▎ 摘　　要

NOVELTY - Horizontal biosensor comprises: a reduced graphene oxide layer formed on a substrate; a molecular linker formed on the reduced graphene oxide layer; and a metal nanoparticle layer formed on the molecular linker. USE - The horizontal biosensor is useful for diagnosing various diseases. ADVANTAGE - The horizontal biosensor: has a charging effect superior to a conventional biosensor; can be prepared in a method i.e. equally or more economical as compared with a conventional method and can be highly commercialized; utilizes reduced graphene oxide that is flexible, has a very high electrical conductivity, an excellent hole and electron mobility, provides a covalent bonding site, and becomes easy to array a monolayer of a metal nanoparticle; is simple; is capable of accurately diagnosing various diseases; has micro concentration detectability and reproducibility; and has an increased electrode effective area, thus exhibiting high sensitivity. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing a horizontal biosensor, comprising: forming a reduced graphene oxide layer on a substrate; forming a molecular linker on the reduced graphene oxide layer; and forming a gold nanoparticle layer on the molecular linker.