▎ 摘　　要

NOVELTY - A fine carbon fiber (5) has diameter of less than 100 nm and contains cylindrical graphene having nest shape. The cross-sectional shape of the right-angled cylindrical graphene has polygonal shape in the length direction. The fiber does not contain iron-group element. USE - Used in biopolymer detection device and medical device (claimed). ADVANTAGE - The fine carbon fiber has excellent electroconductivity, thermal conductivity, mechanical characteristic, chemical reactivity and biochemical reactivity. The device having improved safety and high efficiency is provided without damaging the biopolymer. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: 1) a medical device, such as balloon catheter, which consists of fine carbon fiber; and 2) biopolymer detection device comprises using fine carbon fiber as an electrode. DESCRIPTION OF DRAWING(S) - The figure shows the structure of fine carbon fiber. Arc-welding power supply (1) Hollow carbon anode (2) Carbon cathode (3) Gas supply unit (4) Fine carbon fiber (5)