This work was funded by the European Union (EU) seventh Framework Programme (FP7/2007-2013) under grant agreement no. 611070, "Integrated Flexible Photonic Sensors System (iFLEXIS)" and by the EU Horizon 2020 Programme (European Research Council) under grant agreement no. 716510, 'Transparent and flexible electronics with embedded energy harvesting based on oxide nanowire devices (TREND)" projects. Further fund...