Design, analysis and fabrication of solid polymer microneedle patch using CO₂ laser and polymer molding

Microneedle-based transdermal drug delivery into the skin has gained attraction for the past few years. An affordable and effective fabrication methodology is required for the development of micron size needle. Manufacturing cost-effective microneedle patches in batch production is a challenging process. In this work, we proposed a cleanroom-free technique for fabrication of conical and pyramidal geometry of microneedle array for transdermal drug delivery. Using the COMSOL Multiphysics tool, the mechanical strength of the designed microneedle array under axial, bending, and buckling loads for the geometries during skin insertion was investigated. A CO₂ laser and polymer molding technique are used to fabricate 10 × 10 designed microneedle array structure. On an acrylic sheet, a designed pattern is engraved to produce a 20 mm × 20 mm sharp conical and pyramidal shape master mold. We successfully created a biocompatible polydimethylsiloxane (PDMS) microneedle patch with an average height of 1200 µm, base diameter of 650 µm, and a tip diameter of 50 µm using acrylic master mold. According to structural simulation analysis, the microneedle array will experience resultant stress that is within a safe range. The mechanical stability of the fabricated microneedle patch was investigated using hardness test and universal testing machine. The depth of penetration studies were performed in an in vitro Parafilm^® M model by manual compression tests and its detailed insertion depth was reported. The developed master mold is efficient to replicate several polydimethylsiloxane microneedle patches. The proposed combined method of laser processing and molding mechanism is simple and low-cost for rapid prototyping of microneedle array.