Inkjet Printing of Biomolecules: Interaction Liquid - Solid
Printing is an efficient technology to transfer a fluid onto a solid surface. Printing biomolecules, such as proteins and DNA, into a controlled pattern is of high practical interest. There are two broad categories of printing techniques: contact and non-contact. Non-contact techniques commonly referred to as digital printing, which has grown significantly in the last decade with the development of ink-jet printing. Inkjet printing delivers ink droplets (20 μm diameter) onto rough surfaces.
In an effort to optimize printing resolution, we have investigated drop-drop and drop-solid interactions. Typically, inkjet printing forms a pattern by delivering multilayers of droplets. In certain instances, a drop impinging onto a liquid surface retains it’s shape and simply rolls out of the liquid before collapsing, causing a printing defect. In other instances, a drop delivered over a surface grove forms an irregular pattern as wetting is perturbed by wicking.
It is the objective of the study to quantify the dynamics of droplet-liquid and droplet-rough surface in fundamental terms using model systems. In the first part of the presentation, droplet non-coalescence will be quantified in terms of dimensionless numbers (We). The second part of the study analyses the dispersion of droplets impinged over thin groves of different width and angles, using high speed image analysis. The dynamics of liquid distribution will be analyzed and modeled in terms of kinetic energy, dynamic wetting and capillary flows.