▎ 摘　　要

NOVELTY - Preparation of graphene microtube comprises using ethanol as carbon source, nitrogen or inert gas as auxiliary gas, tantalum wires arranged in parallel and positioned on the same plane as deposition substrate, electrifying the deposition substrate, performing chemical vapor deposition, and obtaining graphene microtube on the deposition substrate. The diameter of the tantalum wire is 0.4-0.8 mm. USE - The method is for preparation of graphene microtube used for three-electrode system useful for detecting salicylic acid. The three-electrode system is used for microelectrode array (all claimed) useful for plant living body detection. ADVANTAGE - The method has wide carbon sources for chemical vapor deposition, low cost, and reduced risk compared to common method, which uses normal methane gas as carbon source, is more simple and safe, and provides graphene microtube, which has high quality and provides three-electrode system, which has small size. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) three-electrode system comprising platinum wire and first PTFE tube, graphene microtube, second PTFE tube and titanium tube, which are sequentially sleeved outside the platinum wire; and (2) microelectrode array comprising three-electrode systems connected in parallel.