Fig. 3. (A) Fabrication of the GelMA MN patch. The patch was prepared by a molding approach, in which the GelMA prepolymer was cast into a predesigned mold by centrifugation. (B) Workflow of ISF extraction and target molecule recovery using the GelMA MN patch. (C) SEM images showing the side view of the GelMA MN array. Appearance of the GelMA MN patch (D and E) before and (F and G) after pressing against the agarose hydrogel. (H) Detected glucose concentrations in ISF compared to glucose concentrations in blood. (I) Detected vancomycin (VCM) concentrations in ISF compared to VCM concentrations in plasma (reproduced from ref. 77 with the permission of John wiley & Sons, Inc, copyright 2020).