Papers by Keyword: Biosensors

Abstract: Advanced biocompatible piezoelectric composites have gained significant attention for the development of flexible medical devices and especially related to materials structures that mimic the natural tissue structures. Natural piezoelectricity within the human tissues is reviewed, together with nature-based piezoelectric materials, their advantages and potential for designing the structures for biomedical applications. Electrospun Polyvinylidene fluoride (PVDF) nanofiber matrix, reinforced with silver nanoparticles (AgNPs) is discussed, including specific applications in bone grafts, biosensors and energy harvesting. Processing parameters of the electrospinning fabrication technology have a strong influence on the composite piezoelectricity. Computational models of piezoelectric composites have become a major support in material design for the real case applications. Existing approaches to the numerical modeling of piezoelectric composites have been shortly reviewed toward a recent trend of AI supported modeling for providing effective composite properties, prediction and optimization of material properties and behavior, such as the output voltage and power. Polymer-based biomedical piezoelectric composites have shown excellent results in laboratory research from aspects of their flexibility and possibility to tailor their electro-mechanical properties. However, output piezoelectric signals are still much lower than in the case of traditional ceramic-based materials, including challenges related to the stability of the electric signal, signal noise, piezoelectric impedance and durability of composites with nature-based reinforcements. Future directions in custom composite design, including currently available computational models to enable more rapid development of biomedical piezoelectrics are elaborated at the end.

Abstract: Infectious disease such as COVID-19 is one of the major concerns in Malaysia as it becomes the second killing disease and causes huge number of death and spread to other regions of the world if left unchecked. In developed countries, infectious diseases are often preventable, but lack of medical devices in detecting it makes the death cases increase. The growth of different COVID-19 mutation has given so much challenges in detecting, preventing and curing. This gives motivation to researchers in order to solve this global problem by creating and advancing the detection tools and methods. Time, equipment availability, and the biological nature of COVID-19 influence the selection of appropriate detection techniques. This paper summarizes the comprehensive review on the type of diagnostic tests and biosensors available in detecting COVID-19 disease.

Abstract: Organic functionalization of carbon nanotubes (CNTs) plays very important role in the development of electrochemical biosensors. In this study, pristine (5,5) carbon nanotube was functionalized by Ethanoic Acid (CH₃COOH) using First Principles Density Functional Theory (DFT). It was found that the encapsulation of CH₃COOH into the (5,5) CNT is endothermic due to the small diameter of the tube. However, interacting it outside the sidewall of the tube gives an exothermic process indicating a stable geometry. Accordingly, additional electronic bands and peaks are observed in the electronic structures of the functionalized CNT. Further, it was shown that that the p orbitals of the oxygen atoms and carbon atoms of the acid are the main contributors of the additional peaks in the valence and conduction regions, respectively. Finally, there were observed optical transitions in the functionalized CNT caused by the hybridization of the armchair CNT. Evidently, this study provided insights on more potential applications of carbon nanotubes as biosensors.

Abstract: One of the most often credited materials for opening up new possibilities in the creation of next-generation biosensors is graphene oxide (GO). GO has good water dispersibility, biocompatibility, and high affinity for specific biomolecules due to the coexistence of hydrophobic domains from pristine graphite structure and hydrophilic oxygen containing functional groups, as well as properties of graphene itself that are partly dependent on preparation methods. The high signal output and a strong potential for rapid industrial growth rate, graphene-based materials, such as graphene oxide (GO), are receiving substantial interest in bio sensing applications. Some of graphene's most enticing qualities are its superior conductivity and mechanical capabilities (such as toughness and elasticity), as well as its high reactivity to chemical compounds. The existence of waves on the surface (natural or created) is another property/variable that has immense potential if properly utilized. Single cell detection can be performed by optical biosensors based on graphene. The present state of knowledge about the use of graphene for bio sensing is reviewed in this article. We briefly cover the use of graphene for bio sensing applications in general, with a focus on wearable graphene-based biosensors. The intrinsic graphene ripples and their impact on graphene bio sensing capabilities are extensively examined.

Abstract: In this paper, a focus is placed on the recent applications and trends of the uses of optical and photonic sensors with applications in environmental monitoring and health and biological applications represents an overview of most articles which concerned with the Gold nanoparticles (Au) and photonic crystal fiber of sensors. A gold nanoparticles (Au) based on sensors has found is widely used in integrated and guided-wave optics because of the Gold is chemically steady also in an aqueous environment, also it reveals the greater wavelength change at the resonant frequency, which helps to quickly detect and improve the sensitivity of the unknown analyse.

Abstract: The microfluidic Lab-On-Chip (LOC) systems, based on the CMOS technology, today grow rapidly based on requirement of the Point-of-care-testing (POCT). It is a need for a high sensitive biotransducers, as a part of biosensors to be integrated on LOC system. To detect low-level of light emitted by an analyte, promising material and devices are a p-i-n a-Si:H photodiodes. The observed absorbance of blue light in human cells HeLa (cervical carcinoma) induct H₂O₂ in same cells and consequently, chemical reaction with NO, detected as chemiluminescence signal by the photodiode, as well as formation of cytotoxic singlet oxygen. On the other side a-Si:H p-i-n photodiode has a high sensitivity on blue light at low-light intensity, good spectral responsivity and small reflectance for blue light, low dark current, low-noise in the range of low reverse bias voltages. The photoconductivity of a-Si:H p-i-n photodiode is influenced by the native and light induced localized state density and their energy distribution in the energy gap of intrinsic a-Si:H. It is observed that the defect states of i-layer at various bias voltages contribute to the detection of HeLa cells chemiluminescence. The optical bias dependence of modulated photocurrent method (OBMPC) using the blue LED light is applied to clarify the energy gap density of state nature and energy distribution, respectively in a-Si:H p-i-n photodiode i-layer.

Abstract: The last 19 years have seen intense research made on zinc oxide (ZnO) material mainly due to the ability of converting the natural n-type material into p-type. For a long time, the p-type state was impossible to attain and maintain. The review focuses on ways of improving the doped ZnO material which acts as a channel for nanowire field effect transistor (NWFET) and biosensor. The biosensor has specific binding which is called functionalisation achieved by attaching a variety of compounds on the designated sensing area. Reference electrodes and buffers are used as controllers. Top-down fabrication processes are preferred over bottom-up because they pave way for mass production. Different growth techniques are reviewed and discussed. Strengths and weaknesses of the FET and sensor are also reviewed.

Abstract: Surface plasmon resonance (SPR) based biosensor is a gold standard optical sensor for biological protein interaction in life science. In this paper, we firstly discuss how the SPR based sensor can give unique advantages over other sensing techniques for food safety and food quality control in food industry. We discuss the differences in sample preparation process for the SPR system and other screening methods and point out that the SPR can reduce the food screen quality control cost and time. A brief review of food analysis that has been tested under SPR system. Key requirements for building up a surface plasmon resonance based sensor for food industry especially in Thailand are highlighted. An SPR based sensor has been recently developed and constructed based on the requirements. We also discuss practical issues and how to possibly get around them.

Abstract: Optical resonator biosensors have emerged as one of the most sensitive and practical microsystem biodetection technology. Here, we have developed a model for an optical microring resonator to be used as an ultrasensitive biosensor. A linear correlation between increasing the radius of the microring and the red shift in the resonance wavelengths has been observed. In fact, resonance shifts for very small changes in microring radius, as low as 10 nm, have been detected. Furthermore, sensing capability of the resonator has been simulated by introducing TiDO₂ nanoparticles and protein molecules to the resonator surface by varying both thickness and effective refractive index of the attached layer such that the layer size has been changed from 10 nm to 100 nm with an increment of 10 nm. We have observed readily detectable unique resonance shifts for both TiDO₂ nanoparticles and protein molecules. Moreover, effective medium approach has been implemented in order to account for refractive index fluctuations in sensing medium. As a consequence, combination of optical resonators with microfluidics could produce a simple-to-operate, portable and robust diagnostic tool enabling new insights into biomolecular function and recognition.

Abstract: Vertically aligned carbon nanotubes (VACNTs or CNTs) were synthetized by thermal chemical vapor deposition method on the Si/SiO2 substrates, using Al/Fe as catalyst. In the present study, the influence of the annealing duration and synthesis time on the length, grow rate and quality of the VACNTs according to 9 different regimes was investigated. The outcomes of the study was observed using scanning electron microscope, atomic force microscopy and Raman spectroscopy analysis was utilized in order to evaluate the quality of the obtained nanotubes. Results have shown that the length of the VACNTs increases with the rise of annealing time, however only to a certain degree, after which the deterioration of the nanotubes occurs and the reduction of their length is noticeable.