A passive micro gas regulator for hydrogen flow control

This paper presents the design, fabrication process, experimental characterizations and simulations of a novel passive micro gas regulator. The device is to be used in a miniature fuel cell for portable electronic applications in order to regulate the hydrogen flow feeding the fuel cell from a high-pressure tank. Its structure and working principle are similar to some macroscopic devices. Using MEMS technologies, e.g., deep-RIE etching and multiple wafer bonding, the dimensions of the device have been made less than 8 x 8 x 1 mm(3). Moreover, as it is passive, it consumes no power from the fuel cell. Thanks to these two features, it is well suited for portable applications. To our knowledge, this is the first passive micro gas regulator, except those actuated by hydrogels. The experimental characterization shows that the opening and closing are controlled by the released gas pressure. Up to an input pressure of 8 atm, the device has been successfully driven and the leakage has been measured to be below 0.1 sccm nitrogen. Analytical models for the moving part and for the flow rate show a good agreement when compared to the experimental data.