The Fabrication And Detection Of Microelectrode For Dissolved Oxygen Sensor

With the appearance of water problem, people pay more attention to theprotection of water resource. Dissolved oxygen, which is an important parameter ofwater self-depuration capability, is always a significant part of water detection. Thereare many traditional DO detection methods which make the detection inconvenientdue to some disadvantages such as complicated detection structures, expensive cost,not be used for continuously in-situ detection and so on. Therefore, it is a trend for usto research small size and handheld DO detection instrument. In this dissertation, onthe basis of Clark principle for DO detection, we take advantage of MEMStechnology to fabricate two parallel microelectrodes. Then we successfully makeClark DO sensor microelectrodes through modifying surface and carry out somerelative electrochemistry tests that indicate the response of DO strengthens. The topicsof this dissertation are discussed as follows:1. Design and fabrication of microelectrode. On the basis of microelectrodesuperiority, we designed the microelectrode pattern. Through MEMS and plasmatechnology, we fabricated Pt microelectrode which was deposited by aluminum film.2. The modification for the surface of microelectrode. The anticathode of DO sensormicroelectrode is an Ag-AgCl electrode which was prepared by CV electrochemicaldeposition of Ag and treatment of HCl; the aluminum film on the Pt cathode wasprepared under30V by anodization and the curve of current-time. Finally,electrochemical deposition of Pt was carried out through porous alumina templateabove. 3. The test of microelectrode. According to the microelectrode before and afternano-modification, we carried out some relative electrochemistry test. It is foundout that electrochemical impedance of nano-modified microelectrode reducedobviously and the response current for DO improved dramatically, from40μA to130μA. Then we detected DO using nano-modified Clark DO electrode. The currentsignal was improved evidently relative to un-modified DO electrode.It was proved that through nano-modified DO microelectrode, theelectrochemistry activation and sensitivity enhance obviously. In addition, thedetection signal is direct electrical signal that complicated signal conversion is notneeded, and the DO microelectrodes can be used for miniaturized DO sensor.