What is a “smart” material? Can a seemingly inanimate object demonstrate “intelligence?”
“Smart materials” are a class of materials that possess unique and adaptive properties, allowing them to change their characteristics in response to external stimuli such as temperature, light, pressure, electrical fields, or magnetic fields. These materials are designed to be highly sensitive and responsive, and they can alter their physical properties without the need for external intervention.
Some of the most common types of smart materials include:
- Shape Memory Alloys (SMAs): These materials can “remember” their original shape and return to it when subjected to heat or other stimuli. Nitinol (a combination of nickel and titanium) is a well-known shape memory alloy used in various applications, such as medical stents and actuators. This category of alloys is what most people think of when “smart materials” is mentioned.
- Piezoelectric Materials: These materials generate an electric charge when mechanically stressed or deformed. Conversely, applying an electric field to them can cause a change in shape. They find applications in sensors, actuators, energy harvesting devices, and even in piezoelectric inkjet printers.
- Electrochromic Materials: These materials change their color or opacity in response to an electric current. They are used in smart windows and eyewear, allowing them to adjust their transparency based on environmental conditions.
- Thermochromic Materials: These materials change color with variations in temperature. Applications include mood rings and temperature-sensitive labels.
- Photochromic Materials: Photochromic materials change their color when exposed to light, reverting to their original state when the light source is removed. They are used in sunglasses, lenses, and eyeglasses that darken in bright light.
- Magnetostrictive Materials: These materials change their shape in response to a magnetic field and find applications in sensors and actuators. As mentioned on last month’s post that included Ames Lab Success Stories, Terfenol-D is a material licensed by TdVib and produces sonic actuators with this special material.
- Electroactive Polymers (EAPs): EAPs are a type of smart material that changes shape in response to an electric field. They have applications in artificial muscles, haptic feedback devices, and soft robotics.
- Self-healing Materials: These materials can repair damage and recover their original properties without external intervention. They have potential uses in coatings, composites, and structural materials to enhance durability and longevity.
The U.S. along with many of our allies, are funding government agencies, universities, and non-governmental think tanks and labs, to find options and ideas that can help make our future safe, healthy, and sustainable.
Government Labs and Research Institutions:
- NASA: The National Aeronautics and Space Administration (NASA) is probably the first agency that comes to mind when we think of innovation in so many areas of science and technology. They have been actively researching smart materials for aerospace applications, such as shape memory alloys for aircraft components.
- National Institute of Standards and Technology (NIST): NIST is involved in research related to advanced materials, including smart materials for various applications.
- Department of Energy, Ames Lab: We mentioned Ames Lab in our post on Sustainable Materials in March, but here is a specific Ames Lab post that highlights their research to develop a metallurgical production process for smart material Terfenol-D; an alloy of terbium, iron and dysprosium that exhibits giant magnetostriction – it changes shape when subjected to a magnetic field (concept was conceived by the Naval Ordnance Laboratory in the 1970s).
- Defense Advanced Research Projects Agency (DARPA): DARPA, a U.S. government agency, has invested in research on smart materials for defense applications, including adaptive camouflage and responsive structures.
As you might also guess, many of the world’s top players in smart materials, are also the large companies and well known brands we use every day:
- 3M has been involved in various smart material technologies, including optical films, adhesives, and conductive materials.
- BASF is a global chemical company that has been actively engaged in smart materials research, particularly in the development of shape memory polymers and other functional materials.
- Corning is known for its expertise in glass and ceramics and has been involved in the development of smart glass technologies for various applications.
- Saint-Gobain is known for its advanced materials and has worked on smart materials such as electrochromic glass.
- General Electric (GE) has been involved in research and development related to smart materials, particularly in aerospace and energy sectors.
- We would also add that many up and coming startups are working on smart materials and readers may want to check out Greentown Labs mentioned in our Sustainable Materials post last month.
Products in development or potential types of products to spur your imagination (some of these are based on brainstorming from what we’ve seen or read about on the web, or from the companies and research agencies above, but are limited to those):
- Shape Memory Alloys (SMAs): A self-folding origami toy that changes its shape upon heating.
- Piezoelectric Materials: A wearable fitness tracker that generates power from the user’s movements.
- Electrochromic Materials: Smart sunglasses that adjust tint based on the intensity of sunlight.
- Thermochromic Materials: Temperature-sensitive baby bath toys that change color with water temperature.
- Photochromic Materials: Sunglasses that automatically darken when exposed to sunlight.
- Magnetostrictive Materials: A miniature robotic arm controlled by a magnetic field. Electroactive
- Polymers (EAPs): Soft robotic grippers that respond to electric signals for precise manipulation.
- Self-healing Materials: A scratch-resistant smartphone cover that repairs minor damages over time.
Smart materials are an exciting area of science that demonstrates and shows promise for real-world applications, as we’ve seen in the above examples. As we look ahead, novel materials will continue to change our lives, spark creativity for more new inventions, and provide opportunities for students interested to explore these different fields of study.