Sensors and Actuators B 126 (2007) 387–393 New sensing technology for detection of the common inhalational anesthetic agent sevoﬂurane using conducting polypyrrole ﬁlms Ren-Jang Wu a,∗ , Yu-Ching Huang a , Murthy Chavali b , Tzu Hsuan Lin c , Shih-Lin Hung c , Hsiang-Ning Luk d a Department of Applied Chemistry, Providence University, 200 Chungchi Road, Shalu, Taichung Hsien 433, Taiwan, ROC b Environmental Techniques Center, U-CAN Dynatex Inc., No. 95 Nankang 3rd Road, Nankang Ind. Park, Nantou City 540, Taiwan, ROC c Department of Civil Engineering, National Chiao Tung University, Hsinchu 300, Taiwan, ROC d Department of Anesthesiology, Taichung Veterans General Hospital, Taichung, Taiwan, ROC Received 27 August 2006; received in revised form 17 March 2007; accepted 19 March 2007 Available online 27 March 2007 Abstract 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. © 2007 Elsevier B.V. All rights reserved. Keywords: Sevoﬂurane; Polypyrrole; Conducting polymer; UV-photopolymerization; VOC sensor 1. Introduction Among numerous inhalational anesthetic agents in cur- rent use are potent volatile liquids of halogenated derivatives of alkanes, particularly halothane (CF 3 CHClBr; 1956 as ﬂu- orothane), the halogenated derivatives of ethers, especially enﬂurane (CHClFCF 2 OCHF 2 ; 1972 as ethrane), the malodor- ous isoﬂurane (CF 3 CHClOCHF 2 ; 1981 as forane), the more volatile but equally malodorous desﬂurane (CF 3 CHFOCHF 2 ; 1992 as suprane), and lastly the non-irritating, sweet to taste, highly insoluble sevoﬂurane (C 4 H 3 F 7 O; 1990 as ultane). All play vital roles in the pain management of patients undergoing surgery [1–4]. The most commonly used inhalational anesthetic agent, sevoﬂurane, is a ﬂuorinated derivative of methyl isopropyl ether (International Union and Applied Chemistry, IUPAC nomen- clature; ﬂuoromethyl 2,2,2-triﬂuoro-1-(triﬂuoromethyl) ethyl ∗ Corresponding author. Tel.: +886 4 26328001x15212; fax: +886 4 26327554. E-mail address: rjwu@pu.edu.tw (R.-J. Wu). ether). Its structure is shown in Fig. 1. Owing to its many med- ical applications, sevoﬂurane has rapidly replaced halothane as an inhaled anesthetic agent. Its beneﬁts include a quick induction and emergence from anesthesia, a non-pungent odor, allowing for mask induction, and decreased airway irritation. On the downside are several side effects, including seizures during induction and maintenance, elevation in plasma, and an increased incidence of emergence delirium over halothane. Monitoring the concentration of sevoﬂurane, particularly in the surgical wards where support staff may be exposed, is essen- tial. In recent times, measuring the concentration of sevoﬂurane in blood and in clinical inhalation has become important [5,6]. Exposure to waste anesthetic gases can strongly impact workers in operating rooms, dental ofﬁces, and veterinary ofﬁces. It has also been reported that some of the highest levels of waste anes- thetic gases have been found in post-operative recovery rooms [1(b)]. Several instrumental techniques, such as simple gas chromatography and hyphenated/coupled methods like gas chromatography-mass spectrometry (GC–MS), are applied to the detection of concentrations of sevoﬂurane in blood [5–7]. Ho 0925-4005/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2007.03.026