Germany-based design firm WertelOberfell has teamed up with material scientists, material suppliers, end-users and manufacturers to develop ESUB Tracks, a conceptual design for a smart bicycle helmet powered by flat-printed organic photovoltaics. Designed to prioritize safety, the proposed smart bicycle helmet is equipped with proximity sensors, a printed piezoelectric microphone that accepts basic voice commands for hands-free use, turn signal indicator lights and printed piezoelectric bone conduction speakers that provide audio via Bluetooth without distracting from the surrounding environment. To maximize solar access, the designers covered the entire surface of the uniquely shaped helmet with flat printed organic photovoltaics to recharge the printed organic batteries tucked inside a unit in the lower rear part of the helmet.