Search results

This paper aims to improve the device performance from the perspective of reducing ohmic contact resistance; the effects of different electrode structures and alloying parameters on the series resistance and power-current-voltage of laser diodes (LDs) have been investigated in this paper.

Four groups of p-GaAs side metal electrodes with different metal layer arrangements and thicknesses are fabricated for the investigated LDs. The investigated p-GaAs side electrodes are based on Ti/Pt/Au material and the n-GaAs side metal electrodes all have a same structure of Ni/Ge/Ni/Au/Ti/Pt/Au. The LDs with different electrodes were alloyed at 380°C for 60 s and 420°C for 80 s.

The experimental results show that the series resistance decreases by 14%–20%, the output power increases by 2%–2.2% and the conversion efficiency increases by 1.69%–2.16% for the LDs prepared with optimized alloying parameters (420°C for 80 s). The laser diode with p-GaAs side Ti/Pt/Au electrode of 30/70/100 nm has the best device characteristics under both annealing conditions.

The utilization of this improvement on ohmic contact property in electrode is not only very important for upgrading high-power LDs but also helpful for GaAs-based microelectronic devices such as HBT and monolithic microwave integrated circuit.

The purpose of this paper is to report on metal‐oxide‐semiconductor (MOS) capacitor‐based O₂ sensors with different catalytic metal electrode (Al or Pd), deposited on both smooth and porous surface (pore diameter ranging from 2.76 to 71.6 μm) of ZrO₂ thin film.

The ZrO₂ thin film has been prepared by RF sputtering and DC magnetron sputtering process followed by thermal oxidation process, whereas the electrodes were deposited on thin film by thermal evaporation. The sensors are exposed to O₂ gas ambient at room temperature and the O₂ sensing performance has been examined by surface characterizations and on‐line sensing electrical characterizations.

MOS capacitor O₂ sensor with Pd electrode on porous ZrO₂ thin film has the best sensitivity in term of both adsorption and desorption of gas. This sensor is proved to be operated in both capacitor and diode modes.

The paper demonstrates that room temperature MOS‐based O₂ sensor operates in capacitor and diode mode conditions with focus on the effect of ZrO₂ surface morphology on the sensing properties.

The development of chemical sensors based on nanostructures, such as nanotubes or nanowires, depends on the capability to reproducibly control the processing of the sensor. Alignment and consistent electrical contact of nanostructures on a microsensor platform is challenging. This can be accomplished using labor‐intensive approaches, specialized processing technology, or growth of nanostructures in situ. However, the use of standard microfabrication techniques for fabricating nanostructured microsensors is problematic. The purpose of this paper is to address this challenge using standard photoresist processing combined with dielectrophoresis.

Nanostructures are suspended in photoresist and aligned between opposing sawtooth electrode patterns using an alternating current (AC) electric field (dielectrophoresis). The use of photoresist processing techniques allow the burying of the nanostructures between layers of metal, thus improving the electrical contact of the nanostructures to the microsensor platform.

This approach is demonstrated for both multi‐walled carbon nanotubes and tin oxide nanowires. Preliminary data show the electrical continuity of the sensor structure as well as the response to various gases.

It is concluded that this approach demonstrates a foundation for a new tool for the fabrication of microsensors using nanostructures, and can be expanded towards enabling the combination of common microfabrication techniques with nanostructured sensor development.

This approach is intended to address the significant barriers of deposition control, contact robustness, and simplified processing to realizing the potential of nanotechnology as applied to sensors.

This review provides an overview of recent advances in electrochemical sensors for analyte detection in saliva, highlighting their potential applications in diagnostics and health care. The purpose of this paper is to summarize the current state of the field, identify challenges and limitations and discuss future prospects for the development of saliva-based electrochemical sensors.

The paper reviews relevant literature and research articles to examine the latest developments in electrochemical sensing technologies for saliva analysis. It explores the use of various electrode materials, including carbon nanomaterial, metal nanoparticles and conducting polymers, as well as the integration of microfluidics, lab-on-a-chip (LOC) devices and wearable/implantable technologies. The design and fabrication methodologies used in these sensors are discussed, along with sample preparation techniques and biorecognition elements for enhancing sensor performance.

Electrochemical sensors for salivary analyte detection have demonstrated excellent potential for noninvasive, rapid and cost-effective diagnostics. Recent advancements have resulted in improved sensor selectivity, stability, sensitivity and compatibility with complex saliva samples. Integration with microfluidics and LOC technologies has shown promise in enhancing sensor efficiency and accuracy. In addition, wearable and implantable sensors enable continuous, real-time monitoring of salivary analytes, opening new avenues for personalized health care and disease management.

This review presents an up-to-date overview of electrochemical sensors for analyte detection in saliva, offering insights into their design, fabrication and performance. It highlights the originality and value of integrating electrochemical sensing with microfluidics, wearable/implantable technologies and point-of-care testing platforms. The review also identifies challenges and limitations, such as interference from other saliva components and the need for improved stability and reproducibility. Future prospects include the development of novel microfluidic devices, advanced materials and user-friendly diagnostic devices to unlock the full potential of saliva-based electrochemical sensing in clinical practice.

The purpose of this paper is to design and fabricate a three-dimensional (3D) bionic airflow sensing array made of two multi-electrode piezoelectric metal-core fibers (MPMFs), inspired by the structure of a cricket’s highly sensitive airflow receptor (consisting of two cerci).

A metal core was positioned at the center of an MPMF and surrounded by a hollow piezoceramic cylinder. Four thin metal films were spray-coated symmetrically on the surface of the fiber that could be used as two pairs of sensor electrodes.

In 3D space, four output signals of the two MPMFs arrays can form three “8”-shaped spheres. Similarly, the sensing signals for the same airflow are located on a spherical surface.

Two MPMF arrays are sufficient to detect the speed and direction of airflow in all three dimensions.

This study aims to evaluate the efficiency of metal electrode and electrolytes on the electroflocculation of indigo wastewater, produced by printing and dyeing factory, and to optimize the treatment system.

For effective purging, various types of metal electrodes (graphite, pure aluminum and stainless steel) and supporting electrolytes (sodium chloride and sodium sulfate) were selected for electroflocculation experiments. The decolorization rate and chemical oxygen demand (COD) removal rate were characterized.

The treatment effects of stainless steel and aluminum were similar, but the dissolution loss of aluminum and the production of flocs greatly limit its application. Electrolytes gave obvious effects to these systems. Sodium sulfate was better than sodium chloride, the decolorization rate was increased by 3.31%, the removal rate of COD in the solution was increased by 28.65% and the weight of flocculation precipitation was reduced by 0.214 g.

The electrochemical treatment system was constructed to compare and analyze the influence of experimental parameters and to provide a reference for the actual treatment of indigo wastewater.

Electrochemical flocculation can remove the insoluble indigo solids and it plays a key role in wastewater treatment.

It is novel to optimize the combination of electrode and electrolyte to improve the efficiency of electroflocculation, which can be widely used in the actual wastewater treatment process.

The purpose of this study is to explore the machining characteristics of electrical discharge machining (EDM) when a tool is fabricated using powder metallurgy. Because pure Cu tools obtained using conventional machining pose problems of high tool wear rate, tool oxidation causes loss of characteristics in tool shape.

The research investigation carried out experiments planned through Taguchi’s robust design of experiments and used analysis of variance (ANOVA) to carry out statistical analysis.

It has been found that copper and chromium electrodes give less metal removal rate as compared to the pure Cu tool. Analytical outcomes of ANOVA demonstrated that MRR is notably affected by the variable’s polarity, peak current, pulse on time and electrode type in the machining of EN9 steel with EDM, whereas the variables pulse on time, gap voltage and electrode type have a significant influence on EWR. Furthermore, the process also showed that the use of powder metallurgy tool effectively reduces the value of SR of the machined surface as well as the tool wear rate. The investigation exhibited the possibility of the use of powder metallurgy electrodes to upgrade the machining efficiency of EDM process.

There is no major limitation or implication of this study. However, the composition of the powders used in powder metallurgy for the fabrication of tools needs to be precisely controlled with careful control of process variables during subsequent fabrication of electrodes.

To the best of the authors’ knowledge, this is the first study that investigates the effectiveness of copper and chromium electrodes/tools fabricated by means of powder metallurgy in EDM of EN9 steel. The effectiveness of the tool is assessed in terms of productivity, as well as accuracy measures of MRR and surface roughness of the components in EDM machining.

The purpose of this paper is to develop feasible composite electrodes with a long cycle life and large specific capacitance and to investigate optimal ratio between aniline and activated carbon materials.

PANI/AC composite electrode materials were synthesised by in situ polymerisation of aniline on activated carbon with ammonium persulphate as oxidant. Hybrid supercapacitors are assembled by putting Ni‐MH battery separator between positive and negative electrodes. The electrochemical performances of PANI/AC composite electrode materials and supercapacitors are studied.

The results show that the optimal ratio between aniline and activated carbon is 1:1.08. The specific capacitance of polyaniline electrode materials is 956 F g⁻¹. The specific capacitance of supercapacitors is 159.37 F g⁻¹. This result could be attributed to the pseudocapacitive effect of Ni(OH)₂. What's more, the activated carbon addition reduced the resistance of polymer electrode materials thus improving the cyclic life.

The supercapacitors can be used in the field of automobiles and can solve the problems of energy shortage and environmental pollutions.

A hybrid supercapacitor, which was immersed in alkaline solution, was assembled by putting Ni‐MH battery separator between two electrodes Ni(OH)₂ as positive electrode and polyaniline composites as negative electrode. In the case of alkaline solution, the capacitive performance of hybrid supercapacitor was improved and excellent.

Recent developments in wearable technologies have paved the way for continuous monitoring of the electrocardiogram (ECG) signal, without the need for any laboratory settings. A number of wearable sensors ranging from wet electrode sensors to dry sensors, textile-based sensors, knitted integrated sensors (KIS) and planar fashionable circuit boards are used in ECG measurement. The purpose of this study is to carry out a comparative study of the different sensors used for ECG measurements. The current challenges faced in developing wearable ECG sensors are also reviewed.

This study carries out a comparative analysis of different wearable ECG sensors on the basis of four important aspects: materials and methods used to develop the sensors, working principle, implementation and performance. Each of the aspects has been reviewed with regard to the main types of wearable ECG sensors available.

A comparative study of the sensors helps understand the differences in their operating principles. While some sensors may have a higher efficiency, the others might ensure more user comfort. It is important to strike the right balance between the various aspects influencing the sensor performance.

Wearable ECG sensors have revolutionized the world of ambulatory ECG monitoring and helped in the treatment of many cardiovascular diseases. A comparative study of the available technologies will help both doctors and researchers gain an understanding of the shortcomings in the existing systems.

This paper aims to investigate the corrosion inhibition effects of indole-3-carbaldehyde and 2-methylindole on mild steel in 1 M HCl solution.

Indole-3-carbaldehyde and 2-methylindole as corrosion inhibitors of mild steel in 1 M HCl solution were investigated by polarisation and electrochemical impedance spectroscopy (EIS). Adsorption isotherm and mechanism were calculated. Quantum chemical calculations were used to find out a correlation between electronic structure of inhibitors and inhibition efficiency. Changes in the properties of metal surface in HCl solution in the presence of inhibitors were studied by contact angle measurements.

Polarisation results revealed inhibitors could reduce cathodic and anodic reactions rates on metal surface. EIS analysis showed that inhibition efficiency of indoles increases by increasing the inhibitors’ concentration; maximum inhibition efficiency was 95 and 94 per cent in solutions containing 1 mM indole-3-carbaldehyde and 2-methylindole, respectively. Inhibitors’ adsorptions on metal surface were confirmed by analysing the exposed metals’ surface through contact angles measurements. The adsorption of inhibitors was found to follow Langmuir isotherm. Quantum chemical calculations showed that a more positively charged benzene ring in the structure of two indole-based inhibitors would lead to higher adsorption to metal.

This research was carried out to understand the effects of two different functional groups (-C=O, -CH3) with different induction effects on the indole structure and on inhibition efficiency of corrosion inhibitors with the purpose of using these components in industrial application as acid wash solutions to etch and remove rusts from metal surfaces.