(a) Schematic showing the screen-printing process. (b) Image of the Chem–Phys printing stencil. (c) An array of printed Chem–Phys flexible patches. (d) Image of a Chem–Phys patch along with the wireless electronics. (e) Schematic showing the LOx-based lactate biosensor along with the enzymatic and detection reactions. (f) Block diagram of the wireless readout circuit.