Figure 5

(a) A flexible self-powered glucose indicator immersed in a glucose solution; device is in operation with the LED flashing red. Video is available in the Supporting Information. (b) A flexible self-powered glucose indicator with the biofuel cell electrodes sandwiching a nanocellulose sheet soaked with glucose solution, showing the autonomous operation of the device in an isolated environment. Video is available in the Supporting Information. (c) Final form of the flexible self-powered glucose indicator reduced to a 5 mm × 5 mm square in operation.