An ultrathin organic–inorganic integrated device for optical biomarker monitoring

Organic electrochemical transistors can be used in wearable sensors to amplify biological signals. Other wireless communication systems are required for applications in continuous health monitoring. However, conventional wireless communication circuits, which are based on inorganic integrated chips, face limitations in terms of conformability due to the thick and rigid integrated circuit chips. Here, we report an ultrathin organic–inorganic device for wireless optical monitoring of biomarkers, such as glucose in sweat and glucose, lactate and pH in phosphate-buffered saline. The conformable system integrates an organic electrochemical transistor and a near-infrared inorganic micro-light-emitting diode on a thin parylene substrate. The device has an overall thickness of 4 μm. The channel current of the transistor changes according to the biomarker concentration, which alters the irradiance from the light-emitting diode to enable biomarker monitoring. We combine the device with an elastomeric battery circuit to create a wearable patch. We also show that the system can be used for near-infrared image analysis.