NOx sensor chip

The invention relates to an NOx sensor chip which is mainly characterized by comprising a first substrate, a second substrate, a third substrate, a fourth substrate, a fifth substrate, a six substrate which are sequentially overlapped from top to bottom, wherein a pump oxygen outer electrode is arranged on the upper surface of the first substrate, the second substrate includes a first cavity, a second cavity, a third cavity and a fourth cavity, a diffusion barrier layer with a certain porosity is arranged between the third cavity and the fourth cavity, a main pump oxygen electrode is arranged in the third cavity, an auxiliary pump oxygen electrode and a test electrode are arranged in the fourth cavity, a porous protection layer is covered on the test electrode, the fourth substrate is provided with a reference gas channel, a reference electrode is arranged at the top of the channel, and a heating electrode is arranged between the fifth substrate and the sixth substrate. By adopting the structure, the NOx sensor chip has the advantages that the pollution caused by volatilization of gold in the electrode can be prevented, the substrates are sintered and tightly combined, the structure is simple, the process is simple, and the concentration of oxynitride in automobile exhaust can be accurately measured.