthermore, the sensor confirmed high humidity tolerance up to 80% RH and excellent repeatability. Density functional theory calculations discovered an 8-fold increase in adsorption energy (-1.51 eV) and significant charge transfer (-0.086 e(-)) upon Pd decoration, correlating the electronic sensitization of the Schottky barrier to the observed ppb-level sensitivity. With the use of first-principles calculations that explain the underlying sensing process, this work presents a practical strategy to develop efficient H2S gas sensors through the use of CVD-grown sulfide semiconductors with decoration of noble metal NPs.

Uric acid (UA), the terminal metabolite of purine catabolism, serves as a critical clinical biomarker; its dysregulation is associated with oxidative stress and pathologies including gout, renal disease, and cardiovascular disorders. This necessitates the development of highly sensitive, selective, and cost-effective sensing platforms for precise UA quantification in biomedical and clinical diagnostics. Herein, we report a chemiresistive biosensor fabricated from a chemical vapor deposition (CVD)-grown β-In2S3 flakes, sequentially functionalized with sputtered SnO2 and gold nanoparticles (Au NPs) to enable enhanced UA detection. The synergistic integration of SnO2 and Au NPs conferred superior electrical and catalytic sensitivity compared to both pristine β-In2S3 and SnO2-functionalized In2S3 devices. Sensor performance was systematically evaluated by measuring the response to UA, with selectivity assessed against a panel of interfering biomolecules. The β-In2S3-SnO2-Au heterostructure exhibited a pronounced and selective response to UA, achieving a 161% response to 168.11 mg/dL UA a 2.7-fold enhancement over the pristine β-In2S3 device. This improvement is attributed to the facilitated charge transport and augmented catalytic activity afforded by the SnO2-Au NP functionalization. The developed biosensor demonstrates significant potential for effective UA monitoring, offering a promising platform for applications in biomedical diagnostics, healthcare, and analytical sensing.

Nonlinearity, baseline drift, humidity interference, and selectivity are among the primary challenges associated with direct current measurements in semiconducting gas sensors today. This study demonstrates that integrating PtSnO2 and MXene-based sensors enables high-performance gas sensing by effectively mitigating humidity-induced interference. Impedance measurements across multiple frequencies were employed, yielding sensors with tunable gas responses, low noise, extended dynamic range, enhanced baseline stability, and minimal humidity cross-sensitivity. PtSnO2 was optimized for simultaneous NH3 and relative humidity (RH) detection, while MXene served as a dedicated RH sensor. A multilayer perceptron was trained on the impedance dataset to deconvolute and accurately predict RH and NH3 concentrations. The proposed sensor system and analytical framework were benchmarked against commercial DHT22 (humidity) and DFrobot (NH3) sensors, demonstrating superior performance and sensitivity. This methodology is extendable to other material systems, including metal oxides and transition metal dichalcogenides, for advanced gas-sensing applications. These findings advance gas-sensing technology by improving detection accuracy and robustness in industrial safety, environmental monitoring, and biomedical diagnostics, including early disease detection.

The environment is seriously threatened by elevated nitrate (NO3−) levels in drinkable water brought on by geogenic and anthropogenic activity. Here, we present a CuNPs@rGO@AgNWs nanocomposite-based electrochemical sensor system for NO3− detection that is incredibly effective. On a glassy carbon electrode (GCE), the NO3− sensor's electrochemical performance was incredibly dependable and long-lasting. The catalytic activity of copper nanoparticles (CuNPs), the large surface area and conductivity of reduced graphene oxide (rGO), and the rapid electron-transport pathways provided by interconnected silver nanowires (AgNWs) are integrated in this system. The sensor demonstrated a linear detection range of 10-100 μM with a detection limit of 0.128 μM, stability for up to 5 weeks with a slight 1.5% signal loss, and good selectivity for NO3− (P ≤ 0.03). It also successfully identified NO3− in actual soil samples and demonstrated reliability of a relative standard deviation (RSD < 2%). Due to its excellent stability and reproducibility, this reliable sensor helps protect public health by offering a useful tool for real-time NO3− environmental evaluation.

As conventional memory technologies face limitations in scalability, volatility, and energy efficiency, resistive random-access memory (RRAM) has emerged as a promising candidate for next-generation memory and neuromorphic computing. Among various oxide materials, copper oxide (CuO) has been studied for RRAM applications due to its simple binary structure, ease of synthesis, and inherent defect-mediated switching behavior. However, despite these advantages, CuO-based devices often suffer from limited endurance and poor retention. To overcome these drawbacks, we explore CuGa2O4, a complex spinel oxide, as a more stable and tunable alternative. The multinary composition and the spinel structure of CuGa(2)O(4 )offer enhanced control over defect chemistry and switching dynamics, leading to improved reliability and multifunctionality. The device demonstrates analog switching characteristics, including transition from short to long-term plasticity under repeated stimulation, mimicking biological synapses. Furthermore, associative learning behavior, reminiscent of the Pavlovian conditioning model, is observed, demonstrating the device's potential in neuromorphic systems.

Ascorbic acid (AA) is crucial in metabolic activities, serving as a scavenger to avert oxidative damage. Consequently, there is an imperative requirement for a highly sensitive, selective, and cost-effective sensing platform for the detection of AA. We introduced a useful method for detecting AA using SnS2 anchored with gold-silver (Au-Ag) nanoparticles (NPs). These bimetallic NPs usually have better catalytic abilities than single-metal ones. Here, we grow SnS2 flakes utilizing a simple chemical vapor deposition (CVD) method to address the growing demand for a reliable detection platform. To optimize device properties, we deposited Au/Cr contacts using a shadow mask on the SnS2 flakes and subsequently passivated them with Si3N4 to avert electrical shorting. The sensor's resistance was measured in the absence and presence of AA, while selectivity was analyzed for various biomolecules, revealing a high selectivity for AA. The Au-Ag-S-2-based device exhibited a response of 129.7% to 1 mM of AA biomolecules, surpassing all other devices and demonstrating almost double increase in sensing response compared to the pristine SnS2 device. The outcomes of this work illustrate the effectiveness of Au and Ag NP-anchored SnS2 as a desirable material for AA detection. This discovery advances our ability to monitor and identify AA, promoting progress in biomedical, industrial, and environmental applications.

This study presents a biosensor utilizing electrospun SnO2 nanofiber films for real-time monitoring of C2C12 cells. The biosensor demonstrates sensitivity towards cellular behaviors, including adhesion, proliferation, and detachment. Alterations in semi-circle and dielectric properties are validated through Nyquist plot and an EEC model, highlighting the biosensor's potential for analyzing cellular dynamics.

In this study, we report a power-efficient and highly selective H2S gas sensing platform based on a pulse-modulated sensor of nanostone-structured CuO thin films. Nanostone morphology chemiresistive sensors exposed to H2S at moderate temperatures (∼150 °C) undergo irreversible surface transformations, converting the active CuO phase into highly conductive CuS or Cu2S, which results in unstable current output and loss of sensing capability. To address this, we introduce a dynamic pulse modulation technique that cyclically toggles the sensing temperature ON and OFF at 200 °C, enabling in situ regeneration of CuO from CuS without external thermal treatment. This effect is attributed to enhanced sulfur desorption kinetics and reactivation of surface oxygen during cooling cycles, which collectively disrupt the thermodynamic equilibrium that stabilizes Cu-S bonds under continuous heating. Morphological features, such as a nanostone-like surface texture and vertically aligned columnar grain architecture, further contribute to rapid gas diffusion, increased surface reactivity, and improved charge transport pathways. Experiments reveal that pulse modulation decrease reaction and recovery time, increase long-term stability, and material reversibility, even at higher H2S concentrations where irreversible behavior is typically observed.

The development of advanced hydrogen (H2) sensors is crucial for ensuring the safe handling of H2, widely regarded as an optimal energy carrier to address the ongoing energy crisis. The development of H2 detection equipment is critical because of increasing H2 production from water electrolysis, H2 fuel cells, and other H2 businesses. The creation and characterization of palladium-anchored NiO-ZnO thin films for H2 gas sensing applications are investigated in this work. We fabricated the thin films using sputtering techniques to ensure a uniform distribution of dopants and effective anchoring of Pd (0.31 wt%). The results revealed that the Pd (0.31 wt%) anchored 4 wt% NiO-ZnO thin films demonstrate significantly improved sensitivity, selectivity, and response-recovery times compared with the NiO-ZnO variant. The combined effects of Ni and palladium anchoring, which enhance the adsorption and dissociation of H2 molecules, are responsible for this enhancement. This, in turn, increases the charge carrier concentration and alters the electrical resistance of the films. We found that the Pd (0.31 wt%) anchored NiO-ZnO thin films worked best at 150 degrees C. They were able to detect 65 % of 50 ppm H2 with a response time of about 48 s and a recovery time of about 216 s. The results show that Pd (0.31 wt%) anchored NiO-ZnO thin films could be used as reliable and effective sensors for finding H2 gas. These sensors could be used in environmental monitoring, renewable energy, and safety in the workplace. These films present a promising solution for advanced gas sensing technologies due to their enhanced performance, ease of fabrication, and scalability.

Defect engineering in metal oxides presents a promising approach for tailoring material properties. This strategy enhances gas sorption, catalysis, and control over key physical characteristics such as bandgap, magnetic behavior, and electrical conductivity. Despite its potential, the role of defect engineering in advancing metal oxide semiconductor (MOS) gas-sensing performance remains underexplored. This review introduces defect engineering strategies, emphasizing their applications in gas sensing. Gas sensors play a vital role in environmental monitoring, industrial safety, healthcare, and in improving energy efficiency. The demand for advanced gas sensors has never been more critical, given the need for real-time, accurate, and cost-effective detection of pollutant gases. MOS-based gas sensors are widely used in air quality monitoring, industrial safety, and health diagnostics. Vacancies and defect architectures in MOS have been widely studied for their role in sensing performance, as they fundamentally influence sensor efficiency. The effectiveness of MOS sensors largely depends on the type and concentration of defects. This review introduces vacancies and defects in MOS, followed by an in-depth discussion of defect types, factors influencing defect formation, and their role in charge transport. Additionally, it examines the correlation between elemental chemical properties and defect chemistry. Special attention is given to the defect chemistry of metal oxides, including TiO2, ZnO, Co3O4, ZrO2, WO3, and CeO2. It concludes with an examination of surface engineering methods for defect control to improve gas-sensing capabilities.

Hydrogen sulfide (H2S) is recognized as a toxic gas, renowned for its capacity to inflict significant harm upon the respiratory and nervous systems. Consequently, the development of high-performance H2S sensors holds significant importance. However, traditional fabrication methods such as brush painting and drop casting often yield sensors with inconsistent batch responses due to the unpredictable film formation process, hindering their mass industrial production. Here, we have devised a novel approach to fabricate highly sensitive and selective H2S sensors utilizing Pd-anchored CuO/SnO2 heterostructures thin films. An investigation was conducted to analyze the impact of different noble metals (Pt, Au, Ag, and Pd) on CuO/SnO2 heterostructure thin films concerning their response to H2S. These films were synthesized through RF sputtering and subsequently decorated with varying durations of CuO (15, 30, 45, 60, and 75 s) and Pd nanoparticles (Nps) (3, 6, 9, and 12 s) using a sputtering process. Notably, a sputtering time of 60 s for CuO and 9 s for Pd significantly enhanced the H2S sensing performance and selectivity over other gases. The Pd-anchored CuO/SnO2 thin films revealed an exceptional result of 75.45% to 100 ppm H2S, demonstrating a detection capability down to 0.5 ppm. These noteworthy outcomes were attained under optimal operating conditions at a temperature of 150 degrees C. This innovative fabrication technique holds promise for the advancement of gas sensor technology, enabling the creation of portable sensor prototypes suitable for real-time sensing applications.

Metal oxide-based chemiresistive gas sensors are reliable for detecting low concentrations of hydrogen sulfide (H2S) gas, which pose significant harm to human health. This article highlights the improvement in H2S gas detection by using CuO-decorated SnO2 nanofibers, which are synthesized by combining electrospinning and sputtering. The electrospun PVP/SnO2 fibers are calcinated at 600 degrees C, reducing the diameter from 498 to 220 nm, which enhances crystallinity, favoring improved H2S sensing. The efficacy of H2S gas detection using CuO-decorated SnO2 nanofibers was explored at a temperature ranging from 50 to 200 degrees C. CuO sputtered nanoparticles for 30, 60, and 90 s, respectively, on SnO2 nanofibers improve the gas relative response, showing the importance of composite material toward sensing. The catalytic abilities of CuO sputtered nanoparticles for 60 s on SnO2 nanofibers boost the gas relative response to 85.71% for 50 ppm of H2S gas at 200 degrees C & horbar;an improvement of 25% more than the pristine SnO2 nanofibers. CuO-decorated SnO2 nanofibers showed an excellent adsorption/desorption property with response and recovery times of 100 and 109 s for 50 ppm of H2S. First-principles calculations indicate that the O-adsorbed SnO2/CuO system has potential for H2S gas detection due to its high adsorption energy of -2.21 eV, charge transfer of 0.65 e(-), and orbital interactions. Our findings conclude the superiority of CuO-decorated SnO2 nanofibers in detecting the H2S gas at low concentrations for industrial applications.

To minimize harmful gas exposure and enable early disease diagnoses in low-resource settings, it is crucial to create an H2S gas sensor that can detect low ppb levels at room...

This paper presents a two-stage high gain singleended operational amplifier design for Σ-Δ analog-to-digital converters (ADCs) in very-large-scale-integration (VLSI) technology. The high-gain operational amplifier design eliminates wasted drain current at the output of the operational amplifier. The first stage of the amplifier, differential pair with active load, provides high gain. The second common source stage provides a high output voltage swing. The high-gain operational amplifiers (two-stage singleended configuration) with a gain of more than 80dB and bandwidths between 3.5MHz to 5MHz have been designed and simulated using Cadence Virtuoso Analog Design Environment in 90nm and 180nm standard CMOS processes.

This article discusses the direct effect of the seed layers on the growth of the ZnO nanorods (ZNRs) and related photovoltaic parameters of the hybrid perovskite solar cell (PSC). Four different types of ZnO seed layer samples are prepared to analyze the growth of ZNRs over the respective seed layers. Various device parameters for the respective PSCs made of different seed layers are investigated. The ZnO quantum dot-based seed layer shows the well-aligned, vertical, and uniform distribution of ZNRs and improves SC parameters over the other three samples. The ZnO seed layer deposited via drop cast methods results in less density, random, and nonuniform distribution of the ZNRs. The surface morphology, optical absorption, transmission, and crystalline structure were analyzed with high resolution scanning electron microscopy (HRSEM), TEM, UV-visible absorption, and X-ray diffraction (XRD) techniques. 10.69% of power conversion efficiency with improved open-circuit voltage ( ${V}_{OC}$ ) of 1.01 V is achieved for device structure, fluorine doped tin oxide (FTO)/ZnO QDs seed layer/ZNRs/perovskite/poly[bis(4-phenyl)(2,5,6-trimethylphenyl)amine (PTAA)/gold (Au).

In this paper, we demonstrate the ZnO quantum dot thin film based UV light Photodetector with a different metal electrode. ZnO quantum dot synthesized using a colloidal synthesis method. The prepared ZnO QD thin film is characterized by X-ray diffraction (XRD), Photoluminance (PL), and UV spectroscopy. XRD result confirmed the formation hexagonal structure of ZnO, UV spectroscopy result confirm the bandgap of ZnO quantum dot is 3.25 eV using Tauc plot. Finally, ZnO quantum dot-based thin film is investigated for electrical and optical characteristics using interdigitated metal-semiconductor-metal (MSM) Ag and Au metal electrode. The comparative study of Ag and Au metal electrodes is investigated in terms of I-V characteristics under the dark condition and with a monochromator light at a wavelength of 375 nm with a power density 43 mu w/cm(2). It is found that the ZnO quantum dot-based fabricated photodetector device using Au interdigitated electrode has better electrical and optical performance as compared to Ag electrodes.

In this work, multifunctional CuO nanowires (NWs) electrode-based extended-gate (EG) field-effect transistor (FET) has been explored for both pH and glucose sensing applications. The CuO nanowires (NWs) electrode-based EGFET gives good pH sensitivity (~48.34 mV/pH), high linearity (99.84%), good stability for pH level in between 2 and 12 for 12 hours with a drift rate of 2.5mV/h, and good reversibility in terms of low hysteresis loss of 2.5mV. The selectivity of this pH sensor towards hydrogen ion is significantly higher as compared to Na + , K + , Zn ++ and Mg ++ ions. In addition to the pH sensing, CuO NWs based electrode-based EGFET has also been explored for glucose-sensing for the first time without taking the help of neither any enzyme nor any organic receptor. The proposed glucose sensor gives a good sensitivity of 3.03 mV/mM with a high range of linearity (1mM-12mM), which covers up the glucose level of human blood ranging from 3.6 mM to 6.6 mM. This novel concept of CuO NWs based EG-FET glucose sensing is believed to be extended for sensing other saccharides such as fructose, sucrose, and mannose.

This paper reports the fabrication, characterization and simulation of hybrid perovskite solar cells (PSCs) in ambient condition. The proposed PSC structures use a CH3NH3PbI3 hybrid perovskite based active layer sandwiched between a ZnO nanorods (NRs) electron transport layer (ETL) and a spiro-OMeTAD (undoped and doped) hole transport layer (HTL). The ZnO NRs are grown using low-cost solvothermal process at relatively low temperature. The performance of fabricated PSCs are analyzed for both the undoped and doped (with TBP and LiTFSI) spiro-OMeTAD based HTLs. All the solar parameters namely, short circuit current density (JSC), open circuit voltage (VOC), fill factor (FF), power conversion efficiency (PCE) and external quantum efficiency (EQE) are calculated from experimentally measured current density versus voltage (J-V) and wavelength transient characteristics in ambient condition. The maximum PCE of 10.18% is obtained for the doped HTL whereas 9.51% for undoped HTL. The improved performance due to HTL doping is attributed to the enhanced charge transportation of the HTL. The experimental results obtained from the fabricated PSCs are also compared with the SetFos™ TCAD simulation data using drift-diffusion model. The simulated results are observed to be well matched to the experimental data.