Search results

A bio-sensor has been developed in this study for the purpose of point-of-care diagnostics. Point-of-care-diagnostic is a type of diagnosis where the diagnostic centre, i.e. the diagnosis kit is made available at the location of the patient when the patient needs immediate action. In this process of diagnosis a compact, portable, integrated kit must be available which can diagnose the disease of the patient by testing various analytes.

Using a fully experimental methodology, a blood glucose sensor is made by conducting carbon interdigitated electrode (IDE) on a flexible substrate. IDEs are used to increase the effective capacitance of the structure, as well as the effective electroactive area of the sensor. Interdigitated structure permits two-electrode sticks with “each other” and “infuse” together. As a consequence, the distance between electrodes can be tuned to a much smaller value than traditional thin-film architectures. Narrowing the distance between electrodes allows for fast ion diffusion that offers better rate capability and efficiency in power density. The fabricated device exhibits a remarkable value of sensitivity in the order of 2.741 µA mM-1 cm⁻².

A highly sensitive, portable and inexpensive blood glucose sensor has been developed in this context.

This research study can be a scope for future research in the field of bio-sensors.

Nature and occurrence of food-borne pathogens in raw and processed food products evolved greatly in the past few years due to new modes of transmission and resistance build-up against sundry micro-/macro-environmental conditions. Assurance of food health and safety thus gained immense importance, for which bio-sensing technology proved very promising in the detection and quantification of food-borne pathogens. Considering the importance, different studies have been performed, and different biosensors have been developed. This study aims to summarize the different biosensors used for the deduction of food-borne pathogens.

The present review highlights different biosensors developed apropos to food matrices, factors governing their selection, their potential and applicability. The paper discusses some related key challenges and constraints and also focuses on the needs and future research prospects in this field.

The shift in consumers’ and industries’ perceptions directed the further approach to achieve portable, user and environmental friendly biosensing techniques. Despite of these developments, it was still observed that the comparison among the different biosensors and their categories proved tedious on a single platform; since the food matrices tested, pathogen detected or diagnosed, time of detection, etc., varied greatly and very few products have been commercially launched. Conclusively, a challenge lies in front of food scientists and researchers to maintain pace and develop techniques for efficiently catering to the needs of the food industry.

Biosensors deduction limit varied with the food matrix, type of organism, material of biosensors’ surface, etc. The food matrix itself consists of complex substances, and various types of food are available in nature. Considering the diversity of food there is a need to develop a universal biosensor that can be used for all the food matrices for a pathogen. Further research is needed to develop a pathogen-specific biosensor that can be used for all the food products that may have accuracy to eliminate the traditional method of deduction.

The present paper summarized and categorized the different types of biosensors developed for food-borne pathogens.

This paper aims to focus on research work related to metamaterial-based sensors for material characterization that have been developed for past ten years. A decade of research on metamaterial for sensing application has led to the advancement of compact and improved sensors.

In this study, relevant research papers on metamaterial sensors for material characterization published in reputed journals during the period 2007-2018 were reviewed, particularly focusing on shape, size and nature of materials characterized. Each sensor with its design and performance parameters have been summarized and discussed here.

As metamaterial structures are excited by electromagnetic wave interaction, sensing application throughout electromagnetic spectrum is possible. Recent advancement in fabrication techniques and improvement in metamaterial structures have led to the development of compact, label free and reversible sensors with high sensitivity.

The paper provides useful information on the development of metamaterial sensors for material characterization.

Nanopore-based molecular sensing and measurement, specifically DNA sequencing, is advancing at a fast pace. Some embodiments have matured from coarse particle counters to enabling full human genome assembly. This evolution has been powered not only by improvements in the sensors themselves, but also in the assisting microelectronic CMOS readout circuitry closely interfaced to them. In this light, this paper aims to review established and emerging nanopore-based sensing modalities considered for DNA sequencing and CMOS microelectronic methods currently being used.

Readout and amplifier circuits, which are potentially appropriate for conditioning and conversion of nanopore signals for downstream processing, are studied. Furthermore, arrayed CMOS readout implementations are focused on and the relevant status of the nanopore sensor technology is reviewed as well.

Ion channel nanopore devices have unique properties compared with other electrochemical cells. Currently biological nanopores are the only variants reported which can be used for actual DNA sequencing. The translocation rate of DNA through such pores, the current range at which these cells operate on and the cell capacitance effect, all impose the necessity of using low-noise circuits in the process of signal detection. The requirement of using in-pixel low-noise circuits in turn tends to impose challenges in the implementation of large size arrays.

The study presents an overview on the readout circuits used for signal acquisition in electrochemical cell arrays and investigates the specific requirements necessary for implementation of nanopore-type electrochemical cell amplifiers and their associated readout electronics.

The present study aims to summarize different non-invasive techniques for continuous glucose monitoring (CGM) in diabetic patients using glucose-oxidase biosensors. In diabetic patients, the self-monitoring of blood glucose (BG) levels through minimally invasive techniques provides a quick method of measuring their BG concentration, unlike conventional laboratory measurements. The drawbacks of minimally invasive techniques include physical pain, anxiety and reduced patient compliance. To overcome these limitations, researchers shifted their attention towards the development of a pain-free and non-invasive glucose monitoring system, which showed encouraging results.

This study reviews the development of minimally and non-invasive method for continuous glucose level monitoring in diabetic or hyperglycemic patients. Specifically, glucose monitoring using non-invasive techniques, such as spectroscopy-based methods, polarimetry, fluorescence, electromagnetic variations, transdermal extraction-based methods and using body fluids, has been discussed. The various strategies adopted for improving the overall specificity and performance of biosensors are discussed.

In conclusion, the technology of glucose oxidase-based biosensors for glucose level monitoring is becoming a strong competitor, probably because of high specificity and selectivity, low cost and increased patient compliance. Many industries currently working in this field include Google, Novartis and Microsoft, which demonstrates the significance and strong market potential of self-monitored glucose-oxidase-based biosensors in the near future.

This review paper summarizes comprehensive strategies for continuous glucose monitoring (CGM) in diabetic patients using non-invasive glucose-oxidase biosensors. Non-invasive techniques received significant research interest because of high sensitivity and better patient compliance, unlike invasive ones. Although the results from these innovative devices require frequent calibration against direct BG data, they might be a preferable candidate for future CGM. However, the challenges associated with designing accurate level sensors to biomonitor BG data easily and painlessly needs to be addressed.

Molecularly imprinted polymers (MIPs) have aroused focus in medicinal chemistry in recent decades, especially for biomedical applications. Considering the exceptional abilities to immobilize any guest of medical interest (antibodies, enzymes, etc.), MIPs is attractive to substantial research efforts in complementing the quest of biomimetic recognition systems. This study aims to review the key-concepts of molecular imprinting, particularly emphasizes on the conformational adaptability of MIPs beyond the usual description of molecular recognition. The optimal morphological integrity was also outlined in this review to acknowledge the successful sensing activities by MIPs.

This review highlighted the fundamental mechanisms and underlying challenges of MIPs from the preparation stage to sensor applications. The progress of electrochemical and optical sensing using molecularly imprinted assays has also been furnished, with the evolvement of molecular imprinting as a research hotspot.

The lack of standard synthesis protocol has brought about an intriguing open question in the selection of building blocks that are biocompatible to the imprint species of medical interest. Thus, in this paper, the shortcomings associated with the applications of MIPs in electrochemical and optical sensing were addressed using the existing literature besides pointing out possible solutions. Future perspectives in the vast development of MIPs also been postulated in this paper.

The present review intends to furnish the underlying mechanisms of MIPs in biomedical diagnostics, with the aim in electrochemical and optical sensing while hypothesizing on future possibilities.

The purpose of this paper is study of the type of functional group and its situation on phenyl molecule, in increasing the corrosion protection of modified graphene layers by it. Corrosion protection efficiency of graphene was raised via modifying the surface of graphene-coated carbon steel (CS/G) by using aromatic molecules. Phenyl groups with three different substitutions including COOH, NO₂ and CH₃ grafted to graphene via diazonium salt formation route, by using carboxy phenyl, nitro phenyl and methyl phenyl diazonium salts in ortho, meta and para spatial situations.

Molecular bindings were characterized by using X-ray diffractometer, fourier-transform infrared spectroscopy (FTIR), Raman and scanning electron microscopy (SEM)/ energy dispersive X-ray analysis (EDXA) methods. Anti-corrosion performance of modified CS/G electrodes was evaluated by weight loss and electrochemical techniques, potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy, in 3.5 per cent NaCl solution.

The obtained results confirmed covalently bonding of phenyl groups to the graphene surface. Also, the observed results showed that substitution spatial situations on phenyl groups can affect charge transfer resistance (R_ct), corrosion potential (E_corr), corrosion current density (j_corr) and the slope of the anodic and cathodic reaction (ß_a,c), demonstrating that the proposed modification method can hinder the corrosion reactions. The proposed modification led to restoring the graphene surface defects and consequently increasing its corrosion protection efficiency.

The obtained results from electrochemical methods proved that protection efficiency was observed in order COOH < NO₂ < CH₃ and MPD in the para spatial situation and showed the maximum protection efficiency of 98.6 per cent in comparison to other substitutions. Finally, the ability of proposed graphene surface modification route was further proofed by using surface methods, i.e. SEM and EDXA, and contact angles measurements.

The purpose of this paper is to review recent progress in electronic nose technologies, focusing on hybrid systems combining biological elements with physical transducers.

Electronic nose technologies are moving rapidly towards hybrid bioelectronic systems, where biological odour-recognition elements from the olfactory pathways of vertebrates and insects are being utilised to construct new “bionic noses” that can be used in industrial applications.

With the increased understanding of how chemical senses and the brain function in biology, an emerging field of “neuromorphic olfaction” has arisen.

Important components are olfactory receptor proteins and soluble proteins found at the periphery of olfaction called odorant-binding proteins. The idea is that these proteins can be incorporated into transducers and function as biorecognition elements for volatile compounds of interest.

Major drivers are the security, environmental and medical applications, and the internet of things will be a major factor in implementing low-cost chemical sensing in networked applications for the future.

Widespread take up of new technologies that are cheap will minimise the impact of environmental pollution, increase food safety and may potentially help in non-invasive screening for medical ailments.

This review brings together diverse threads of research leading to a common theme that will inform a non-expert of recent developments in the field.

The purpose of this paper is to predict a suitable paper substrate which has high capillary pressure with the tendency of subsequent fluid wrenching in onward direction for the fabrication of microfluidics device application.

The experiment has been done on the Whatman^TM grade 1, Whatman^TM chromatography and nitrocellulose paper samples which are made by GE Healthcare Life Sciences. The structural characterization of paper samples for surface properties has been done by scanning electron microscope and ImageJ software. Identification of functional groups on the surface of samples has been done by Fourier transform infrared analysis. A finite elemental analysis has also been performed by using the “Multiphase Flow in Porous Media” module of the COMSOL Multiphysics tool which combines Darcy’s law and Phase Transport in Porous Media interface.

Experimentally, it has been concluded that the paper substrate for flexible microfluidic device application must have large number of internal (intra- and interfiber) pores with fewer void spaces (external pores) that have high capillary pressure to propel the fluid in onward direction with narrow paper fiber channel.

Surface structure has a dynamic impact in paper substrate utilization in multiple applications such as paper manufacturing, printing process and microfluidics applications.

The purpose of this work is to explore electrical properties of an electrochemical sensor designed for the detection of malachite green (MG) present in an aqueous solution.

The present sensor consists in the spatial coupling of a polymeric membrane and an ion-sensitive electrode (platinum electrode). The preparation of the polymeric membrane involves the incorporation of an ionophore (D2HPA), a polymer (polyvinylchloride [PVC]) and a plasticizer (dioctyl phthalate [DOP]). Several techniques have been used to characterize this sensor: the cyclic voltammetry, the electrochemical impedance spectroscopy and the optical microscopy. The sensibility, the selectivity and the kinetic study of a modified platinum electrode have been evaluated by cyclic voltammetry.

The obtained results reveal the possibility of a linear relationship between the current of reduction peaks and MG concentration. A linear response was obtained in a wide-concentration range that stretches from 10⁻⁵ to 10⁻¹³ mol L⁻¹, with a good correlation coefficient (0.976) and a good detection limit of 5.74 × 10⁻¹⁴ mol L⁻¹ (a signal-to-noise ratio of 3). In addition, the voltammetric response of modified electrode can be enhanced by adding a layer of Nafion membrane. Under this optimal condition, a linear relationship was obtained, with a correlation coefficient of 0.986 and a detection limit of 1.92 × 10⁻¹⁸ mol L⁻¹.

In the present research, a convenient, inexpensive and reproducible method for the detection of MG was developed. The developed sensor is capable of competing against the conventional techniques in terms of speed, stability and economy.