Figure 5.

Wireless, skin‐integrated, microelectronic system for continuous sweat monitoring, powered by a sweat‐activated battery array. a) Schematic diagram of the exploded view of the wireless, flexible microelectronic system with the sweat‐activated battery cells for long‐term monitoring Na⁺, glucose, and pH value of sweat. b) Schematic diagram of the whole system with the microelectronic system and four integrated battery cells. c) Optical image of the four integrated sweat‐activated battery cells connected in series with the top, bottom, and inner views. d) Optical images of the microelectronic systems with detachable microfluidic system. e) Optical images of the enlarged details of the circuit. f) Exploded‐view schematic diagram of the replaceable biosensors with optical images of each layer. g) Process of the microfluidic system absorbing colored water drop. h‐j) Open circuit voltage (OCV) responses of the glucose, Na⁺ and pH sensors.