Polymer separator to minimize crossover in microfluidic direct methanol fuel cells

Microfluidic direct methanol fuel cell (DMFC) overcome some key issues- fuel crossover and water management - that typically hampers conventional polymer electrolyte-based fuel cells. Here we report a method to further minimize fuel crossover in microfluidic DMFC. First, a polymer separator at the interface of the fuel and electrolyte streams in a single-channel microfluidic DMFC to reduce the cross-sectional area across which methanol can diffuse. Maximum power densities of 6.8 mW cm^-2 were obtained with a separator with when using 2 M methanol. This simple design improvement reduces loss at the cathode leading to better performance.