Textile-based sensors, a new category of wearable technology, offer potential for leading-edge adaptability and functionality for healthcare monitoring and other applications. The term "smart textiles" refers to sensors that are structurally or mechanically incorporated into a textile.
The genre of wearable electronic devices, known as electronic textiles (e-textiles), is designed to address novel and sophisticated applications in the healthcare, military, security, sports and fitness industries. Wearable e-textiles are able to incorporate optical, capacitive and resistive sensors, enabling the textile to sense a variety of stimulants (e.g., humidity, strain, temperature and pressure). Furthermore, they can also serve as carriers for originally produced sensors (by forming straps or pockets) or by assisting a sensor that is an inherent feature of the textile. The material itself is regarded as a component of the sensor as it is embedded into the textile.
Yarns, fibers and fabrics must be created in such a way that they meet the criteria for a certain application; for instance, a hydrophobic surface with a suitable morphology is necessary for printing on the outer surface. However, pre-treatment of substrates is key to successful sensor production. The surface architecture of the base substrate dictates the grade of their interfacial properties and deposited films. The following sub-sections further highlight how the above-mentioned textile components are being used for wearable electronics.
Fibers provide unmatched benefits in terms of durability and low weight, making them ideal for a variety of practical applications. For example, functional fibers are an important component for manufacturing conductive textile sensors because of their unique properties such as flame retardancy, high elasticity, thermal insulation, ion exchange, antibacterial and antistatic properties, light guide and radiation protection.
Yarns are a long-lasting product with a relatively narrow cross-section made up of filaments and fibers with or without a twist. Combining non-stretchable metallic fibers with polymeric yarns results in a metal-based yarn with excellent elongation and recovery capabilities that may be woven, knitted or embroidered into textiles for different purposes such as tracking human body temperature. Some researchers created extremely scalable engineering graphene flakes for next-generation wearable electronics applications using an ultrafast yarn dyeing method.
Cotton fabrics' air permeability and breathability, as well as their softness and comfort, have made them a favored option for use adjacent to the skin. Sensor applications based on polyethylene terephthalate (PET) fiber have deposits of metallic layers on a flexible PET substrate have steadily gained in popularity due to their electromagnetic shielding efficacy, high electrical conductivity, and healthcare applications. PET is a polyester derivative with chemical resistance, quick-drying capabilities, antiwrinkle qualities and dimensional stability. Therefore, polyester-based fabric sensors are critical in a variety of sectors. Both knitted and woven cotton fabric sensors are advantageous for UV-shielding material applications for producing disposable and sustainable e-textiles. This is for tracking user body activities such as pulse control, breathing, heart function and body temperature with increased user luxury level; and for measuring the pH of sweat for illness detection.
Sensing devices for 'communicative' wearable clothing apparel are utilized to monitor the physical condition of athletes and record the health statistics and investigation of patients in real-time. Moreover, they are also required for personal protective equipment such as gloves and helmets that guard against a variety of mechanical or chemical hazards. Electronic mechanisms have been incorporated into textile structures to provide traditional clothing with smart features such as monitoring, information processing and sensing.
Wearable sensors, whether worn by people or animals (such as cattle or poultry), are critical for tracking physical indicators because they act as the interface between the sensor and the body. For example, they can be used for analyzing sheep’s fundamental physiological features like skin temperature and heart rate. Wearable sensors must be put on the human body to track complicated human gestures in an appropriate fashion for the user and a broader range of areas. Electronic textiles have also been created in a variety of configurations for a variety of uses, including energy storage and strain recognition of angular displacements.
The proliferation and deployment of wearable textile-based sensors, particularly e-textiles, necessitates a paradigm shift in thinking. Flexible smart textiles are in increasing demand to suit the unique features associated with new prospects in a variety of fields such as sports and healthcare. Last but not the least, the impacts of wear and care on the performance of textile-based sensors must be recognized, and methods should be developed for prolonging their life and effectiveness.