Portable micro/nanoscale devices that are self-powered through mechanical motions in the surroundings have a wealth of applications within medical devices and personal electronics. Wearable devices include sensors monitoring environmental conditions or personal health conditions as well as devices that improve life quality. Currently, the prevailing energy supply for such devices are Li-ion batteries that are large compared to the devices they drive and require wire connections and replacement/recharging over time. Replacement of batteries with devices that harvest energy from the movements of the person wearing the device will widen the flexibility and the field of applications of such devices.
Piezoelectric generators can produce electricity directly from mechanical movements of the human body. A key challenge with micro/nanoscale electrical generators is the power density that they can deliver. Furthermore, piezoelectric materials are rigid compared to organic structures making up human bodies. However, imagine generators constructed from piezoelectric materials formed as springs on a nanometer scale with designed elastic properties. It is the hypothesis of the current project that three-dimensional (3D) sculpturing of piezoelectric nanowires (NWs) in order to secure pure bending modes and thus large strains in the wires will significantly increase the efficiency of nanowire energy generators. Furthermore, such angled and spiraled arrangement of the wires will make them sensitive to both vertical and lateral displacements, thus facilitating new effective designs of piezo generators. In this project, Glancing Angle Deposition (GLAD) techniques will be investigated as synthesis technique to enable 3D control over the growth of NWs.