A flexible and transparent graphene-based triboelectric nanogenerator - Shankaregowda, Smitha Ankanahalli; Nanjegowda, Chandrashekar Banankere; Cheng, Xiao-Liang; Shi, Ma-Yue; Liu, Zhong-Fan; Zhang, Hai-Xia (IEEE Transactions on Nanotechnology, 2016)