JEPJournal of Environmental Protection2152-2197Scientific Research Publishing10.4236/jep.2012.38082JEP-21752ArticlesEarth&Environmental Sciences High-Sensitivity Ozone Sensing Using 280 nm Deep Ultraviolet Light-Emitting Diode for Detection of Natural Hazard Ozone oshinobuAoyagi1*MisaichiTakeuchi1KaoruYoshida1MasahitoKurouchi1TsutomuAraki2YasushiNanishi2HiroyasiSugano3YumiAhiko4HirotakaNakamura5Ritsumeikan University, Faculty of Engineering Science, 1-1-1, Noji-higashi, Shiga, JapanHikari Tec; 4Miura-ori Lab., 1687, kanamori, Machida, Tokyo, JapanMiura-ori Lab., 1687, kanamori, Machida, Tokyo, JapanTokyo Metropolitan Industrial Technology Research Institute 3-13-10, Nishigaoka, Kitaku, Tokyo, JapanRitsumeikan University, Global Innovation Research Organization* E-mail:aoyagi@fc.ritsumei.ac.jp(OA);200820120308695699February 22nd, 2012April 3rd, 2012 May 13th, 2012© Copyright 2014 by authors and Scientific Research Publishing Inc. 2014This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/

Recently ozone is one of natural hazards which comes from cars, industry using ozone for sterilization of organic and inorganic materials and for water purification. So, ozone sensing becomes very important, and convenient and accurate ozone sensor is required. A new high sensitivity ozone sensing system using an deep ultra-violet light emitting diode (DUV-LED) operated at the wavelength of 280 nm has been successfully constructed. The fabrication of diode operated at 280 nm is much easier than that of DUV-LED operated at Hg lamp wavelength of 254 nm. The system is compact and possible to sense the ozone concentration less than 0.1 ppm with an accuracy of 0.5% easily with low power DUV-LED of around 200 micro Watts operated at 280 nm without any data processing circuit.

Ozone Sensing; Deep Ultra Violet Light Emitting Diode; DUV-LED; High Sensitivity; Long Life; Compact1. Introduction

The importance of ozone sensing has recently increased, because ozone is harmful gas which is generated from industrial use of ozone for sterilization and cleaning of biomaterials and semiconductor devises and also water sterilization. Furthermore, ozone is produced in the surface air by photochemical reactions involving unburned fuel vapors and nitrogen oxides produced at high temperatures by car engines. So, the depletion of ozone is very important. So, continuous, high-sensitivity easy detection of ozone is indispensable.

Ozone sensing is currently conducted by monitoring the conductance change in thin-film-like semiconductors containing ZnO [1,2], In2O3 [3,4]. Previous studies have tried to measure ozone using a galvanic technique [5]. These devices have the advantages of being compact and very cheap, but their lifetime is less than one year and their accuracy is very low at ±50%. Ozone sensing using a Hg lamp was used for the purpose of solar-blind sensing in the aerospace industry [6,7]. Researchers have also applied UV light to the chemiluminometric measurement of atmospheric ozone [8]. There have been attempts to use optical fibers for sensing [9]. However, there are few reports on the determination of ozone concentration in the air using Hg lamp systems, because of the difficulties in accurate system construction with a high sensitivity suitable for ozone monitoring and with a long life that would provide an accuracy of approximately ±0.5%. An attempt was made to use a long-pass absorption chamber to achieve high sensitivity [10]. However, the cost of this system was very high and it was unstable. The life of the Hg lamp was only about one year and the size of the system was much larger than conventional sensors. Moreover, the Hg used in the lamp is a harmful metal, which has potentially detrimental environmental affects.

We recently developed a new type of ozone sensing system using a low-power deep ultra violet light emitting diode (hereafter DUV-LED) operated at the wavelength of 280 nm as a light source, instead of an Hg lamp. This system has the advantages of being very compact, having a long lifetime, and being free from any harmful materials.

In this report, we present our experimental results and demonstrate the utility of this system.

2. Experiments and Discussion

Figure 1 shows the typical spectra of a Hg lamp and DUV-LED operated at the wavelength of 280 nm. The

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