Perforated PVP encapsulated AgNWs for high mass loading in silver nanowire inks for printed RFID integrated wearable smart bands

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2024-01, Vol.12 (2), p.575-592
• Main Authors: Pillai, Adarsh Sivan, Sudhakar, Sumith, Benny, Steffy, Sahoo, Swaroop, Chandran, Achu, Peethambharan, Surendran Kuzhichalil
• Format: Article
• Language: English
• Subjects: Antennas; Bend radius; Dispersion; Encapsulation; Flexible components; Inks; Nanowires; Polyvinylpyrrolidone; Position sensing; Printed circuits; Radio frequency identification; Screen printing; Stability; Wearable technology
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d3tc03868h

Silver nanowire (AgNW) based conductive inks have gained considerable attention for realizing printed flexible electronics (PFE). The present work discusses a novel approach to producing highly dispersible silver nanowires, easing the formulation of screen-printing inks with high nanowire loading. A perforated encapsulation of polyvinylpyrrolidone (PVP) with an average thickness of 5.03 ± 1.16 nm was produced on the AgNWs' surface through a controlled washing procedure, which increased the dispersibility of AgNWs at higher mass loadings. A screen-printing ink formulation with nearly 36% AgNW loading was developed, which generated highly conductive traces with a conductivity of (1.16 ± 0.06) × 10 6 S m −1 at a low annealing temperature of 120 °C. The printed traces exhibited superior adhesion (ASTM Class 5), stability towards bending (10 000 cycles), resistance to accelerated ageing (Δ R / R 0 < 2.5% at 60 °C - 95% RH), and stability towards sweat exposure (Δ R / R 0 = 0.5%), making them a suitable candidate for PFE. Utilizing this conductive ink, a highly flexible UHF antenna operating at 945 MHz was fabricated, and an RFID tag was developed by integrating the antenna with a chip. The fabricated tag exhibited exceptional communication performance with a handheld reader and had high stability toward bending (at a bending radius of 1.5 cm for 500 cycles). A wearable smart band for Android-based human position sensing was also developed using the tag, which precisely located the wearer's position. A perforated PVP coating on AgNWs produces high-mass loading and low-temperature curing inks. The ink produces prints of high conductivity, and an RFID-assisted smart band for wearable position sensing is developed using the ink.