Inkjet\nPrinting of Reactive Silver Ink on Textiles

Abstract

Inkjet printing of functional inks\non textiles to embed passive\nelectronics devices and sensors is a novel approach in the space of\nwearable electronic textiles. However, achieving functionality such\nas conductivity by inkjet printing on textiles is challenged by the\nporosity and surface roughness of textiles. Nanoparticle-based conductive\ninks frequently cause blockage/clogging of inkjet printer nozzles,\nmaking it a less than ideal method for applying these functional materials.\nIt is also very challenging to create a conformal conductive coating\nand achieve electrically conductive percolation with the inkjet printing\nof metal nanoparticle inks on rough and porous textile and paper substrates.\nHerein, a novel reliable and conformal inkjet printing process is\ndemonstrated for printing particle-free reactive silver ink on uncoated\npolyester textile knit, woven, and nonwoven fabrics. The particle-free\nfunctional ink can conformally coat individual fibers to create a\nconductive network within the textile structure without changing the\nfeel, texture, durability, and mechanical behavior of the textile.\nIt was found that the conductivity and the resolution of the inkjet-printed\ntracks are directly related with the packing and the tightness of\nfabric structures and fiber sizes of the fabrics. It is noteworthy\nthat the electrical conductivity of the inkjet-printed conductive\ncoating on pristine polyethylene terephthalate fibers is improved\nby an order of magnitude by in situ heat-curing of the textile surface\nduring printing as the in situ heat-curing process minimizes the wicking\nof the ink into the textile structures. A minimum sheet resistance\nof 0.2 ± 0.025 and 0.9 ± 0.02 Ω/□ on polyester\nwoven and polyester knit fabrics is achieved, respectively. These\nfindings aim to advance E-textile product design through integration\nof inkjet printing as a low-cost, scalable, and automated manufacturing\nprocess.