Influence of Low-Frequency Vibration and Skin Strain on Insertion Mechanics and Drug Diffusion of PVA/PVP Dissolving Microneedles

Influence of Low-Frequency Vibration and Skin Strain on Insertion Mechanics and Drug Diffusion of PVA/PVP Dissolving Microneedles

Microneedles (MNs) offer a promising solution for increasing the effectiveness of transdermal drug delivery and diagnostics. However, challenges such as large-scale manufacturing, partial MN penetration, and uncontrolled drug delivery limit the effectiveness of the technology. To overcome these challenges, current research examines the effects of skin strain and vibration on MN insertion and drug delivery. A novel multifeatured impact applicator are developed for improving skin insertion that features a combination of skin stretching, eccentric rotating mass (ERM), and linear resonant actuator (LRA) micro-vibration capabilities. In addition, a scalable replication method for dissolving microneedle patches (DMNPs) are developed using two-photon polymerization (TPP) and soft embossing processes. The DMNPs are used to evaluate the diffusion and concentration of a model drug, fluorescein sodium salt (FSS), when applied using ERM and LRA micro-vibration at different frequencies. Additionally, a new computer simulation method is presented to model the MN insertion into the multilayered hyperelastic skin model, incorporating skin strain and vibrational effects. The results indicate that applying skin strain and vibration decreases the force required for MN insertion and enhances the dissolution and diffusion depth of the drug in the skin, which can enhance the drug permeability and effectiveness of MN devices.