Individually addressable and flexible pressure sensor matrixes with ZnO nanotube arrays on graphene
Junbeom Park, Ramesh Ghosh, Minho Song, Yunjae Hwang, Youngbin Tchoe, Rajendra K. Saroj, Asad Ali, Puspendu Guha, Bosung Kim, Sang‐Woo Kim, Miyoung Kim, Gyu‐Chul Yi
Abstract
Abstract We report the fabrication of individually addressable, high-density, vertical zinc oxide (ZnO) nanotube pressure sensor arrays. High-sensitivity and flexible piezoelectric sensors were fabricated using dimension- and position-controlled, vertical, and free-standing ZnO nanotubes on a graphene substrate. Significant pressure/force responses were achieved from small devices composed of only single, 3 × 3, 5 × 5, and 250 × 250 ZnO nanotube arrays on graphene. An individually addressable pixel matrix was fabricated by arranging the top and bottom electrodes of the sensors in a crossbar configuration. We investigated the uniformity and robustness of pressure/force spatial mapping by considering the pixel size, the number of ZnO nanotubes in each pixel, and the lateral dimensions of individual ZnO nanotubes. A spatial resolution as high as 1058 dpi was achieved for a Schottky diode-based force/pressure sensor composed of ZnO nanotubes on a flexible substrate. Additionally, we confirmed the excellent flexibility and electrical robustness of the free-standing sensor arrays for high-resolution tactile imaging. We believe that this work opens important opportunities for 1D piezoelectric pressure/force sensor arrays with enormous applications in human-electronics interfaces, smart skin, and micro- and nanoelectromechanical systems.