A Roll-to-Roll Gravure-Printing System for Manufacturing Near-Field Energy-Harvesting Labels

Billions of costless near-field communication (NFC) sensor labels per day are demanded to practically enable edge computing between smartphones and everyday objects. However, to activate the billions of NFC sensor labels daily, providing an inexpensive manufacturing method for billions of wireless energy-harvesting labels (WeHL) per day will become a decisive issue for realizing the practical applications. Herein, a roll-to-roll (R2R) gravure, a typical high-throughput additive manufacturing method, is explored to print WeHLs where six diodes and six capacitors are integrated. To meet the high-throughput manufacturing speed (90 mm s⁻¹) of the R2R gravure system, six different electronic inks are formulated to print the WeHLs to harvest ±10 V from the smartphone's NFC carrier. To attain a practical device yield under the given printing speed, the web tension, nip force, doctor blade angle, and overlay printing registration accuracy are well controlled and optimized to print six different layers within a high overlay printing accuracy, while printing patterns to connect two electrodes with a height difference greater than 3 μm. The fully R2R-printed WeHLs can successfully harvest energy from the smartphone's NFC carrier with the conversion efficiency of 50%.