Transport processes associated with inkjet printing of colloidal drops for printable electronics fabrication

This paper presents an experimental investigation of deposition dynamics of inkjet-printed colloidal drops on glass and PET substrates. Using fluorescent particles and confocal microscopy, the evaporatively-driven and thermal Marangoni flows inside a colloidal drop, as well as the particle self-assembly and deposition on the substrate are directly observed. In addition, Ar plasma treatment is used to modify the substrate surfaces. Wetting properties (i.e., advancing /receding contact angle and contact angle hysteresis) of colloidal drops on different substrates, substrate surface roughness, and final particle deposition morphologies are characterized using goniometer, AFM, and SEM. A correlation between the substrate surface roughness, static receding contact angle, contact line pinning/de-wetting, and final particle deposition morphology is explored. This study seeks to provide design guidelines for substrate surfaces that will improve the resolution and edge definition of printable electronics fabrication.