We present a straightforward method for fabricating functional micro-, submicro-, and nano-channels embedded in a porous carbon film and the application of this microfluidic platform for electrochemical sensing. A skin layer of poly(methyl methacrylate) (PMMA) fibers was first electrospun on a thoroughly cleaned Si wafer substrate, followed by spin coating of a polyacrylonitrile (PAN) film on top of the skin. High-temperature carbonization of the composite film decomposed the PMMA fibers and produced embedded microchannels in the PAN-derived amorphous monolithic carbon electrode. The channels were decorated with Pt nanoparticles by in situ thermal decomposition of a precursor metal salt to enhance functionality of the carbon electrode. Carbon electrodes decorated with Pt nanoparticles (carbon-Pt), with and without embedded microchannels, were used to detect the food toxin aflatoxin B1 (AFB1) by surface biofunctionalization with the antibodies of AFB1 (anti-AFB1) via an electrochemical impedance technique. The aligned nanochannels in the porous carbon film act as a reaction chamber for antigen-antibody interactions and provide channels for fast electron transport toward the electrode from the electrolyte, resulting in improved electrochemical performance of the biosensor. The fabricated immunosensor is highly sensitive to 1 pg/mL of AFB1 with a concentration range of 10(-12)-10(-7) g/mL. (C) 2016 Elsevier B.V. All rights reserved.