Fabrication‐Aware Mechanical Design of SLA ‐Printed Polymeric Microneedles: Integrating Geometry, Dimensional Fidelity, and Structural Instability

ABSTRACT

Stereolithography (SLA) enables rapid fabrication of polymeric microneedles with tunable geometries, but their mechanical response depends on both nominal CAD parameters and fabrication‐induced dimensional deviations. Here, we investigated how microneedle architecture, dimensional fidelity, and slenderness influence the compressive response and insertion performance of SLA‐printed polymeric microneedles. Conical and pyramidal arrays with systematic variations in basal dimension and height were characterized in terms of height, basal dimension, tip‐region dimension, and base‐to‐tip ratio. Axial compression tests showed that increasing basal dimension generally increased resistance to deformation, whereas increasing height promoted more compliant and instability‐sensitive responses. Experimental instability loads were determined from force–displacement curves and compared with Euler–Johnson‐based predictions using nominal CAD geometry, as‐printed equivalent‐section geometry, and a local critical‐section approximation based on measured tip‐region dimensions. The global as‐printed equivalent‐section model markedly overestimated the experimental instability loads, whereas the local critical‐section representation provided the closest agreement for both geometries. Optical Coherence Tomography of multilayer Parafilm M provided complementary assessment of microchannel formation under insertion‐like conditions. These findings establish a fabrication‐aware framework for mechanically evaluating SLA‐printed polymeric microneedles.