Figure 6.

Combinatorial drug microneedle patch for the simultaneous dual delivery of different payloads. a) Schematic of square microneedle arrays as different active and passive compartments. b) Digital photograph of a 3D printed microneedle array by stereolithography and SEM images of needle rows with equal spacing. Scale bars, 5 mm, 1 mm, and 500 μ m respectively. c) Schematic of a combinatorial dissolvable microneedle patch with two different microneedle compartments (active and passive). d) Side-by-side SEM image of active and passive microneedles along with the corresponding EDX images illustrating the Mg in magenta, and C in cyan. Scale bars, 500 μ m. e) Digital photograph of a combinatorial dissolvable microneedle patch loaded with FITC (passive delivery compartment) and Rh6G + Mg particles (active delivery compartment). Scale bar, 5 mm. f) Side-by-side optical and fluorescence microscopy images showing active and passive microneedles. Scale bars, 500 μ m. g) Fluorescence time-lapse images show the dissolution of an active microneedle tip at 10 s intervals. Scale bars, 500 μ m. h) Fluorescence time-lapse images showing the dissolution of a passive microneedle tip. Scale bars, 500 μ m.