Inkjet Technology for Digital Fabrication

Chapter 5

When the Drop Hits the Substrate

Jonathan Stringer¹ and Brian Derby²

¹ Department of Mechanical Engineering, University of Sheffield, United Kingdom

² School of Materials, University of Manchester, United Kingdom

5.1 Introduction

Inkjet printing is a method for the generation and precise placement of liquid drops on a substrate. The final desired image or pattern is a solid object on the substrate. Thus an important stage in the generation of the image or pattern is the impact of the liquid drop on a substrate and the subsequent phase change that transforms the liquid into a solid. The liquid-to-solid phase change can occur by a number of mechanisms including: solvent evaporation, cooling through a transition temperature, gelling of a polymer precursor and chemical reaction. In all these cases, solidification occurs post-deposition and the printed pattern must retain some stability in the liquid state prior to solidification. In order to fully understand the processes that occur between the printed drop and the substrate prior to attaining the final structure, we must identify the interactions that occur between the substrate and the fluid drop prior to solidification.

Whilst droplet impact and its subsequent interaction with a substrate have been studied extensively for a number of years (Worthington, 1876; Armster et al., 2002; Yarin, 2006), a complete understanding of the possible mechanisms involved in the process has not yet been obtained. This is due to the complex ...