A fully capillary-driven μDMFC twin-stack operating in all orientations

A novel concept of fully automatic fuel supply for passive micro direct methanol fuel cells (μDMFCs) twin-stack is presented. A special capillary pump featured by symmetric channel array is designed to transport methanol fuel spontaneously by capillary force and allows the stack operating in all spatial orientations. The prototype was demonstrated to exhibit a power density of 22.5 mWcm^-2 in the preferred vertical orientation and of 17.1 mWcm^-2 in the least favorable inverted orientation with fuel tank facing downwards. Furthermore, the stack achieved continuous operation in different orientations more than 300 minutes without significant performance degradation. As such, it is more applicable for portable devices.