(A) Picture of a patterned AgNWs layer deposited on a hydrophobic PTFE filter membrane. Six 1.5 mm diameter circular spots are arranged with a radial bicycle spokes-like geometry. The AgNWs linear components have lengths of 2 mm and widths of 0.5 mm, respectively. (B) Schematic representation of a wearable SERS-active chip. The AgNWs@PTFE substrate is “sandwiched” between biocompatible and adhesive Tegaderm^TM and Leukomed^® T tapes. Both PTFE membrane and Leukomed^® T tape are drilled in the centre in order to obtain an hole with a diameter of 2 mm that allows the direct flow of sweat from the skin to the hydrophilic AgNWs on top of PTFE. The Tegaderm^TM tape instead acts as transparent and protective layer of the entire chip.