@Article{icces.2023.09741,
AUTHOR = {Hongfei Ye, Chenguang Yin, Jian Wang, Yonggang Zheng, Hongwu Zhang},
TITLE = {Self-Driven Droplet on the Bilayer Two-Dimensional Materials and Nanoscale Channel with Controllable Gradient Wettability},
JOURNAL = {The International Conference on Computational \& Experimental Engineering and Sciences},
VOLUME = {27},
YEAR = {2023},
NUMBER = {1},
PAGES = {1--1},
URL = {http://www.techscience.com/icces/v27n1/54107},
ISSN = {1933-2815},
ABSTRACT = {The wetting behavior is ubiquitous in natural phenomenon as well as engineering application. As an intrinsic 
property of solid surface, the wettability with a controllable gradient has been an attractive issue with a 
wide application in various fields, including microfluidic devices, self-driven transport, biotechnologies, etc. 
Generally, it often requires elaborate design of microstructure or its response under the electrical, thermal, 
optical, pH stimuli, etc. However, the relevant complex underlying mechanism makes it difficult to construct 
quantitative relations between the wettability and the external field for the fine design. In this work, based 
on the bilayer two-dimensional materials, a simple controlling method of the wettability gradient is 
established. Molecular dynamics simulation is utilized to examine the controlling strategy and its 
performance for self-driven motion of water droplet. The results show that the coupling wettability of the 
bilayer materials always develops towards the hydrophilicity relative to the wettability of the upper layer. 
But the variation extent becomes small with increasing the interlayer distance, and the coupling wettability 
approaches the wettability of the upper layer material gradually. For this simple controlling strategy, a 
theoretical model of governing relationship is established based on the work of adhesion, which correlates 
the overall surface wettability with the interlayer distance and the wettabilities of individual materials. 
Based on the varying interlayer distance, the uniform gradient wettability can be achieved through inclining 
the bottom material. Thus, a surface with the bilayer two-dimensional materials and a channel composed of 
two gradient surfaces are constructed for droplet transport, respectively. The results indicate the 
spontaneous and steady motion of droplet under the corresponding gradient wettability. A theoretical 
model is proposed to describe the acceleration behavior of the droplet, which reveals the crucial role of the 
bottom layer. The present work provides essential guidelines for manipulating two-dimensional materials 
to design unconventional wettability surfaces, paving new routes to many applications such as micro-fluidic 
chip, virus diagnosis, intelligent sensor, etc.},
DOI = {10.32604/icces.2023.09741}
}