Geometric Parameter Optimization of 3D-Printed Microneedle Arrays Based on Comprehensive Mechanical Testing and Failure Analysis

This study provides a systematic mechanical characterization and manufacturing analysis of stereolithography-printed microneedle arrays across six geometric designs (300-400 μm diameter and three aspect ratios: 2:1, 3:1, and 4:1) and three array configurations (1 × 1, 5 × 5, 10 × 10). Compression testing to 50 N revealed geometry-dependent optimization: low-aspect-ratio designs (Designs 1, 4, 5) exhibited superior performance in high-density arrays (10 × 10), while high-aspect-ratio designs (Designs 2, 3) performed better as single needles. Manufacturing success rates increased significantly with array density: from 44.2% (95% CI: 41.1-47.3%) for single needles to 67.3% (95% CI: 63.2-71.4%) for 10 × 10 arrays, with 400 μm diameter designs showing higher reliability. Two-way ANOVA confirmed significant effects of both geometric design [F(5, 72) = 145.3, <i>p</i> < 0.001, η² = 0.91] and array configuration [F(2, 72) = 78.2, <i>p</i> < 0.001, η² = 0.68] on compressive displacement. Design 5 (400 μm diameter, 3:1 aspect ratio) in a 10 × 10 format exhibited optimal mechanical characteristics, including controlled displacement (0.578 ± 0.036 mm), a high safety factor (SF = 13.32), and a superior manufacturing yield. These findings provide quantitative design guidelines for optimizing 3D-printed microneedle arrays.