▎ 摘　　要

NOVELTY - A device consists of a biopolymer membrane (10) comprising a biopolymer, a passivation layer (20), a graphene layer, a source electrode and a drain electrode, formed in order. The graphene layer extends between the source electrode and the drain electrode. The thickness of the biopolymer membrane is less than 10 mu m. The biopolymer membrane preferably comprises a bacterial cellulose. USE - Device e.g. transistor and sensor (all claimed) for medical diagnosis and monitoring, neural prosthetics and brain-machine interface. ADVANTAGE - The device has excellent durability and flexibility, high carrier mobility and low drain voltage and gate potential, and can be microfabricated by economical process with high yield. The sensor comprising the biopolymer does not cause damage with respect to tissues and nerves. DESCRIPTION OF DRAWING(S) - The drawing shows schematic cross-sectional view of graphene transistor. Biopolymer membrane (10) Graphene (12) Gate insulator (17) Gate electrode (18) Passivation layer (20)