Figure 2.

Fabrication and characterization of 3D-printed MNAs. A) Schematic of 3D-printing MNAs showing i) the fabrication process and ii) a representative computer model view of the designed hollow MNAs. B) Microscopic image of sample MNAs. C) SEM images of i) front view and ii) top view of a single hollow needle. D) Multimaterial printing of MNAs for creating rigid needles on a flexible base. E) The characterization of the mechanical properties of MNA islands (four needles) (n = 4). F) Microscopic view of MNAs i) before and ii) after pig skin penetration test (n = 4). G) Characterization of the insertion and pull out force of the MNA islands applied to pig skin and image of pig skin targeted with painted MNAs (inset).