AVS 56th International Symposium & Exhibition
    Inkjet Technology: Printing, Materials Processing, and Microfluidics Fundamentals Topical Conference Wednesday Sessions
       Session IJ+BI+MN-WeM

Invited Paper IJ+BI+MN-WeM9
Interplay between Simulation, Theory, and Experiment in Nonstandard Inkjet Printing: From New Devices to Complex Fluids

Wednesday, November 11, 2009, 10:40 am, Room B3

Session: Microfluidic Fundamentals and Inkjet Technology
Presenter: O.A. Basaran, Purdue University
Correspondent: Click to Email
During its early days, applications of inkjet printing were restricted almost exclusively to the graphic arts. In the late 1990s, the method found widespread application in DNA arraying. More recently, the applications of inkjet technology have broadened considerably to span areas as diverse as direct printing of electronic circuits and solar cells and drop-by-drop construction of organs and other biological structures. Inkjet printing involves the formation of drops from nozzles and the subsequent impact and deposition of such drops on suitable substrates. Both drop formation and drop impact are prototypical free surface or free boundary problems involving large deformation and breakup of fluid-fluid interfaces. Given the ever decreasing time and length scales inherent to inkjet printing, e.g. micron size drops are formed from an inkjet nozzle in time scales of microseconds, and that inkjet printing is a free boundary problem that involves finite time hydrodynamic singularities, e.g. pressures and velocities blow up in finite time as the drop surface approaches breakup or pinch-off, simulation, theoretical description, and experimental visualization of the dynamics of inkjet drops are challenges to the modeler, the theorist, and the experimentalist alike. Moreover, many of the emerging applications of inkjet printing involve fluids that can be characterized as complex fluids in that their bulk rheologies are non-Newtonian and/or their surface tensions vary in time. Motivated by research being carried out in the PI’s group on inkjet printing of drops of complex fluids containing pharmaceutical active ingredients on edible substrates, this talk will focus on how computation, theory, and experiment are being used in concert to advance the state-of-the art in the field. Examples that will be used to highlight the computations will include construction of phase diagrams that help identify regions of the parameter space where high quality drops can be produced and efforts aimed at producing nanoscopic drops from microscopic nozzles. To tie the simulations and theory, the excellent agreement between computed predictions and scaling theories of pinch-off will be demonstrated. The excellent agreement between the simulation results and the experiments will be highlighted by means of photographs obtained with an imaging system that is capable of capturing 100 million frames per second. Since complex fluids cannot be characterized by their shear viscosity alone and drop formation involves predominantly extensional deformations, efforts underway to infer the extensional viscosity of such fluids will also be described.