Sessile droplet evaporation on patterned surface

• Main Author: Koh, Han Jie
• Other Authors: Fei Duan
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Mechanical engineering::Fluid mechanics
• Online Access: http://hdl.handle.net/10356/63466
• Institution: Nanyang Technological University

Developing and understanding fluidic systems in the area of droplet evaporation requires wide range of studies and such technologies can be useful in microchip manufacturing and ink jet printing with particles. How the droplet evaporate on the different surfaces are what the researches are interested on. Hence the objective of this project is to analyze the drying pattern and duration of the droplet evaporation on different nanoscale pillar designs which will be relating to printing, coating and material design. Also to measure and record at which volume ratio the mixture will start to change its shape during evaporation and how will the droplet shape change during the evaporation. As far as this project is concerned, all studies done are experimental and duration of the evaporation require without the input of other elements such as heat or external forces. 7 different designs of pillars are used namely triangle, square, diamond, circle, rounded squares and stripes. Height of 100μm, diameter and intervals of 25μm are used throughout all the 7 designs, volume ratios of 0.2 to 1.0, are used for this experiment. The Droplet of various volume and concentrations for evaporation on diverse designs of surfaces and dimensions are widely studied and this report contains a small area of it. Dimensions ranging from 20-180μm pillar height, 5-500μm intervals, volume of less than 1μl and particle sizes of 18-1000μm are used. Cassie and Wenzel models help to shed some light on how they affect and cause the droplets to behave in certain ways or help the evaporation to slow down or speed up compared to others. Understanding from how the surface designs affect the droplet evaporation patterns can also allow better material manufacturing on what properties the material requires and hence allow better development of future materials. Further studies such as particle addition and using of different compound mixtures at different environment can be further done to further improve and broaden the study done from this project. Different surface design can also be explored on top these mentioned study patterns.