Fabrication and performance of nanostructured ZnO/SnO₂ based humidity sensor / Nor Diyana Md Sin

Humidity sensors were fabricated using zinc oxide/tin oxide (ZnO/SnO₂) composite nanorods and novel structures of ZnO/ SnO2 nanoblock arrays and ZnO/SnO2 composite nanocubes. The ZnO/SnO₂ composite nanorods and ZnO/SnO₂ nanoblock arrays were successfully synthesised using thermal chemical vapour deposition (CVD). The ZnO/SnO₂ composite nanocubes were prepared using a novel sol-gel immersion method. First, ZnO thin films were synthesised to prepare the ZnO/SnO₂ composite nanorods and the ZnO/SnO₂ composite nanocubes. These ZnO thin films acted as template layers, which were deposited using a radio frequency (RF) magnetron sputtering system. To obtain a conductive template layer, parametric studies were conducted by varying the RF power and the temperature of the substrate. This template was optimised using a RF power of 200 watts and a substrate temperature of 500°C to obtain the ZnO template with the highest conductivity of 73.1 S cm-1. The ZnO/SnO₂ composite nanorods were studied by varying different parameters including the ZnO/SnO₂ composition, the type of tin precursor (i.e., dibutyltin diacetate, tin powder and tin chloride pentahydrate), the substrate temperature (between 200 and 600°C) and the oxygen flow rate (5, 10 and 15 sccm). The sensitivity of the humidity sensor and the response and recovery times were studied in each experiment. The experimental results were used to relate the sensor performance to the surface conditions in terms of the dimension of the active layer

The design of an efficient class E-LCCL capacitive power transfer system through frequency tuning method

In this work, the optimum zero voltage switching (ZVS) of Class E-LCCL capacitive power transfer (CPT) was determined via frequency tuning method. Through this an efficient system can be guanranteed although there is a change in the capacitive plates distance. This study used a Class-E LCCL inverter, as it can operate at a high alternate current frequency, besides producing low switching losses and minimal power losses. Specifically, this study conducted simulations and experiments to analyse the performance of an LCCL CPT System at 1 MHz operating frequency and 24 V DC supply voltage. Using an air gap distance of 0.1 cm, the designed CPT system prototype successfully achieved an output power of 10W and an efficiency of 95.45%. This study also found that by tuning the resonant frequency of the Class E-LCCL system, the optimum ZVS can be obtained although capacitive plate distance was varied from 1-3 cm via experimental. The results of this study could benefit medical implant and portable device development, consumer electronics, and environments that involve electrical hazards

Heterogeneous SnO2/ZnO nanoparticulate film: Facile synthesis and humidity sensing capability

Highly sensitive and extremely thin tin oxide/zinc oxide (SnO2/ZnO) heterojunction films were prepared via a two-step solution-based method for humidity-sensing application. The average diameters of the ZnO and SnO2 nanoparticles were 26 and 6 nm, respectively. The deposition of SnO2 for 3 min reduced film resistance from 6.74 MΩ to 0.40 MΩ. Remarkably, the humidity-sensing performance of the heterojunction sensors was critically dependent on deposition time, and sensors subjected to 3 min deposition exhibited the highest sensitivity (90.56) to humidity, which was significantly higher than that of bare ZnO. This study indicates that the use of SnO2/ZnO heterojunction has a great potential in humidity sensing applications

Artificial intelligence technique in solving nano-process parameter optimization problem / Norlina Mohd Sabri...[et al.]

Nanotechnology has brought huge impacts to our modern life in many ways. The technology has been adapted in various domains such as biotechnology, chemicals, computing, electronics, metals, materials, renewable energy and also telecommunications. This research is focusing on the RF magnetron sputtering process, one of the nanotechnology processes which are widely used in the thin film technology. The conventional method that is currently practiced in the optimization of the RF magnetron sputtering process parameters is trial and error method. However, the practice of repetitively conducting experiments has consumed a lot of time and cost in the thin film construction. This research is proposing artificial intelligence (AI) technique as the alternative technique to overcome the sputtering process parameter optimization problem. Three artificial intelligence techniques have been selected to solve this parameter optimization problem. The techniques are Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Gravitational Search Algorithm (GSA). In the process parameter optimization, automated process has never been implemented to optimize the six deposition parameters of the RF magnetron sputtering. Based on the results, GA has shown the best performance compared to PSO and GSA in terms of the fitness value and processing time. Laboratory results have shown that GA has produced the highest values of electrical and optical properties of thin film. It is expected that AI techniques could complement the conventional method of trial and error in obtaining the optimized process parameter combination

Optimization of Nano-Process Deposition Parameters Based on Gravitational Search Algorithm

This research is focusing on the radio frequency (RF) magnetron sputtering process, a physical vapor deposition technique which is widely used in thin film production. This process requires the optimized combination of deposition parameters in order to obtain the desirable thin film. The conventional method in the optimization of the deposition parameters had been reported to be costly and time consuming due to its trial and error nature. Thus, gravitational search algorithm (GSA) technique had been proposed to solve this nano-process parameters optimization problem. In this research, the optimized parameter combination was expected to produce the desirable electrical and optical properties of the thin film. The performance of GSA in this research was compared with that of Particle Swarm Optimization (PSO), Genetic Algorithm (GA), Artificial Immune System (AIS) and Ant Colony Optimization (ACO). Based on the overall results, the GSA optimized parameter combination had generated the best electrical and an acceptable optical properties of thin film compared to the others. This computational experiment is expected to overcome the problem of having to conduct repetitive laboratory experiments in obtaining the most optimized parameter combination. Based on this initial experiment, the adaptation of GSA into this problem could offer a more efficient and productive way of depositing quality thin film in the fabrication process

The role of iot technologies in Malaysia during the Covid-19 pandemic: A mini-review

The Covid-19 global infection has significantly influenced people’s health, resulting in sudden changes in lifestyle through social exclusion and isolation. To break the transmission and terrifying health threat of Covid-19, the Malaysian Government imposed a Movement Control Order (MCO) starting March 18, 2020, by restricting movement and contact. The Covid-19 pandemic emphasized the importance of the digital inclusion agenda, and the application of Internet of Things (IoT) services has given tremendous benefits in various disciplines, as it helps maintain physical distance during the pandemic. Modern lifestyles are being transformed by the IoT revolution by embracing technological, economic, and social prospects. In fact, many sectors in Malaysia would be transformed through the application of IoT, particularly in productivity, and services. Thus, this review paper discusses IoT’s most recent breakthroughs and applications that are used in Malaysia during the Covid-19 crisis. Furthermore, it investigates current IoT implementation and discusses the potential impact of the pandemic on the application of IoT in terms of technology trends and economic impact. IoT is worth mentioning as one of the technologies demonstrating its importance and capabilities in mitigating the severity of the pandemic within the country. This article delves into the applications, social and economic impact, and barriers to the widespread adoption of IoT in the Covid-19 pandemic. This review paper will be useful to academic researchers, business professionals, organizations in various sectors, and anyone interested in determining IoT services’ impact on pandemics

The Design Of An Efficient Class E-LCCL Capacitive Power Transfer System Through Frequency Tuning Method

In this work, the optimum zero voltage switching (ZVS) of Class E-LCCL capacitive power transfer (CPT) was determined via frequency tuning method. Through this an efficient system can be guanranteed although there is a change in the capacitive plates distance. This study used a Class-E LCCL inverter, as it can operate at a high alternate current frequency, besides producing low switching losses and minimal power losses. Specifically, this study conducted simulations and experiments to analyse the performance of an LCCL CPT System at 1 MHz operating frequency and 24 V DC supply voltage. Using an air gap distance of 0.1 cm, the designed CPT system prototype successfully achieved an output power of 10W and an efficiency of 95.45%. This study also found that by tuning the resonant frequency of the Class E-LCCL system, the optimum ZVS can be obtained although capacitive plate distance was varied from 1-3 cm via experimental. The results of this study could benefit medical implant and portable device development, consumer electronics, and environments that involve electrical hazards

Effects of Annealing Environments on the Solution-Grown, Aligned Aluminium-Doped Zinc Oxide Nanorod-Array-Based Ultraviolet Photoconductive Sensor

We have fabricated metal-semiconductor-metal- (MSM-) type ultraviolet (UV) photoconductive sensors using aluminium- (Al-) doped zinc oxide (ZnO) nanorod arrays that were annealed in different environments: air, oxygen, or a vacuum. The Al-doped ZnO nanorods had an average diameter of 60 nm with a thickness of approximately 600 nm that included the seed layer (with thickness ~200 nm). Our results show that the vacuum-annealed nanorod-array-based UV photoconductive sensor has the highest photocurrent value of   2.43  ×  10-4 A. The high photocurrent is due to the high concentration of zinc (Zn) interstitials in the vacuum-annealed nanorod arrays. In contrast, the oxygen-annealing process applied to the Al-doped ZnO nanorod arrays produced highly sensitive UV photoconductive sensors, in which the sensitivity reached 55.6, due to the surface properties of the oxygen-annealed nanorods, which have a higher affinity for oxygen adsorption than the other samples and were thereby capable of reducing the sensor’s dark current. In addition, the sensor fabricated using the oxygen-annealed nanorod arrays had the lowest rise and decay time constants. Our result shows that the annealing environment greatly affects the surface condition and properties of the Al-doped ZnO nanorod arrays, which influences the performance of the UV photoconductive sensors

Nanosheet Zinc Oxide Synthesized by Solution-Immersion Method for Triboelectric Nanogenerator

Most global problems are being solved by using sustainable energy harvesting technologies to retain the social ecosystem in great condition. The triboelectric nanogenerator (TENG) which is a renewable energy harvesting device, collects the waste mechanical energy from its surroundings and performs the electric signal conversion. TENG have garnered increased attention in recent years by offering prospective use in energy harvesting technology. Particularly, there is a need for flexible energy conversion that serves as a power supply for portable electronic equipment. In this study, ZnO nanosheet thin film prepared on the flexible conductive aluminium foil through a low temperature immersion technique was used to generate electrical energy. The effect of heat treatment on ZnO nanosheet thin film was also investigated on the surface morphology, strutural properties and nanogerator performance. The high density of interconnected ZnO nanosheet were observed before and after heat treatment as confirmed by FESEM studies. The analysis using XRD confirmed that ZnO nanosheet thin film was successfully deposited on the aluminium foil. Additionally, the ZnO nanosheet thin films improved significantly with heat treatment, enhancing their crystalline quality. The triboelectric nanogenerator (TENG) was successfully constructed in contact and separation mode using Kapton tape on top and ZnO nanosheet thin film on the bottom to generate electricity by a force of hand pressing. The output electrical voltage of the device doubled from around 2 V to 4 V after underwent the heat treatment. This study provides an essential insight into fabrication of TENG using the ZnO nanosheet thin film through a clean and effective method for nanogenerator applications