A practical fabrication method of the gecko-inspired easy-removal skin adhesives

Abstract

Abstract Easy-removal skin adhesives require a robust reversible adhesion. This requirement is addressed in this study with the fabrication of PDMS micro-patterned surfaces that inspired by gecko feet. The design of these gecko-inspired structures were aimed to maximize the ratio between pull-off strength and peel strength. They were fabricated using the laser cutting technology which is typically used for industrial manufacturing applications. Several kinds of PDMS specimens in triangular, square and hexagonal patterns, as well as triangular, square, diamond and circular cross-sections were made. The wetting properties of the gecko-inspired surfaces were evaluated by contact angle measurements. Pull-off strength and peel strength measurements were performed against a silicon skin substitute. Multiple attachments were achieved on a range of preloads. The averaged pull-off strength under a preload 10 N for 10 s can reach up to approximately five times of peel strength when the peel angle is 30 degree. Also compared with conventional Band-Aids, a slight enhancement in attachment ability and a significant decrease in peel strength between the skin and the adhesives were consistently observed. Therefore, the fabrication of the gecko-inspired structures on the micro-molding of PDMS appeared to offer a near-practical way for manufacturing an easy-removal skin adhesives, albeit in its present form with a comparable adhesion strength and a decreased peel strength. The originality of this work is the reverse de-molding approach based on the combination of the cost- and time-efficient laser cutting methods and the Teflon film as the mold material, which avoid the limitation caused by taking PDMS structure out of the molds, so that provide more variations of the tip geometry. As such, a further development of this fabrication method might be of significant interest in a number of practical applications in skin tissue industrial design.