TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Component: The mechanism comprises a housing having at least one opening, and a vibrator for injecting the gas contained inside the housing into the flow channel through the opening. The vibrator comprises a first surface facing the exterior of the housing and a second surface facing the interior of the housing. The housing comprises chambers partitioned by the vibrator. The opening in the housing (102) comprises openings connecting the chambers with the exterior of the housing. The vibrator (104) injects the gas contained inside the chambers (105) through the openings. The chambers have the same volumes. The spaces between the vibrator and each of the openings are the same. The fuel-cell unit comprises an inlet for introducing the gas injected from the mechanism to the flow channel, the inlet facing the opening. The gap between the opening and the inlet is 1-10 (2-5) times larger than the width of the opening. The fuel-cell unit comprises an inlet for introducing the gas injected from the mechanism to the flow channel, the inlet facing the opening (103). The opening area of the opening is smaller than that of the inlet. The total opening area of the openings is smaller than the opening area of the inlet. The vibrator comprises a vibrating plate (121) having a first surface perpendicular to the vibrating direction of the vibrator and a second surface parallel to the first surface, and at least one coil attached to at least one of the first surface and the second surface. The mechanism comprises at least one permanent magnet (124) opposing the coil (128). A supporting body supports the permanent magnet and the vibrating plate so that the vibrating plate vibrates by the interaction between a magnetic field generated by the permanent magnet and generated when the coil is energized. The vibrating plate has a first region and a second region surrounding the first region. A lead wire is electrically connected to the coiled and detached to a gas-injecting unit.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The gas injected from the mechanism is air.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The gas injected from the mechanism is air.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The first region is mainly composed of a resin from an epoxy resin, a polyimide resin, a polyetherimide resin, or a polyethylene-terephthalate resin. The second region is mainly composed of butyl rubber.