What are ‘Smart’ Materials?
The words “Smart textiles”, “Smart Fabrics” or “Smart Materials” are as over used as “Wearable Tech” and include many categories. Fabdesigns does engineer e-textiles, embedding wires, circuits, and leads for sensors, heating elements, light, and data transfer. However, we firmly believe that there is so much more to do with smart textiles than just embedding wires. Once every brand commercializes their version of wired-up garments, the question remains: will this be a fad, or the way of the future for clothing? Exploring other properties of materials beyond electronics to improve our clothing, our cars, our homes, our jobs, and our play time is so much more fun. Contemplate the opportunities.
But what are “Smart Materials” really?
Smart materials are materials that possess the ability to change their physical properties in a specific manner in response to specific stimulus or their environment. Physical properties could be shape, viscosity, stiffness, color, dimension, etc.
Smart means programmed by human intellect manipulating: composition, processing, modifying tiny structures or molecules Introduction of intentional defects that adapt to levels of stimuli in a controlled way. This means that actual people need to solve the problem, then engineer the materials to respond as needed. Materials include many diverse fibers, yarns, fabrics, pigments, finishes, etc. These can be individual attributes and as combinations of all the above.
Stimuli could be:
• Electric current
• Magnetic fields
• Nuclear radiation
• Emotions . . . Yes, emotions - And more
Classification of Smart Materials
• Passive Smart Materials - Lack the inherent capability to transduce energy in response to stimuli. These act as sensors not as actuators or transducers. Example – fiber optic cable.
• Active Smart Materials – possess the capability of modifying their geometric, and material properties under the application of stimulus (input) of electric, thermal, or magnetic fields, thereby acquiring an inherent capacity to transduce energy. Can be used as force transducers and actuators Examples: Piezo-electric, magnetostrictive materials, shape memory alloys, Electrorheological fluids
How do we describe change?
The associated changeable physical properties could be shape, stiffness, viscosity, damping, etc. The changes should be significant, measurable, and happen over a specific period of time. They can change with environment – one way or reversible. (example of one way is shipping humidity sensors)
Cause and Effect
Why would we want Smart materials?
We are used to controlling the world around us, to find the settings that suit us best. Many of these technologies are based on bio-mimicry and will harmonize our environments.
What are some examples of Smart Materials?
Non-Newtonian Polymers that react to Pressure.
• Non-Newtonian fluids flow and stretch easily. But when you move it quickly, the viscosity changes and it locks together tightly, instantly absorbing the energy.
• Sheer thickening fluids absorb the force of Kinetic energy. Corn starch, Silly putty, some soups
Application: Smart Armor
• Example of a polymer: D3O® can be found in more than 100 products—everything from cell phone cases to kneepads to ballet shoes. It is soft but reacts to impact. https://www.d3o.com/what-is-d3o/
• Kevlar fabrics impregnated with a ‘shear thickening fluid’, the exhibits the same kinetic energy dampening effect – like the oobleck, offer fabric flexibility, and light weight armor. At impact, the fluid thickens, creating hydro clusters in a lattice formation that become as hard as ceramic for a split second, enhancing the ballistic protection, while also preventing knife / shank penetration. Plain Kevlar does not prevent knife point penetration. Applications: Sanitation, first responders, industrial . . .
• Electrorheological fluids are a type of ''smart'' colloid capable of varying viscosity or even solidification in response to an applied electric field. The rheological variation is reversible when the field is removed. The response time can be as short as a few milliseconds. These are used in mechanical vibration control.
• Electro-rheological fluids (ER) (mixing corn flour in a light vegetable oil or silicon oil)
Application: Intelligent Glass
• Selectively reflects the infrared on hot days
• The secret is super thin coating of vanadium dioxide molecules doped with tungsten – Liquid crystals - LC
• At low temperatures vanadium dioxide is transparent to infrared
• At higher temperatures the bonding between the molecules changes and the material becomes reflective, like metal.
• Piezoelectricity is Electric polarization in a substance resulting from the application of mechanical stress. Voltage is produced when stress is applied.
• Piezoelectricity is the electric charge that accumulates in certain solid materials in response to stress or pressure. Materials include crystals, ceramics, and biological matter such as bone, DNA and proteins.
· Pressure sensitive to shock, impact, and strain.
· Reversible and Irreversible Color change at a given pressure and color recovery when the constraint decreases.
· Reversible Applications: visualization of the mechanical behavior of various materials under pressure (tensile, compressive and torsion loading), material health testing.
· Irreversible Applications: non-destructive material testing during production, use or maintenance (folds, breaks, wear, corrosion, cracks) / Visual detection of impacts and shocks for the industrial and transport sectors.
· Humidity: sensitive to moisture.
· Reversible and Irreversible Color change at a given humidity and color recovery when the ambient humidity decreases. This is usually blotting paper impregnated with cobalt (II) chloride base, or less toxic, copper (II) chloride base.
· Reversible Applications: weather indicator
· Irreversible Applications: packaging for electronics, clean rooms, etc.
· Magnetostrictive materials - electrostriction) is a property of ferromagnetic materials that causes them to change their shape or dimensions during the process of magnetization. The variation of materials' magnetization due to the applied magnetic field changes the magnetostrictive strain until reaching its saturation value, λ. -Wikipedia
· Magneto-strictive materials (cobalt, Terfenol-D, etc.)
· Example: We use the piezoelectric effect in our daily lives. The igniter on most gas grills, consists of a piece of a piezoelectric material. This piezoelectric element when it is stressed by the impact of a small hammer which is cocked and released by pushing the button, creates an electrical spark across two electrodes placed near the gas burner.
Application: Magnetostrictive – Telescope mirror
• We can correct deformation by coating the non-reflective side of the mirrors with “smart” materials that respond to various stimuli, such as temperature changes, magnetic fields, or voltages.
• This project specifically uses magnetic smart materials (MSMs) to try to counteract mirror deformation. We can use a magnetic field to actively control the surface profile of the mirror and consequently improve the quality of the telescope imaging.
Application: Earthquake dampers – Seismic mitigation of buildings - The Magnetorheological fluid inside modern dampeners are kept solid in normal conditions but change to liquid and back as sensors activate and deactivate a magnetic field during an earthquake, allowing the dampeners to absorb the shockwaves and reducing damage to the structure. The fluid can change from liquid to solid and vice versa. Fluid is 3 ingredients: carbonyl iron, lubricant, and hydrocarbon oil. The Magnetorheological fluid inside the dampeners changes a building from a rigid structure that must absorb the shockwaves to a 'smart' structure which adapts instead.
Application: Shock absorbers – ‘Magnaride’
The strength of the bonds between the magnetized iron particles causes the viscosity of the fluid to apparently increase. The magnetized fluid is not, technically, more viscous, but it is more resistant to passage through the restrictions in the damper because the concentration of magnetized fluid forms a kind of deformable plug.
Application: Magnetorheological polishing
High precision finishing methods with automated finishing without manual intervention, using magnetorheological Nano finishing without any manual (human) effort in manufacturing processes.
Application: Ceramics are extremely sensitive to surface defects.
Shape Memory Alloy
• NiTinol Nickle Titanium
• Self-assembly is when independent parts come together on their own to create specific things.
Fabdesigns presented two examples of shape memory applications:
· a self-disassembling fabrication knit on Stoll ADF. Polyester and NiTinol knitted to shape as a box. At 30 degrees Celsius the box disassembles to a flat fabric, unassisted.
· a self-deploying dish fabrication knit on Stoll ADF. Polyester and NiTinol knitted to shape as a cone. At 30 degrees Celsius the flat cone deploys into to a 3D shape unassisted.
• NiTinol Nickle Titanium muscle wire. Biocompatible
• Nylon fishing wire twisted on itself 1000’s of times and heat set.
• Carbon nanotubes – lightweight, transparent, conductive, thermo-conductive, 40 times stronger than steel & 32 times stronger than human muscle– electrical charges cause the tubes to repel each other – result is compression.
• Pros: Mimics tendons and muscles and compresses with heat or electrical charge. Cons: Graphene oxide is toxic to humans.
Biological Smart Materials
• Concrete that heals itself with bacteria. The bio concrete is mixed just like regular concrete, but with an extra ingredient -- the "healing agent." It remains intact during mixing, only dissolving and becoming active if the concrete cracks and water gets in. The bacteria are active in concrete and produce repair material for the concrete -- and that is limestone.
Hydro responsive Smart Concrete
By adding carbon fiber to concrete mixture, a slab of concrete can conduct electricity and enhance a material that has been used for eons. "Smart concrete" has many potential applications, including helping structural engineers to identify hidden trouble spots of damage or deformation in a concrete structure long before stress or cracking is visible to the human eye. It can detect minute changes in stress. As the compression increases, the electrical resistance decreases, making the concrete more conductive. Unistress – Pittsburg Patent US 005817944A
• Left: Reversible and Irreversible Color change at a given temperature and color recovery when the temperature of the surface of the pigment decreases. Thermometer application.
• Right: Lauren Bowker, founder of The Unseen created a calfskin backpack that shows vivid flushes of color in response to air pressure as the atmosphere brushes across its surface, and an Italian alligator-skin shoulder bag with environmentally responsive ink that changes to reflect the different seasons in the UK. It turns black in the winter, red in the spring, blue in the summer and green fading to red in the autumn.
• Chameleonic gemstones map brain activity across headdress by The Unseen. Lauren Bowker, founder of The Unseen has created a gemstone-encrusted headdress that changes color in response to varying energy levels in the brain. Excitement, nerves, and fear all produce different colors, and quicker shifts in emotion create more dramatic patterns. She has also has created an ink that is responsive to wind – uses – aerodynamics.
• New York designer Nikolas Bentel has developed a range of color changing dye patterned shirts that change color in response to air pollution or radioactivity. The Carbon Monoxide shirt functions in a similar way to a CO spot detector, which features a patch of palladium and molybdenum salts that turns black (oxidizes) when carbon monoxide is present, and an iron metal salt robs back the oxygen and turns clear when the CO is removed. As CO oxidizes on the shirt, the dye's color is white as it loses oxygen atoms. Once the carbon monoxide is removed from the air, the metal salts absorb oxygen from the air. This changes the dye back to its original chemical form, and the color to black again. Ink Patent US20030199095 A1
What will Future Smart Materials be like?
• Next generation will change color, emulate muscles, respond to light, heat, radiation and magnetic fields.
• Materials will become more light weight with super strengths and multiple functions varying with their environment
• Materials which can discriminate whether the loading is static or shock and can generate a large force against shock stresses (mega and micro shock absorbers)
• Materials possessing self-repairing properties which can heal damage in due course of time (self-healing materials)
• Materials that can be used in ultra-high temperatures by changing the composition through transformation (application in space shuttles which encounter high temp in reentry to atmosphere)
The Future: Combining Material Science with Communication
• Interactive Wearable for health and sports
• Adapt to Physiology
• Biomechanics – replacement of canes, wheel chairs, etc.
• Improve efficiency, accuracy, balance
• Customize gear, clothing and home – Physiological analytics 3D
• Mitigate risk of injuries
• Assess readiness for competition
• Quantify return to play. Healing wounds
• Faster recovery with less clumsy products
• Automatic massage for better circulation
The Future: Piezo-electric flooring
Check out sustainabledanceclub.com to see the future. Their energy floor modules flex slightly when stepped on. Inside each module is an electromechanical system, which transforms the small vertical movement produced by dancing or walking people into a rotating movement that drives a generator. Each module by the size of 75x75x20 cm can produce up to 35 watts of sustained output, between 5-20 Watt per person.
Veranu – Italian company from Sardegna recycles Foot Traffic:
Louvre 20 million visitors/yr. 20-meter passageway powers LED strips, the Pyramid, and façade at night. Annual savings .55 tons of CO2 emissions
Rockefeller Center 70 million/yr. – 40 sq. meters of tile powers LED strips and 30,000 lights on tree. Annual savings .8 tons of CO2 emissions
Other places: Colosseum in Rome; Flinders Railway Melbourne
The Future: Piezo-electric Roads
Good Vibrations? California to Test Using Road Rumbles as a Power Source. A total of US $2.3 million will be invested in two projects. First up, a 60-meter (200 foot) stretch of roadway near the campus of the University of California, Merced, north of Fresno.
The other project, to be run by Pyro-E, LLC of San Jose, will use similar devices to generate power for off-road use; the company speaks of scavenging enough power to supply 5,000 homes.
The Future: Electro oobleck
Assistive materials that electronically change shape and become stiff when needed and flex. Like an electronic wetsuit. Replaces a cane.
The Future: Piezoelectric agility - Transportation
• Work and Transportation: Next generation will change color, emulate muscles, respond to light, heat, radiation and magnetic fields.
• NiTinol Nickle Titanium muscle wire.
• Dielectric elastomer – shape shifts and compresses with a charge on each side.
• Is silent, and light weight
Presented by Connie Huffa of Fabdesigns, Inc.
A secure and confidential engineering laboratory for Extreme textile projects.
n. If you would like to read more about Brenda: https://frenchragshappenings.wordpress.com/the-principals/
Connie Huffa – Fabdesigns, Inc.
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