Figure 4: Microwave passive elements and integrated circuit on CNF paper.

(a) An exploded view schematic illustration of the inductor and capacitor on a CNF substrate. (b) Array of inductors and capacitors on a CNF substrate put on a tree leaf. (c) Optical image of the measured 4.5 turn inductor. Scale bar, 100 μm. (d) Optical image of the measured MIM capacitor. Scale bar, 100 μm. (e) Inductance plotted against frequency with an inset plot showing the inductor Q factor as a function of frequency. (f) Capacitance plotted against frequency with an inset plot showing the capacitor Q factor as a function of frequency. (g) An optical microscopy image of a full bridge rectifier built on a CNF paper. Here the microwave Schottky diodes and an MIM capacitor were integrated. Scale bar, 50 μm. (h) Measured rectified DC output power of the rectifier while applying RF input power from 10 to 21 dBm at 5.8 GHz.