Textile electronic circuits

Textile electronic circuits based on organic fibrous transistors... 

The transistor as a component of the e-textile plays a crucial role in the textile electronic circuit. The existing fibrous transistors can be divided into two categories wire thin film transistors (WTFTs Lee and Subramanian, 2003 Maccioni et al., 2006 Locci et al., 2007) and wire electrochemical transistors (WECTs Hamedi et al., 2007 De Rossi, 2007 Tao et al., 2011). WTFT, also called WFET, is based on the field-effect transistor (FET) technology and WECT is based on electrochemical technology. With the help of these transistors, the textile electronic circuit can be achieved without loss of mechanical properties such as flexibility or softness. 

This chapter reviews the current status of the fibrous transistor development and textile electronic circuit. It covers semiconducting materials, fibrous transistors, and textile electronic circuits. Section 25.2 will discuss the materials employed in semiconductor manufacturing, especially in fibrous transistors. Section 25.3 will present traditional and fibrous transistors. Textile electronic circuits are discussed in Section 25.4. The different methodologies of use will be compared. And finally, the conclusion and perspectives will be discussed. 

As humans we prefer to wear comfortable textiles rather than hard, rigid boxes, and in order to add advanced functions first efforts have been made to use the textiles themselves as a substrate for electronic functions (Post et al., 2000). Hence, the electronic circuit plays an important role in the development of textile electronic functionalization. The electronic components and their interconnections are preferred to be intrinsic or less visible to the fabric. As a result, the textile electronic circuit can be considered as the platform for the application of textile sensors and actuators. 

From the application standpoint, textile electronic circuits can be used for stretch sensor, pressure sensor, electrochemical sensor, electrocardiogram sensor, electromyography sensor, electroencephalography sensor, temperature sensor, energy harvesting, wearable antenna, etc. 

Structurally, textile electronic circuits can be classified into two categories conventional electronic component implemented on fabric-based flexible planar circuit board (PCB) and intrinsic functional fiber/yarn-based circuit. 

Tao, X., Koncar, V., Dufour, C., 2012. Realization of fibrous electrochemical transistors and textile electronic circuits. I actualite chimique 360—361, 65—68. 

Basic yarn components along with conventional filaments/yarns constitute the feedstock of the weaving process. Selectively fed into a loom and manipulated through an advanced textile manufacturing process, this feedstock can be woven into a complex variety of designs that result in a structurally sound, environmentally compatible fabric that provides electrical and mechanical functionality. Electronic circuits can be formed from the selective interconnection of fibre components during the weaving process. 

Textile circuitry It refers to an electronic circuit on the textile platform. 

Textile electronics is another exciting area of apphcation. Fibrous diodes and transistors have already been developed in different laboratories. Flexible sensors and actuators (textile displays, heating fabrics) will in the future be part of our clothes, car interiors and home textiles. Therefore, flexible textile-based electronic circuits will be fully integrated to fabrics and connected to databases and servers making possible new ways to utilize clothing and other textiles. 

Transistors as the basic and crucial component for electronic circuits have been vigorously studied since 1947. The essential function of a transistor comes from its ability to control a larger signal by an apphed small signal between one pair of its terminals. This property makes the transistor as an amplifier or switch. According to the mechanism of the generation of carriers in the channel, transistors can be divided into three categories bipolar junction transistor, field-effect transistor, and electrochemical transistor. In electronic textile applications, the EET and ECT are employed to realize fibrous transistors. 

When Lee and Subramanian invented the first fibrous transistor (Lee and Subramanian, 2003), they did not use it to develop a textile circuit. The reason may be in the rigidity, stability, and reproductivity of the fibrous transistor. The wire was in aluminum. It was difficult to insert it into woven fabric as a normal textile filament. Moreover, its evaporated semiconductor and source-drain electrodes were delicate. They would be easily destroyed during the assembly process. Besides, the source-drain electrodes were only in one side of the wire. The alignment with other conductive yams was a problem in the source-drain position. Even if this kind of fibrous transistor was ameliorated by using stainless wire as gate and depositing the source-drain around the whole wire (Lee and Subramanian, 2005 Maccioni et al., 2006), there still was no laboratory prototype of a fibrous transistor-based electronic circuit published. Because the deposition should be carried out in vacuum, it became impossible to exploit series manufacturing for... 

The incorporation of flame retardants into plastics, textiles, electronic equipment (e.g. printed circuit boards) and other materials is big business, and demand in the US reached approximately US 1.3 billion in 2008. The chart on the right shows the split between the three main categories of flame retardants in the US in 2003. A range of brominated organics is used commercially, the most important being ... 

HBCD has been used as an additive flame retardant for more than 20 years. Its main use is in the construction industry, where it is used in polystyrene foams, which are a part of the thermal isolations, and even small concentrations provide sufficient protection against burning. The second major application of HBCD is in the upholstery and textile industries. Products in which the HBCD occurs, for example, include upholstered furniture, various textiles, car seats and upholstery, insulation in trucks and caravans as well as many types of building materials. Unlike other flame retardants, HBCD is not used in electronic circuits. 

With ever increasing intensity of researeh in material seience coupled with computational capabilities, with tremendous inerease of eommodity produets involving electronic circuits and signals and with more awareness of environmental, health, seeurity and safety hazards due to electromagnetic emissions, researeh on EMI, EMC and EMI shielding is intensifying like never before. Fibrous materials as a substrate or component of effective shield have interesting potential due to the unique features of textile stmeture. 

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