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Design, fabricate and evaluate all-solid-state wearable sensor systems that can monitor ion concentrations in human sweat to provide real time health analysis and disease diagnosis capabilities.

A human health monitoring system includes disposable customized flexible electrode array and a compact signal transmission-processing electronic unit.

Patterned rGO (reduced-graphene oxide) layers can replace traditional metal electrodes for the fabrication of free-standing all solid film sensors to provide improved flexibility, sensitivity, selectivity, and stability in ion concentration monitoring. Electrochemical measurements show the open circuit potential of current selective electrodes exhibit near Nernst responses versus Na+ and K+ ion concentration in sweat. These signals show great stability during a typical measurement period of 3 weeks. Sensor performances evaluated through real time measurements on human subjects show strong correlations between subject activity and sweating levels, confirming high degree of robustness, sensitivity, reliability and practicality of current sensor systems.

In improving flexibility, stability and interfacial coherency of chemical sensor arrays, rGO films have been the developed as a high-performance alternative to conventional electrode with significant cost and processing complexity reduction. rGO supported solid state electrode arrays have been found to have linear potential response versus ion concentration, suitable for electrochemical sensing applications. Current sweat sensor system has a high degree of integration, including electrode arrays, signal processing circuits, and data visualization interfaces.

Selection of a gas sensor requires consideration of environmental effects that can significantly affect performance and cause false alarms. Metal‐oxide sensors have high sensitivity due to the specific interactions of gas molecules with thin metal‐oxide films, however, the films can also be sensitive to variations in temperature and humidity and some oxidizing and deoxidizing gases. The purpose of this paper is to evaluate the environmental effect on metal‐oxide nitrogen dioxide (NO₂) sensors quantitatively.

Three commercial metal‐oxide NO₂ sensors and one electrochemical sensor were tested simultaneously under controlled gas concentrations and various environmental conditions. For this test, a customized sensor testing setup was prepared including a gas mixer, heating module, gas chamber, electronics, and data acquisition units.

Based on the test results for NO₂ gas concentrations ranging from 0 to 10 ppm, the metal‐oxide sensors showed significant signal variations at elevated temperatures and humidity. The results provide overall sensor performance. Linearity, repeatability, selectivity and sensitivity of the metal‐oxide sensors were measured and compared to an electrochemical sensor.

A systematic evaluation to characterize metal‐oxide NO₂ sensors is presented, and their comparison regarding sensitivity, selectivity, linearity, and dependence on humidity and temperature is reported. The result provides sensor performance data and guideline for sensor evaluation.

The purpose of this paper is to describe, review, classify and analyze the current challenges in three-dimensional printing processes for combined electrochemical and microfluidic fabrication areas, which include printing devices and sensors in specified areas.

A systematic review of the literature focusing on existing challenges is carried out. Focused toward sensors and devices in electrochemical and microfluidic areas, the challenges are oriented for a discussion exploring the suitability of printing varied geometries in an accurate manner. Classifications on challenges are based on four key categories such as process, material, size and application as the printer designs are mostly based on these parameters.

A key three-dimensional printing process methodologies have their unique advantages compared to conventional printing methods, still having the challenges to be addressed, in terms of parameters such as cost, performance, speed, quality, accuracy and resolution. Three-dimensional printing is yet to be applied for consumer usable products, which will boost the manufacturing sector. To be specific, the resolution of printing in desktop printers needs improvement. Printing scientific products are halted with prototyping stages. Challenges in three-dimensional printing sensors and devices have to be addressed by forming integrated processes.

The research is underway to define an integrated process-based on three-dimensional Printing. The detailed technical details are not shared for scientific output. The literature is focused to define the challenges.

The research can provide ideas to business on innovative designs. Research studies have scope for improvement ideas.

Review is focused on to have an integrated three-dimensional printer combining processes. This is a cost-oriented approach saving much of space reducing complexity.

To date, no other publication reviews the varied three-dimensional printing challenges by classifying according to process, material, size and application aspects. Study on resolution based data is performed and analyzed for improvements. Addressing the challenges will be the solution to identify an integrated process methodology with a cost-effective approach for printing macro/micro/nano objects and devices.

Continuous glucose monitoring (CGM) is a notable invention introduced in the biomedical industry. It provides valuable information about intermittent capillary blood glucose that is normally unattainable by regular clinical blood sample tests. CGM includes several progressive facilities such as instantaneous and real-time display of blood glucose level, “24/7” coverage, continuous motion of alerts for actual or impending hypo- and hyperglycemia and the ability to characterize glycemic variability. CGM allows users and physicians to visualize and diagnose more accurate and precise rate of change of glucose by capacitating small, comfortable, user-friendly sensor devices. Sometimes, this vital information is shared to the personal message box over Internet. In short, CGM is capable to inform, educate, motivate and alert (IEMA) people with diabetes. Despite the huge expectation with CGM, the available solutions have not attracted much attention among people. The huge potential of CGM in future diabetic study relies on the successful implication of the CGM. This paper aims at disseminating of state-of-the-art knowledge about existing work around the CGM.

This paper presents a comprehensive systematic review on the recent developments in CGM development techniques that have been reported in credible sources, namely PubMed, IEEE Xplore, Science Direct, Springer Link, Scopus and Google Scholar. Detailed analysis and systematic comparison are provided to highlight the achievement and future direction of CGM deployment.

Several key challenges are also portrayed for suitable opportunistic orientation. CGM solutions from four leading manufacturers such as Tandem, Dexcom, Abbott and Medtronic are compared based on the following factors including accuracy (% MARD); sensor lifetime, calibration requirement, smart device, compatibility and remote monitoring. Qualitative and quantitative analyses are performed.

This work can be a valuable source of reference and guidance for future research in this field.

Ascorbic acid (AA) is an essential vitamin for human health. Therefore, fast and cost-effective detecting of AA is essential, whether in human or food samples. The purpose of this paper is to develop an electrochemical nanosensor for AA detection.

The proposed nanosensor was developed by printing carbon nanoparticles ink and silver nanoparticles ink on a polydimethylsiloxane (PDMS) substrate. The surface of the PDMS substrate was first treated by corona plasma. Then, the nanomaterials printer was used to deposit both inks on the substrate. The working electrode surface was modified by drop-casting of carbon nanotubes. Morphological evaluation was applied using scanning electron microscopy and cyclic voltammetry. Also, a potentiostat was used to detect AA by differential pulse voltammetry.

It has been shown that the developed nanosensor linearly worked at a range of (0–5 mM), with a limit of detection lower than 0.8 mM and a relative standard deviation of 6.6%.

The developed nanosensor is characterized by a simple and cost-effective sensing tool for AA. In particular, the nanomaterials enhanced the nanosensor’s sensitivity due to the high catalytic activity.

This article aims to review the different devices that are available for the in situ monitoring of analytes found in the marine environment.

Following a short introduction to the topic, this paper discusses physical‐ and chemical‐based sensors, automatic analysers (flow injection, spectroscopic and spectrometric), electrochemical devices and biosensors.

A wide range of in situ monitoring systems (and associated deployment apparatus) for measuring concentrations of various analytes (e.g. nutrients, organic chemicals and metallic elements) have been developed in recent decades. Many of these systems are still at the laboratory or prototype stage and are yet to be fully developed into commercially available products. The harsh conditions often found in the marine environment can further limit the utility and application of these sensors. Further development work is needed; however, the need now is for field deployments, validation and inter‐calibration between sensors and other analytical measurement techniques.

This paper provides up‐to‐date information on in situ technologies that are available, either at the laboratory and prototype stages or commercially, and are suitable for deployment in the marine environment. Applications of these sensing systems are discussed together with their associated advantages and disadvantages over other existing water monitoring methods.

Summarizes some of the most commonly used gas sensors and describes how each one works. Covers solid state gas sensors; aqueous electrochemical gas sensors; paramagnetic gas sensors, photometric gas sensors; thermal conductivity gas sensors and fibre‐optic gas sensors.

This information will be useful in the selection of materials and technology for the detection and removal of mercury ions at a low cost and with high sensitivity and selectivity. The purpose of this study is to provide the useful information for selection of materials and technology to detect and remove the mercury ions from water with high sensitivity and selectivity. The purpose of this study is to provide the useful information for selection of materials and technology to detect and remove the mercury ions from water with high sensitivity and selectivity.

Different nano- and bio-materials allowed for the development of a variety of biosensors – colorimetric, chemiluminescent, electrochemical, whole-cell and aptasensors – are described. The materials used for their development also make it possible to use them in removing heavy metals, which are toxic contaminants, from environmental water samples.

This review focuses on different technologies, tools and materials for mercury (heavy metals) detection and remediation to environmental samples.

This review gives up-to-date and systemic information on modern nanotechnology methods for heavy metal detection. Different recognition molecules and nanomaterials have been discussed for remediation to water samples. The present review may provide valuable information to researchers regarding novel mercury ions detection sensors and encourage them for further research/development.

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.