Slippery liquid-infused porous surfaces with inclined microstructures to enhance durable anti-biofouling performances.

In the development of biocompatible materials for biomedical applications, infections and their resulting inflammation responses are important issues caused typically by the adhesion of micro-organisms on medical devices. Recently slippery liquid-infused porous surfaces (SLIPS) has provided a new strategy for anti-biofouling and low-adhesion surfaces, however, there are still some bottlenecks in practical uses, particularly the loss of lubricant significantly restricts the durability and stability of SLIPS. In this paper, we micro-fabricated well-controlled micro-cavities with different profiles (vertical or inclined walls) to investigate the long-term anti-biofouling effect of SLIPS. We explored microstructure geometries in two aspects: the aspect ratio and the slope angle relevant with the Laplace pressure and the oil contact area which lead to different oil-locking abilities. High aspect ratio and inclined slope were demonstrated with better oil-locking ability as well as significantly increased anti-fouling performances. Under the same experimental setup, the Escherichia coli and Staphylococcus aureus bacteria coverage on SLIPS with 80 μm-depth 20° inclined micro-cavities was only ∼30 % of that with vertical micro-cavities, while increasing aspect ratio by 4 times induced ∼3 times enhanced anti-fouling effect. On basis of these findings, we propose the enhanced SLIPS with inclined microstructures to achieve better oil-locking ability and long-term anti-biofouling performance, which may broaden many practical applications of SLIPS.