Biocompatible 3D Printed Microneedles for Transdermal, Intradermal, and Percutaneous Applications

Microneedles (MNs) are playing an increasingly important role in biomedicalapplications, where minimally invasive methods are being developed that requireimperceptible tissue penetration and drug delivery. To improve the integration ofMNs in microelectromechanical devices, a high-resolution 3D printing techniqueis implemented. A reservoir with an array of hollow MNs is produced. Theflowrate through the MNs is simulated and measured experimentally. The mechan-ical properties of the 3D printed material, such as elasticity modulus and yieldstrength, are investigated as functions of printing parameters, reaching maxi-mum values of 1750.7 and 101.8 MPa, respectively. Analytical estimation of theMN buckling, fracture, and skin penetration forces is presented. Penetration testsof MNs into a skin-like material are conducted, where the piercing force rangesfrom 0.095 to 0.115 N, confirming sufficient stability of MNs. Furthermore, 200and 400μm-long MN arrays are used to successfully pierce and deliver intomouse skin with an average penetration depth of 100 and 180μm, respectively.A biocompatibility assessment is performed, showing a high viability of HCT 116cells cultured on top of the MN’s material, making the developed MNs a veryattractive solution for many biomedical applications