Laser-induced reduction and pattern regulation of graphene oxide film with high biosafety for wearable micro-supercapacitors

Abstract

A two-step laser process consisting of surface treatment and pattern scribing was developed to prepare micro-supercapacitors (MSCs) with high electrochemical performance and structural robustness. First, an ultrathin and uniform graphene oxide (GO) film was deposited onto a copper foil by electrophoretic deposition, after which a laser beam with a wavelength of 450 nm was used to remove the oxygen-containing functional groups and introduce porous structures into the GO film. Subsequently, another laser beam with a wavelength of 1064 nm was used to scribe the film to form finger-patterned electrodes. After being assembled into flexible MSCs, the volume specific capacity of the MSCs reached 1.94 F cm−3, and the power and energy densities reached 4 mW cm−3 and 0.172 mWh cm−3, respectively. After 7000 charge-discharge cycles, the device showed excellent cycling stability with a capacitance retention rate of ∼87.5%. Moreover, the MSCs could be bent into different forms with marginal capacitance loss, confirming their high structural tolerance. Remarkably, the laser-irradiated GO (L-GO) film showed high biosafety toward human empirical cells in the biotoxicity tests, indicating that the devices could be adopted as reliable micro-devices with high biosafety for fabricating wearable electronics on human skin.