This study investigates the potential enhancement in model drug (acid/dye) delivery by integrating microneedle (MN) technology with iontophoresis (ITP), focusing on transitioning from cone-shaped MNs to bio-inspired variants. It aims to assess the influence of altering MN geometry, particularly incorporating barbs on bio-inspired MNs, on the electric field, and surface area to understand their impact on acid/dye delivery. Anticipated outcomes suggest increased penetration depth of model drugs over time using bio-inspired MNs with ITP, indicating superior model drug delivery across gel. Detailed findings and comparative analyses elucidate differences in penetration depths between bio-inspired and cone MN configurations, providing insight into drug delivery efficiency. The study merges bio-inspired MNs with ITP for enhanced transdermal model drug delivery (TDD).

Using COMSOL Multiphysics 6.1, parameters like voltage distribution, electric field strength, and drug concentration within the skin are simulated. Bio-inspired MNs show superior electric field strengths, particularly at their edges, augmenting electrophoretic and diffusive flux, thereby improving drug concentrations within the skin. The maximum electric field strength measured is 50 V/m for cone MNs and significantly higher at 900 V/m for bio-inspired MNs, concentrated particularly at the edges of the bio-inspired MNs in contrast to the overall surface of cone MNs.

Length of created channels by cone MN is 1600 m and by bio-inspired is 2400 μm. Moreover, the combined effect of cone MNs and ITP exhibits the deepest penetration, reaching ~2000 μm after 10 mins. The implementation of ITP as a driving force further amplifies the model drug's permeation through the punctured gel. Ultimately, bio-inspired microneedle array (MA) and ITP achieve a remarkable and synergistic enhancement in dye and acid delivery. The confluence of bio-inspired MA and ITP displays the deepest penetration depth, reaching ~2600 μm after 10 mins.

The diffusion of the model drug through microholes created by the cone MA significantly enhances permeation, reaching a depth of approximately 1000 μm, even without the application of ITP. Similarly, the bio-inspired MA-created microholes allow for model drug diffusion to deeper layers, enhancing permeation up to ~1400 μm without ITP after 10 mins. Higher fluorescence intensity, observed specifically in microholes created by the bio-inspired MA,signifies a more extensive diffusion of the model drug solution into deeper gel layers facilitated by these microholes.

The investigation covers design, fabrication, experimental investigations, and discussions on outcomes and synergies between MNs and ITP. Examining varied MN geometries' impact on model drug permeation rates promises advancements in drug delivery methods.