Smart Textiles(ST) is defined as fabric/material which has the capability to sense eitherenvironmental, mechanical, thermal, magnetic, chemical or electrical conditions and simulate its behavior in predefined manner accordingly. ST products are often designed to perform a specified function/s in a smart and easiest way. ST have gained importance in the field of health care, sports activities,military and defense. The basic function of fabric to protect human being from extreme environmental condition has now been moving towards smart and interactive fabric. ST is basically comprised of three important components i.e. sensors, actuators and controlling units. These components are integrated in a special fabric to perform predefined tasks, making them smart and eventually maintaining the purpose of fabric.
A. Classification of ST
i. Passive ST
The first generation of ST were able to perform passive tasks, since it did not have sensors, actuators or controlling units. The fabrics were designed keeping the single functionality in the mind. Insulating coat, rain coat and bullet-proof jacketare the examples of passive ST.
ii. Active ST
The second generation of ST has both actuators and sensors but no controlling units. These fabrics were able to modify their functionalities according to external environment conditions. These included
iii. Ultra ST
The third generation of ST can sense, react and adapt themselves to environmental conditions and simulate their behavior accordingly. They consist of a controlling unit, which works like the brain, having recognition, reasoning and activating capacities. Finally, ultra ST present a reality where the integration of traditional fabric with new age fabric, designed using material science, structural mechanics, sensor and actuator technology, advance processing technology, communication, artificial intelligence, biology etc. has taken place.
B. Materials used in ST
In ultra ST, an intellectual fabric used is used which can sense, interact as well as communicate with the surroundings. Polymeric or carbon coated threads conductive yarn, conductive rubber, and conductive ink have been developed into sensors or used as an interconnection substrate. Conductive yarns and fibers are made by mixing pure metallic or natural fibers with conductive materials. Pure metallic yarns can be made of composite stainless steel or fine continuous conductive metal-alloy combination of fibers with conductive materials. Metallic silk, organza, stainless steel filament, metal clad aramid fiber, conductive polymer fiber, conductive polymer coating and special carbon fiber have been used to make fabric sensors. Materials such as optical fibers and conductive polymers are integrated into the textile structure, thus providing electrical conductivity and sensing capability. Organic polymers may provide a solution to overcome the stiffness of inorganic crystals such as silicon.
i. Metal fibers
Metal threads are made up of verythin metals. The fibers are made using either through a bundle-drawing process or shaving off the edges of thin metal sheets. These metallic threads and yarns are then knitted or woven into a textile to interconnect various components. These metal fibers are also used as electrodes to monitor physiological activities.
ii. Conductive inks
A layout can be screen-printed using conductive inks to provide conductivity to specific areas in the garment. Carbon, copper, silver, nickel and gold particlesare added to conventional printing inks to make them conductive. Printed areas can be subsequently used as switches or pressure pads for the activation of circuits.
iii. Electrically conductive textiles
Electrically conductive textiles have already been used by industries for the purpose of controlling static current, to provide shielding from electromagnetic interference etc. Nowadays, electrically conductive textiles are used as an electrodesor to provide interconnection between various components.
C. Applications of ST
1. Smart Vest
The development of wearable monitoring systems have already produced a positive impact on healthcare industries. Wearable devices allow continuous monitoring ofvarious physiological parameters during normal daily activities and hence, can overcome the problem of frequent clinical visits for the monitoring of basic physiological parameters. This is done using ST and making a “Smart Vest”, shown in Figure 1, with embedded textile sensors for simultaneous acquisition and continuous monitoring of Electro Cardio Gram (ECG), respiration, and physical activity. The smart vest has embedded astrain fabric sensor based on piezo resistive yarn and fabric electrodes, which arerealized using metal based yarn, portable electronic board for motion assessment, signal pre-processing unit, and bluetooth connection for data transmission.
2. Smart Belt
Smart belt, shown in figure 2, is a trans-abdominal wearable device for long-term health monitoring that facilitates the prenatal monitoring procedure for both the mother and the fetus. This belt is beneficial for pregnant women living in remote areas and face certain health problems such as high blood pressure, kidney or heart disease, multiple pregnancies etc. This smart wearable device is connected to obstetrician using wireless connection, who can monitor patients remotely and evaluate on the basis of preliminary data gathered.
3. Smart Military and defense Apparel
Around the world military forces are exploring how smart clothing can be used to increase the safety and internet connectivity effectively. In extreme environmental conditions and hazardous situations, there is a need for real time monitoring, protection and survivability of the people. Improvements in performance and additional capabilities are looking forward in situations where monitoring of vital organs and degree of injuries, monitoring of in hazardous environment, is critically required and necessary action can be taken with in time through wireless communication.
Prospect of Smart Textiles
Rising demand for smart and interactive textiles from the transportation, media, military/defence, and healthcare industries are likely to be major sectors. Furthermore, growth in medical and healthcare industries is anticipated to lead to higher demand for smart textilesduring the forecast period. However, market growth is likely to be sluggish due to high prices of finished products of smart textiles as compared to conventional textiles. Rising number of research and development activities for product and technological innovation is expected to provide new opportunities for market growth.
Smart fabrics have absolutely huge potential to influence not only fashion, but fitness, health and well-being sectors. Technology now enables sensors and active materials to be woven and embedded in fabric, creating innovative opportunities to track data, monitor health and to use technology seamlessly. Smart fabrics are also being developed to actively reduce injury and improve athletic performance, making the future extremely exciting for manufacturers, designers and consumers alike.