# Smart Textiles: A Review and Bibliometric Mapping
## 3 Results and Discussion
### Clusters of KW as indicators of research areas
Therefore, triboelectric nanogenerators can have different structures, such as (a) a thread with a tubular structure, e.g., elastomeric material and a spiral inner electrode adhered to a tube with the dielectric layer and the outer electrode; (b) a modified fabric containing surfaces with microstructures of different materials; (c) a fibre with a core-shell structure with a conductive core and an insulated shell, e.g., a silicone rubber coated stainless-steel thread sewn onto an elastic textile with a serpentine shape; (d) a triboelectric nanogenerator based on a three-dimensional textile [41]. Textile triboelectric nanogenerators' basic modes of operation include single-electrode mode, lateral-sliding mode, vertical contact-separation mode, and free-standing triboelectric layer mode, each of which has its application possibilities and ranges [15]. Potential approaches to improve mechanical-to-electrical conversion and increase the power output of textile triboelectric nanogenerators include surface/interface physical treatments, chemical modifications at the atomic level, structural optimization, control of the working environment, and integrated energy management [42]. **Gait analysis**. Gait analysis is the systematic study of locomotion, analysing parameters such as body movements, body mechanics, and muscle activity. Soft wearable electronic technologies used for gait analysis consist of flexible sensors, microcontrollers, and power supply units. Flexible, stretchable, lightweight, mechanically and temperature stable, and body-compatible materials are used, such as textile polymers, conductive organic polymers, inorganic MXenes, nanomaterials, metals, ionic liquids, and hydrogels [221]. Smart textiles for gait analysis include smart socks, smart shoes and shoe insoles, smart trousers, exosuits, knee pads, skin-mounted textile sensors, and whole-body networks [120; 144; 221; 222; 223; 224; 225; 226; 227; 228]. Gait analysis is essential in medicine (medical diagnostics, rehabilitation or prevention in orthopaedics, physiotherapy, neurology, psychiatry, gerontology), sports (performance improvement, rehabilitation after injuries), biometrics (identification, authentication, surveillance of persons, criminal investigation), and virtual reality and game controllers [144; 222; 225; 226; 229]. **Self-cleaning**. The term self-cleaning in smart textiles refers to coatings that work with two mechanisms [185]. The first mechanism is based on the lotus effect, which is achieved by alkyl- and fluoroalkyl-substituted silanes and fluorine in the form of fluorocarbon polymers. This type of self-cleaning surface is based on the superhydrophobic properties of coated surfaces, which can be achieved by introducing micro nanostructures on a surface, together with the use of low surface energy materials. The lotus leaf has a low surface free energy due to its specific surface structure and composition, which translates into low adhesion between the surface and water droplets. On such a surface, the water forms spherical droplets with a contact angle of more than 150\({}^{\circ}\). In this case, the water droplet rolls down the surface, picks up dirt from the surface, and cleans it. Hydrophobic surfaces with self-cleaning properties can be achieved using fluorinated polymers, such as poly(pentafluorostyrene) and poly(pentafluorophenyl acrylate) [230]. Fluorocarbon resin-coated phase change conductive fibres show excellent hydrophobic and self-cleaning properties [231]. It should be emphasised that fluorinated compounds are being used less and less in coating systems due to possible risks to human health and the environment. Therefore, fluorine-free silicone elastomer coatings have been synthesised, such as polymethyl siloxane (PMS), PDMS, hexadecyltrimethox-ysilane (HDTMS), noctyltriethoxysilane (OTES), octadecyltrimethoxysilane (ODTMS), trichloro(octadecyl)silane (OTS), aminosilone emulsions, and polyvinylsselesquioxane (PVSQ) [232; 233; 234].