Fig. 4.

Skin permeabilization methods. a Skin abrasion device, in which a sandpaper device is placed on the skin (1), scraped across the skin in a controlled fashion (2) and then a vaccine patch is applied to the abraded skin (3) (Courtesy of Intecell). b Hand-held skin electroporation device, which uses microneedles as electrodes to cause highly localized electroporation in the skin to facilitate DNA vaccine delivery into skin cells (Courtesy of Cyto Pulse Sciences). c Heat-based device for thermal ablation of the skin. The microheater array (left side of inset) is used to ablate the skin and then a vaccine patch (right side of inset) is applied to the ablated skin (Courtesy of Altea Therapeutics)