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Fabrication and Characterization of a Biodegradable Hollow Microneedle from Chitosan

A biodegradable chitosan-acetate microneedle is developed based on the proboscis of a mosquito, which consists of chitin and protein. The formability of chitosan, which is a deacetylated compound of chitin, is improved by dissolving it in dilute acetic acid. Thereafter, the dissolved chitosan is coated around an Al wire by a dip-coating method, followed by drying. Afterward, the Al wire is removed by etching using an alkaline solution to form the chitosan micropipe. Subsequently, the micropipe is baked at 200°C for 0.20 min. The optimum baking time was found to be 17 min. Finally, the micropipe is cut and its tip sharpened to transform it into a microneedle with a length, an outer diameter, and an inner diameter of 4 mm, 150 μm, and 100 μm, respectively. The Young’s modulus of the fabricated chitosan microneedle is approximately 10 GPa. This microneedle could be inserted into an artificial skin made of silicone rubber without buckling, and it could aspirate blood from a frog at a rate of 2.5 μL/s.