Rapid and simple assembly of a thin microfluidic fuel cell stack by gas-assisted thermal bonding

Abstract

The rapid growth of portable systems has recently been a driving force behind the efforts for fuel cell (FC) miniaturization. However, approaches taken to scale down conventional FC architectures face the challenge of inefficient utilization of volume and mass. In this paper, we present the technique of gas-assisted thermal bonding (GATB) as a rapid and simple assembly method for constructing FCs with high specific power density. As a proof-of-concept, we use thin polymethylmethacrylate (PMMA) substrates to demonstrate that GATB can be used to seal a porous template within thin polymer substrates to assemble microfluidic devices. This approach is then adopted to directly laminate gas diffusion electrodes (GDEs) with proton exchange membranes (PEMs) to create a microfluidic fuel cell (MFC) based on the membrane itself. The device is composed of two identical cells that are connected in parallel and share a hydrogen-fed microchannel that feeds a common anode chamber. The stack is conditioned with humidified gas and is characterized under different hydrogen flow rates. Finally, the stack specific power density (1131 mW cm−3) is compared with several represantative reports on air-breathing FCs. The GATB method in this work offers a simple, one-step unitized construction approach for flexible devices, in which the package is integral with the functional parts of the device.