Screen-Printed Flexible Bandstop Filter on Polyethylene Terephthalate Substrate Based on Ag Nanoparticles

We present a low-power, cost-effective, highly reproducible, and disposable bandstop filter by employing high-throughput screen-printing technology. We apply large-scale printing strategies using silver-nanoparticle-based ink for the metallization of conductive wires to fabricate a bandstop filter on a polyethylene terephthalate (PET) substrate. The filter exhibits an attenuation pole at 4.35 GHz with excellent in-and-out band characteristics. These characteristics reflect a rejection depth that is better than −25 dB with a return loss of −0.75 dB at the normal orientation of the PET substrate. In addition, the filter characteristics are observed at various bending angles (0°, 10°, and 20°) of the PET substrate with an excellent relative standard deviation of less than 0.5%. These results confirm the accuracy, reproducibility, and independence of the resonance frequency. This screen-printing technology for well-defined nanostructures is more favorable than other complex photolithographic processes because it overcomes signal losses due to uneven surface distributions and thereby reveals a homogeneous distribution. Moreover, the proposed methodology enables incremental steps in the process of producing highly flexible and cost-effective printed-electronic radio devices

Silver-Nanoparticle-Based Screen-Printing and Film Characterization of a Disposable, Dual-Band, Bandstop Filter on a Flexible Polyethylene Terephthalate Substrate

This paper presents a silver-nanoparticle-based, screen-printed, high-performance, dual-band, bandstop filter (DBBSF) on a flexible polyethylene terephthalate (PET) substrate. Using screen-printing techniques to process a highly viscous silver printing ink, high-conductivity printed lines were implemented at a web transfer speed of 5 m/min. Characterized by X-ray diffraction (XRD), optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), the printed lines were shown to be characterized by smooth surfaces with a root mean square roughness of 7.986 nm; a significantly higher thickness (12.2 μm) than the skin depth; and a high conductivity of 2×107 S/m. These excellent printed line characteristics enabled the implementation of a high-selectivity DBBSF using shunt-connected uniform impedance resonators (UIRs). Additionally, the inductive loading effect of T-shaped stubs on the UIRs, which were analyzed using S-parameters based on lumped parameter calculations, was used to improve the return losses of the geometrically optimized DBBSF. The measured minimum return loss and maximum insertion loss of 28.26 and 1.58 dB, respectively, at the central frequencies of 2.56 and 5.29 GHz of a protocol screen-printed DBBSF demonstrated the excellent performance of the material and its significant potential for use in future cost-effective, flexible WiMax and WLAN applications

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%