Introduction:
A smart textile are materials and structures that allow the textile product to respond or react to the wearer or the environment in the fibre, yarn, fabric, dye or finish state; basically, they are intelligent materials. Smart textiles may contain electronic components and enhance the features of wearables, automobiles, and other products.
Basically smart textiles are two types; active smart textiles and passive smart textiles. For active smart textiles requires power to work. These textiles are known as electronic textiles and examples include switches, sensors, antennae and solar panels. But passive smart textiles will function without any power. Used for vapour control and chemical barriers. In this article I will explain different passive smart textiles examples and their properties, uses.
What is Passive Smart Textiles?
Passive smart textiles are fabrics that incorporate technology to enhance their functionality without requiring an external power source. These textiles are designed to sense and respond to environmental changes or stimuli, often through the use of specialized materials or coatings.
Traditionally, fibres were developed and the fabrics were produced. The properties of the fabric were then investigated and from these results it was decided what products could be made. Since the 1980s, the process has changed: now, the specification of a product determines how the fabrics are developed. The following are functional, technical and performance fabrics, some of which are proprietary to specific companies as indicated.
Examples of Passive Smart Textiles:
There are various types of passive smart textiles, such as Antimicrobial fabrics, Aqueduct fabrics, AquaPro fabrics, Bamboo Fresh Cool Fabric, Biopolyesters, Chitopoly, Coolmax®, Fastskin, Floprene, Gore-Tex®, Microencapsulates, Phase-changing materials (PCM), Shape-Changing Materials and Alloys, Shear Thickening Fluid, Stomatex, SympaTex, UV-Protection fabrics etc.
Each Passive Smart Textiles are described with properties and uses.
Antimicrobial fabrics:
Antimicrobial fabrics contain Triclosan, an antimicrobial agent that can be applied to fabric by being soaked in a bath solution, added to the dye solution that is applied to it or sprayed directly onto the fabric, which is usually made out of acrylic, cotton or polyester. The agent prevents the growth of bacteria, fungi and yeast, which stops germs from spreading. If the agent is placed in the fiber solution before extrusion, the fiber will release the agents to the fabric’s surface when in use.
Properties:
- Inhibit growth of bacteria, fungi and yeast
- Can be laundered
- Quick-Drying
- Wick moisture
- Soft
- Retains shape
- Crease-Resistant
- Maintain body temperature
Trade Names: BioFresh (made by Comatex) and Microban.
Uses: Underwear, sportswear, socks, hosiery, footwear, dishcloths, sleeping bags, bedding, curtains, non-woven wipes, filters, pillows, mattresses etc.
Aqueduct fabrics:
Aqueduct is a moisture-transferring, microfibre fabric made from knitted, gradient denier polyester with a finer denier on the face than on the back. It transfers moisture via capillary action from the back to the front, which leaves the body dry and comfortable.
Properties:
- Lightweight
- Flexible
- Breathable
- Soft
- Durable
- Variations of Aqueduct can be wind-resistant, water-resistant and highly elastic.
Uses: T-shirts, shirts, tops, fleece products, outdoor garments and sportswear.
AquaPro fabrics:
This fabric incorporates polypropylene, which does not absorb any moisture; instead, it transfers the moisture to other absorbing layers, such as cotton, where it can evaporate to remain dry next to the skin.
Properties:
- Lightweight
- Good Thermal properties
- Cling-Resistant
Uses: Sportswear.
Bamboo Fresh Cool Fabric:
A microfibre fabric that is naturally antimicrobial; a natural property of bamboo.
Properties:
- Highly absorbent
- Antibacterial
- Hygroscopic
- Breathable
- Soft
- Repels moisture and cold from the outside
- Cooler; the fabric stays 1—2°C cooler than conventional materials
- Expensive
Uses: Summer garments, quilts, pillows, bedding etc.
Biopolyesters:
Biopolyester is a generic name given to polyester that has been produced from natural sugars rather than glycol. It is eco-friendly because the sugars are renewable and therefore reduces the dependency of petrochemical use; the production requires less energy and creates less greenhouse gas.
Biophyl
Biophyl is produced using sucrose produced from corn starch, which makes Polytrimethylene terephthalate (PTT) polyester. This process uses 30% less energy than polyamide production, and may produce up to 63% less green house gas. These polyesters can be dyed and finished at lower temperatures and at a quicker rate. The fabrics are soft handle, drape well and an excellent elasticity of stretch and recovery.
Biopol
A number of companies have produced naturally occurring polyester, polyhydroxylbutyrate, via bacterial fermentation of the cellulose of a sugar feedstock (called Biopol). It is cheaper and easier to produce than natural fibres. Biopol biodegrades completely in any microbe-rich environment, e.g. compost heaps, and attempts are being made to clone the active gene that produces the polymer so that a natural crop, such as oil rapeseed, can be created. Biopol can be extruded as a fiber, film or mould – the method is determined by the end use. It has a variety of textile applications, such as medical gauzes, sutures and implants. Other products include eco-friendly fishnets, stereo diaphragms, filters and odour absorbers. Fine films can be used for paper coating e.g. compostable garden bags.
Corterra
Corterra is a Polytrimethylene terephthalate (PTT) that can be spun into fibres or yarns and used for apparel, engineered thermoplasticity for pleats and creases, carpeting and non-wovens. It has a soft hand, it can be dyed vibrant colours, it has excellent stretch with superb recovery and is easy care because it resists staining, cleans easily and dries quickly.
Uses: Casual clothing, swimwear, sportswear, carpets, curtains, sheets, pillowcases, wall coverings, automobile upholstery etc.
Chitopoly:
Chitopoly was developed as a medical fibre for people with sensitive skin. It is made from chitosan, which is removed from the shells of crabs and shrimp, reduced to a fine powder, mixed with polynosic rayon and then spun into a fibre.
Properties:
- Absorbent
- Keeps the skin warm and dry
- Antibacterial
- Deodorizer
- Soft handle
- Non-Toxic
Care should be taken when constructing garments to ensure that seams are smooth and soft threads are used to embed the use of the fabric.
Coolmax®:
Coolmax ® transfers perspiration from the body, through the fabric where the air can evaporate it to enable the wearer to feel cooler, more comfortable and therefore fresher to enable you to maintain performance longer. The high tech fabric is engineered using four or six channels on the surface of Dacron ® (polyester) fibres which provide a transport system to take moisture from the skin to the outer layer of the fabric where it will dry quickly due to the wider surface area of the channelled fibres so regulating the body temperature.
Properties:
- Wick moisture
- Breathable
- Soft handle
- Easy care but fabric softeners and chlorine bleaches should not be used as these will affect the performance of the fabrics.
- Energy-Efficient as it dries quickly and does not need to be tumble dried
Uses:
- Clothing for sportswear, such as leggings, shorts, socks, suits, tops and T-shirts for a range of sports including aerobics, athletics, climbing, cycling, skiing and snowboarding, tennis etc.
- Fashion for the ready-to-wear sector, including hosiery, skirts, tops, trousers to provide comfort, Coolmax ® garments worn for their breathability in a busy lifestyle for underwear, bras and pants, to provide dry comfort and prevent the increase of bacterial growth due to the rapid movement of moisture and evaporation when wearing the product. This provides potential for garments to be worn not only for leisure and social occasions but also in the workplace as it will aid concentration and performance.
Fastskin:
Fastskin is patterned, knitted polyester with elastane which has a scale pattern incorporated into the knit structure that mimics those found on sharks’ skin; tiny hydrofoils have V-shaped ridges. The scale pattern on the fabric allows water to glide over the surface, making it hydrodynamic in water and increasing the swimmer’s speed. The fabric has the same density as water, which helps swimmers travel higher in the water; in competitive sport the swimsuit was made to fit tightly by the competitor having a 3d body scan and the suit was designed to take into account the movement and technique of the swimmer. These suits were so tightly fitted it took a while to get on as they compressed the muscles which aided the aerodynamics in the water, and the swimwear was constructed so that seams were not bulky and the garment remained flat. This fabric was first used in the 2000 Olympic Games. At that time, thirteen out of fifteen world records were smashed in various swimming events, and 83% of the medal winners were wearing swimsuits made out of Fastskin. However, in 2010, swimsuits made from this fabric were banned in the Olympics because they were made out of polyurethane, which increased buoyancy and reduced drag in the water by artificial means. Such benefits were deemed contrary to the spirit of the sport.
Further developments of this fabric have been introduced to the market including Super Elite Fastskin but it is not only the fabric itself which is important but the design and construction of the product plays an important part in the dynamics of the garment in relation to the sporting activity; Fastskin products are also used in other sports where speed is of the essence; such as bobsleigh.
Properties:
- High elasticity to prevent muscle rippling
- Hydrodynamic and aerodynamic
- Quick-drying
- Low surface resistance to allow for fast movement in water
Uses: Swimwear, sportswear and footwear.
Floprene:
A three-layered, laminated fabric that uses neoprene; a polychloroprene or synthetic rubber, with small holes sandwiched between open weave towelling on the inside and a double knit on the outside. This construction allows for airflow in either direction.
Properties:
- Highly Flexible
- Good Insulator due to the gaps in the knit and the open weave towelling, which traps air
- Breathable in both directions due to the structure of the outer laminates and the holes in the neoprene
- Comfortable
- High tensile strength
- Reduces perspiration
- Controlled microclimate
Uses: Active sportswear – tops, thermal vests, pants and trousers. Support for joints – knee, wrist and elbow. Face masks for motorbikes, ski and snowboarding.
Gore-Tex®
A smart, microporous, bicomponent membrane made from a composite of an oleophobic substance and PTFE (polytetrafluroethylene). The PTFE part of the membrane is breathable due to the nine billion holes per square 2.5 cm it contains. These holes allow perspiration to pass through, but they are too small for raindrops and wind to penetrate them. The oleophobic substance creates a physical barrier to contaminating substances such as oil, insect repellents, cosmetics and food, but it still allows water vapour to pass through it. It can be laminated to any fabric to provide two, three or more layers of fabric; the composite is used for products that need to be able to handle the most demanding outdoor conditions. It is also used in electronics, industrial products and medical materials or as Gore-Seam Tape to heat seal the seam where machine needles have created holes in the manufacture of waterproof or windproof garments.
Properties:
- Breathable
- Waterproof
- Windproof
- Good Durability
- Highly cold Resistance
- Lightweight
- Easy care – can be machine-washed, steam-ironed and tumble dried
- Dry-Cleanable
Phase-changing materials (PCM):
Phase-changing materials (PCM) are substances that can store and release large amounts of energy. Outlast is one such fabric. Paraffin wax is encapsulated, and the fabric absorbs energy (heat) by liquefying the paraffin wax. The energy is released back to the body without a change in the fabric’s temperature when the wax solidifies. These encapsulated materials are called Thermocules™.
Properties:
- Regulates body temperature – reduces overheating and being too cold
- Adapts to thermal requirements, including low temperatures
- All day comfort
- Soft
- Easily Cleaned; can be laundered and dry-cleaned
- Lightweight
- Good water-resistance
- Flexible
- Good abrasion resistance and Wear-Resistance
- Works well in high temperatures
- UV-Resistant
Uses: Sportswear: ski and snowboard garments such as gloves, hats, jackets and jacket linings to keep the wearer warm whilst waiting for lifts and then cool down when skiing. Cycling tops and helmet linings, walking jackets and gillets, socks, lining of boots and shoes e.g. hiking boots, golf shoes. Automotive seating, filters, agricultural clothing, military equipment e.g. antiballistic vests, combat uniforms and protective suits. Mattresses, pillows, duvets, nappies and sanitary products.
Shape-Changing Materials and Alloys:
These can be produced in both yarns and fabrics. The shape can be changed and recovered by water temperature or body heat. They can be either fibres, mainly cotton, which are coated with temperature-sensitive-polymers (TSP) to heat change their shape or foam made from polyurethane with other chemicals to increase viscosity and density.
Properties:
- Reactive: high-density polyurethane reacts to body heat and pressure, which causes the material to mould to the shape of the body while in contact with it; it reverts to its previous shape after being removed.
- Submersible: hydrogels can be placed in hot water to cause the following effects: a change in size of the fabric by 39% at 30⁰c and by 57% at 80⁰c in five seconds.
- Sensitive: pH-sensitive polymers (PSP) can change shape in length and diameter in response to pH levels; they are used mainly on acrylonitrile.
Uses: Both TSP and PSP are used in medical textiles for making artificial muscles, sensors, and actuators. Other examples include a shirt by Cope Nove that can be scrumpled up into a ball before it is blasted with hot air. The hot air returns the fabric to its original, pristine, non-creased state. Mattresses and pillows take on the user’s body shape whilst providing support, but they return to the original shape after the person moves position or gets out of bed.
Stomatex:
Stomatex was designed by Dr Nigel Middleton, a dentist from Cornwall, who developed the fabric to enable his body to breathe more easily while playing sports. On the underside of a leaf, there are tiny holes called stomata; they help the plant transpire; Stomatex has dome-shaped vapour chambers that have tiny pores in the centre that mimic the stomata of leaves. These chambers allow body heat and perspiration to rise inside the dome and exit through the pore at a controlled rate. When someone exercises, the chambers flex and stretch to give a pumping action, which expels excess heat and perspiration while allowing the cool, dry air outside to enter into the chamber to maintain a microclimate. The fabric is made from neoprene, and it is often laminated with a knitted fabric of equal flexibility and breathability.
Properties:
- Responsive: adjusts to the needs of the wearer
- Maintain body temperature
- Controlled microclimate
- Non-Absorbent
- Strong
- High Elasticity
- Highly Compression-Resistant
- Weatherproof, Water-Resistant and Wind-Resistant
- Insulating
- Flexible
- Comfortable
- Durable
- Lightweight
Uses:
- Sportswear—acclimatisation of athletes in hot, humid conditions, water sports, snow sports, motorcycling, parascending and parachuting, field sports, acclimatisation suits etc.
- Rescue Services—garments for police, firemen, mountain rescue, lifeboat crew, survival suits etc.
- Military and combat uniforms from arctic to extreme wet environments.
- Medical—lightweight joint support, support bandages, splints, increase blood supply, sport injuries, seating and bedding for those incapacitated spending long periods of time in bed or wheelchairs as Stomatex will improve blood circulation, maintain microclimate and keep the pressure against the patients skin to a low level to prevent bedsores.
- Geotextiles – blanket for ground cover to speed up germination, maintain water in the ground to reduce the amount of watering required.
- Equestrian – saddle pads, support bandages, training and mud fever boots.
- Footwear – sole inserts, water sports, ski and snowboarding, skating, motor bike.
- Fashion – designers are beginning to incorporate stomatex in a range of different colours in garments, accessories, such as handbags and luggage, and it is also used in stage costumes.
SympaTex:
SympaTex is a poreless, compact, copolymer membrane consisting of hydrophobic polyester (water hating) with hydrophilic polyether (water loving) channels. The channels absorb perspiration from the body and transport it to the surface of the fabric. The hydrophobic polyester does not allow rain to penetrate the membrane, and the droplets are too big to enter the hydrophilic polyether.
This membrane can be laminated to woven and knitted fabrics, fleece, foam and leather. It can be laminated to outer, inner and lining fabrics to produce a number of layers (2, 2.5, 3 and 4), depending upon the end use.
Properties:
- Breathable
- Waterproof
- Windproof
- Lightweight
- Comfortable
- Biodegradable
- Recyclable
Uses: Sportswear and outdoor wear such as jackets, coats, trousers and gaiters. It can also be used for horse blankets, fashionable garments, shoes, boots, gloves etc.
UV-Protection fabric:
With the number of cases of skin cancer growing, the textile industry has developed fabrics that have UV-Protection Factor (UPF) built-in ranging from fifteen for good protection, twenty five for very good protection to fifty for excellent protection. These fabrics are made with ceramics which can be either made from staple polyester mixed with powdered ceramics or by melting the ceramic, extruding it as a very fine fibre and then blending it with other fibres. Two manufacturers produce UV protection fibres; Invista produces Coolmax and Kuraray produces Sunfit, both of which not only protect the wearers from heat but also absorb and neutralize UV light rays. Other manufacturers may use silver coatings (See the silver technology section for more information).
Properties:
- High UPF
- Keeps the wearer cool
- Quick-Drying
- Moisture management of the body
- Easy aftercare – it’s machine-washable
- Soft
- Comfortable
Uses:
- Sportswear – golf, cycling, running, swimsuits and football.
- Outdoor Wear – hiking and fishing. High factor UPF garments are a legal requirement for Australian outdoor workers.
- Active Wear – swimsuits, shirts, shorts, blouses and skirts.
