Highly scalable design of 3D copper-doped graphene printed microfluidic chip for the electrochemical quantification of plasma homocysteine

•Three-dimensional (3D) Cu-doped graphene printed on a polyimide film by CO2 laser.•Cu doping levels optimized for the 3D graphene morphology and catalytic sites.•A microfluidic homocysteine sensing chip was developed from 3D-Cu-doped graphene.•Chip efficiency and practicality are tested with plasma samples.