This is part 2 of ‘Living in the Material World’, a series presenting a vision of how smart materials can be applied to create more human-centric smart cities.
“The fundamental importance of materials is made clear from the naming of ages of civilizations — the stone, iron and bronze ages, with each new era being brought about by a new material”, argues Mark Miodownik, a renowned material scientist, about how materials have been the foundation of human progress. Though materials go unnoticed because of their sheer ubiquity, they have tremendously impacted our world, all the way from the hammerstone to the silicon chip.
The 21st century is no different. Today, as industries brace themselves for the post-digital era, advances in material sciences will blur the boundaries between the material and physical properties of objects and the computational functions they support. To that effect, a new generation of materials — called smart materials — is being developed to transform the way we interact with the technology that shapes every aspect of our lives.
So, what makes materials ‘smart’?
Traditionally, smart materials are defined as materials that can sense and react to external stimuli such as pressure, temperature, magnetism, etc. in a visible and tangible way, through a change in their molecular structure.
Consider Nitinol, a shape memory alloy used in arterial stents for minimally invasive surgery. After deformation, nitinol can revert to its original shape on heating. The effect of the unidirectional shape memory in this material is based on the single-time preservation of the programmed geometry. It is inserted in the patient’s artery in compressed form, where it gradually re-expands using heat from the body to keep the artery open.
Thermochromic pigment is another common example of traditional smart materials. These pigments can change color in response to a change in temperature. Most often seen as a coating on color-changing coffee mugs, their robust operation and low-cost opens up a diverse range of other applications as well, including cold chain and food storage tracking, hot surface warning, and monitoring patient’s temperatures during medical procedures.
More recently, however, the term ‘smart materials’ can also refer to the approach of directly combining specialized materials and electronics to create material systems that are responsive. Examples of such systems include conductive threads used in e-textiles, conductive inks for printed electronics, and 4D printing technology.
4D printing technology lends shape-changing capabilities to 3D printed objects. Through precise engineering of stresses within the 3D printing process, flat plastic objects can be created that, when heated, fold themselves into predetermined shapes. This process can be used to produce flat-packed furniture that expands and morphs into its final shape at its destination, reducing packaging waste and making shipping efficient.
Smart materials can also enable calmer and more seamless designs. The Jacquard jacket by Google and Levi’s® is one example of how conductive threads were used to create gesture-responsive clothing that seamlessly connects to our smartphones for distraction-free biking.
What unifies materials and material systems under the umbrella term of ‘smart materials’ is that their behavior and properties can be controlled in predictable, repeatable, and useful ways. Besides simplifying design, smart materials also reduce the number of parts needed, reduce weight, offer new form factors, and make designs more robust.
Stay tuned to read more about how current and emerging R&D in Smart Materials is poised to enhance our daily lives by improving comfort, privacy, and productivity.