The use of the term smart is increasingly common in our vocabulary. Words like smartphone, smartwatch or smart TV are part of our daily life and refer to multifunctional products, capable of performing tasks beyond basic ones.

In the case of materials, there are also so-called smart materials or intelligent materials, which are materials that react to different external stimuli. Within this context, in today’s blog we will tell you in detail what these materials are capable of, what types of smart materials exist, some of their applications and the benefits they can bring to both a product and an industrial process.

What are Smart Materials?

As we anticipated, smart materials, also known as active or multifunctional materials, are materials capable of reacting, reversibly or irreversibly, before different external stimuli. This reaction, or answer, is usually carried out by varying one or more of its properties.

The main external stimuli that can activate these smart materials are: changes in temperature, variations in humidity, chemical compounds, variations in pressure, pH, electric current or magnetic fields.

On the other hand, the answer made by these materials comes in the form of a variation of some of their properties, such as color, shape, size, viscosity, crystallographic arrangement or opacity.

Smart Materials types

Depending on the stimulus that activates the material, or its response, there are different types of smart materials. Furthermore, based on their ability to return to the initial state, all smart materials can be classified as reversible or non-reversible.

Then, we present a classification with the most common smart materials according to the stimuli that activate them and their answer:

Chromoactive materials. This group of smart materials is characterized by its ability to change color when faced with an external stimulus. Depending on the stimulus that activates the material, the following types are differentiated: 

 

    • Thermochromic materials. The color change occurs after a temperature variation. These types of materials are prepared to change color when they exceed a set temperature limit. There is a great variety of colors and temperature ranges, making them one of the most interesting options in the industrial field.

    • Photochromic materials. In this case, the color change of the material is generated after exposure to a certain light. These materials are generally activated using ultraviolet (UV) wavelengths.

    • Hydrochromic materials. In hydrochromic materials, the color change occurs when the material comes in contact with water.

    • Electrochromic materials. Electrochromic materials achieve color changes by passing electrical current through them. These materials, less developed than the previous ones, allow a great control through electronics.

    • Halochromic materials. Halochromic materials are capable of changing color upon changes in pH. They have been used for years as pH indicators in chemical laboratories.

Photoative materials. Unlike the previous ones, photoactive materials are capable of emitting light under the action of different external stimuli. Within this group we distinguish the following types:

 

    • Electroluminescent materials. In these materials, light emission is achieved by connecting them to electric current. This allows a fairly precise control of its operation through electronics.
    • Photoluminescent materials. In this case, the photoluminescent materials are able to emit light when exposed to a certain wavelength, usually within the ultraviolet (UV) range.

Materials with shape change. This type of material has the ability to change its shape when subjected to a certain stimulus, usually heat, tension or humidity. Within this group we differentiate:

 

    • Shape memory materials. These materials are capable of recovering an initial shape after being deformed. A clear example of this type of material is Nitinol, nickel-titanium alloy.
    • Self-healing materials. As their name suggests, they are materials capable of recover from damage sustained. For their recovery they usually need the action of temperature.

    • Materials with volume change. Finally, the materials with volume change are those capable of modifying their size due to the action of an external element. Metals with a high coefficient of expansion could be considered materials capable of changing their volume, however, the clearest example of this behavior is the hydrogel, capable of increasing its volume up to 400 times in contact with water.

Are there other smart materials? Yes, there are more types, but they are not as developed and are not applicable to the industry in general. For the most curious, we will prepare another post with some of them.

Applications of Smart Materials

As you can see, there is currently a wide variety of smart materials. For this reason, the range of possible applications they present is very wide. Here are some of the most interesting:

  • Products with new designs. The use of smart materials allows to achieve differentiating effects that provide great added value to the final product. A clear example is the materials that change color with sunlight or in contact with the temperature of the hand.
  • WOW effect. Due to their ability to change some of their properties, they are of great interest in sectors such as advertising. Through different stimuli it is possible to achieve the appearance or disappearance of logos or images. Here we leave you a example of a Project where we have used a thermochromic ink to achieve this effect.
  • Security element. One of the most interesting applications for smart materials is their use as warning sensors. In particular, thermochromics can be used as a risk temperature alert.
    They don’t need electric current and have a reversible operation, so their possibilities are very wide.
  • Quality control. It is also very interesting to use them as elements to ensure that a product hasn’t been outside the recommended working conditions (temperature, light or humidity). For example, if a product mustn’t be in humid environments or in contact with water, a hydrochromic element can be used to alert it.
  • Multifunctional products. Thanks to smart materials, it is possible to provide products with new functionalities. For example, a conventional polymer can be modified to have the ability to emit light, self-healing or conduct electricity.

 

Benefits / Advantages of Smart Materials

The main advantage of smart materials is that they give to a material new capabilities without the need of sensors, actuators or electronics. For this reason, it is possible to get products that interact with the environment or with people without the need for them to be connected to the electricity supplies.

How to introduce a Smart Material into a product

At ATRIA, we study each case in maximum detail to carry out each of the smart materials Projects. Then, we show you, in a very brief way, the main steps to incorporate an smart material into a product or process.

  1. Depending on the needs of our client, we select the material or technology that best suits each case. Within this selection, several options are considered and the technical and economic feasibility of all of them are studied.
  2. Materials development. If there is no solution on the market, at ATRIA we develop personalized solutions for each case.
  3. Preparation of prototypes on a laboratory scale. Once the material is selected, prototypes will be prepared on a laboratory scale. This stage is essential to evaluate the viability of the idea.
  4. In order to validate the proposed solution, all functionality and resistance tests will be carried out.
  5. Industrial implementation. All our Projects are aimed at industrial implementation, therefore, the last stage will be to adapt the solution to the production process of our client.

 

Do you want to use Smart Materials in any of your Projects? Contact us!

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