Abstract
An inkjet printer head, which is capable of depositing liquid droplets with a resolution of 22 picoliters and high repeatability, is employed to investigate the wetting dynamics of drops printed on a horizontal plane as well as on a granular monolayer. For a sessile drop on a horizontal plane, we characterize the contact angle hysteresis, drop volume and contact line dynamics from side view images. We show that the evaporation rate scales with the dimension of the contact line instead of the surface area of the drop. We demonstrate that the system evolves into a closed cycle upon repeating the depositing-evaporating process, owing to the high repeatability of the printing facility. Finally, we extend the investigation to a granular monolayer in order to explore the interplay between liquid deposition and granular particles.
Highlights
Granular materials are ubiquitous in nature, industry and daily lives [1]
In the pendular regime [3] with capillary bridges formed between adjacent particles, previous investigations showed that the collective behaviors of partially wet granular materials, such as clustering, phase transitions and pattern formation, are related to the capillary force induced by the wetting liquid [9,10,11,12,13]
We use a commercial inkjet printer head (HP 51645A) to explore the dynamics of wetting, because it enables a fine control of the drop volume with high repeatability
Summary
Granular materials are ubiquitous in nature, industry and daily lives [1]. Despite intense investigations motivated by applications in geoscience, chemical and civil engineering, the physics of granular materials, are still far from being understood, when they are partially wet [2,3,4]. In the pendular regime [3] with capillary bridges formed between adjacent particles, previous investigations showed that the collective behaviors of partially wet granular materials, such as clustering, phase transitions and pattern formation, are related to the capillary force induced by the wetting liquid [9,10,11,12,13]. We use a commercial inkjet printer head (HP 51645A) to explore the dynamics of wetting, because it enables a fine control of the drop volume with high repeatability. For both a horizontal plane and a granular monolayer, repeating the print-evaporate process leads to reproducible contact line dynamics. The average droplet volume is determined to be 22.4(11) pL by image analysis of side view images
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
