Investigation of Polymer-Coated Film Bulk Acoustic Wave Resonator for Acetone Vapor Detection

In this paper, we fabricate the polymethylmethacrylate (PMMA) coated film bulk acoustic wave resonator (FBAR) gas sensors and investigate the sensing performance. The FBARs work at near 2.48 GHz and have high performances. The 10~70 nm thick PMMA layer were deposited on the surface of the FBARs as the sensitive coating. The influence of the thickness of PMMA on the sensing performances is investigated in detail. The experimental results indicate that the PMMA coated FBARs can be quite sensitive to acetone vapor. After PMMA coating, the resonance frequency and Q-factor are lineally decreased due to the added mass loading onto the electrode. The PMMA coated FBAR is able to detect acetone vapor as low as 0.04% with a gas sensitivity as high as 685 kHz/%. These PMMA coated FBARs could be further developed as a handheld sensor for vapor detection.