 A two-dimensional phononic crystal sensor model was developed for detecting acetone concentrations in a wide frequency range, 25 to 45 kHz. The model was composed of quasi-crystalline and gradient cavity structures, resulting in high quality factors and sensitivities for different acetone concentrations. The sensor's performance was verified through calculations of its sensitivity to sound velocity and density. This article was authored by Chen Yinfang, Xiaowei Sun, Xiaodong Wen, and others.