Development of a Flexible Printed Circuit Board-Based Potentiometric Urea Biosensor Combined With Power Management Circuit Chip

This study proposes a power management circuit integrated with a readout circuit for measuring urea biosensors. The proposed power management circuit replaces the bulky power supply traditionally used in measurement systems. It operates with only a single 3V button cell for voltage reduction and stabilization. We have designed and manufactured a printed circuit board (PCB) that integrates passive components and power management readout circuit chip for measuring a urea biosensor. A RuO2 thin film was prepared on a flexible printed circuit board (FPCB) through radio frequency (RF) sputtering. To fabricate the urea sensor, we used 3-Aminopropyltriethoxysilane ( $\gamma $ -APTES), glutaraldehyde, and urease. The average sensitivity of the urea sensor was evaluated to be 3.121 (mV/(mg/dL)), with a linearity of 0.994 and a reproducibility of 2.59 %. These results confirm the stability and reliability of the sensor architecture.