# Conductive Textiles for Signal Sensing and Technical Applications
## 2 Materials Used to Impart Conductivity on Textiles
### Conductive Polymers
#### 2.1.3 Poly(3,4-ethylenedioxythiophene) (PEDOT)  
PEDOT demonstrates an intrinsic electroconductive polymer that incorporates two linked groups of benzene rings where two carbon atoms of each are substituted by oxygen atoms and a sulfur-based pentagonal thiophene ring. PEDOT can be easily synthesized from a 3,4-ethylenedioxythiophene (EDOT) monomer through oxidative [31] and electrochemical [32] vapor phase polymerization (VPP) techniques [33], but it cannot be executed commercially due to its lower dispersion in water. As a result, a template polymer poly (styrene sulfonate) (PSS) is utilized during the synthesis of PEDOT, which yields a water-dispersible and transparent film-like polymer that can be conveniently processable [34].  
Uniform dispersion in water, convenient methods to adapt electrical properties, high flexibility, excellent transparency (up to 95%), stability against humid air and high temperature are some of the features that allow PEDOT:PSS to add a new dimension over the other intrinsic polymers in terms of diversified practical applications of conductive textiles, such as solar cells [35], electricity storage devices [36], electrochromic devices [37], electrochemical transistors [38], OLED [39], patch antenna [40], supercapacitors [41], actuators [42], and strain sensors [43]. Several variants of PEDOT:PSS dispersions are available according to their molecular weight under the trade name of Clevios and Orgacon given by Heraeus Epurio and Agfa Gevaert, respectively; however, the corrosiveness and unfavorable impacts of PSS cause impediments to the expedition of conductive textiles approach towards the green industry. Studies on the eco-friendly application of conductive PEDOT films on textiles have been reported. [PERSON] et al. experimented with a customized vacuum chamber for the eco-friendly deposition of PEDOT films on the substrates, thereby resulting in conductive substrates that exhibit a noteworthy conductivity of 105 \(\mathrm{Scm}^{-1}\), including an 84% transmittance of visible light [44]. [PERSON] et al. applied the VPP technique to synthesize eco-friendly PEDOT: Tosylate films coated with conductive electrodes [45]. Later, Vacuum vapor phase polymerization (VVPP) was acquainted with feasible scale-up production of PEDOT-coated conductive textiles with significant conductivity (1485 \(\mathrm{Scm}^{-1}\)) [46].  
Figure 2: Chemical structure of different forms of PANI, adapted from [28] following Creative Common Licence.  
Though being one of the most promising conductive polymers, the employment of PEDOT in conductive textiles is limited to research projects and narrow fields of practical application due to its relatively lower conductivity for the proper optimization of PEDOT in wearable electronics; unstable conductivity for any change of temperature, humidity, bending and washing cycles [47]; and maintaining the precise process control parameters during the in situ polymerization of EDOT monomer [7].  
Notable works are ongoing to deal with these challenges of PEDOT [48; 49]. Until now, the commercial aspects of PEDOT have been fully established in the applications of capacitors, printed wiring boards, packaging films, photographic films, electronic films, and electroluminescent lamps [7].