Wireless Optical Biomarker Monitoring Using an Ultraflexible Organic-Inorganic Integrated Device

Wireless communication systems for ultrathin organic electronics are essential for highly sensitive health monitoring. Organic electrochemical transistors (OECTs) are emerging as powerful amplifiers with high transconductance and can be used in wearable sensors to amplify biological signals. However, implementing wireless communication with OECTs presents significant challenges. Additional wireless communication systems are required for applications in continuous health monitoring, and conventional wireless communication circuits based on inorganic integrated chips face limitations in conformability due to the thick and rigid integrated circuit chips. Here, we present an ultraflexible organic-inorganic integrated wireless optical communication device with high conformability, which integrates OECT biochemical sensors and near-infrared (NIR) inorganic micro light-emitting diodes (μLEDs). The channel current of the OECT varies with biomarker concentration, which alters the irradiance of the μLED. The integrated device enables wireless optical monitoring of biomarkers, such as glucose, lactate, and pH. The OECT exhibits high transconductance and excellent flexibility, while the μLED demonstrates outstanding stability and electrical characteristics. The conformable system integrates an OECT and the μLED on a thin parylene substrate. Consequently, a 4-micrometer-thick ultrathin integrated device enables reliable data amplification and transmission while maintaining high conformability. To validate the wireless transmission ability, the integrated device was fabricated as a wearable patch powered by an elastomeric battery circuit, and wireless sweat glucose monitoring was performed. Furthermore, the utility of the system was demonstrated through NIR image analysis. The simple circuit structure and low-power operation of the integrated device suggest its potential use in various circuit applications. Furthermore, due to the biological application of OECTs and skin transmittance of NIR μLEDs, this system holds promise for various wearable and implantable device applications.