Chemosensors

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4 pages, 187 KiB

Open AccessEditorial

Polymer-Based Chemical Sensors

by José Antonio Reglero Ruiz, Saúl Vallejos, Félix Clemente García and José Miguel García

Chemosensors 2018, 6(3), 42; https://doi.org/10.3390/chemosensors6030042 - 19 Sep 2018

Cited by 4 | Viewed by 3345

Abstract

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(This article belongs to the Special Issue Polymers Based Chemical Sensors)

Research

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8 pages, 1299 KiB

Open AccessArticle

Theoretical Investigations of the Interaction of Gaseous Pollutants Molecules with the Polyacrylonitrile Surface

by Victor Petrov and Marta Avilova

Chemosensors 2018, 6(3), 39; https://doi.org/10.3390/chemosensors6030039 - 13 Sep 2018

Cited by 3 | Viewed by 3260

Abstract

This work presents theoretical studies of the interaction of molecules of several gaseous pollutants with polyacrylonitrile (PAN) surface in the presence of a water and/or oxygen molecule. For this purpose, a PAN cluster model has been proposed by the methods of quantum chemical [...] Read more.

This work presents theoretical studies of the interaction of molecules of several gaseous pollutants with polyacrylonitrile (PAN) surface in the presence of a water and/or oxygen molecule. For this purpose, a PAN cluster model has been proposed by the methods of quantum chemical calculations and molecular modeling. The energy-favorable positions, in which the gas molecules are located relative to the surface of the PAN cluster, are determined and the thermodynamic and the following geometric parameters of the systems are calculated: “PAN cluster − oxygen molecule”, “PAN cluster − oxygen molecule − gas molecule”, “PAN cluster − water molecule − molecule of oxygen”, and “PAN cluster − a molecule of water − an oxygen molecule − a gas molecule”. It is concluded that PAN in atmospheric air in the presence of oxygen molecules is sensitive to carbon oxide (IV), sulfur (IV) oxide, chlorine, hydrogen sulfide and carbon oxide (II). In an anoxic environment, PAN films will show selective sensitivity to chlorine. The presence of water molecules in the investigated air should not affect the gas sensitivity of PAN films. Full article

(This article belongs to the Special Issue Polymers Based Chemical Sensors)

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11 pages, 4002 KiB

Open AccessArticle

Effect of Dangling Bonds on De-Poling Time for Polymeric Electric Field Optical Sensors

by Amir R. Ali, Amal S. Tourky and Roushdy A. Ali

Chemosensors 2018, 6(1), 3; https://doi.org/10.3390/chemosensors6010003 - 12 Jan 2018

Cited by 4 | Viewed by 4909

Abstract

This paper investigates the possible chemical changes in polydimethylsiloxane (PDMS) caused by two different techniques of fabrication for ultra-sensitive electric field optical sensors. The sensing element is a micro-sphere made from 60:1 PDMS (60 parts base silicon elastomer to one part polymer curing [...] Read more.

This paper investigates the possible chemical changes in polydimethylsiloxane (PDMS) caused by two different techniques of fabrication for ultra-sensitive electric field optical sensors. The sensing element is a micro-sphere made from 60:1 PDMS (60 parts base silicon elastomer to one part polymer curing agent by volume). The measurement principle is based on the morphology dependent resonances (MDR) shifts of the micro-sphere. We present the effects of curing and poling of polymer micro-spheres used as optical sensors. The degree of curing leads to changes in the de-poling time which results from dangling bonds in the polymeric chains. Consequently, the longevity of the sensitivity of the sensor can extended by two orders of magnitude. An analysis is carried out along with preliminary experiments to investigate that behavior. Full article

(This article belongs to the Special Issue Polymers Based Chemical Sensors)

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5501 KiB

Open AccessArticle

Biochars as Innovative Humidity Sensing Materials

by Daniele Ziegler, Paola Palmero, Mauro Giorcelli, Alberto Tagliaferro and Jean-Marc Tulliani

Chemosensors 2017, 5(4), 35; https://doi.org/10.3390/chemosensors5040035 - 12 Dec 2017

Cited by 26 | Viewed by 5741

Abstract

In this work, biochar-based humidity sensors were prepared by drop-coating technique. Polyvinylpyrrolidone (PVP) was added as an organic binder to improve the adhesion of the sensing material onto ceramic substrates having platinum electrodes. Two biochars obtained from different precursors were used. The sensors [...] Read more.

In this work, biochar-based humidity sensors were prepared by drop-coating technique. Polyvinylpyrrolidone (PVP) was added as an organic binder to improve the adhesion of the sensing material onto ceramic substrates having platinum electrodes. Two biochars obtained from different precursors were used. The sensors were tested toward relative humidity (RH) at room temperature and showed a response starting around 5 RH%, varying the impedance of 2 orders of magnitude after exposure to almost 100% relative humidity. In both cases, biochar materials are behaving as p-type semiconductors under low amounts of humidity. On the contrary, for higher RH values, the impedance decreased due to water molecules adsorption. When PVP is added to SWP700 biochar, n-p heterojunctions are formed between the two semiconductors, leading to a higher sensitivity at low RH values for the sensors SWP700-10% PVP and SWP700-20% PVP with respect to pure SWP700 sensor. Finally, response and recovery times were both reasonably fast (in the order of 1 min). Full article

(This article belongs to the Special Issue Polymers Based Chemical Sensors)

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3165 KiB

Open AccessArticle

vQRS Based on Hybrids of CNT with PMMA-POSS and PS-POSS Copolymers to Reach the Sub-PPM Detection of Ammonia and Formaldehyde at Room Temperature Despite Moisture

by Abhishek Sachan, Mickael Castro, Veena Choudhary and Jean-François Feller

Chemosensors 2017, 5(3), 22; https://doi.org/10.3390/chemosensors5030022 - 12 Jul 2017

Cited by 14 | Viewed by 6748

Abstract

Nanocomposite-based quantum resistive vapour sensors (vQRS) have been developed from the assembly of hybrid copolymers of polyhedral oligomeric silsesquioxane (POSS) and poly(methyl methacrylate) (PMMA) or poly(styrene) (PS) with carbon nanotubes (CNT). The originality of the resulting conducting architecture is expected to be responsible [...] Read more.

Nanocomposite-based quantum resistive vapour sensors (vQRS) have been developed from the assembly of hybrid copolymers of polyhedral oligomeric silsesquioxane (POSS) and poly(methyl methacrylate) (PMMA) or poly(styrene) (PS) with carbon nanotubes (CNT). The originality of the resulting conducting architecture is expected to be responsible for the ability of the transducer to detect sub-ppm concentrations of ammonia and formaldehyde at room temperature despite the presence of humidity. In particular, the boosting effect of POSS is evidenced in CNT-based nanocomposite vQRS. The additive fabrication by spraying layer-by-layer provides (sLbL) is an effective method to control the reproducibility of the transducers’ chemo-resistive responses. In dry atmosphere, the two types of sensors showed a high sensitivity towards both hazardous gases, as they were able to detect 300 ppb of formaldehyde and 500 ppb of ammonia with a sufficiently good signal to noise ratio (SNR > 10). They also exhibited a quick response times less than 5 s for both vapours and, even in the presence of 100 ppm of water, they were able to detect small amounts of gases (1.5 ppm of NH₃ and 9 ppm of CH₂O). The results suggest promising applications of POSS-based vQRS for air quality or volatolome monitoring. Full article

(This article belongs to the Special Issue Polymers Based Chemical Sensors)

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Review

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20 pages, 1346 KiB

Open AccessReview

Smart Polymers in Micro and Nano Sensory Devices

by José Antonio Reglero Ruiz, Ana María Sanjuán, Saúl Vallejos, Félix Clemente García and José Miguel García

Chemosensors 2018, 6(2), 12; https://doi.org/10.3390/chemosensors6020012 - 21 Mar 2018

Cited by 32 | Viewed by 6681

Abstract

The present review presents the most recent developments concerning the application of sensory polymers in the detection and quantification of different target species. We will firstly describe the main polymers that are being employed as sensory polymers, including, for example, conducting or acrylate-based [...] Read more.

The present review presents the most recent developments concerning the application of sensory polymers in the detection and quantification of different target species. We will firstly describe the main polymers that are being employed as sensory polymers, including, for example, conducting or acrylate-based polymers. In the second part of the review, we will briefly describe the different mechanisms of detection and the target species, such as metal cations and anions, explosives, and biological and biomedical substances. To conclude, we will describe the advancements in recent years concerning the fabrication of micro and nano sensory devices based on smart polymers, with a bibliographic revision of the research work published between 2005 and today, with special emphasis on research work presented since 2010. A final section exposing the perspectives and challenges of this interesting research line will end the present review article. Full article

(This article belongs to the Special Issue Polymers Based Chemical Sensors)

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24 pages, 3220 KiB

Open AccessEditor’s ChoiceReview

Recent Advances in the Detection of Neurotransmitters

by Bo Si and Edward Song

Chemosensors 2018, 6(1), 1; https://doi.org/10.3390/chemosensors6010001 - 4 Jan 2018

Cited by 144 | Viewed by 19053

Abstract

Neurotransmitters are chemicals that act as messengers in the synaptic transmission process. They are essential for human health and any imbalance in their activities can cause serious mental disorders such as Parkinson’s disease, schizophrenia, and Alzheimer’s disease. Hence, monitoring the concentrations of various [...] Read more.

Neurotransmitters are chemicals that act as messengers in the synaptic transmission process. They are essential for human health and any imbalance in their activities can cause serious mental disorders such as Parkinson’s disease, schizophrenia, and Alzheimer’s disease. Hence, monitoring the concentrations of various neurotransmitters is of great importance in studying and diagnosing such mental illnesses. Recently, many researchers have explored the use of unique materials for developing biosensors for both in vivo and ex vivo neurotransmitter detection. A combination of nanomaterials, polymers, and biomolecules were incorporated to implement such sensor devices. For in vivo detection, electrochemical sensing has been commonly applied, with fast-scan cyclic voltammetry being the most promising technique to date, due to the advantages such as easy miniaturization, simple device architecture, and high sensitivity. However, the main challenges for in vivo electrochemical neurotransmitter sensors are limited target selectivity, large background signal and noise, and device fouling and degradation over time. Therefore, achieving simultaneous detection of multiple neurotransmitters in real time with long-term stability remains the focus of research. The purpose of this review paper is to summarize the recently developed sensing techniques with the focus on neurotransmitters as the target analyte, and to discuss the outlook of simultaneous detection of multiple neurotransmitter species. This paper is organized as follows: firstly, the common materials used for developing neurotransmitter sensors are discussed. Secondly, several sensor surface modification approaches to enhance sensing performance are reviewed. Finally, we discuss recent developments in the simultaneous detection capability of multiple neurotransmitters. Full article

(This article belongs to the Special Issue Polymers Based Chemical Sensors)

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2149 KiB

Open AccessReview

Polymeric Materials for Printed-Based Electroanalytical (Bio)Applications

by Stefano Cinti

Chemosensors 2017, 5(4), 31; https://doi.org/10.3390/chemosensors5040031 - 24 Nov 2017

Cited by 18 | Viewed by 5573

Abstract

Advances in design of selective interfaces and printed technology have mighty contributed to the expansion of the electroanalysis fame. The real advantage in electroanalytical field is the possibility to manufacture and customize plenty of different sensing platforms, thus avoiding expensive equipment, hiring skilled [...] Read more.

Advances in design of selective interfaces and printed technology have mighty contributed to the expansion of the electroanalysis fame. The real advantage in electroanalytical field is the possibility to manufacture and customize plenty of different sensing platforms, thus avoiding expensive equipment, hiring skilled personnel, and expending economic effort. Growing developments in polymer science have led to further improvements in electroanalytical methods such as sensitivity, selectivity, reproducibility, and accuracy. This review provides an overview of the technical procedures that are used in order to establish polymer effectiveness in printed-based electroanalytical methods. Particular emphasis is placed on the development of electronalytical sensors and biosensors, which highlights the diverse role of the polymeric materials depending on their specific application. A wide overview is provided, taking into account the most significant findings that have been reported from 2010 to 2017. Full article

(This article belongs to the Special Issue Polymers Based Chemical Sensors)

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