What is E Textiles? Classification of Smart Textiles

Smart Electronic textile is an advanced research area of textile; which is attracting huge attention in the last few years. In this new era of IoT (Internet of Things), the integration of sensors into smart textile opens the ultimate opportunity under the name of smart electronic textiles. Today, Smart Electronic Textiles is shortly known as E textiles. In this context, we will discuss about classification of smart textiles.

Smart electronic textiles or E-textiles are capable of sensing, communicating, power transmission, and interconnection technology to other information processing devices to a network within a woven fabric.

Smart electronic textiles usually contain conductive yarns which are spun or twisted to enable electrical conductivity. Consequently, Smart electronic textiles allow computation to occur on the human body.

Difference Between E-Textile and Smart Electronic Textile:

In short smart electronic textiles is popular as E-textile. Smart electronic textile is almost similar to smart textile. But all smart textile is not electronic textile, but at the same time, all Electronic Textile is Smart Textile. The textile has a smart textile property in its electronic textile is known as smart electronic textile.

Classification of Smart Textiles:

Today Electricity dominates our daily life in many directions. Obviously, it is a clear advancement that has been made in past few years. Here, we will discuss four kinds of smart electronic textiles based on different functionalities, electricity generation, electricity storage, electricity utilization, and their inter-integration. The detailed classification of electronic textiles are as follow:

1. Electricity-Generating Textiles

The conventional power system is not effectively meet the demand for portability in wearable electronics. To solve this problem organic solar cells, thermoelectric and piezoelectric devices came into textiles.  Therefore, textiles can convert the other three energy sources into electric energy. These are:

a. Conversion from Light Energy:

1. Fiber-Shaped Solar Cells,
2. Textile-Shaped Solar Cells

b. Conversion-from Thermal Energy:

1. Thermoelectricity,
2. Pyroelectricity

c. Conversion from Mechanical Energy:

1. Fiber-Shaped Piezoelectric Generators,
2. Textile-Shaped Piezoelectric Generators

Light, thermal, and mechanical energy is the most accessible forms of energy from our environment. Among sources of energy harvesting, Sunlight, ambient temperature fluctuation, and human motion are able to convert into electric energy by the photovoltaic, thermoelectric, and piezoelectric effects, respectively.

2. Textiles for Electricity Storage

Electricity Storage is an important issue after generating electricity for effective use. Today Lithium-ion batteries and supercapacitors are the main using formats for storing electricity.

a. Lithium-Ion Batteries:

Mainly two types of batteries have been used in today’s smart textiles:

1. Fiber-Shaped Lithium-Ion Batteries
2. Textile-Shaped Lithium-Ion Batteries

Generally, a lithium-ion battery consists of a positive and negative electrode, as well as an electrolyte. In lithium cells, lithium ions have moved from the negative to the positive electrode during discharge. Go to the reverse direction during charging.

b. Supercapacitors:

There are two types of Supercapacitors according to their structure:

1. Fiber Shaped Supercapacitors
2. Textile Shaped Supercapacitors

According to the energy-storage mechanism, it may categorize as electrostatic double-layer capacitors and pseudocapacitors. An electrostatic double-layer capacitor made from carbon electrodes and realizes charge separation at the interface between the electrolyte and electrode.

Supercapacitors are similar to lithium-ion batteries. It has a structure with the electrolyte sandwiched between two electrodes. A pseudo capacitor uses redox reactions to store energy. It is fabricated from metal oxide or conducting polymer electrodes and. Both of capacitor has been made into fibers and fabric.

3. Electriconic Textiles

A lot of electronic textile devices such as displays, light-emitting electrochemical cells, as well as mechanical actuators have been put into textiles. Some of them, electrically driven systems show high performance. That is impossible without its planar counterparts. There are three representative functions that are discussed to highlight fiber and textile shapes.

a. Electrochromism

Electrochromic materials demonstrate several and reversible colors in reply to the applied current or electricity. It is devoted to the next generation of wearable displays. Though it has the ability to work on at low power consumptions.

In electrochromic devices, Active material is sandwiched between two planar electrodes and immersed in liquid electrolytes. These electrodes are composed of transparent rigid glasses coated with conductive indium tin oxide layers.

Conducting polymers are explored as active materials for flexible electrochromic devices. Cause it has a wide color spectrum, good coloration efficiency, low operation voltage, rapid switching ability, and so on qualities.

Electrochromic textiles are mainly depending on the electrical field, electrothermal effect, and electrochemically as well as redox reactions. It produces by weaving electrochromic fibers into textiles. Therefore, the material displays several colors.

i. Electrochromic Fibers:

Electrochromic fibers synthesized from aligned CNTs as well as conjugated polymers. It displays reversible color changes when electric currents are applied.

ii. Electrochromic Textiles:

After being woven from electrochromic fibers, electrochromic textiles can make from real fabrics that are lightweight and comfortable. Spandex is a commercially available and commonly used fabric in our clothing.

b. Electroluminescence

Electrochromic textiles can only demonstrate effectively in place with light. Therefore, Electroluminescent devices provide brightness by transforming electric energy into light.

Generally, an electroluminescent device fabricates by sandwiching a phosphor layer between two electrodes. Light emits as the molecule in the excited singlet state and returns to the ground state when it’s excited by the electric weave. The emitted color depends on the phosphors and the dopant materials.

To increase deformability, breathability, and comfortability of electroluminescent textiles it needs to develop at the fiber level. Electroluminescent fibers have been integrated into textiles by weaving, knitting, lamination, embroidery, or stitching.

Nowadays The integration of LEDs mounted onto clothing has been achieved on a commercial scale. Philips to Lumalive represents the effort to weave fibers with LEDs into textiles. Philips already has developed a baby blanket by working on it.

c. Electromechanical Actuation:

Electrically driving actuators already has been widely used in mechanical applications in robotics. It composes of active materials which can change shapes and dimensions by using electricity.

The most advanced active materials in smart textiles are electroactive polymers. The electroactive polymers can easily process with inorganic materials. Therefore, it has many advantages; Such as being lightweight, soft, and flexible.

4. Multifunctional Electronic Textiles

A single function never can meet the requirements of electronics in Electronic textiles. So, Functional integration among the electricity generation, storage, and utilization of electricity and others functionalities introduces us to electronic textiles.

The mainstream of such Multifunctional Electronic Textiles integration is summarized here:

a. Integration of Generation, Storage, and Utilization of Electricity

i. Generation and Storage of Electricity:

It is important to generate and store electricity in textile control system to realize self-powering electronics textile. It mainly focuses on integrating DSSCs and supercapacitors. As their primary materials, fabrication as well as structure, methods are compatible with each other.

ii. Electric Storage and Utilization:

Electric energy can store electro-chemically in super-capacitors. But electro-chromism is only realized through the electro-chemical redox reactions of conducting textile materials or polymer. So, the integration of electric storage and utilization dedicates to wearable textiles with self-powered chromatic transitions in the working state.

b. Integration with Sensing Functionality

For the electricity generation, storage, and utilization of electricity, it is essential to intercommunicate electronic textiles with other functionalities. Among them, sensing environmental change has been mostly explored in electronic textiles.

Due to promising applications in many scientific applications like intelligent control, personal protective textile, healthcare, and so on. But in the advanced textile industry, fiber and textile sensors are first utilized according to their different stimulations such as mechanical stimuli, temperature, chemical substances, etc.

Some of the Integration with Sensing Functionality in Textile is as follows:

1. Strain and Pressure Sensors: Resistive Sensors, Capacitive Sensors.
2. Temperature Sensors.
3. Sensors for Chemicals.
4. Humidity Sensors.
5. Self-Powering Sensors.

Challenges of Smart Electronic Textiles:

After so much advancement of science, there are some critical challenges that remain. Its needs to be addressed.

1. In smart electronic textiles, it is difficult to fabricate highly efficient fiber. And the textile-shaped electronic devices have a large scale. Consequently, its performances greatly decrease as the increase of its length.
2. It is difficult to connect a lot of fiber electrodes after the fiber-shaped electronics are woven or knitted into textiles.
3. It is a very important and reverent question is that after seal the electronic textiles, it becomes less stable as well as soon fail without sealing. But It cannot effectively display its 100% advantages of the textile structure after sealing.
4. Though today’s smart electronic textiles clothing is washable. But it remains possible that stop working after contact with water.

Development of Smart Electronic Textiles:

The development of textiles reflects human civilization to a certain extent. Once Natural fibers like cotton, silk, were then woven into a real textile material. Gradually with the development of science, invent man-made fiber like nylon, Kevlar, and so on. But Recently, textiles have been facing new challenges with the advancement of the internet and smart materials. Today we expect to exhibit comfortable clothing as well as additional smart functionalities.

For example, as people want to self-powered clothing’s is able to convert energy sources such as solar energy and mechanical energy into electric energy. Portable electronics like smartphones can be more effectively and conveniently powered if our clothes can store these electric energies efficiently. Wearable smart clothing is excellently promising to make our electronic devices into textiles for more efficient use smart electronic textile such as sensing and displaying.

Future E-Textile Opportunity & Research Area:

Textile Electro-chromic technologies are close to practical applications and are now facing a bright future. It has a strong interest in consumer products. Nike patented the concept of changing the color of a pair of sneakers with an android phone.

Today Smart Electronic Textiles’ main focus has been to optimize the materials and structures. The first and most important aspect is the preparation of high-performance fiber and textile electrodes.

But metal-based, as well as polymer-based textiles, has a serious issue. Metal-based textiles have high electrical conductivities. But it has low flexibility and has not had to be stretched. On the other hand, polymer-based conductive electrodes show lower electrical conductivities; but higher flexibility and stretchability.

In brief, they could not make the demand of comfortability, flexibility, breathability, wearability, safe, as well as decoration. Carbon nanomaterials will be able to balance the new demands of the above properties.

Nano-textiles based Smart electronic textiles effectively satisfy the electrode applications. Consequently, a lot of research needs to develop both the preparation and structure.

Day by day more smart electronic textiles prototypes are becoming available. But it remains a large gap between the best electronics textile applications. Consequently, our textile industry must more and more invent on the research and development of smart electronic textiles.

References:

1. Smart Electronic Textiles International Edition: DOI: 10.1002/anie.201507333
2. Application of Smart Textiles has Changed World!
3. https://site.unibo.it/semiconductor-physics/en/research/smart-electronic-textiles
4. https://www.fibre2fashion.com/industry-article/7124/manufacturing-of-electronic-textile
5. https://www.businesswire.com
6. https://onlinelibrary.wiley.com/doi/10.1002/anie.201507333