System-on-Board Integrated Flexible OEGFET Aptasensor for Multianalyte Testing in Saliva

The need for oral health monitoring point-of-care (PoC) systems is ever growing. We have recently reported a novel, aptamer-based flexible biosensor for detection of a high impact hormone—cortisol—in saliva samples using organic electrolyte-gated FET (OEGFET) technology. In this work, we are reporting a system-on-board (SoB) level integration of an improved flexible OEGFET aptasensor, which was previously reliant on a bench-top measurement setup. The reported flexible OEGFET aptasensor has integrated soft microfluidics and a low-power (< 300 mW) customized printed circuit board. The interfacing of flexible aptasensor to the circuit board was achieved using a low-temperature extrusion printing technique. The system was assessed using spiked saliva supernatants, which established comparable detection threshold for the miniaturized, board-based configuration. In this expanded article, we furthermore demonstrate improvements to device structure and the integration process, which improves the signal-to-noise resolution. By implementing 3-D printing technology, the interconnects between the flexible sensor and conventional printed circuit board (PCB) are more durable and possess better conductivity. The optimized transistor pattern allows for multiple analytes to be tested concurrently. A side-by-side analysis of a device that is specific to cortisol biomolecules and a nonspecific device shows that the SoB is capable of distinguishing between binding and nonbinding device behavior. The portable oral biosensor has the potential to be transformed into a multianalyte sensing platform and is therefore a promising prototype for future clinical validation.