Mohd Hafiz Jali

In this study, a carbon black-doped europium oxide (Eu2O3) thick-film gas sensor was developed and systematically evaluated for CO2 sensing applications. The sensing layers were fabricated using a screen-printing technique, with Eu2O3 paste prepared with an organic binder, followed by the incorporation of carbon black at different doping concentrations (0.1-5 wt.%). The structural and compositional characteristics of the films were investigated using field-emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX), while their electrical properties were evaluated through current-voltage (I-V) measurements. Gas-sensing performance was investigated in a controlled chamber with CO2 concentrations ranging from 1000 to 5000 ppm. The results revealed that the carbon black incorporation significantly improved the microstructure of the sensing film by reducing particle agglomeration and generating a more porous, uniform morphology, thereby facilitating gas diffusion and charge transport. Among the tested samples, the sensor with 2 wt.% carbon black doping exhibited the best performance, achieving high linearity (97.66%) and enhanced sensitivity of 0.05327 mV/ppm compared with the undoped Eu2O3 sensor (0.01476 mV/ppm). The optimized sensor exhibited good repeatability, satisfactory stability, and reduced hysteresis during successive CO₂ exposure cycles. These improvements may be attributed to the formation of conductive pathways and the increased availability of active surface sites introduced by carbon black within the Eu2O3 matrix. The results establish carbon black-modified Eu2O3 thick films as promising candidates for room-temperature CO₂ gas sensing, with competitive sensing performance.

Thermoelectric materials offer a sustainable solution for converting waste heat into electricity, with bismuth telluride (Bi2Te3) being highly effective at room temperature. However, enhancing its electronic and mechanical properties in film form remains challenging. This study investigates the improvement of Bi2Te3 films through the inclusion of graphene and carbon nanofibers (CNFs). The nanocomposite films were synthesized via a three-electrode electrochemical deposition technique. Electrolytes were prepared using 0.75 g/L graphene nanoparticles and 1 g/L CNFs, subjected to rigorous stirring and intermittent sonication to ensure proper dispersion and suspension. Cyclic voltammetry guided deposition voltage selection. Graphene integration resulted in a 200% increase in electrical conductivity due to its superior conductive nature. CNFs enhanced mechanical strength, doubling hardness and increasing Young’s modulus by 34%, attributed to the Hall-Petch effect and CNF reinforcement. This study highlights the potential of graphene and CNF integration to improve Bi2Te3-based thermoelectric materials for a range of waste heat recovery applications.

This study presents a novel sensing device for lactose detection, using ZnO nanorods on glass substrate with a light side coupling technique, as this integration enhances light scattering and adsorption, improving sensing performance. The proposed sensor was exposed to ranging lactose concentrations (0% to 100%) to validate its performance. The results were compared with a classic single light source technique to evaluate several parameters, such as sensitivity, linearity, repeatability, stability, response time, and hysteresis. Τhe experimental findings exhibited a higher sensitivity of 0.0201 V/% concentration, superior linearity of 99.61%, and improved resolution by a factor of 1.5 compared to traditional methods. Due to its cost-effectiveness, simple fabrication process, and superior performance, this sensing platform presents a viable alternative for industrial optical sensing applications, particularly in food quality monitoring and biomedical diagnostics.

The fabrication of effective sensing technology for real-time carbon dioxide (CO2) monitoring is required due to the serious environmental and health risks posed by the atmosphere's rising CO2 levels. The current study investigates the development and characterisation of thick films of Europium oxide (Eu2O3) by screen-printing method for CO2 gas sensing applications. The primary objective is to create a high-performance sensor that can operate effectively at room temperature. The research entails fabricating three thick films of Eu2O3 gas sensors identified as sample1, sample2, and sample3 were fabricated on Kapton substrates and subjected to morphological and structural analyses using Field Emission Scanning Electron Microscopy (FESEM) for surface morphology evaluation and X-ray Diffraction (XRD) for crystallographic characterisation. The gas sensors' performance was evaluated at different CO2 concentrations at room temperatures of 30, 50, and 70 standard cubic centimeters per minute (sccm). The graph of current-voltage (I-V) measurements of Eu2O3 gas sensor sample2 yielded linear results. Sample2 displayed a very effective varied concentration of CO2 gas at 30 sccm and 70 sccm, despite having the second highest in 50 sccm concentration of CO2 only and the lowest resistance. This decrease in resistance is the result of redox interactions between CO2 and Eu3+ ions at the Eu2O3 surface, which raise the concentration of charge carriers and improve the electrical conductivity of the sensor material. Eu2O3 distinct optical, electrical, and structural properties allowed for the development of a highly effective luminous CO2 gas sensor with quick reaction and recovery periods that function well under normal conditions. These findings highlight the unique optical, electrical, and structural properties of Eu2O3, showcasing its potential as an efficient CO2 gas sensor for a variety of industrial applications, such as monitoring indoor air quality, detecting greenhouse gasses, and detecting air quality in car cabins. This study shows that Eu2O3-based sensors can effectively detect CO2 and pave the path for future environmental sensing technologies.

This research investigated evanescence field effect using a microfiber as a sodium hypochlorite sensor. The microfiber was built using the "tapering" approach, which transformed silica fiber SMF-28 into a micro size with the diameter is 10micro. The microfiber is then employed as a sodium hypochlorite sensor with a range of sodium hypochlorite concentrations ranging from 50% pmm to 100% pmm. The microfiber performance is clearly excellent, as measured by sensitivity based on wavelength shift. The linearity defined more than 99% is defined as a performed sensor. This microfiber repeatability makes them promising as sodium hypochlorite sensors.

Over the past decade, fibre laser technology has garnered significant technological focus and benefits. They improve the instability, affordability of maintenance, efficient heat dissipation, simplicity, and reliability of existing bulk lasers. Q-Switched fibre lasers have recently garnered significant attention. They possess the capacity to generate pulses with considerable energy levels, making them valuable for a range of applications such as micro-machining, biomedical imaging, communication, remote sensing, laser range finding, and medical surgery. Fibre lasers may generate ultra-short pulses at repetition rates of millions and thousands of cycles per second by functioning in the mode-locked or Q-switched states. Molybdenum Aluminium Boride (MoAlB) is employed as a saturable absorber for investigating the lasing properties of erbium-doped fibre. Moreover, a Q-switched EDF laser is observed utilising a MoAlB thin film as a saturable absorber in the 1.55µm wavelength range. The Q-switched fibre laser can be realised using either a passive or active technology. In this investigation, the passive approach is a suitable technique because using a saturable absorber (SA) for passive Q-switching simplifies cavity construction and eliminates the demand for external Q-switching electronics. The laser cavity was built utilising Erbium-Doped Fibre Laser as the gain medium. Increasing the pump power to 980 nm allows it to get results of Q-switched pulses running at 1550 nm.

The laser generation was produced at a wavelength of 1562.4 nm with a small spectral bandwidth of 0.4 nm using a short-pulse erbiumdoped fibre laser with unique group delay dispersion. This process was generated by Q-switching, which was accomplished using a vanadium oxide polyethylene glycol (V2O5-PEG) film saturable absorber (SA) within an all-fiber ring cavity arrangement. The laser generated a peak output power of 0.4 mW, a maximum pulse energy of 3.2 nJ, and an astonishingly brief pulse width of 4.7 s. These results highlight the possibility of the V2O5 film as a workable SA substitute for producing pulsed lasers.

Optical fibre, also referred to as fibre optics, is a method and medium of transmitting data using bursts of light through strands of glass or plastic. When light signals travel through fibre optic cables, they bounce off the core and cladding in a series of zigzag bounces, which is a phenomenon known as total internal reflection. Microfiber optic sensors have recently gained considerable attention due to their high sensitivity, quick detection, and adaptability to harsh environments. To produce microfibers in various diameters, a tapering technique is used. However, the sensor's performance may vary depending on the transmitted power levels produced by the different taper microfiber sizes. Several diameters of taper microfiber will be used as sensors to determine the sensing performance. The results indicate that the best performing sensors are those with smallest diameters.

An optical characterization of the proposed sensing scheme comprises of ZnO nanorods coated glass substrate based on side coupling technique for different scattering area is reported. The glass substrate was coated with a highly responsive nanomaterial which is Zinc Oxide (ZnO) nanorods using hydrothermal technique. The scattering area were varied into five samples of 0.016m ² , 0.018m ² , 0.020m ² , 0.022m ² and 0.024m ² . The samples were exposed to a range of RI solutions spanning from a concentration of 0% to 100%. Based on experimental results, the sample with an area of 0.022m ² exhibited outstanding characteristics in most of the performance parameters such as α, γ, output light intensity and sensitivity towards different RI solution. The sample demonstrates a notably elevated level of light intensity and output voltage in comparison to the closest best samples by a factor of 1.1. Besides it produced linearity of 97.5% and sensitivity of 0.0125V/%. The proposed sensor exploits the visible light using the side coupling technique applied on the glass surface that was coated with Zinc Oxide (ZnO) nanorods to enhance the output coupling voltage. It effectively employed the scattering and surface absorption properties to interact with different refractive index solutions.