# Smart Textiles: A Review and Bibliometric Mapping
## 3 Results and Discussion
### Clusters of KW as indicators of research areas
Examples of recent research include development of flexible textiles with improved strain sensing properties composed of conductive nanomaterials of Ti\({}_{3}\)C\({}_{2}\)Tx MXene/carbon nanotubes, immersion-deposited onto thermoplastic polyurethane nonwoven fabrics [158]; multilayer pressure/strain sensors with improved pressure sensitivity and surface roughness, composed of a knitted cotton/spandex textile with a polypyrrole surface on which rose-like silver flowers were produced by electrodeposition [159]; continuous, twisted graphene fibres with high tensile strength, improved breaking strain, and stable electrical and mechanical properties woven into breathable, wettable, and washable strain sensors used to assemble anti-jamming wearable electronics for sensing human motion in the air or underwater [160]; and an integrated and scalable fabrication process for composite, stretchable, and conductive core/shell fibres for weaving TENGs, applied for strain sensors self-powered smart textiles with strain sensors [135]. **Sustainability**. The issue of sustainability in the context of smart textiles is addressed from two perspectives. First, it addresses the issue of sustainability in the production, recycling, and waste treatment of smart textile products. The sustainability of smart textiles depends on the choice of materials used, the manufacturing processes, and the end-of-life options for the textiles [23]. Researchers are exploring new sustainable and environmentally friendly materials, green manufacturing methods, end-of-the-life processes, and standardized sustainability assessment methods, such as life cycle analysis, recyclability, and biodegradability [23; 161; 162]. Second, numerous positive contributions of smart textiles to sustainability are highlighted in the following areas [163]: environmental monitoring (temperature and humidity sensors, gas sensors) [164; 165; 166]; fresh water purification and harvesting (filtering, mist collection, collection by coalescence or mechanical squeezing) [167; 168; 169]; personal protection (warming, cooling, electromagnetic protection, EMI shielding, protection against UV radiation, toxic substances and microorganisms) [35; 37; 170; 171; 172; 173]; power supply on the body with energy harvesting and storage (triboelectric nanogenators [174; 175; 176; 177; 178; 179; 180], including thermoelectric generators [181; 182], photovoltaic textiles [183; 184; 185], bio-physicochemical energy harvesting [186], textiles with perovskite solar cells and other perovskite materials [187; 188], dry batteries and flexible electrodes [189; 190; 191; 192], and wearable all-in-one power sources that integrate energy harvesting and storage capability into one textile [193; 194; 195; 196]. **Artificial muscles**. Artificial muscles refer to fibrous materials and devices that can contract, expand, or rotate reversibly in response to external stimuli such as magnetic fields, electricity, irradiation, heat, and atmosphere [197; 198]. Materials that convert electrical, chemical, or thermal energy into a shape-change, such as fibres composed of CNT, graphene, organic polymers, shape memory alloys, or their composites, can be used to form artificial muscles [199; 200]. More recent inventions are based on sheath-run artificial muscles, in which the material that drives actuation is a sheath on a twisted or coiled core, which may be a low-cost yarn [201; 202]. Other examples include woven hydraulic artificial muscles [203], aerogel fibres [204], printed hydrogel artificial muscles [205], and artificial muscles made from hierarchically patterned helically wound yarns that are self-adaptive to ambient humidity and temperature changes and exhibit plant-like tropisms [206]. Artificial muscles can be creatively used in wearable electronics, soft robotics, and medical applications. **Joule heating. ** The concept of Joule heating, a physical effect in which the passage of current through an electrical conductor generates thermal energy, is used in smart textiles for active warming.