Highly anisotropic power generation in piezoelectric hemispheres composed stretchable composite film for self-powered motion sensor

Highly-stretchable piezoelectric hemispheres composed composite thin film nanogenerators are fabricated as a self-powered, exceptionally sensitive sensor for providing sensitive motion information from a human body. The composite films are based on the highly-ordered piezoelectric hemispheres embedded in a soft matrix, polydimethylsiloxane (PDMS) and generate large power output up to 6 V and 0.2 mu A/cm(2) under normal bending force. The electrical outputs increase by stacking such hemispheres layer-by-layer. The strain sensitivity of the films differs according to the bending direction, and the high sensitivity is achieved by convex bending for hemisphere composite due to the strong electric dipole alignment. The films are attached on the surface of a wrist and its output voltage/current density provides the information on the wrist motion. (C) 2014 Elsevier Ltd. All rights reserved.