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

Abstract

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.

Recent Advances in Solution‐Processable Organic Photodetectors and Applications in Flexible Electronics

“…[112][113][114] The flexible OPD had excellent storage stability up to %100 000 min under ambient air conditions, e.g., with a temperature of %20 C and humidity of 30% RH. [115] One should note that unlike OSCs and OLEDs operating under a high current flow in the devices, the OPDs are usually operated under mild conditions, such as room temperature, weak light condition, and low humidity. The intrinsic stability of the OPDs should be improved.…”

“…A self‐powered flexible device was developed for wearable PPG monitoring by integrating an OSC power source, an OLED light emitter, and an OPD sensor unit on an ultrathin flexible substrate. [ 115 ] The ultrathin flexible OPDs are promising for wearable electronic applications. The environmental stability and mechanical robustness of the flexible devices can be further improved by a double‐side coating with a plastic elastomer.…”

“…Published by IEEE Access. (d) Reproduced under terms of the CC-BY license [115]. Copyright 2021, The authors.…”

Soft Stretchable Conductive Carboxymethylcellulose Hydrogels for Wearable Sensors

“…Soft and stretchable devices that can intimately interface with various biological tissues, such as skin, brain, heart as well as peripheral nerves have attracted huge attention in realizing the ultimate closed-loop bioelectronics capable of personalized healthcare monitoring and feedback precise treatment [ 1 , 2 , 3 , 4 , 5 , 6 ]. In the beginning of such devices, their stretchability with low stiffness was achieved by adopting some deformable designs such as a buckled structure in a neutral mechanical plane or rigid active cell island with wavy interconnects [ 7 , 8 , 9 ].…”

Thermal Analysis on Active Heat Dissipation Design with Embedded Flow Channels for Flexible Electronic Devices

“…In recent years, electronic products have emphasized intelligence and miniaturization, which require higher performance at the integration level. In particular, flexible electronic devices represent a rapidly developing branch, which has enabled many new applications such as curvilinear electronics and bio-integrated electronics [1][2][3][4][5][6] due to their unique advantages of stretchability and flexibility [7][8][9][10]. Furthermore, hybrid flexible systems have been investigated, such as electrophysiology [11], multimodal [12], large-area pressure [13] and other functions [14]; such functions may lead to overheating in the system.…”