Electro-capillary peeling of thin films

Abstract

Thin films being a universal functional material have attracted much interest in academic and industrial applications, such as flexible electronics, soft robotics, and micro-nano devices. With thin films becoming micro/nanoscale, developing a simple and nondestructive peeling method for transferring and reusing remains a big challenge. Here, we present an innovative detaching approach for thin films: Electro-capillary peeling method. The electro-capillary peeling method achieves thin films' detachment by driving liquid to percolate and spread into the bonding layer under electric fields. Compared with traditional methods, thin film detached by this novel peeling mode shows a much lower deformation and strain of film (reaching 86%). Evaluated by various applied voltages and films, the electro-capillary peeling method shows active control characterizations and is appropriate in a broad range of films. Theoretically, it is demonstrated that the electro-capillary peeling method is actualized by utilizing Maxwell stress to compete with the film's adhesive stress and tension stress. The peeling length versus time, applied voltage, film's thickness, and elastic modulus are described by $r\sim t$, $r \sim U$, $r\sim d_{0}^{-1/2}$, and $r\sim E^{-1/2}$, respectively. Additionally, observations of critical peeling voltage present that the thin film is readily detached by using the electro-capillary peeling method at the ultra-low voltage of only 0.7 V. This work clearly shows the great potential of electro-capillary peeling method to provide a new way for transferring films and open novel routes for applications of soft materials.