MIT News November 20, 2024 Challenges in miniaturizing and characterizing acoustic metamaterials in high-frequency (megahertz) regimes have hindered progress toward experimentally implementing ultrasonic-wave control. A team of researchers in the US (MIT, Kansas City National Security Campus) presented an inertia design framework based on positioning microspheres to tune responses of 3D microscale metamaterials. They demonstrated tunable quasi-static stiffness by up to 75% and dynamic longitudinal-wave velocities by up to 25% while maintaining identical material density. The researchers explored the tunable static and elastodynamic property relation. According to the researchers their design framework expands the quasi-static and dynamic metamaterial property space […]
Tag Archives: Metamaterials
This screen stores and displays encrypted images without electronics
Nanowerk September 17, 2024 While computation functions have been demonstrated in mechanical systems, they rely on compliant mechanisms to achieve predefined states, which impose inherent design restrictions that limit their miniaturization, deployment, reconfigurability, and functionality. Researchers at the University of Michigan describe a metamaterial system based on responsive magnetoactive Janus particle (MAJP) swarms with multiple programmable functions. They designed MAJPs with tunable structure and properties in mind, that is, encoded swarming behavior and fully reversible switching mechanisms, to enable programmable dynamic display, non-volatile and semi-volatile memory, Boolean logic, and information encryption functions in soft, wearable devices. According to the researchers […]
A new metamaterial concept offering the potential for more efficient data storage
Nanowerk July 16, 2024 Researchers in Germany demonstrated that not just individual bits, but entire bit sequences can be stored in cylindrical domains. They used high perpendicular magnetic anisotropy synthetic antiferromagnets in the form of multilayer-based metamaterials whose antiferromagnetic interlayer exchanged energy was purposefully reduced below the out-of-plane demagnetization energy controlling magnetic domain formation. They demonstrated via macroscopic magnetometry and microscopic Lorentz transmission electron microscopy, that it was possible to stabilize nanometer-scale stripe and bubble textures consisting of ferromagnetic out-of-plane domain cores separated by antiferromagnetic in-plane Bloch-type domain walls. According to the researchers this coexistence of mixed ferromagnetic/antiferromagnetic order on […]
Micro-optical technology based on metamaterials takes center stage
Phys.org August 30, 2023 To date research on metasurfaces has mainly focused on the full control of electromagnetic characteristics, including polarization, phase, amplitude, and even frequencies. Consequently, versatile possibilities of electromagnetic wave control have been achieved, yielding practical optical components such as metalenses, beam-steerers, metaholograms, and sensors. Researchers in South Korea focused on integrating the metasurfaces with other standard optical components for commercialization with miniaturization trends of optical devices. In this review they described and classified metasurface-integrated optical components, and subsequently discussed their promising applications with metasurface-integrated optical platforms including those of augmented/virtual reality, light detection and ranging, and sensors. […]
New method simplifies the construction process for complex materials
MIT News August 2, 2023 Cellular metamaterials are small scale, tileable structures that can be architected to exhibit many useful material properties. But their “architectures” vary widely making it difficult to explore them using existing representations. An international team of researchers (USA – MIT, Austria) created a technique to include many different building blocks of cellular metamaterials into one, unified graph-based representation using which engineers can quickly and easily model metamaterials, edit the structures, and simulate their properties. Their procedural graph succinctly represents the construction process for any structure using a simple skeleton annotated with spatially varying thickness. To express […]
Scientists presents a one-step laser synthesis method for fabricating wideband microwave absorption metamaterial
Phys.org July 13, 2023 Microwave absorption in radar stealth technology is faced with challenges in terms of its effectiveness in low-frequency regions. An international team of researchers (UK, Singapore) has developed a new laser-based method for producing an ultrawideband metamaterial-based microwave absorber with a highly uniform sheet resistance and negative magnetic permeability at resonant frequencies, which results in a wide bandwidth in the L- to S-band. The electrical sheet resistance uniformity was achieved with less than 5% deviation resulting in a microwave absorption coefficient between 97.2% and 97.7% within a 1.56–18.3 GHz bandwidth for incident angles of 0°–40°, and there […]
Physicists develop a metamaterial that can count
Phys.org July 3, 2023 Researchers in the Netherlands have designed irreversible metamaterials that count mechanical driving cycles and store the result into easily interpretable internal states. They extended the designs to aperiodic metamaterials that were sensitive to the order of different driving magnitudes and realized “lock and key” metamaterials that only reach a specific state for a given target driving sequence. The metamaterials were robust, scalable, and extendable, gave insight into the transient memories of complex media, and opened new routes towards smart sensing, soft robotics, and mechanical information processing. Video https://youtu.be/soO2OzbdRzU… read more. TECHNICAL ARTICLE
New research on self-locking light sources presents opportunities for quantum technologies
Nanowerk June 19, 2023 An international team of researchers (Argentina, Germany) demonstrated that light emitters with different resonance frequencies can asynchronously self-lock their relative energies by exchanging mechanical energy. They introduced polaromechanical metamaterials, two-dimensional arrays of μm-sized traps confining zero-dimensional light-matter polariton fluids and GHz phonons. A strong exciton-mediated polariton-phonon interaction induced a time-dependent inter-site polariton coupling J(t) with remarkable consequences for the dynamics. When locally perturbed by continuous wave optical excitation, a mechanical self-oscillation started and polaritons responded by locking the energy detuning between neighbor sites at integer multiples of the phonon energy showing asynchronous locking involving the polariton […]
Researchers discover new radiation effects in photonic time crystals
Phys.org April 26, 2023 Time metamaterials offer a great potential for wave manipulation. Researchers at the City University of New York explored the exotic wave dynamics of an anisotropic photonic time crystal (APTC) formed by an anisotropic medium whose optical properties are uniformly and periodically changed in time. Based on a temporal transfer matrix formalism, they showed that a stationary charge embedded in an APTC emits radiation, in contrast to the case of isotropic photonic time crystals, and its distribution in momentum space is controlled by the APTC band structure. According to the researchers their approach greatly extends the concept […]
Researchers show a new way to induce useful defects using invisible material properties
Nanowerk December 23, 2022 Researchers at the University of Illinois constructed a Dirac material consisting of a chain of magnetic-mechanical resonators and demonstrated that when any of these “atoms” was mechanically excited the excitation spread to the rest of the crystal, just like electrons injected into a semiconductor. After demonstrating that a completely uniform Dirac metamaterial does not allow mechanical excitations to pass through, they introduced a specific set of nonlinearities into the system. This new property added sensitivity to the level of the mechanical excitation and could subtly change the resonance energy of the magneto-mechanical atoms. With the right […]