Breath analysis is of great significance for the early diagnosis of diabetic ketoacidosis. Gas sensors with simple structure and low cost have become candidates for breath analysis. The detection range and reliability of the device play an important role in the actual application. In this work, we used Bi1-xSr_xFeO₃(x = 0.2, 0.4, 0.6, 0.8) prepared by sol-gel method to fabricate Ce_0.8Gd_0.2O_1.95(GDC)-based mixed potential type acetone sensors, and obtained satisfactory sensing performance. The amount of Sr substitution in sensing materials could change the content of deficient oxygen inside the material and the electrochemical catalytic activity of the material, thereby improving the sensitivity of the sensor. Mixed potential sensing mechanism and the reason for sensitivity seg-mentation phenomenon were also explained. In addition, we did clinical tests for the sensor towards the exhalation of diabetic patients and healthy people, which displayed the potential of the sensor used for breath analysis.