Az5214 photoresist

PDMS (Sylgard 184), Cu electroplating kits, including Microfill EVF Carrier, Brightner, and Leveler, were purchased from Dow Corning, Midland, MI, USA. Potassium hydroxide pellet (KOH) was purchased from Fisher Scientific, Waltham, MA, USA. AZ 5214 photoresist was purchased from MicroChemicals, Ulm, Germany. Trichloro(1H,1H,2H,2H-perfluorooctly)silane, NaClO₂, NaOH, and Na₃PO₄·12H₂O were purchased from Sigma Aldrich, St. Louis, MI, USA. Cu etchant (CE-100) was purchased from Transene, Danvers, MA, USA. Hydrochloric acid (HCl) was purchased from Macron Fine Chemicals, Allentown, PA, USA.

Microscopic patterning of graphene was carried out using standard photolithography procedures. In brief: the graphene-covered SiO₂/Si substrates were covered by AZ5214 photoresist (MicroChemicals GmbH) by spin coating at 3500 rpm. A photomask with desired patterns were aligned on top with a Karl Suss MA6 mask aligner followed by 6 s of UV exposure at 8 mW. After removing the non-irradiated photoresist using AZ Developer, the exposed graphene was removed by O₂ plasma etching at 100 W for 60 s. The remaining photoresist was then striped using acetone followed by a 1 hour baking step at 450 °C under Ar protection to thoroughly remove the remaining photoresist residues. vTANI was then selectively grown on the patterned graphene, followed by sputtering of desired inorganic materials via vacuum deposition.

For the nanotube fabrication (Fig. 5 and 6), the ITO-coated vTANI were embedded in AZ5214 photoresist (MicroChemicals GmbH) via spin coating. An optical microscope was used to examine the piece to ensure the arrays were completely embedded in the photoresist. Directional etching of the photoresist was carried out using a Technics Micro-RIE Series 800 Plasma System at 1 min intervals. SEM was used to examine the sample after each minute of etching until the desired height of tips was exposed. The sample was then sonicated in a bath sonicator for 4–5 min to break off the exposed tips. Finally, the entire wafer was soaked in heated acetone (∼50 °C) for 40 min with intermittent agitation to dissolve both the remaining photoresist and the TANI core.