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1 – 10 of 23Mariam Mir, Murtaza Najabat Ali, Umar Ansari, Patrick J. Smith, Amber Zahoor, Faisal Qayyum and Sabtain Abbas
The fabrication and characterization of a hydrogel-based conductometric sensor have been carried out. The purpose of this research is to fabricate a small robust hydrogel-based…
Abstract
Purpose
The fabrication and characterization of a hydrogel-based conductometric sensor have been carried out. The purpose of this research is to fabricate a small robust hydrogel-based conductometric sensor for real-time monitoring of pH in the physiological range.
Design/methodology/approach
A pH-responsive Chitosan/Gelatin composite hydrogel has been used for this purpose. This study reports and analyzes the sensing response obtained from four hydrogel compositions with varying Chitosan/Gelatin ratios. The pH-responsive nature of the hydrogel has been mapped out through volumetric and conductometric tests. An attempt has been made to correlate these characteristics with the physico-chemical nature of the hydrogel through scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques.
Findings
The four hydrogel compositions differed on the basis of gel composition ratios; the conductometric analysis results prove that the sensor with the hydrogel composition (Chitosan 2 per cent, Gelatin 7 per cent, ratio 1:2) produces the best pH resolution in the pH range of 4 to 9. The sensing mechanisms and the differences obtained between individual sensor outputs have been discussed in detail. On the basis of this extensive in vitro assessment, it has been concluded that while key pendant functional groups contribute to pH-responsive characteristics of the hydrogel, the overall sensitivity of the sensors gel component to surrounding pH is also determined by the crystalline to amorphous ratio of the hydrogel composite, its interpenetrating cross-linked structure and the relative ratio of the hydrophilic to the pH-sensitive components.
Practical implications
The conductometric sensor results prove that the fabricated sensor with the shortlisted hydrogel composition shows good sensitivity in the physiological pH range (4 to 9) and it has the potential for use in point of care medical devices for diagnostic purposes.
Originality/value
This is the first reported version of the fabrication and testing and analysis/comparison of a hydrogel-based conductometric sensor based on this composition. The work is original and has not been replicated anywhere.
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Jayaraman Kathirvelan and Rajagopalan Vijayaraghavan
This work encompasses the various laboratory-based and portable methods evolved in recent times for sensitive and selective detection of ethylene for fruit-ripening application…
Abstract
Purpose
This work encompasses the various laboratory-based and portable methods evolved in recent times for sensitive and selective detection of ethylene for fruit-ripening application. The role of ethylene in natural and artificial fruit ripening and the associated health hazards are well known. So there is a growing need for ethylene detection. This paper aims to highlight potential methods developed for ethylene detection by various researchers, including ours. Intense efforts by various researchers have been on since 2014 for societal benefits.
Design/methodology/approach
The paper focuses on types of sensors, fabrication methods and signal conditioning circuits for ethylene detection in ppm levels for various applications. The authors have already designed, developed a laboratory-based set-up belonging to the electrochemical and optical methods for detection of ethylene.
Findings
The authors have developed a carbon nanotube (CNT)-based chemical sensor whose performance is higher than the reported sensor in terms of material, sensitivity and response, the sensor element being multi-walled carbon nanotube (MWCNT) in comparison to single-walled carbon nanotube (SWCNT). Also the authors have developed infrared (IR)-based physical sensor for the first time based on the strong IR absorption of ethylene at 10.6 µm. These methods have been compared with literature based on comparable parameters. The review highlights the potential possibilities for development of portable device for field applications.
Originality/value
The authors have reported new chemical and physical sensors for ethylene detection and quantification. It is demonstrated that it could be used for fruit-ripening applications A comparison of reported methods and potential opportunities is discussed.
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Igor S. Nadezhdin, Aleksey G. Goryunov and Yuliya Yu Nadezhdina
This paper aims to focus on the development of an optical concentration sensor designed for measuring the concentration of components in solutions.
Abstract
Purpose
This paper aims to focus on the development of an optical concentration sensor designed for measuring the concentration of components in solutions.
Design/methodology/approach
The operating principle of the developed sensor is based on the Bouguer–Lambert–Beer law. An optical measuring system using fiber optical cables was used for the practical implementation of the concentration sensor.
Findings
As a result of fiber optical cable use in the concentration sensor, the remote measurement principle was implemented, ensuring the instrument’s reliability and the reduction of operating costs.
Originality/value
The advantage of the proposed measuring system is that the sensitive element is maintenance-free, does not require power supply and can operate under severe industrial conditions. Using a fiber optic cable to transmit a light signal allows placing the sensitive element at a distance of several tens of meters from the electronics unit (the smart part).
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Dinesh Ramkrushna Rotake, Anand Darji and Nitin S. Kale
This paper aims to report an insightful portable microfluidic system for rapid and selective sensing of Hg2+ in the picomolar (pM) concentration using microcantilever-based…
Abstract
Purpose
This paper aims to report an insightful portable microfluidic system for rapid and selective sensing of Hg2+ in the picomolar (pM) concentration using microcantilever-based piezoresistive sensor. The detection time for various laboratory-based techniques is generally 12–24 h. The majority of modules used in the proposed platform are battery oriented; therefore, they are portable and handy to carry-out on-field investigations.
Design/methodology/approach
In this study, the authors have incorporated the benefit of three technologies, i.e. thin-film, nanoparticles (NPs) and micro-electro-mechanical systems, to selectively capture the Hg2+ at the pM concentration. The morphology and topography of the proposed sensor are characterized using field emission scanning electron microscopy and verification of the experimental results using energy dispersive X-ray.
Findings
The proposed portable microfluidic system is able to perform the detection in 5 min with a limit of detection (LOD) of 0.163 ng (0.81 pM/mL) for Hg2+, which perfectly describes its excellent performance over other reported techniques.
Research limitations/implications
A microcantilever-based technology is perfect for on-site detection, and a LOD of 0.163 ng (0.81 pM/mL) is outstanding compared to other techniques, but the fabrication of microcantilever sensor is complex.
Originality/value
Many researchers used NPs for heavy metal ions sensing, but the excess usage and industrialization of NPs are rapidly expanding harmful consequences on the human life and nature. Also, the LOD of the NPs-based method is limited to nanomolar concentration. The suggested microfluidic system used the benefit of thin-film and microcantilever devices to provide advancement over the NPs-based approach and it has a selective sensing in pM concentration.
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Abstract
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Mokhtar Aarabi, Alireza Salehi and Alireza Kashaninia
The purpose of this study is use to density functional theory (DFT) to investigate the molecular adsorption by PEDOT:PSS for different doping levels. DFT calculations are…
Abstract
Purpose
The purpose of this study is use to density functional theory (DFT) to investigate the molecular adsorption by PEDOT:PSS for different doping levels. DFT calculations are performed using the SIESTA code. In addition, the non-equilibrium Green’s function method is used within the TranSIESTA code to determine the quantum transport properties of molecular nanodevices.
Design/methodology/approach
Density functional theory (DFT) is used to investigate the molecular adsorption by PEDOT:PSS for different doping levels. DFT calculations are performed using the SIESTA code. In addition, the non-equilibrium Green’s function method is used within the TranSIESTA code to determine the quantum transport properties of molecular nanodevices.
Findings
Simulation results show very good sensitivity of Pd-doped PEDOT:PSS to ammonia, carbon dioxide and methane, so this structure cannot be used for simultaneous exposure to these gases. Silver-doped PEDOT:PSS structure provides a favorable sensitivity to ammonia in addition to exhibiting a better selectivity. If the experiment is repeated, the sensitivity is increased for a larger concentration of the applied gas. However, the sensitivity will decrease at a higher ratio than smaller concentrations of gas.
Originality/value
The advantages of the proposed sensor are its low-cost implementation and simple fabrication process compared to other sensors. Moreover, the proposed sensor exhibits appropriate sensitivity and repeatability at room temperature.
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Huda Abdullah, Norshafadzila Mohammad Naim, Kok Seng Shum, Aidil Abdul Hamid, Mohd Hafiz Dzarfan Othman, Vidhya Selvanathan, Wing Fen Yap and Seri Mastura Mustaza
Regular monitoring of bacteria, especially Escherichia coli, in wastewater is crucial to ensure the maintenance of public health. Amperometric detection proves to be a fast…
Abstract
Purpose
Regular monitoring of bacteria, especially Escherichia coli, in wastewater is crucial to ensure the maintenance of public health. Amperometric detection proves to be a fast, sensitive and economically viable solution for E. coli enumeration. This paper reported a prototype amperometric sensor based on PANI-ZnO-NiO nanocomposite thin films prepared by sol–gel method and irradiated with gamma ray. The purpose of this study is to investigate the sensor performance of PANI-ZnO-NiO nanocomposite thin films to detect E. coli in water.
Design/methodology/approach
The films were varied with different compositions of ZnO and NiO by using the formula PANI-(ZnO)1-x-(NiO)x, with x = 0.2, 0.4, 0.6 and 0.8. PANI-ZnO-NiO nanocomposite thin films were characterized by using X-ray diffraction (XRD) and atomic force microscopy (AFM) to study the crystallinity and surface morphology of the films. The sensor performance was conducted using the current–voltage (I-V) measurement by testing the films in clean water and E. coli solution.
Findings
XRD diffractograms show the peaks of ZnO (1 0 0) and NiO (1 0 2). AFM analysis shows the surface roughness, and the grain size of PANI-ZnO-NiO thin films decreases when the concentration ratios of NiO increased. I-V curves show the difference in current flow, where the current in E. coli solution is higher than the clean water.
Originality/value
PANI-(ZnO)1-x-(NiO)x nanocomposite thin film with the highest concentration of ZnO performed the highest sensitivity among the other concentrations, which can be used to indicate the presence of E. coli bacteria in water.
Marina Stramarkou, Achilleas Bardakas, Magdalini Krokida and Christos Tsamis
Carbon dioxide (CO2) has attracted special scientific interest over the last years mainly because of its relation to climate change and indoor air quality. Except for this, CO2…
Abstract
Purpose
Carbon dioxide (CO2) has attracted special scientific interest over the last years mainly because of its relation to climate change and indoor air quality. Except for this, CO2 can be used as an indicator of food freshness, patients’ clinical state and fire detection. Therefore, the accurate monitoring and controlling of CO2 levels are imperative. The development of highly sensitive, selective and reliable sensors that can efficiently distinguish CO2 in various conditions of temperature, humidity and other gases’ interference is the subject of intensive research with chemi-resistive zinc oxide (ZnO)-based sensors holding a privileged position. Several ZnO nanostructures have been used in sensing applications because of their versatile features. However, the deficient selectivity and long-term stability remain major concerns, especially when operating at room temperature. This study aims to encompass an extensive study of CO2 chemi-resistive sensors based on ZnO, introducing the most significant advances of recent years and the best strategies for enhancing ZnO sensing properties.
Design/methodology/approach
An overview of the different ZnO nanostructures used for CO2 sensing and their synthesis methods is presented, focusing on the parameters that highly affect the sensing mechanism and, thus, the performance of CO2 sensors.
Findings
The selectivity and sensitivity of ZnO sensors can be enhanced by adjusting various parameters during their synthesis and by doping or treating ZnO with suitable materials.
Originality/value
This paper summarises the advances in the rapidly evolving field of CO2 sensing by ZnO sensors and provides research directions for optimised sensors in the future.
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V. Koncar, C. Cochrane, M. Lewandowski, F. Boussu and C. Dufour
The need for sensors and actuators is an important issue in the field of smart textiles and garments. Important developments in sensing and heating textile elements consist in…
Abstract
Purpose
The need for sensors and actuators is an important issue in the field of smart textiles and garments. Important developments in sensing and heating textile elements consist in using non‐metallic yarns, for instance carbon containing fibres, directly in the textile fabric. Another solution is to use electro‐conductive materials based on conductive polymer composites (CPCs) containing carbon or metallic particles. The purpose of this paper is to describe research based on the use of a carbon black polymer composite to design two electro‐conductive elements: a strain sensor and a textile heating element.
Design/methodology/approach
The composite is applied as a coating consisting of a solvent, a thermoplastic elastomer, and conductive carbon black nanoparticles. In both applications, the integration of the electrical wires for the voltage supply or signal recording is as discreet as possible.
Findings
The CPC materials constitute a well‐adapted solution for textile structures: they are very flexible, and thus do not modify the mechanical characteristics and general properties of the textile structure.
Research limitations/implications
In the case of the heating element, the use of metallic yarns as electrodes makes the final structure a more rigid. This can be improved by choosing other conducting yarns that are more flexible, or by developing knitted structures instead of woven fabrics.
Practical implications
The CPC provide a low cost solution, and the elements are usually designed so as to work with a low voltage supply.
Originality/value
The CPC has been prepared with a solvent process which is especially adapted to flexible materials like textiles. This is original in comparison to the conventional melt‐mixing process usually found in literature.
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Susan Samadi, Ghasem Asadi Cordshooli, Mohammad Yousefi, Khadijeh Kalateh and SeyedAmirabbas Zakaria
This paper aims to introduce constructed CeO2/TiO2 core/shell nanoparticle as sensitive substance organic compounds.
Abstract
Purpose
This paper aims to introduce constructed CeO2/TiO2 core/shell nanoparticle as sensitive substance organic compounds.
Design/methodology/approach
The CeO2 nanoparticles were synthesized by hydrothermal treatment. Then CeO2/TiO2 core/shell was fabricated by sol–gel method preparation of TiO2 in the presence of ceria nanoparticles and applied as the sensitive material to make a sensor.
Findings
Formation of the nanoparticles was confirmed by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). The synthesized sensor exhibited not only good sensitivity to volatile organic compounds at room temperature but also logarithm of sensitivity versus concentrations was linear.
Research limitations/implications
The sensor shows acceptable sensitivity to volatile organic compound at room temperature.
Practical implications
Experimental data revealed satisfactory reproducibility and short response and recovery times.
Originality/value
A radical mechanism for gas sensor reaction in two pathways was considered and activation energies were calculated by density functional theory (DFT) method to describe different sensitivities of tested volatile gases. The experimental results were consistent with the calculations.
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