Optimized Shelf-Stacked Paper Origami-Based Glucose Biofuel Cell with Immobilized Enzymes and a Mediator

Recently, as an efficient renewable power source, paper microfluidic enzymatic biofuel cells have received significant attention. Due to their inherent characteristics and outstanding performance, a microfluidic paper-based analytical device for enzymatic biofuel cells (μPAD-EBFCs) has emerged as the best alternative to conventional power supplies for various miniaturized devices. This work presents a novel, user-friendly, and cost-efficient enzyme and mediator-immobilized electrochemistry-based shelf-stack-configured μPAD-EBFC. This Y-shaped colaminar fluid-flow EBFC has been realized using multiwall carbon nanotube (MWCNT)-composed Bucky paper (BP) as a bioelectrode, where GOx (anodic enzyme) and laccase (cathodic enzyme) were immobilized with optimized chemistry. The potentiometric oxidation and reduction performances of fabricated bioelectrodes were characterized using different electrochemical techniques. Subsequently, four such Y-shaped μPAD-EBFCs were realized in a shelf-stack configuration using a mini-three-dimensional (3D) printed platform, where the μPAD-EBFCs were connected in various series–parallel arrangements. With such shelf-stack configurations, 4 series-connected μPAD-EBFCs delivered the maximum stable open circuit potential of 1.65 V, with a peak power density of 46.4 μW/cm2 (58 μA/cm2) at 0.8 V. The generated output power is sufficient to power the small portable device, which can be easily and suitably tuned depending on the application.