Microfluidic detection unit and fluid detection method

A microfluidic detection unit for detecting a fluid and a biochemical or chemical reaction occurring therein, the microfluidic detection unit comprising:

• a substrate comprising:
• at least one fluid injection section, each fluid injection section defining a fluid outlet;
• a fluid storage section which is in gas communication with the atmosphere and defines a fluid inlet;
• a detection section defining a first end and a second end, the first end being in communication with the fluid outlet of the fluid injection section, the first end being configured to receive the fluid from the fluid injection section, and the second end being in communication with the fluid inlet of the fluid storage section, the second end being configured to output the fluid to the fluid storage section;
• and
• at least one input channel, each input channel communicating from the fluid outlet to the first end of the detection section;
• wherein a height difference is defined between the fluid outlet of the fluid injection section and the fluid inlet of the fluid storage section along a direction of gravity such that the fluid outlet of the fluid injection section has a gravitational potential of greater than that of the fluid inlet of the fluid storage section;
• wherein when a first fluid is injected from the at least one fluid injection section, the first fluid is driven by gravity to pass through the at least one input channel to enter the detection section and is stopped between the fluid outlet of the fluid injection section and the fluid storage section to accumulate to form a droplet at the fluid inlet of the fluid storage section, and a height along the direction of gravity of the droplet is between a bottom surface of the substrate and the fluid outlet of the fluid injection section, such that a gravitational potential and a capillary force opposite to the direction of gravity of a portion of the first fluid in the at least one input channel and between the fluid outlet and a position with the height along the direction of gravity of the droplet are offset to establish a state of fluid pressure equilibrium.