Enhancing spontaneous and continuous liquid directional transport on peristome-mimetic surface with hierarchical microgrooves

Directional liquid transport function discovered on the peristome of Nepenthes alata has attracted considerable attention for its diverse potential applications. Despite the extensive efforts made for the peristome-mimetic surface fabrication and the anisotropic liquid spreading regulation, it remains a daunting challenge to reveal the synergistic effect of hierarchical structures on the liquid spreading and pinning dynamics. Here, we demonstrate the first-tier microgroove morphology, as well as the presence of second-tier microgrooves, play an important role in homogenous film formation and the directional liquid transport control. Through experimental investigation and theoretical analysis, the enhanced spreading and pinning effect is validated. Moreover, the preferential directional liquid spreading will collapse on the peristome-mimetic surface without a rational parameter design, and the threshold value for the transition of liquid propagation dynamics is determined. Spontaneous directional liquid transport from the cold region to the hot region and smart liquid transport regulation was also realized on the peristome-mimetic surface. This work will provide guidance to the design of effective open microfluidic systems, and open a new way for thermal management and lab-on-chip applications.