Reproducible Fabrication Method for Micrometer-Sized Au Disk UMEs

The reproducible fabrication of Au disk ultramicroelectrode (UME) is a significant challenge. Particularly, for Au UMEs with sizes in the range of several micrometers, the common fabrication method involves inserting a gold wire into a glass capillary and pulling it with annealing. However, this method suffers from poor reproducibility. Herein, we propose a novel method for fabricating Au UMEs by first creating a glass tip using a puller, then producing a hollow carbon UME through pyrolysis, electroplating gold onto it, and finally milling it using focused ion beam (FIB). This method not only allows the electrode area to be adjusted to the desired size using FIB but also enables control over the RG ratio by modifying the glass capillary fabrication process with the puller.