Enhanced biaxial stretchability of wrinkled SiO2 thin films for stretchable encapsulation

Abstract

Enhanced biaxial stretchability of highly impermeable SiO2 encapsulation thin film with wrinkle structures is demonstrated. Submicron-thick SiO2 films are grown on single-crystalline Si wafers to endure local strain on wrinkled film, and their high elastic deformation limit stabilizes wrinkle structure. SiO2 films are transferred onto prestrained elastomer, and two types of wrinkle structures are formed by removal of the prestrain: aligned wrinkles by uniaxial prestrain and random wrinkles by equibiaxial prestrain. The stretchability of the large area film is correlated with the unwrinkling of individual wrinkles, and a mechanics model is suggested to predict stretchability with parameters of wrinkle morphology as well as elastic properties of the encapsulation film and the elastomer substrate.