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.

The inherent fog collection mechanism used by the cactus gives inspirations for constructing energy‐efficient and environmentally friendly water collection devices. However, the related studies meet the bottleneck on improving the collection efficiency because it is hard to replicate real natural clusters of branched spines by traditional manufacturing methods. The immersed surface accumulation based 3D printing provides a tool to reproduce branched cactus spines, enabling the study of water collection of artificial spines with various designs. Here, a cactus‐inspired surface decorated with multiple directional artificial spines for highly efficient water collection and transportation is presented. The nanoscale hydrophobic coating is sputtered on the surface of the 3D‐printed spines to accelerate the water growth rate. The results show that the hexagonally arranged clusters enhance the moisture airflow around 3D‐printed spines, and the printed spines with 10° tip angle and hydrophobic coating achieve the highest weight gain of 2 mg min−1 mm−3. This study opens intriguing perspectives for designing next‐generation structural materials with the special spatial distribution of biomimetic features to achieve energy free and highly efficient water collection. The results reported here are believed to be helpful for the development of environmental friendly water collection, water transportation, and water separation devices.

No abstract

No abstract

Waste energy harvest using thermoelectric (TE) materials will be a potential solution to the serious environmental pollution and energy shortage problems. Due to limitations of current manufacturing techniques in geometry complexity and high density, TE devices are not widely utilized in daily life to gather waste energy. 3D printing brings an opportunity to solve the fabrication limitations. In this paper, a hybrid process was developed to fabricate thermoelectric materials by integrating hot pressing with stereolithography. The mold and punch were designed and printed to fabricate thermoelectric devices used on hot water tubes via stereolithography. The Sb2Te3 powders filled the 3D printed mold in a layered manner, and each layer of powders was compacted under the pressing of punch at a certain temperature and compressive force. The polymer mold was removed after the sintering process to form the final TE components. A series of experiments were conducted to identify the optimal heating temperature and compressive force. The microstructures morphology and electrical conductivity of fabricated Sb2Te3 samples were evaluated. This research work conducted a scientific investigation into the fabrication of TE material with a hybrid process, including hot pressing and 3D printing, to solve the current manufacturing challenges, providing perspectives on developments of TE devices used in various energy harvest applications.