A new type of gas sensor to measure resistance was developed to detect sevoflurane concentrations at room temperature. The measured FTIR spectrum of sevoflurane vapor was given. The sensing material polypyrrole was synthesized in situ by UV-photopolymerization. The relative resistance variation was 3.9 for a sevoflurane concentration of 1.2%. The sensor response time (60 s) and recovery time (20 s) were very short. Molecular dynamic calculations made for sevoflurane adsorption on polypyrrole revealed formation of a new bond, N-H-F. The bond length was predicted to be in the range of 0.2-0.4 nm. The bond energy was about 7.2 kcal/mol. Sensor responses to the concentrations 0.1-10% were 1.57-5.9, respectively.