# Flexible Coated Conductive Textiles as Ohmic Heaters in Car Seats
## 4 Metal-Coating Techniques
### Dip-C Coating Techniques  
Dip-coating (or pad-coating) is relatively simple, low-cost, and scalable; thus, it is a widely used fabrication technique used to apply conductive (nano) materials onto fibres, yarns, or fabrics, as it does not require any special or expensive equipment [66]. The entire process can be continuous, as presented in Figure 7a, or discontinuous (Figure 7b). It involves the immersion of the fibrous substrate for a short period into the respective aqueous-based coating solution, which, in the case of conductive textiles' processing, contains different types of conductive compounds, i.e., electro conductive polymers, carbon-based structures, inorganic metallic (nano)structures, or their combinations [67]. Thereby, the conductive compound is deposited on both sides, over the whole surface [68].  
After depositing the conductive solution onto the fibrous material, the drying phase is carried out at temperatures of 110 \({}^{\circ}\)C up to 180 \({}^{\circ}\)C for a short time period (3 to 15 min), using hot air or infra-red (IR) heating. This process is also known as a curing, during which the excess solvent evaporates and the conductive (nano)compounds fix/crosslink permanently to the textile's surface, ensuring a stable coating [69]. In fact, the dip/dry cycles can be repeated several times, with the aim of increasing the amount of deposited conductive material (the so-called multi-layered dip-coating method). Moreover, the drying temperature versus time should be considered to prevent damage of the basic textile material [70]. The main disadvantage of the dip-coating procedure is the variance in the smoothness/roughness of the textile's surface and the uniformity of the applied conductive layer(s), affecting the variation in electrical resistance [71]. The thickness of  
Figure 6: (**a**) Basic mechanism of the magnetron sputtering process; (**b**) relative change of resistance of Ag coated Cordura subjected to cyclic bending, and corresponding microscopic and SEM images after 10,000 bending cycles (**c**) magnetron sputtered Cu transmission lines on polypropylene nonwoven and responsible SEM images: longitudinal view and cross-section (**d**) monitoring the finger motions by Ag/G-coated cotton: rotation and bending (**e**) sheet resistance of Ag/polypyrrole-coated cotton as a function of sputtering time and corresponding SEM at 10 min. Reproduced with permission from [[PERSON]], [Metallisation of Textiles and Protection of Conductive Layers: An Overview of Application Techniques], published by [MDPI], [2021] [25].  
the layers cannot be fully controlled, since it depends on the surface morphology and the tension of the textile substrate, as well as on processing parameters such as time, temperature, withdrawal speed, compound concentration, composition of the coating bath, etc. [72]. As mentioned above, numerous electro conductive compounds can be applied to fibres/yarms/fabrics by employing the dip-coating technique. In the following sub-sections, the most used materials are presented, as well as different applications [73].