Multiplexed Electrochemical Sensors Based on Printed Circuit Board

Abstract

Electrochemical sensors are widely used in all fields of scientific and industrial analyses. Ion-selective electrodes (ISE) are potentiometric sensors that measure activities of ions and ionic species. These sensors reply on ionophores/ion-exchanging membrane for selectivity and liquid inner reference for ion-to-electron transduction. However, conventional ISEs are primarily used in laboratory settings due to fragility and routine maintenance. In recent years, development of solid-contact ISEs (SCISE) has shown promise to permit sensors to be taken out of the lab for point-of-need or point-of-care applications, including clinical diagnostics, wearable devices, precision agriculture, and in situ environmental monitoring. However, long-term, multi-analyte measurements remain difficult owing to challenges associated with sensor stability, cost of material and automation. In this work, we demonstrated multiplexed, cost-effective SCISEs that are suitable for long-term, standalone measurements. We used mesoporous carbon black (MCB) as a low-cost, readily available solid contact material for ion-to-electron transduction, which substantially improved sensor stability. With MCB, we developed a novel method of fabricating multiplexed SCISEs using printed-circuit board (PCB). PCB technology offers a viable alternative to existing techniques with unparalleled upscaling capability. To enable continuous and automatic analysis, we developed an integrated system that supports sensor readout and, most importantly, the ability to re-calibrate sensor in situ. Finally, we explored applications of the sensor system in complex samples, including plant sap, cell culture media, and artificial saliva. The results here demonstrate that the multiplexed sensing platform can provide a reliable, versatile tool with substantial potential for a variety of point-of-need or point-of-care applications.