Shock-Absorbing, Reusable Body Armor

Mechanical engineers from Johns Hopkins University in Baltimore have found a new way to build body armor with a lightweight elastomer material that relies on a complex liquid crystal structure. The resulting armor is “lighter, stronger, and reusable,” according to the university’s press release. That could be a game-changer in the highly deformable world of body armor.

Sung Hoon Kang—senior author of the new paper, published in February in the journal Advanced Materials—is part of the tantalizingly named Hopkins Extreme Materials Institute (HEMI), established in 2012 to study “science associated with materials and structures under extreme conditions and demonstrating extreme performance.” Its projects are funded by organizations like the U.S. Department of Energy and the National Science Foundation, with areas of study including things like how materials behave in Earth’s mantle.

It’s easy to see how Earth’s mantle is extreme, with some of the highest temperatures and pressures on the planet. Body armor is a different application, but something that is still very extreme: absorbing gunshots, for example, and spreading that energy out in a way that does not harm the wearer is no small feat.

We are excited about our findings on the extreme energy absorption capability of the new material,” Kang says in the statement.

The idea of a material that can outperform today’s helmets and car bumpers piqued Kang’s curiosity. One of the major areas for improvement is deformation, which is the way the force of an impact presses material way out of shape. Think of a car’scrumple zone,” which is literally designed to collapse to absorb impact; you’re not exactly “reusing” that portion of the car afterward, especially in higher-speed crashes.

Many helmet and impact-absorbing materials dissipate energy through inelastic mechanisms, such as plastic deformation and fracture and fragmentation. However, these materials can become permanently damaged after one-time usage and are not suitable for repeated use,” the researchers write.

So if the non-reusable mechanisms are inelastic—which makes sense, the opposite of elastic and therefore unable to “bounce back”—how do we do things differently? This is where the idea of metamaterials comes into play. A metamaterial is something carefully engineered on the micro-scale to have properties that a simple layer of plywood or metal would not have. The goal is to build better functionality starting at the atomic level.


Augmented Reality A Hundred Times Less Expensive

Zombies or enemies flashing right before your eyes and the dizzying feeling of standing on the edge of a cliff using virtual reality and augmented reality (AR and VR) are no longer exclusive to the games or media industries. These technologies allow us to conduct virtual conferences, share presentations and videos, and communicate in real time in virtual space. But because of the high cost and bulkiness of VR and AR devices, the virtual world is not currently within easy reach.

Recently, a South Korean research team developed moldable nanomaterials and a printing technology using , allowing the commercialization of inexpensive and thin VR and AR devices.

Professor Junsuk Rho of the departments of mechanical engineering and chemical engineering and doctoral student in mechanical engineering Gwanho Yoon at POSTECH with Professor Heon Lee and researcher Kwan Kim of the department of material science at Korea University have jointly developed a new nanomaterial and large-scale nanoprinting technology for commercialization of metamaterials. The research findings, which solve the issue of device size and high production that were problematic in previous research, were recently published in Nature Communications.

Metamaterials are substances made from artificial atoms that do not exist in nature but freely control the properties of light. An invisible cloak that makes an illusion of disappearance by adjusting the refraction or diffraction of light, or metaholograms that can produce different hologram images depending on the direction of light’s entrance, uses this metamaterial. Using this principle, the ultrathin metalens technology, which can replace the conventional optical system with extreme thinness, was recently selected as one of the top 10 emerging technologies to change the world at the World Economic Forum last year.

In order to make metamaterials, artificial atoms smaller than the wavelengths of light must be meticulously constructed and arranged. Until now, metamaterials have been produced through a method called electron beam lithography (EBL). However, EBL has hindered the commercialization or production of sizable metamaterials due to its slow process speed and high cost of production. To overcome these limitations, the joint research team developed a new nanomaterial based on nanoparticle composite that can be molded freely while having optical characteristics suitable for fabricating metamaterials. The team also succeeded in developing a one-step printing technique that can shape the materials in a single-step process.


3D Printed Metamaterials With Super Optical Properties

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is possible using conventional optical or electronic materials. The fabrication methods developed by the researchers demonstrate the potential, both present and future, of 3D printing to expand the range of geometric designs and material composites that lead to devices with novel optical properties. In one case, the researchers drew inspiration from the compound eye of a moth to create a hemispherical device that can absorb electromagnetic signals from any direction at selected wavelengths.

The geometry of a moth’s eye provides inspiration for a 3D printed antenna that absorbs specific microwave frequencies from any direction

Metamaterials extend the capabilities of conventional materials in devices by making use of geometric features arranged in repeating patterns at scales smaller than the wavelengths of energy being detected or influenced. New developments in 3D printing technology are making it possible to create many more shapes and patterns of metamaterials, and at ever smaller scales. In the study, researchers at the Nano Lab at Tufts describe a hybrid fabrication approach using 3D printing, metal coating and etching to create metamaterials with complex geometries and novel functionalities for wavelengths in the microwave range. For example, they created an array of tiny mushroom shaped structures, each holding a small patterned metal resonator at the top of a stalk. This particular arrangement permits microwaves of specific frequencies to be absorbed, depending on the chosen geometry of the “mushrooms” and their spacing. Use of such metamaterials could be valuable in applications such as sensors in medical diagnosis and as antennas in telecommunications or detectors in imaging applications.

The research has been published in the journal Microsystems & Nanoengineering (Springer Nature).