# Conductive Textiles for Signal Sensing and Technical Applications
## 2 Materials Used to Impart Conductivity on Textiles
### Coating
#### 3.3.1 Dip Coating  
Dip coating is a simple and cost-effective process commonly used in various industrial fields for depositing coating material onto any substrate, along with metallic and ceramic polymer film and textile materials. The process could be interpreted as depositing aqueous liquid phase coating solutions on the surface of any substrate [224; 225; 226]. Conductive materials are typically dissolved in solutions that are immediately deposited on the surface of the substrate, after which, to obtain the dry film, the sedimentary conductive wet coating has to be evaporated. The technique associates submerging the textile material in the solution of the conductive coating materials, ensuring that the textile material is completely penetrated and then withdrawn from the solution materials. Notably, this supposedly easy process of constructing film through dip coating comprises complex chemical and physical multi-variable norms. The thickness and morphology of depositing thin conductive films were determined by various criteria such as dipping time, withdrawal speed, dipping cycles, substrate (textile material) surface, density, viscosity, surface tension, and evaporation of the conductive coating solution [227; 228; 229]. Various modified dip coating techniques, such as solution dip coating, sol-gel dip coating, multi-layer dip coating, and vacuum-assisted dip coating, are significant to manufacture deposited films on the surface of textile materials. Solution dip coating is the most straightforward technique of forming a film on textile materials' surfaces and is typically used in increasing production. Since it is the most commonly used method in textile manufacturing, dip coating is often referred to as starch finishing or sizing. Solution dip is a user-friendly process to operate and can increase the efficiency of production. However, on the opposite, the solution of dipping the uniformity of the coating is weak and the bonding state is relatively poor [229]. Cotton fabric containing high electrical conductivity has been confirmed to have been established by a two-step dipping and coating. The cotton fabric was immersed in an acetone solution and rinsed properly with deionized water after drying in an oven. Then, GO was coated onto the fabric surface by dipping the modified cotton fabric into GO dispersed solution for two cycles. After that, a padding process was conducted to remove the excess material using a pair of rollers and high vacuum pressure [230]. The dipping process is shown in Figure 3.  
Figure 3: The preparation process of silver/graphene-coated cotton fabric, adapted from [230]. Sol-gel technology is a relatively novel method for endowing unique properties upon textiles and is affiliated with decreased ecological impacts [231]. Various functional characteristics such as antibacterial function [232], UV radiation protection [233], dye fastness [234], anti-wrinkle finishing [235], super-hydrophobicity [236], and biomolecule immobilization have been introduced by this method. MWCNTs for conductive purposes and methyltrimethoxy silane for hydrophobicity purposes were coated by the sol-gel process on cotton fabric [237]. The process involves Sol preparation, which is a mixture of methanol, distilled water, and MWCNTs of definite concentration and quantity. Following this, the Sol was mixed well by a magnetic mixer. Then, the cotton fabric was added to the Sol. After checking several parameters, the ultimate result was 40 k\(\Omega\) cm\({}^{-2}\)[237]. To improve the uniformity characteristics or thickness of the single dip coating film, the researchers investigated the multi-layer dip coating.