Micro-reactive Inkjet Printing of Functional Materials

Abstract

Reactive inkjet printing (RIJP) holds great prospects as a multi-material fabrication method due to its unprecedented advantages involving simultaneous synthesis and patterning of functional materials on the substrates. However, the fabrication of patterned functional materials through reactive inkjet printing presents a number of challenges:1) Marangoni flow of two different reacting droplets on solid substrates, 2) rapid evaporation of the first material on the substrate before deposition of any subsequent material and 3) increased positioning inaccuracies due to surface wetting instabilities. These result in limited performance, which is exacerbated when structures are desired on clean non-porous substrates due to the relative ease of contact line motion. This thesis focuses on circumventing these limitations with a new technique, namely, micro-reactive inkjet printing (MRIJP) technique where two complementary reactive micro-droplets collide in-air to produce a micro-droplet of the desired chemistry before deposition on the substrate. Using this technique, different 2D and 3D structures of alginate hydrogel, polyaniline (PANI) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate/ionic liquid (PEDOT:PSS/IL) were fabricated on glass substrates that would otherwise be challenging or impossible to create using conventional printing techniques. Notably, these MRIJP-based printed functional materials has potential for freeform patterning while maintaining identical performance to those fabricated by conventional methods, potentially leading to substantial progress in next-generation bioelectronics devices and other applications.