Combined Harpoonlike Jagged Microneedles Imitating Mosquito's Proboscis and Its Insertion Experiment with Vibration

Imitating the mosquito's proboscis, the combined microneedles comprising a central straight needle and two outer jagged needles have been already proposed by the authors, and the effectiveness of these needles for easy insertion was investigated by the finite element method (FEM) simulation. Following this, in the present paper, silicon microneedles are practically fabricated by using a silicon on insulator (SOI) wafer and deep reactive ion etching (DRIE) process. A sole straight needle, a sole jagged needle, and combined jagged needles are employed. The fabricated shape and size of the harpoon‐like jagged protrusions are almost the same as the mosquito's. The resistance force during inserting these fabricated needles into an artificial skin of silicone rubber is experimentally investigated. Comparing the results, the effect of combining needles for easy insertion is confirmed. It is also confirmed that applying vibration to the needles with jagged shape is fairly effective for easy insertion. The mechanisms of employing jagged shape needles, applying vibration, and combining needles are discussed. For practical medical applications, a silicon needle is not safe enough on the human body owing to its brittleness. To cope with this problem, coating the silicon surface with biocompatible parylene is proposed. It is proved that parylene‐coated needle surely penetrates silicone rubber, although the necessary force increases.