# Smart Textiles: A Review and Bibliometric Mapping
## 3 Results and Discussion
### Clusters of KW as indicators of research areas
In addition, their output voltage and current are additional readout signals, so they can simultaneously serve as self-powered sensors for content creation and energy supply [21]. Examples of smart textiles as self-powered sensing platforms include a textile thermoelectric generator for monitoring body temperature [142], a smart bedsheet for monitoring human sleep [143], smart textile socks as a human-computer interface in a virtual reality space [144], a smart textile glove for human sign language recognition [145], a textile magnetoelastic generator for monitoring cardiovascular parameters [146], piezoelectric smart textiles for sensing heartbeats and speech [147], a textile biofuel cell that can generate electricity from sweat enzymes to monitor the concentration of ions in sweat [148]. **Silver nanoparticles**. In functional textiles and in older generations of smart textiles, silver nanoparticles have been traditionally used for antibacterial, antifungal, antistatic, free-radical scavenging, catalytic, electronic, water treatment, sun protection, and air treatment purposes [149; 10]. Solution immersion, layer-by-layer deposition, and sonochemical processes are established methods to deposit silver nanoparticles on various textile materials [149]. In the third generation of smart textiles, silver nanoparticles offer new functions, such as the production of smart stimuli-responsive textiles with simultaneous moisture management and controlled antimicrobial activity by embedding silver nanoparticles into temperature- and pH-responsive microgels applied to cotton fabrics [150], conductive inks for e-textiles and screen printing of silver inks for the production of washable, electrically conductive materials for printed circuit boards and RFID tags [22], production of conductive fabrics by dipping and dry coating with silver nanoparticles for applications in EMI shielding, lightweight batteries, and molecular electronic devices [151], use of PVDF nanofibres coated with nonpolar silver nanoparticles as electrodes for piezoelectric sensors [152], and fabrication of textile-based triboelectric nanogenerators consisting of an active layer of graphite carbon nitride nanosheets loaded with silver nanoparticles on carbon fibres for use as wearable power sources [153]. **Strain sensing**. Mechanisms for detecting mechanical deformation in strain sensing are based on resistive, capacitive, piezoelectric, electrical time-domain reflectometry, and triboelectric effects [154]. Signal transmission in new flexible strain sensors is structurally dependent on the conductive material deposited on the substrate material. Flexible base substrates are synthetic or natural textile polymers, while the conductive materials can be metallic (silver nanoparticles), carbon (CNTs, graphene, carbon black nanoparticles), or conductive polymeric materials (PANI, polypyrrole (PPy), polythiophene (PTH), such as PEDOT or PEDOT:PSS, MXenes, ionic gels, or hydrogel fibres) [20; 154; 155; 156; 157]. Desirable properties of strain sensors include flexibility, stretchability, minimal hysteresis, high sensitivity, wide sensing range, fast response, reliability, light weight, long-term stability and durability, comfort, and industrial mass production capability [20; 154]. Moreover, they can be self-powered [155] or self-healing [156]. Strain sensing technologies are used in wearable sensors for personal healthcare (ECG, respiration, pulse, blood pressure, gait measurement, motion monitoring), physiological monitoring, sign-to-speech translation, and human-machine interaction [20; 154; 155].