Ascorbic acid fuel cell with a microchannel fabricated on flexible polyimide substrate

Abstract

We used microelectromechanical system techniques to fabricate a miniature ascorbic acid fuel cell (AAFC) equipped with a microchannel for the circulation of ascorbic acid solution (AAS). The fuel cell was fabricated on a flexible polyimide substrate, and a porous carbon-coated aluminum (Al) anode with the dimensions of 2.8×1 mm2 and a porous carbon-coated Al cathode with the dimension of 2.8×10 mm2 were fabricated using photolithography and screen-printing techniques. The porous carbon was deposited by screen-printing carbon-black ink onto the Al electrode surfaces in order to increase the effective electrode surface areas and to absorb more enzymes (bilirubin oxidase) on the cathode surface. No enzyme was deposited on the carbon coated anode surface. The microchannel with a dimension of 3 ×11×0.2 mm3 was fabricated using a hot-embossing technique. The maximum power of 0.60 μW at 0.58 V, with a corresponding power density of 1.96 μW/cm2, was realized by introducing a 200 mM concentrated AA solution at the flow rate of 30 ml/min at room temperature. No degradation of the anode and cathode was observed up to the radius of curvature of 7.5 mm, which suggests the flexibility of the AAFC.