Challenges and opportunities in the development of planar potentiometric sensors for point-of-care analysis

Despite decades of interest in the development of electrochemical point-of-care sensors, commercial applications are still hindered by unfulfilled needs. This review analyzes work in the field of miniaturized potentiometric devices, with a particular emphasis on reports from the past ten years. Research in this field has focused in particular on the types of underlying substrates to support these sensors, the degree to which sensing components are integrated into the substrate, the use of solid-contact materials to improve performance, and testing in real-life applications. This article highlights challenges in the design and performance of potentiometric point-of-care sensors that are preventing their wider use. Following an overview of differences in the layout of strip-type, sandwich-type, fully integrated, and fiber- and yarn-based sensors, the discussion focuses on the effects of materials and substrates on response slopes, potential reproducibility, and limits of detection.