Programmable activation of mechanical metamaterial using stiffness controllable mechanical pixels

Department of Materials Science and EngineeringSoft materials with negative Poisson???s ratio, also known as auxetics, have been studied since they have unique and unusual mechanical properties induced by abrupt instability under applied external pressure. For instance, periodic void array in 2D structure is one of the common auxetic structures that have been studied with making a variation with changing void???s shape or porosity24-26. However, formal research on auxetic materials focus on the structural changes. Therefore, coupling the material???s characteristics and unique structures of auxetics would pave the way to develop advanced mechanical metamaterials. Here, I developed a mechanical metamaterial with void array integrated with smart materials. Through this approach, I could actively control the macroscopic properties of the engineered material through modifying the stiffness of voids. Each void is comprised of three distinct layers, which are a conductive heating layer, phase-transition layer, and silicone rubber layer. Two electric wires are embedded in the conductive heating layer to make control of each void???s stiffness, and these voids are named as mechanical pixel. The phase transition layer is the core element in this structure because it is stiff when they are in solid phase and become compliant when they are in liquid phase. This layer melts down when the conductive heating layer are heated through Joule heating. Availability of pixelated control of each conductive heating layer, this offer tunable material attribute to the conventional auxetic structure. The programmable activation of the structure provides me to exhibit diverse patterned deformation, and fixation of the deformed shape. I believe these combined properties of materials, and the unusual structure (mechanical metamaterial) will give a novel design and idea to other soft material-based systems, such as wearable devices and soft robotics.clos

Multifunctional micro/nanomotors as an emerging platform for smart healthcare applications

Self-propelling micro- and nano-motors (MNMs) are emerging as a multifunctional platform for smart healthcare applications such as biosensing, bioimaging, and targeted drug delivery with high tissue penetration, stirring effect, and rapid drug transport. MNMs can be propelled and/or guided by chemical substances or external stimuli including ultrasound, magnetic field, and light. In addition, enzymatically powered MNMs and biohybrid micromotors have been developed using the biological components in the body. In this review, we describe emerging MNMs focusing on their smart propulsion systems, and diagnostic and therapeutic applications. Finally, we highlight several MNMs for in vivo applications and discuss the future perspectives of MNMs on their current limitations and possibilities toward further clinical applications.11Nsciescopu

Ultrastrong Coupling Enhancement with Squeezed Mode Volume in Terahertz Nanoslots

Metallic nanogaps have emerged as a versatile platform for realizing ultrastrong coupling in terahertz frequencies. Increasing the coupling strength generally involved reducing the gap width to minimize the mode volume, which presents challenges in fabrication and efficient material coupling. Here, we propose employing terahertz nanoslots, which can efficiently squeeze the mode volume in an extra dimension alongside the gap width. Our experiments using 500 nm wide nanoslots integrated with an organic–inorganic hybrid perovskite demonstrate ultrastrong phonon–photon coupling with a record-high Rabi splitting of 48% of the original resonance (Ω = 0.48ω0), despite having a gap width 5 times larger than previously reported structures with Ω = 0.45ω0. Mechanisms underlying this effective light–-matter coupling are investigated with simulations using coupled mode theory. Moreover, bulk polariton analyses reveal that our results account for 68% of the theoretical maximum Rabi splitting, with the potential to reach 82% through further optimization of the nanoslots