CFMs were fabricated with 7 μm diameter carbon-fibers (Good-fellow Corporation, PA, USA) aspirated into glass capillaries (0.6 mm external diameter, 0.4 mm internal diameter, A-M systems, Inc., Sequim, WA). A carbon-glass seal was formed via a vertical micropipette puller (Narishige Group, Tokyo, Japan). The exposed length of the carbon fiber was trimmed to 150 μm under an optical microscope. Microelectrodes were electro-plated with Nafion as described previously.4 (link)