Development of a Biobased Conductive Ink Formulation and Its Application Through Screen Printing for Electronic Textile Development

The screen printing of conductive inks on flexible substrates is a rapidly advancing technology that offers a wide range of applications. However, the presence of harmful chemicals in conductive ink formulations has posed a significant challenge, leading to substantial environmental issues. Our goal was to address this challenge by successfully developing environmentally friendly inks, an objective we achieved by utilizing a biodegradable cellulose-derived polymer and formulating inks with eco-friendly solvents, namely water and ethanol. To maintain electrical conductivity, we incorporated graphite and graphene as conductive fillers, ensuring the efficiency of printed circuits. Furthermore, the application of these inks to untreated polyester fabrics through screen printing paved the way for the development of flexible and wearable electronic textiles. The printed patterns were then dried at 130 ℃ for 3 min and subjected to electrical and mechanical tests, revealing significant correlations. Notably, we observed a direct relationship between the electrical conductivity of the textiles and the concentration of conductive fillers when transitioning from 10 to 50% in the inks. Values ranged from 7 × 10–3 to 35 × 10–2 S cm−1 for graphite and from 27 × 10–2 to 5 × 10–1 S cm−1 for graphene. We also demonstrated the ability of our textiles to power an LED bulb using a 4.5 V battery, illustrating the potential of our textiles for electronic circuit applications. Additionally, our printed textiles underwent comprehensive testing, including contact angle measurements, showcasing the ability of the printed textile surfaces to repel water, which is advantageous for textile durability. Furthermore, tensile strength tests were conducted, demonstrating the excellent mechanical properties of these textiles. This breakthrough represents a critical step toward sustainable technologies for the future. By utilizing a cellulose-derived polymer with inherent biodegradability and water solubility, we managed to avoid the use of solvents and environmentally harmful chemicals typically found in conductive ink formulations.