Nanomaterial Modification of Ultramicroelectrodes Using Design-of-Experiments Principles

Modification of ultramicroelectrode sensors with electroactive nanomaterials is key to enhancing their microscale sensing performance for advanced applications in cellular biology, disease diagnostics, or scanning electrochemical microscopy (SECM). This work employs a modern design-of-experiment (DoE) approach to develop a systematic, multiple-parameter methodology for the development of robust ultramicroelectrode modification protocols. Specifically, platinum ultramicroelectrode sensors are coated with platinum/nanocarbon nanocomposites through electrophoretic deposition (EPD), using 2k factorial screening designs to systematically investigate the ultramicroelectrode modification process. The steady state current is employed as a quantitative DoE target metric, enabling us to map and model optimum ultramicroelectrode modification conditions. DoE-optimized modification conditions are shown to achieve substantial improvements in coating quality and limit of detection in a model H2O2 sensing study. The DoE-optimized conditions are also successfully translated to the modification of carbon-fiber ultramicroelectrodes (CFM), achieving effective modification in a single experiment. This systematic DoE approach provides a versatile, robust, and highly effective method for developing ultramicroelectrode modification across multiple parameters through a minimal number of experiments. Importantly, the DoE methodology also readily identifies tolerances and limiting conditions for the modification process, vital for broader adoption and future technology translation of functionalized ultramicroelectrodes.