▎ 摘　　要

NOVELTY - A graphene channel comprises a graphene film, and a perylene diimide derivative (I), where cortisol aptamer is bonded to the compound (I). USE - Graphene channel used in biosensor for wearable device useful for detecting cortisol in secretion discharged to outside of body (all claimed). ADVANTAGE - The graphene channel has excellent stability to the external environment, binding density with graphene films, and low steric hindrance in binding with bioprobes. DETAILED DESCRIPTION - A graphene film comprises a graphene film, and a perylene diimide derivative of formula (I), where cortisol aptamer is bonded to the compound (I). R1,R2 = H or hydrocarbyl such as 1-10C alkyl, 3-10C aryl, heteroaryl (all optionally substituted with halo, cyano, hydroxy, thio, amido, alkyl, alkoxy, alkylamino, dialkylamino, aryl, aryloxy, arylamino, diarylamino, or heteroaryl). INDEPENDENT CLAIMS are included for the following: (1) a biosensor, which comprises a silk film, and the graphene channel; and (2) a wearable device, which comprises the biosensor.