Morphology Design and Precision Control of Microneedles by PμSL 3D Printing.

Microneedles (MNs) hold significant potential for applications in transdermal drug delivery and biosensing. However, when traditional 3D printing technology is used for their manufacture, a substantial deviation in output size occurs. The effects of various parameters on the morphology of MNs produced through microscale 3D printing remain unclear. This study investigated the relationship between the design and fabrication of acrylic resin MNs and their output forms via a projection microstereolithography (PµSL) technology system. Modifying the shape parameters and array configurations elucidates the causes of size deviation and proposes a control strategy. This is particularly significant for the prototyping and mold manufacturing of MNs in relevant fields. This study indicates that a printing layer thickness of 10 µm optimally balances efficiency and clinical conversion requirements. Additionally, an exposure intensity of 65 mW/cm² achieves both a high fidelity and an appropriate base size. The printing angle significantly influences the morphology and mechanical properties of MNs. The diameter and aspect ratio of solid MNs correlate with their dimensional stability. Clinically, conical or quadrilateral MNs with defined parameters are recommended. A critical spacing (≥40 µm) and an optimal arrangement of the MN arrays were established. The specific exposure intensity and vertical printing angle of the hollow MNs ensure the precision of the micropore diameter and wall thickness. This approach offers theoretical insights and process parameters essential for high-precision, customizable MN engineering design.