A Double-Bridge Channel Shape of a Membraneless Microfluidic Fuel Cell

A double-bridge shape is proposed as a novel flow channel cross-sectional shape of a membraneless microfluidic fuel cell, and its electrochemical performance was analyzed with a numerical model. A membraneless microfluidic fuel cell (MMFC) is a micro/nano-scale fuel cell with better economic and commercial viability with the elimination of the polymer electrolyte membrane. The numerical model involves the Navier–Stokes, Butler–Volmer, and mass transport equations. The results from the numerical model were validated with the experimental results for a single-bridge channel. The proposed MMFC with double-bridge flow channel shape performed better in comparison to the single-bridge channel shape. A parametric study for the double-bridge channel was performed using three sub-channel widths with the fixed total channel width and the bridge height. The performance of the MMFC varied most significantly with the variation in the width of the inner channel among the sub-channel widths, and the power density increased with this channel width because of the reduced width of the mixing layer in the inner channel. The bridge height significantly affected the performance, and at a bridge height at 90% of the channel height, a higher peak power density of 171%was achieved compared to the reference channel.

Single microfluidic fuel cell with three fuels – formic acid, glucose and microbes: A comparative performance investigation

The development of microfluidic and nanofluidic devices is gaining remarkable attention due to the emphasis put on miniaturization of conventional energy conversion and storage processes. A microfluidic fuel cell can integrate flow of electrolytes, electrode-electrolyte interactions, and power generation in a microfluidic channel. Such microfluidic fuel cells can be categorized on the basis of electrolytes and catalysts used for power generation. In this work, for the first time, a single microfluidic fuel cell was harnessed by using different fuels like glucose, microbes and formic acid. Herein, multi-walled carbon nanotubes (MWCNT) acted as electrode material, and performance investigations were carried out separately on the same microfluidic device for three different types of fuel cells (formic acid, microbial and enzymatic). The fabricated miniaturized microfluidic device was successfully used to harvest energy in microwatts from formic acid, microbes and glucose, without any metallic catalyst. The developed microfluidic fuel cells can maintain stable open-circuit voltage, which can be used for energizing various low-power portable devices or applications.