For the upcoming generation of consumer electronics and the healthcare industry, flexible electronics show great potential. Flexible electronic devices can mechanically adapt to their environment, making them ideal for sensor systems that are applied to the skin. Several flexible technologies were proposed previously, but one of the most promising approaches is based Organic Electrochemical Transistors (OECTs), which can be seamlessly manufactured on thin, biocompatible, and flexible foil substrates. While OECTs have been evaluated as biosensors for multiple applications already, retrieving sensor data wirelessly is still challenging. Often, a high-frequency Radio Frequency Identification (RFID) interface is proposed, which, however, due to its limited switching speed cannot currently be realized using OECTs. Therefore, in this paper, we present a novel approach to integrate a high-speed silicon-based, rigid Integrated Circuit (IC) into a thin flexible foil to create a communication interface for OECTs. The overall thickness of the fabricated sample using hybrid integration varies between a maximum of 215 µm in the area of the IC and a minimum of 15 µm in the foil area. It can handle an applied strain of up to 7% and can easily be bent up to a bending radius of around 5 mm. This method enables the combination of sophisticated silicon-based technology for high-frequency tasks with soft and flexible organic devices on the same substrate combining the advantages of both domains.
Panambur et al. (Thu,) studied this question.