Fig. 3From: Rapid biodegradable microneedles with allergen reservoir for skin allergy testImages of PVP-MAA MN patch. a Optical image of 4 × 4 MN patch containing Rhodamine B (scale bar = 2 mm). SEM images of a single MN (scale bar = 200 µm) (b) and 4 × 4 MN patch (scale bar = 2 mm) (c, d)Back to article page