Experimental investigation of nanoparticles distribution mechanisms and deposition patterns during nanofluid droplet evaporation

Droplet evaporation is fascinating, ubiquitous, and relevant for a wide spectrum of applications, such as printing, drug testing, coating, and biomedical diagnosis. In this paper, the effects of substrate temperature (30 °C, 47 °C, 64 °C, 81 °C) and 20 nm Al2 O3 nanoparticles mass fraction (0.05%, 0.1%, 0.2%) on the nanoparticles distribution mechanisms and deposition patterns during the evaporation of Al2 O3 -H2 O nanofluid droplet were experimentally investigated. An experimental device was designed and realized. The self-assembly and Marangoni forces were first highlighted and compared. Two coffee-ring and inner-ring patterns were then identified and analyzed. The evaporation process characteristics were finally determined and discussed.