DIGITAL LIQUID-LEVEL SENSOR

A digital liquid-level sensor (100, 200) comprising a nonmagnetic tube (1), a float (2) provided outside the nonmagnetic tube (1) and capable of moving along the nonmagnetic tube in the axial direction (1), and a permanent magnet (6) fixed on the float (2). The nonmagnetic tube (1) further comprises a switch unit (3) and an encoding unit (4). The switch unit (3) comprises at least one tunneling magnetoresistance switch (s0-s7), which is turned on or turned off under the influence of the magnetic field produced by the permanent magnet (6); and the encoding unit (4) comprises at least one encoder (15), that receives an on/off signal from the tunneling magnetoresistance switch unit (s0-s7) and outputs a digital signal indicating the position of the float (2). The digital liquid-level sensor has small size, low cost, low power consumption, high reliability, high sensitivity, high resolution, long service life, and a good immunity to environmental interference. It additionally can directly output the fluid level as a digital signal.