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A microneedle has been greatly recognized as one of the most promising devices for novel transdermal drug delivery system due to its capacity of piercing the protective stratum corneum with a minimally invasive and painless manner. During the past two decades, although numerous achievements have been made in the structure and material combination of microneedles, they mostly focus on the pharmacology and functionality of microneedles, and little is reported about how to design the shape of microneedles to reduce insertion force and especially improve penetration efficiency. Using the developed finite element method, we designed three-section microneedles (TSMN) with various sizes and evaluated their maximum insertion force, penetration efficiency, drug delivery amount and strength. The simulation results demonstrate that the well-designed TSMN with shaft width of 60 μm exhibits a lower maximum insertion force of 116.68 mN relative to 167.92 mN of conical microneedle and an effective penetration length of 81.6% relative to 71.38% of conical microneedle. Besides, the optimized TSMN with shaft width of 80 μm shows similar maximum insertion force and 2.3 times the drug delivery amount compared to conical microneedle. These excellent properties are attributed to the optimized design of the shape curve of TSMN sidewall. Such results may provide an inspiration of microneedle design for low insertion force and high penetration efficiency. [ABSTRACT FROM AUTHOR]

Anti-reflective structure can effectively suppress the light reflection on the surface of the object, thereby increasing the absorption of light, it has a wide range of applications in photovoltaics, such as optical sensors and photodetectors. Due to the limitation of low refractive index materials, it is difficult for existing anti-reflective coatings to achieve the expected low reflectance effect. Based on Maxwell's electromagnetic wave theory, this paper uses Finite-Difference Time-Domain (FDTD)-solutions software to research the reflection spectrum of silicon-based pyramidal microstructure in the wavelength range of 200–1400nm, explores the influence of the height (H) and bottom side length (L) of the pyramidal on its reflection spectrum, and studies the changes of its electromagnetic field. On this basis, the absorption performance of the silicon-based pyramidal microstructure is further studied, and it is found that the absorption efficiency of silicon-based pyramidal microstructure for ultraviolet light reaches almost 100%, which provides important significance for its application in optical sensors and photodetectors. Anti-reflective structures are capable of significantly reducing light reflection on object surfaces, thereby minimizing optical losses. This study explores silicon-based pyramidal microstructures that demonstrate superior anti-reflective characteristics, with near-negligible reflection in the ultraviolet spectrum, approaching ideal absorption. The reliability of the absorption formula is confirmed through an analysis of the electric field properties. [ABSTRACT FROM AUTHOR]