Self-powered ultraflexible photonic skin for continuous bio-signal detection via air-operation-stable polymer light-emitting diodes

• Published in: Nature communications 2021-04, Vol.12 (1), p.2234-2234, Article 2234
• Main Authors: Jinno, Hiroaki, Yokota, Tomoyuki, Koizumi, Mari, Yukita, Wakako, Saito, Masahiko, Osaka, Itaru, Fukuda, Kenjiro, Someya, Takao
• Format: Article
• Language: English
• Subjects: 147/3; 639/166/987; 639/301/1005/1007; Air monitoring; Electric Power Supplies; Electronic devices; Electronic equipment; Energy harvesting; Equipment Design; Heart Rate; Humanities and Social Sciences; Humans; Integration; Light; Light emitting diodes; Light intensity; Linearity; Luminous intensity; Monitoring; Monitoring, Physiologic - instrumentation; Monitoring, Physiologic - methods; multidisciplinary; Optical Devices; Optical measuring instruments; Photons; Photovoltaic cells; Polyethyleneimine; Polymers; Polymers - chemistry; Power management; Power sources; Science; Science (multidisciplinary); Sensors; Signal detection; Signal monitoring; Solar cells; Solar Energy; Wearable Electronic Devices
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-22558-6

Ultraflexible optical devices have been used extensively in next-generation wearable electronics owing to their excellent conformability to human skins. Long-term health monitoring also requires the integration of ultraflexible optical devices with an energy-harvesting power source; to make devices self-powered. However, system-level integration of ultraflexible optical sensors with power sources is challenging because of insufficient air operational stability of ultraflexible polymer light-emitting diodes. Here we develop an ultraflexible self-powered organic optical system for photoplethysmogram monitoring by combining air-operation-stable polymer light-emitting diodes, organic solar cells, and organic photodetectors. Adopting an inverted structure and a doped polyethylenimine ethoxylated layer, ultraflexible polymer light-emitting diodes retain 70% of the initial luminance even after 11.3 h of operation under air. Also, integrated optical sensors exhibit a high linearity with the light intensity exponent of 0.98 by polymer light-emitting diode. Such self-powered, ultraflexible photoplethysmogram sensors perform monitoring of blood pulse signals as 77 beats per minute. Flexible electronic devices remain an attractive technology for optical sensor applications that require long-term health monitoring and conformability on human skin. Here, the authors report an ultrathin self-powered integrated organic optical system for plethysmogram monitoring.