Auxetic Material

Metamaterials that can react to changes in their physical environment. This unique behavior makes it useful for applications such as impact-resistant and shock-absorbing materials, protective clothing, and medical implants. There is also the potential for use in smart materials and sensors.
Technology Life Cycle

Technology Life Cycle


Marked by a rapid increase in technology adoption and market expansion. Innovations are refined, production costs decrease, and the technology gains widespread acceptance and use.

Technology Readiness Level (TRL)

Technology Readiness Level (TRL)

Field Validation

Validation is conducted in relevant environments, where simulations are carried out as close to realistic circumstances.

Technology Diffusion

Technology Diffusion

Early Adopters

Embrace new technologies soon after Innovators. They often have significant influence within their social circles and help validate the practicality of innovations.

Auxetic Material

These metamaterials exhibit a negative Poisson's ratio, implying they expand rather than contract in cross-section when stretched along their length. Conventional materials, such as rubber bands or steel, have a positive Poisson's ratio, meaning they contract in cross-section when stretched along their length.

They are programmable by nature, which opens up several possibilities for design and manufacturing. The unique behavior of auxetic materials arises from their complex internal structure. These materials typically have a cellular or lattice-like structure that allows them to deform in a way that leads to expansion in cross-section when stretched.

One of the main advantages of auxetic materials is their ability to absorb and dissipate energy. This makes them useful for applications such as protective clothing and impact-resistant and shock-absorbing materials. Auxetic materials have also been used in medical implants and prosthetics, where their ability to conform to complex shapes and resist deformation can be beneficial. Another benefit of auxetic materials is their potential for use in smart materials and sensors. Their unique deformation behavior can be used to detect and respond to changes in their environment, such as changes in temperature, pressure, or humidity.

There are several methods for fabricating auxetic materials and foams. One is to manipulate molecular compositions in lab environments, but the most promising approach is 3D printing, as it enables precise control over material substructures. When used to print auxetic materials, 3D printing converts itself into 4D printing.

4D printing auxetic monofilaments could be filled with healing or cosmetic agents and applied in smart bandage structures. As the skin expands - due to a wound or change in temperature - the monofilaments could expand by opening the chemical structure and releasing the agent. As the environment goes back to normal —the wound heals, or temperature decreases— the pores close once again, halting any unnecessary release of the agent.

Future Perspectives

The shape-shifting properties of auxetic materials might create a future in which objects interact better with our dynamics. Wearables, in constant contact with the human body, could have a greater impact due to their improved responsiveness. Besides continually tracking and analyzing the human body, they could change their own shape to better adapt to the environment and the agent-specific changes.

Researchers are looking into applications for auxetic materials in water management as well. The materials would enable water supply and drainage pipes to shrink or swell in line to help move water through the system. Alternatively, they could allow pipes to flex with ground movements from earthquakes. In the aerospace industry, the use of auxetic materials as insulating foams could reduce vibration and thermal distortion while also being efficient on impact-absorbent structures.

Besides, their ability to be 4D-printed could foster an even more revolutionizing movement in the industrial world. Once those printers become cheaper and more readily available for the mainstream, a wide range of open-source projects and personalized materials could be created. Furthermore, someone could buy a 3D printable design that would be fastly printed already in place by nano drones. Thanks to its auxetic properties, each object could adapt to user-specific needs. A chair or a couch could shape itself in an ergometric manner, XR headsets could fit perfectly to the user's body shape or even a prosthetic limb would be able to adapt and grow with the user accordingly.

Image: Midjourney

Inspired by these botanical systems, we printed composite hydrogel architectures that are encoded with localized, anisotropic swelling behaviour controlled by the alignment of cellulose fibrils along prescribed four-dimensional printing pathways.
Interest in auxetic materials from the construction and water management industries has been very low. Although researchers at MITs self assembly lab are highly interested in working on auxetic pipes for water management there has been very little support from the industry. Instead, researchers are working in aviation, fashion, medicine and food industries.
Poisson's ratio had long been considered to be an intrinsic material property, confined within a narrow domain and governed solely by the geometry of interatomic bonds. Materials with designed heterogeneity allow for control over the Poisson's ratio.
A group of researchers at MIT have created a new material that can expand and contract when exposed to different temperatures.
Wearable electronics have revolutionized the way physiological parameters are sensed, detected, and monitored. In recent years, advances in flexible and stretchable hybrid electronics have created emergent properties that enhance the compliance of devices to our skin.
Temperature-regulating fabric is a smart material capable of warming up a person when they're cold and cooling them down when they're hot.
Life-changing illnesses and fatalities caused by inefficient personal protective clothing and equipment are increasing day by day. The discrepancy between the test standards, environmental conditions, and infield collision is the reason why personal protection equipment and clothing have not yet decreased the number of injuries in various fields such as military and sports. To further increase the efficiency of personal protection materials, auxetic materials are suggested because of their high energy absorption, good permeability, form-fitting ability, and high indentation resistance. Auxetic materials are nonconventional materials with a negative Poisson's ratio and can shrink under compression and expand when subjected to stretching. In comparison to nonauxetic conventional materials, auxetic materials have improved properties that can be useful for personal protection applications. This review focuses on the importance of auxetic materials for personal protection, focusing on reducing the chances of injury and what possible ideas can further benefit the protection products. The first part of the review discusses the auxetic structures and their protection applications followed by the fabrication of auxetic structures. The review will conclude with limitations, economic prospects, and what possible work can further improve the potential use of auxetic materials in personal protection.
Auxetic materials used in combination with 3D printers are being used to make shape transforming objects of all kinds. Researchers at MIT are exploring the possibilities with responsive objects—including water pipes that change shape with changing demand. Auxetic, or 4D materials promise to revolutionize self assembly or programmable materials construction.
A group of researchers at MIT have created a new material that can expand and contract when exposed to different temperatures. Read more on Dezeen: https://w...
In contrast to classical materials, auxetic materials (from the Greek word αὐξητικόσ / auxetikos) possess negative Poisson's ratios, thereby exhibit reverse deformation mechanism. Under a tensile force applied in the longitudinal direction, auxetics expand in the perpendicular transverse direction. Consequently, auxetic materials possess various useful properties for potential applications. This review contains the classification of auxetic materials according to different criteria: the type of structure, cell geometry and scale, mechanical characteristics, methods of their production, and engineering applications. The aim of this work is to sum up structural information on auxetics.
Mechanical properties of materials are important for engineering applications. In addition, poisson’s ratio is one of the important mechanical properties in terms of shear strength and modulus of the material. However, auxetic materials have a negative poisson’s ratio value, on contrary of conventional materials. Therefore, auxetic materials show different deformation mechanism from conventional materials. In this paper, the different type of auxetic materials are defined by giving information to the readers about history and structure of them. Moreover, in-plane and out-of-plane linear elastic mechanical properties of hexagonal and the anti-tetrachiral honeycomb are described based on homogenization approach. Also, the studies on vibration and energy absorption of auxetic materials are reviewed and found that the auxetic materials can be used as a passive noise controller. Investigated papers show that auxetic materials have significant advantages over conventional materials for their high shear strength and modulus. Thus, auxetic materials are important candidate for the biomedical, aerospace, smart filters, sensor and actuator and electromagnetic launcher application.
An article that describes the properties of auxetic materials and the various uses of the material in the fields of wound care, personal protective equipment, and industrial safety.
Auxetic metamaterials are characterized by a negative Poisson ratio (NPR) and display an unexpected property of lateral expansion when stretched and densification when compressed. Auxetic properties can be achieved by designing special microstructures, hence their classification as metamaterials, and can be manufactured with varied raw materials and methods. Since work in this field began, auxetics have been considered for different biomedical applications, as some biological tissues have auxetic-like behaviour due to their lightweight structure and morphing properties, which makes auxetics ideal for interacting with the human body. This research study is developed with the aim of presenting an updated overview of auxetic metamaterials for biomedical devices. It stands out for providing a comprehensive view of medical applications for auxetics, including a focus on prosthetics, orthotics, ergonomic appliances, performance enhancement devices, in vitro medical devices for interacting with cells, and advanced medicinal clinical products, especially tissue engineering scaffolds with living cells. Innovative design and simulation approaches for the engineering of auxetic-based products are covered, and the relevant manufacturing technologies for prototyping and producing auxetics are analysed, taking into consideration those capable of processing biomaterials and enabling multi-scale and multi-material auxetics. An engineering design rational for auxetics-based medical devices is presented with integrative purposes. Finally, key research, development and expected technological breakthroughs are discussed.
We introduce a new type of auxetic material with ultrahigh strength and ductility that mimics the crystal structures of two natural solids: α-cristobalite and LaNiO3/SrTiO3 superlattice (or ABO3 perovskite). The fabrication method is based on wire-woven metals. Namely, this new auxetic material is fabricated by forming helical wires, assembling them into a wire-woven structure, and then filling the tetrahedron or octahedron cells with another solid. The structure is then transformed similar to the crystal structure of one of the two natural auxetic solids, mentioned above. We evaluate the mechanical and auxetic properties of the material through compression tests on the specimens made of aluminum, followed by numerical analyses. Unlike previous auxetic materials, this material can be mass produced and can absorb ultrahigh energy, needed for heavy duty applications such as a sandwich core of military amour, because the raw material is metallic wire and the fabrication process is uncomplicated, merely comprising conventional metal forming and heat treatment.

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