Smart materials are polymer-based substances that can change their properties in response to external stimuli — such as temperature, pressure, moisture or light — and revert back to their original state without human intervention.
Smart Materials Definition
Smart materials (also called intelligent or smart materials) are substances designed to change in response to changes in temperature, pressure, light, moisture and other external factors. From self-repairing concrete to color-changing camouflage, smart materials are used in a variety of ways.
Smart materials can shapeshift, change color and even self-heal. Their ability to respond to their environment and bounce back without external intervention could unlock technologies still beyond our reach — leading to longer-lasting batteries, regenerative medicine and more efficient renewable energy systems. As new combinations emerge, smart materials are poised to drive the next generation of intelligent technology, enhancing efficiency, durability and sustainability.
What Are Smart Materials?
Smart materials are engineered to respond to their environment and switch back to their original state once the stimulus is removed. By carefully manipulating their chemical and physical properties at the molecular level, engineers can create intelligent structures that adapt dynamically to their surroundings. Some smart materials can self-heal when damaged, for example, while others generate electricity under mechanical stress.
Smart materials are making their mark across a wide range of industries, from self-repairing concrete in construction to color-changing camouflage developed for the defense sector. One of the most common types, shape-memory alloys, return to their original shape under heat, making them ideal for applications in medical devices, robotics and actuators. Meanwhile, piezoelectric materials are being installed into sensors, speakers and energy-harvesting systems for their unique ability to convert mechanical energy into electrical energy.
What Makes Smart Materials Smart?
Smart materials are considered “smart” because they can autonomously change their properties — shape, size, color, conductivity, etc. — based on the environmental conditions they encounter. This responsiveness isn’t just a passive reaction, but an engineered intelligence that enables them to perform specific functions without human intervention.
These materials are designed to harvest energy from their surroundings, allowing them to operate in dynamic environments — whether by shape-shifting, self-healing or converting light and pressure into usable energy.
Types of Smart Materials
Smart materials can be categorized based on their response to stimuli. The following are the types of changes these materials are capable of thus far, with more discoveries to come.
Self-Healing Polymers
Just like our skin heals from cuts and bruises, self-healing polymers can repair themselves when damaged. These materials contain dynamic chemical bonds that reform after being broken, usually activated by heat or pressure. Self-repairing phone screens, carpets and even aircraft wings have been fabricated to heal from minor damage, extending their lifespan.
Piezoelectric Materials
Piezoelectric materials generate electricity when they are squeezed or stretched. This happens because their unique crystal structure changes under mechanical stress, creating an imbalance of electrical charges. It’s only by harvesting this input energy that the material can become conducive, producing an electric charge. You can find these materials in quartz watches, guitar pickups and even barbecue lighters, where pressure creates a spark to ignite a flame.
Shape-Memory Alloys
These metals and polymers are designed to “remember” their original shape and return to it after being deformed. At low temperatures, they can become soft, flexible and easy to shape, whereas in higher temperatures, they become rigid and durable. Shape-memory alloys, like nickel-titanium, are used in medical stents to expand blocked veins and in space applications to reinvent the wheel, specifically for Mars-bound rovers.
Chromoactive Materials
Chromoactive materials change color when exposed to light — namely ultraviolet light. You’ll see this material in photochromic sunglasses, which darken as the user steps out into the sunlight, and smart windows that adjust tint to regulate indoor lighting and temperature. These materials are also used in photovoltaic cells and light-sensitive coatings in food packaging.
Thermochromic Materials
This category includes heat-sensitive materials that shift color in response to temperature changes. As the surrounding temperature jumps or drops, special pigments adjust their molecular structure accordingly. Spoons, car windows and forehead thermometers, as well as color-changing textiles like mood rings and novelty shirts that react to body heat contain thermochromic materials.
Electrorheological and Magnetorheological Fluids
The viscosity level of these fluids change when exposed to electric or magnetic fields. When activated, they shift from a liquid state to a semi-solid state almost instantly. They are used in adaptive clutches, brakes and shock absorbers in high-performance vehicles and in bionic prostheses to provide more natural movement control.
Hydrogels
Hydrogels are water-absorbing materials that expand or contract based on a number of environmental conditions, whether that be the pH and glucose levels present in bodily fluids or food products or the temperature, light and activity in an electric or magnetic field. In medicine, they are woven into wound dressings to release medication gradually, and incorporated into bio-sensory drug delivery systems. And in agriculture they help soil retain water for crops. Hydrogels also play a role in soft robotics, allowing robots to bend and twist, and in regenerative medicine, where they serve as scaffolds for tissue growth and even mimic artificial organs.
Applications of Smart Materials
Smart materials are quite literally shaping the future. Here’s how:
Biomedical Engineering
Shape-memory alloys and hydrogels are used in self-expanding stents, artificial muscles and drug delivery systems that respond to body conditions, such as temperature or pH levels. They also serve as scaffolds in tissue engineering, aiding in cell growth and regeneration.
Aerospace and Defense
Shape-memory alloys work with piezoelectric materials to build better aircraft components, improving aerodynamics and reducing vibrations. Their self-healing composites can also help repair structural damage autonomously.
Automotive Industry
Various smart materials are used to enhance vehicle safety and efficiency through adaptive braking systems, clutches and shock absorbers, as well as self-healing coatings that repair minor scratches. Companies are also turning to smart materials like graphene to “lightweight” the industry at large, improving performance, corrosion resistance, fuel cost savings and reducing carbon emissions for every kilogram lost.
Robotics and Wearable Technology
Soft robotics benefit from flexible, shape-changing materials like silicone-based actuators and hydrogels, which are designed to mimic human muscle movements in prostheses and exoskeletons. Meanwhile, wearables integrate conductive smart fabrics, such as silver-coated fibers and graphene textiles, to detect vital signs like heart rate, temperature and muscle activity in real time.
Construction
Self-healing concrete brands like DuraLink or Autocrete contain embedded microcapsules filled with sealants that are released when cracks form, helping extend the material’s lifespan. Additionally, smart glass technology is designed to adjust its transparency in response to light or electrical signals, improving energy efficiency by reducing the need for artificial heating and cooling.
Energy
Thermoelectric materials convert waste heat into electricity for power generation. Bismuth Telluride, for example, can increase efficiency up to eight percent in devices like seebeck generators, which are used to capture energy from things like car exhaust or industrial machinery. In batteries, smart materials take on phase-changing properties to enhance performance and prevent overheating in things like electric vehicles, drones and next-generation clean energy systems.
Environmental Science
Hydrogels and smart polymers aid in water purification by selectively absorbing pollutants. Shape-memory materials in adaptive wind turbines, such as GE's Haliade-X, can adjust blade shapes in response to varying wind conditions, increasing annual energy production by up to 4 percent.
Benefits of Smart Materials
Smart materials offer real, practical benefits to a variety of industries. These include:
- Energy Efficiency: One of the most significant advantages of using smart materials is its ability to regulate temperature, thus reducing the need for things like artificial heating, cooling and lighting.
- Reduced Maintenance Costs: Materials like self-healing concrete and polymers can repair cracks or damage, extending their lifespan and reducing all of the costs that come with more frequent maintenance.
- Improved Integrity and Safety: Smart materials are helping to make everything from bridges to aircraft safer and more durable against damage caused by weather and other environmental factors.
- Adaptive Functionality: Certain smart materials can change their form based on things like temperature, pH and other stimuli, allowing for a dynamic range of applications across everything from medicine to aerospace.
Challenges of Smart Materials
Despite their many benefits, smart materials also come with some challenges that can limit their widespread adoption. Some of these include:
- High Production Costs: Smart materials tend to be more expensive to produce than their more traditional counterparts, often requiring highly specialized raw materials and intricate fabrication processes.
- Complex Design and Engineering: Developing smart materials often involves intricate molecular design and precise engineering to ensure they respond correctly to environmental stimuli. This complexity requires advanced research, extensive testing and very specific domain expertise — all of which can slow down innovation and commercialization.
- Scalability Issues: While smart materials show great promise in laboratories in prototypes, scaling up their production while maintaining performance, consistency and cost-effectiveness remains a challenge.
- Outdated Regulations: Existing building codes and safety regulations were established before the introduction of smart materials, so they typically don’t account for them. At times, this makes it difficult to legally incorporate smart materials into construction projects, medical devices and consumer products.
Frequently Asked Questions
What is an example of a smart material?
Common examples of smart materials are shape-memory alloys like Nitinol and Copper-aluminum-nickel, which can reshape themselves and return to their original form when exposed to heat.
What items use smart materials?
Smart materials are used in healthcare products to create temperature-sensitive stents, orthopedic implants and catheters as well as drug delivery systems that release medication within a patient’s body. They’re also built into self-tinting windows and sunglasses that react to light, self-healing coatings on cars and aircrafts and piezoelectric sensors, which are designed to detect pressure changes to deploy car airbags and provide real-time readings for heart rate monitors.
What defines a material as being smart?
A material is considered “smart” if it can change its form or behavior in response to external stimuli in a reversible way — without human intervention.
