Organic Sensors: Materials and Applications
2: Instituto de Ciencia de Materiales de Madrid, Madrid, Spain
3: CNR - Advanced Electronic Devices LABoratory, University of Cagliari, Cagliari, Italy
This book reviews the state of the art in the use of organic materals as physical, chemical and biomedical sensors in a variety of application settings. Topics covered include organic semiconductors for chemical and physical sensing; conducting polymers in sensor applications; chemically functionalized organic semiconductors for highly selective sensing; composite organic-inorganic sensors; artificial skin applications; organic thin film transistor strain gauges for biomedical applications; OTFT infrared sensors for touchless human-machine interaction; smart fabric sensors and e-textile technologie; image capture with organic sensors; organic gas sensors and electronic noses; electrolyte gated organic transistors for bio-chemical sensing; ion-selective organic electrochemical transistors; DNA biosensors; metabolic organic sensors; and conductive polymer based sensors for biomedical applications.
Inspec keywords: conducting materials; biosensors; polymer electrolytes; intelligent sensors; electronic noses; DNA; transistors
Other keywords: electrolyte-gated organic transistor; conductive organic material; smart fabric sensor architecture; DNA biosensing application; conducting polymer; electronic nose; artificial skin application; ion sensor; organic gas sensor; organic transistor-based mechanical sensor
Subjects: Chemical sensors; Semiconductor devices; Electrochemistry and electrophoresis; Biosensors; Molecular biophysics; General electrical engineering topics; Textbooks; Chemical variables measurement; Intelligent sensors; Biosensors; Chemical sensors
- Book DOI: 10.1049/PBCE100E
- Chapter DOI: 10.1049/PBCE100E
- ISBN: 9781849199858
- e-ISBN: 9781849199865
- Page count: 310
- Format: PDF
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Front Matter
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1 Conducting polymers in sensor applications
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Conducting (or conjugated) polymers (CPs) are widely used for fabricating chemical and biosensors. These materials enable fabrication of devices in short lead time and at relatively low costs owing to their unique advantages of light weight, easy processability, compatibility with biological systems, tunable electronic and optic properties, large area fabrication and potential for flexible or wearable sensors. This chapter describes the basic concepts underlying the interaction of analyte with CPs as well as the other components of sensors. The operating principles of transducers used in the sensor are discussed in detail. Sensors based on conducting polymers are classified in accordance with the changes in the properties of conducting polymers. These changes involve changes in (i) doping levels, (ii) optical properties and (iii) changes due to weak interactions. Furthermore, the sensors have been reviewed for various conducting polymers such as polyaniline, polythiophene, polypyrrole, polydaicetylene for analysis of wide variety of analysts including toxic gases, radiation, pH, temperature, external stimuli; and recent advances in sensors based on conducting polymers have been discussed. Future directions and thrust in emerging field have been projected in the area of molecular engineering, material synthesis, film preparation and transducers, circuits and algorithms for developing futuristic sensors especially wearable sensors.
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2 Electrolyte-gated organic transistors for biosensing applications
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The interfacing of biomaterials to electronic devices is one of the most challenging research fields that has relevance to both fundamental studies and the development of highly performing biosensors. Important aspects connected to the field of biosensors based on electrolyte-gated organic transistors are discussed. The main features of biomolecules used as recognition elements along with the strategies reported so far for their deposition on the biosensors transducer surface are presented. An introduction of the involving surface interactions such as covalent binding, physical adsorption, self-assembly and bio-affinity binding strategy is given. Besides, the most relevant surface materials for electronic biosensors development are analysed. In the last part, different electronic biosensors based on electrolyte-gated organic transistors are presented. Particular attention is paid to the biosensors operation mechanism and to the analytical figure of merits. Specific applications such as DNA and proteins detection are also discussed.
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3 Conductive organic materials for DNA biosensors
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Conductive organic materials have attracted great interest due to their excellent electronic and biochemical properties, which make them suitable for promising applications in chemical and biological sensing. With many advantages like labelfree and easy fabrication, DNA biosensors based on conductive organic materials have shown significant benefit for the rapid and highly sensitive genetic detection. Organic DNA sensors can be mainly divided into two types, which are based on electrochemical detection and organic thin-film transistors, respectively. This chapter gives a comprehensive description to these two types of DNA sensors, while the principles of sensors, relative organic materials, detection methods, transduction mechanisms, and their pros and cons are well addressed in detail. Moreover, some new developments and future perspectives in this field are also discussed.
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4 Organic transistor-based mechanical sensors for artificial skin applications
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The human skin is endowed with a big amount of tactile receptors, which perceive mechanical and thermal stimuli and allow the arising of different feelings (smoothness/roughness, softness/hardness, hotness/coldness, pain, etc.), also detecting stimulus position, size and duration. The biggest challenges that come from the development of tactile systems concern not only the need of fabricating multimodal tactile transducers, but also the fact that these sensing capabilities must be distributed on large, complex areas and possibly at low fabrication costs, dealing with still open issues such as the reduction of the numbers of connecting cables, the realization of a dedicated network architecture, the reduction of power dissipation and last but not the least the reduction of fabrication costs. From this point of view, Organic Electronics represents a step forward as conjugated polymers join the mechanical characteristics of plastics, therefore highly flexible and easily transferrable on whatever kind of surface, with the possibility of being solution processable. This property is particularly important, because it allows processing and deposition of these materials on large areas with very easy and cost-efficient technologies suitable for mass production, such as inkjet printing. The focus of this chapter is in particular on the employment of electronic devices based on conjugated materials for the realization of strain/pressure sensors that may be used for the fabrication of artificial skin.
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5 Smart fabric sensor architectures and technologies
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This chapter presents a possible path towards fully wearable and fabric-based electronic platforms. It provides an overview of materials and methods in the field of smart fabrics and e-textiles with the perspective of achieving fabric-based standalone platforms. Electronic components, interconnects and sensors can be made out of fabric and polymeric materials. Smart fabric sensors can measure force, pressure, strain, temperature and chemicals, among other parameters. Fabric power elements compatible with textile platforms are found in textile capacitors, supercapacitors, solar cells and energy-harvesting components. All these elements can be integrated such that a complete sensing and electronics platform is primarily made of compliant materials. Flexible macroelectronics technologies have a direct impact on wearables and development of functionalized textiles.
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6 Organic gas sensors and electronic noses
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Smell is one of the five human senses. It is fundamental to people and to many living creatures and by extension it is of great importance for the quality control of online production processes in many mass-production industries. G. Dodd and K. Persaud published the first work regarding the artificial sensing of smells and odours and a few years later Gardner defined the technological solution to an electronic nose as: 'an instrument, which comprises an array of electronic chemical sensors with partial specificity and an appropriate patternrecognition system, capable of recognising simple or complex odours.' In agreement with the definition, a competent electronic nose should be capable of working continuously providing useful information of the samples under test and presenting no fatigue over the measurements. Two key elements should be the base of every electronic nose: a sensor array of cross-selective electrodes and a pattern recognition tool to statistically analyze the samples, which has to be able to point out the similarities and dissimilarities among all the measured samples. These statistical methods are known as chemometrics, which combined with sensors arrays has been recognized by many as a method to enhance the results of sensor systems. One of the most classic sensor arrays with which the first electronic noses were built, and that are still in use, is based on metal oxides. However they present some problems and soit has been necessary to investigate and develop new technologies. These will permit the characterisation of gases, vapours and aromas in a fast, economic and, if possible, online manner, in order to generalise the use of electronic noses in many distinct areas and applied technologies. Sensors using semiconducting polymers have been used since the 1970s due to their favourable features. Recently, there have been a number of further developments in the field of organic semiconductors, which suggests that devices based on these may become even more relevant in the near future. This chapter discusses about semiconducting polymers, organic polymers used in gas sensors, their recognition principles and about adsorbent organic conducting polymer composites. Three configurations are used for organic sensors: chemiresistors, transistors (and diodes) and optodes. Some applications in which these sensors are used are also described, such as humidity, ammonia, nitrogen oxide, hydrogen chloride and nitroaromatic explosives.
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7 Ion sensors based on organic transistors
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This chapter presents the ion sensors which convert the activity of an ion dissolved in a solution into an electrical potential. This type of sensors is well-known and they are widely used in analytical chemistry and biochemistry. The use of organic polymers as active part of the ion sensors has led to a new way of research in these sensors. The chapter is divided into two parts: pH sensors and general ion sensors. The two parts are further divided based on the type of organic semiconductor used in the device fabrication: P3MT, PANI, PEDOT, etc. As a result of the organic electronic applications into the field of organic sensors, a wide variety of devices have been developed, for instance, ISOFET, OFET, EGOFET. For this reason, some applications of these devices have been explained for each organic semiconductor.
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Back Matter
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