A, Operation mechanism and system construct of a soft electronic skin with multiplexed and wireless sensing functions powered by nanoengineered biofuel cells (BFCs). B, Block diagram of the system function (upper), schematic illustration (lower left) and photographs (lower right) of the BFC-powered wireless E-skins. C, Device structure and operation principle of sweat-activated batteries for driving epidermal electronic and microfluidic systems. D, Block diagram of the system function (upper), and photograph of the electronic (lower left) and microfluidic (lower right) modules.