Systematic Review of Conductive Inks for E-textiles: Formulation, Printing Methods, Challenges, and Opportunities

The development of e-textiles for various sensing and health monitoring applications has remained difficult because the printed electronic inks must be highly stable on textile substrates, yet flexible enough to adapt to the human contour. Despite the adverse challenges, significant progress has been made over the last few years in the formulation and application of conductive inks for e-textiles. This mini systematic review, therefore, presents the recent advancements in the formulation and application of conductive inks for e-textiles in concert with the clarion call for sustainable textiles. The Scopus database was used to identify relevant publications within the field for effective analysis. After scrutinizing the bulk of publications, a total of 30 studies comprising articles and conference papers were selected and structured in 3 themes, namely, formulation of conductive inks for e-textiles, fabrication and printing methods, and challenges of fabricating conductive inks on textiles. Findings show that significant progress has been made toward formulating silver nanowire inks with exceptional conductivity and flexibility, stabilization of carbon nanotubes and graphene inks with consistent electrical properties, and high substantivity to different textile substrates without pretreatment. Subsequently, deposition techniques such as screen printing, ultrasonic spray coating, syringe-based deposition systems, and direct-write printing are being used for the full realization of printing conductive inks for e-textiles, and are highlighted in this paper. In general, technological advancements have increased the capabilities of e-textile devices made with conductive inks.