▎ 摘　　要

NOVELTY - The filter has substrate that is made of graphene ammonia sensitive material. A filter paper (1), graphene oxide layer (2) and silver electrode (3) are arranged from bottom to top in order. The filter paper is set with reduction-oxidation graphene film layer. USE - Filter of ammonia detector. ADVANTAGE - The filter is provided with simple structure and easy to produce. The filter is processed into different sizes and different shapes. The ammonia detector is flexible and portable. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a preparation method of filter. DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of the filter. Filter paper (1) Graphene oxide layer (2) Silver electrode (3) Direct current ammeter (4) Direct current power source (5)