An inlet structure (200) is adapted to be connected to a microchannel (300). The inlet structure includes an inlet portion (210) and at least one micro structure (220). The inlet portion contains an inner surface. The micro structure is disposed in the inlet portion and connected to the inner surface. When a fluid is injected into the inlet portion, the micro structure destroys a surface tension of the fluid to cause the fluid to flow into the microchannel by capillary action.
