Handwriting enabled harvested piezoelectric power using ZnO nanowires/polymer composite on paper substrate

We here, present a flexible handwriting driven nanogenerator (NG) based on zinc oxide (ZnO) nanowires (NWs)/polymer composite grown/deposited on paper substrate. The targeted configuration is composed of ZnO NWs/PVDF polymer ink pasted and sandwiched between two pieces of paper with ZnO NWs grown chemically on one side of each piece of paper. Other configurations utilizing a ZnO/PVDF ink with different ZnO morphologies on paper platform and others on plastic platform were fabricated for comparison. The mechanical pressure exerted on the paper platform while handwriting is then harvested by the ZnO NWs/polymer based NG to deliver electrical energy. Two handwriting modes were tested; these were slow (low pressure) and fast (high pressure) handwriting. The maximum achieved harvested open circuit voltage was 4.8 V. While an out power density as high as 1.3 mW/mm(2) was estimated when connecting the NG to a 100 Omega load resistor. The observed results were stable and reproducible. The present NG provides a low cost and scalable approach with many potential applications, like e.g. programmable paper for signature verification. (C) 2014 Elsevier Ltd. All rights reserved.