Application of Nanoimprint Technology in MEMS-Based Micro Direct-Methanol Fuel Cell ( $\mu$ -DMFC)

This paper presents the application of the nanoimprint technology in microelectromechanical-systems (MEMS)-based micro direct-methanol fuel cell (mu-DMFC) for high performance and low cost. We first reported the nanoimprint behavior of the protonated Nafion 117 membrane with different micro patterns within the temperature range of 100degC -150degC. The best pattern transfer was achieved at 130degC for the nanoimprint of the protonated Nafion 117 membrane. Micro pillar structure with an average height of about 60 nm was successfully formed on the protonated Nafion 117 membrane using silicon molds with the optimized nanoimprint parameters. The nanoimprinted Nafion 117 membrane was coated with 20-nm-thick Pt films as catalyst by sputtering and then sandwiched with microfabricated silicon electrodes to form a nanoimprinted mu-DMFC prototype. With passive feeding of 1-M methanol solution and air, the nanoimprinted mu-DMFC had an open-circuit voltage of about 0.74 V and a maximum power density of 0.2 mW², which were much higher than those of the state-of-the-art MEMS-based mu-DMFC. The experimental results suggested that large triple-phase reaction surface, high catalyst efficiency, and thin diffusion layer thickness had been realized in the nanoimprinted mu-DMFC prototype with the absence of traditional carbon-paper-based porous electrode. An attractive prospect was demonstrated for the application of the nanoimprint technology in MEMS-based mu-DMFC and other micro power devices.