Oct 27, 2024 In a few of our late virtual events, our audience and speakers began mentioning the word “metamaterial.” True, “meta” seems over-used in media lately. For example, Facebook even rebranded itself after this all-encompassing word, but few people truly understand it, let alone what “metamaterial” really is. This article attempts to clarify that confusion and its relationship to the universe of 3D printing. In short, “meta” frequently signifies going beyond traditional boundaries to look at a system or concept from a higher, more abstract perspective. Similarly, unlike conventional materials like wood or metal, which have characteristics based on their atomic structure, metamaterials derive their unique properties from their design at a microscopic or nanoscopic level. One recent example of metamaterial is “auxetic materials” presented by Dr. Jeong Hun Park. (See video below.) Scientists create these materials by arranging small, often repeating structures (like tiny coils or patterns) in a specific way. This precise structure allows metamaterials to manipulate waves—like light, or sound —in unusual ways.
What is a brief history of metamaterial?
The history of metamaterials is a fascinating journey that spans over a century, with significant developments occurring in the latter half of the 20th century and accelerating into the 21st century. Here’s an overview of the key milestones in the history of metamaterials:
Early Foundations
The concept of artificial materials with unusual properties dates back to the late 19th century. However, the term “metamaterial” wasn’t coined until much later. In 1904, early wave studies related to metamaterials began, progressing through the first half of the 20th century.
Veselago’s Breakthrough
A pivotal moment came in the 1960s when Soviet physicist Victor Veselago proposed some revolutionary ideas:
- In 1967, Veselago theoretically described materials with negative refractive indices.
- He published an article in 1976 detailing the properties of these materials, including unusual light refraction.
These concepts were visionary but beyond the technological capabilities of the time.
Post-World War II Developments
Much of the historical research related to metamaterials is rooted in microwave engineering and antenna beam shaping that emerged after World War II.
Artificial Dielectrics
Throughout the late 1940s, 1950s, and 1960s, research on artificial dielectrics laid the groundwork for metamaterials. These were primarily used in the microwave regime for antenna beam shaping.
Coining of the Term
In 1999, Roger Walser suggested the term “metamaterials” for substances with properties not found in nature.
Practical Realization
The early 2000s marked a significant breakthrough:
- Researchers figured out how to create materials to achieve negative refraction.
- The first samples of metamaterials were made from arrays of thin wires and worked with microwave radiation.
What are the key features of metamaterial?
Artificial Design:
In ordinary materials, properties like strength, flexibility, or conductivity come from the types of atoms they contain and how these atoms are arranged. In metamaterials, however, it’s the overall design of tiny units (often called “unit cells” or “meta-atoms”) that determines how the material behaves. For example, a metamaterial can be designed to bend light “backward,” which would be impossible with natural materials. This happens not because of the atoms themselves but because of how they are arranged in intricate patterns. In other words, designed structures determine behaviors.
Unique Properties:
By carefully designing these structures, we can create materials with extraordinary characteristics. For example, some metamaterials can bend light in ways that seem to defy the laws of physics, like making objects appear invisible (a concept known as “cloaking”). One of the most fascinating properties of some metamaterials is their ability to exhibit a negative refractive index. They can bend light or other waves in the opposite direction compared to ordinary materials. This property opens up possibilities for creating “super lenses” that could potentially image objects smaller than the wavelength of light, previously thought impossible.
Customizable Behavior:
The properties of metamaterials come from their structure rather than their chemical composition. This means we can fine-tune their behavior by adjusting the arrangement of their components.
What is the relationship between metamaterial and 3D Printing?
Metamaterials and 3D printing have a synergistic relationship, with each technology enhancing the capabilities of the other. Metamaterials can introduce novel properties into 3D-printed medical devices and implants that standard materials can’t provide. Some potential areas of advancement include:
Better implants and prosthetics:
A realistic potential benefit of metamaterial in healthcare 3D printing includes accelerating the development of implants with superior mechanical properties (i.e., flexibility, strength, lightweight) in addition to morphologically personalized for individual anatomy. Such implants could be more biocompatible and comfortable and reduce long-term failure rates. However, that is just the low-hanging fruit.
Better diagnostic and therapeutic devices:
The enhanced optic, acoustic, and vibration control of metamaterials, plus the freedom of design from 3D printing, could accelerate an array of diagnostic and therapeutic medical devices. For example, 3D-printed sensors with metamaterial structures can monitor physiological parameters with higher sensitivity and specificity. 3D-printed soft robots with metamaterial can be made more flexible, durable, and responsive, improving existing minimally invasive surgeries.
Better biodegradable implants:
Metamaterials can help design biodegradable implants and tissue scaffolds. These scaffolds provide temporary support for healing tissues and then naturally degrade as the body recovers. With 3D printing, these materials can be precisely customized to degrade at controlled rates, allowing tissues to gradually take over without needing further surgeries to remove the implant.
Conclusion:
In conclusion, metamaterials represent a new frontier in material science. They allow us to push beyond the limitations of naturally occurring materials and design materials with properties tailored to specific applications. They’re reshaping our understanding of how materials can interact with energy and opening up exciting possibilities for future technologies. While metamaterials are very new to us, hence the confusion, the lack of material selection for 3D printing requires us to understand them better because they could be the key to making 3D printing a more powerful tool.
References :
- https://altair.com/blog/articles/beyond-lightweighting-the-benefits-of-3d-printed-metamaterials
- https://en.wikipedia.org/wiki/Metamaterial
- https://en.wikipedia.org/wiki/History_of_metamaterials
- https://serious-science.org/metamaterials-8178
- https://www.nanowerk.com/what-are-metamaterials.php
- https://blog.metamaterial.com/what-are-metamaterials
Related Links:
3D Printing & Biofabrication For Breast Reconstruction (On Demand, 2024)
3DHEALS Biomaterials 2024 (On Demand, 2024)
Interview with Dr. Jeong Hun Park: Auxetics For Soft Tissue Engineering
Interview with Julien Payen: Lattice Medical
Interview Dr. Mohit Chhaya: BellaSeno
Interview with Esther Valliant: Bioglass for 3D Printing
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