[IEEE 2019 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS) - Glasgow, United Kingdom (2019.7.8-2019.7.10)] 2019 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS) - Detectors and light-sources for optical spectrometry: from a 3D-printed light-source to a self-powered sensor fabricated on a flexible polymeric substrate, and from there on to an IoT-enabled "smart" system