Dynamic mechanical insertion analysis of gelatin methacryloyl microneedles under realistic insertion conditions

Despite the great potential of Gelatin Methacryloyl (GelMA) microneedles (MNs) for minimally invasive drug delivery and interstitial fluid extraction, their performance under realistic insertion conditions and across diverse geometrical and mechanical parameters has remained uncharacterized. In this study, dynamic and static finite-element analyses were conducted for the first time to compare three types of crosslinked GelMA MNs: conical, pyramidal, and tapered-conical with and without base support. Insertion force, von Mises stress, and safety factors were evaluated at insertion velocities of 2-6 m/s under varying crosslinking times and polymer concentrations. The tapered-conical geometry demonstrated the best overall mechanical reliability, combining moderate insertion forces with exceptional bending and buckling resistance. Adding a minimal base support further reduced peak stresses and smoothened insertion profiles by up to 20%. Rate-dependent simulations identified an optimal insertion speed of 3-4 m/s that minimizes tissue stress by balancing viscoelastic deformation and impact effects. Longer crosslinking and higher polymer concentrations slightly enhanced needle stiffness and reduced skin stress without increasing penetration force. Together, these results establish a comprehensive design approach that integrates needle geometry, mechanical properties, and applicator dynamics to guide the development of GelMA MN arrays with improved safety and efficacy for clinical translation.