Microneedle arrays show many advantages in drug delivery applications due to their convenience and reduced risk of infection. Compared to other microscale manufacturing methods, 3D printing easily overcomes challenges in the fabrication of microneedles with complex geometric shapes and multifunctional performance. However, due to material characteristics and limitations on printing capability, there are still bottlenecks to overcome for 3D printed microneedles to achieve the mechanical performance needed for various clinical applications. The hierarchical structures in limpet teeth, which are extraordinarily strong, result from aligned fibers of mineralized tissue and protein‐based polymer reinforced frameworks. These structures provide design inspiration for mechanically reinforced biomedical microneedles. Here, a bioinspired microneedle array is fabricated using magnetic field‐assisted 3D printing (MF‐3DP). Micro‐bundles of aligned iron oxide nanoparticles (aIOs) are encapsulated by polymer matrix during the printing process. A bioinspired 3D‐printed painless microneedle array is fabricated, and suitability of this microneedle patch for drug delivery during long‐term wear is demonstrated. The results reported here provide insights into how the geometrical morphology of microneedles can be optimized for the painless drug delivery in clinical trials.
Creatures in nature possess unique smart material systems that can sense environmental changes with evolved selfresponsible architectures. For example, the Japetella heathi octopus exhibits a remarkable ability to change its appearance to evade the attention of predators. Here, we present an approach to produce Japetella heathi-inspired smart materials with thermal sensing architectures by multimaterial three-dimensional (3D) printing, where both conventional acrylic-based ultraviolet resins and reactive liquid crystals (LCs) are photocured to form an object with desired patterns. The levels of orientational and positional orders of LCs in unique thermodynamic phases (e.g., nematic and isotropic phases) can be modulated by the local temperature of the material. As a result, the 3D printed liquid crystalline materials (within the printed multimaterial object) possess a unique optical property that can reversibly transition from opaque (in the nematic phase) to transparent (in the isotropic phase) in response to external thermal stimuli. The multimaterial 3D printing process provides a versatile manufacturing tool that enables the design and fabrication of bioinspired smart materials with complex 3D shapes for various potential applications, such as soft robots, flexible sensors, and smart anticounterfeiting devices.
Traditional honeycomb‐like structural electromagnetic (EM)‐wave‐absorbing materials have been widely used in various equipment as multifunctional materials. However, current EM‐wave‐absorbing materials are limited by narrow absorption bandwidths and incidence angles because of their anisotropic structural morphology. The work presented here proposes a novel EM‐wave‐absorbing metastructure with an isotropic morphology inspired by the gyroid microstructures seen in Parides sesostris butterfly wings. A matching redesign methodology between the material and subwavelength scale properties of the gyroid microstructure is proposed, inspired by the interaction mechanism between the microstructure and the material properties on the EM‐wave‐absorption performance of the prepared metastructure. The bioinspired metastructure is fabricated by additive manufacturing (AM) and subsequent coating through dipping processes, filled with dielectric lossy materials. Based on simulations and experiments, the metastructure designed in this work exhibits an ultrawide absorption bandwidth covering the frequency range of 2–40 GHz with a fractional bandwidth of 180% at normal incidence. Moreover, the metastructure has a stable frequency response when the incident angle is 60° under transverse electric (TE) and transverse magnetic (TM) polarization. Finally, the synergistic mechanism between the microstructure and the material is elucidated, which provides a new paradigm for the design of novel ultra‐broadband EM‐absorbing materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.