Performance Characteristics Of Passive Paper-based Microfluidic Fuel Cells Based On Fuel And Ion Transfer Enhancement

In recent years,the paper-based microfluidic chip based on electrochemical reaction has realized the quantitative detection with high sensitivity and high specificity,which is widely used in biomedical field and has a promising prospect.At present,the lithium ion battery is mainly used in the market as a micro power supply.However,lithium ion batteries have disadvantages,such as storage safety,high one-time use cost and complex post-processing procedures.Therefore,the development of high-performance micro power supply with convenient storage and low price has become a research focus at home and abroad.Paper-based microfluidic fuel cells(PMFCs)utilize the capillary flow driven by the pressure difference at the gas-liquid interface in paper porous media of fuel and oxidant to enable passive transport of reactants,and use the co-laminar flow nature to separate the anolyte and catholyte,thereby eliminating the proton exchange membrane and micro-pumps.It makes the design,manufacture and operation simpler and more conducive to system integration.However,the poor performance of the PMFC limits its practical application.In this study,the novel structures of fuel cell were proposed in terms of enhancing fuel transport and reducing ion transport resistance including a PMFC with mini-hole array in the anode flow channel,a double-layer PMFC with wedge-shaped flow channel and a stacked PMFC with longitudinal arrangement of anode and cathode.The effect of the mini-hole array,wedge-shaped flow channel,the interspace between the anode and cathode,electrode length,fuel and electrolyte concentration on the cell performance were discussed.The main research results of this study are as follows:(1)The paper-based microfluidic fuel cell with mini-hole array in the anode flow channel was fabricated.The mini-hole array in the anode flow channel can increase the contact area between fuel and anode,and enhance fuel diffusion,and also reduce the ohmic resistance.As compared to the PMFC with the conventional flow channel,the PMFC with mini-hole array in the anode flow channel yielded 41.2%higher maximum power density.The optimal power density reached 29.7 m W/cm~2 by the proposed PMFC at the anode and cathode interspace of 1.0 mm,the electrode length of 5.0 mm,and the fuel and electrolyte concentrations of 2.0 mol/L.(2)The double-layer PMFC with wedge-shaped flow channel was constructed to accelerate the fuel velocity near the anode,and also increase the effective area of fuel and catalyst on anode surface and inside to strengthen the fuel transfer.The maximum power density of the PMFC with wedge-shaped flow channel was 59.9 m W/cm~2,which was 245.8%and 125.5%higher than that of single-layer PMFC and double-layer PMFC,respectively.(3)The stacked PMFC with longitudinal arrangement of anode and cathode was constructed.Through the design of the longitudinal arrangement of anode and cathode electrode,the ions were transferred along the vertical direction,and shortening the ion transfer distance,thereby strengthening the ion transfer.The optimal power density reached 63.0 m W/cm~2 by the proposed PMFC at the width of paper-based flow channel of 2 mm,the fuel concentrations of 2.0 mol/L and electrolyte concentrations of 1.0mol/L.And the cell showed a good discharge stability.