The microneedle array was fabricated by Anycubic SLA printer, which has a XY resolution of 16.8 × 24.8 μm. As shown in Figure , the hollow microneedle array was composed of 5 × 5 HMN array (12 × 12 × 1.5 mm, L × W × H) with side openings (hole diameter of 0.16 mm) and throughmicrochannels (diameter of 0.6 mm). The base diameter, tip diameter, wall thickness and length of each HMN were 750 μm, 100 μm, 75 μm and 1000 μm, respectively. The center-to-center interspacing between HMN tips was optimized to 2 mm for optimal skin permeability and a reduction of insertion force . For superior sharpness and dimensional accuracy, the HMN patch was printed with a 45° print angle along X and Y axes with the side opening of the HMNs facing downward . The scanning electron microscopy (SEM) image, shown in Figure depicts the morphology of the printed HMNs.