The Preliminary Research On The Miniaturization Gas Discharge Emission Spectrum System

In the industrial environment, detecting the combustible or poisonous gas can prevent explosion, fire, poisoning accidents, and to ensure safety in production. As a result, real-time monitoring of poisonous and harmful gases in the process of its storage and transportation become more and more important. At present, the gas sensor often use electrical signal such as voltage, current and conductivity as a means of detection. However, this kind of sensor is affected by some factors, such as poor selectivity, low sensitivity, or limits of temperature and humidity. This thesis embarks from the detection means, and light signal produced in the process of gas discharge as test object, built a miniaturization of portable gas discharge emission light source device. This device provided a new determination method for the detection of analytes.A set of direct current(DC) discharge device of N2 plasma was developed, carbon nanotubes(CNT) modified ITO electrode was used as anode, aluminum plate as cathode, with ~80 μm separation between them. Nitrogen emission spectrum was observed at room temperature and low DC voltage(less than 150 V) and analyst the emission line of emission spectra. The effect of oxygen and hydrogen on the emission spectra of nitrogen was investigated. CNT modified ITO electrode can reduce the breakdown voltage, and it was found that the luminescence intensity had a linear correlation with the concentration of nitrogen at low voltage of 10.The Pt/CNTs nanocomposites were prepared by microwave, and characterized with TEM. The modified layer of Pt/CNTs nanocomposites on FTO electrode notably improved the analytical performance such as precise and linear correlation. The discharge voltage, discharge distance, gas flow rate and different modified electrodes were investigated to choose the optimum condition for hydrogen gas discharge. Under the optimization condition, the emission intensity was linear to hydrogen concentration in the range of 0.17 %-4.0 % v/v. The developed system can also be applied to the determination of other analyte such as oxygen, sodium and potassium. The certain concentration range of oxygen has a good linear relationship. The 10-7 mol/L of Na+ can be clearly detected from the blank of water. The potassium content of eight different fruit was measured, and it was found that the potassium content is highest in the banana. It can make guidance to people to select the rich potassium intake of fruit. Maintain normal levels of potassium content enable people to maintain the normal function of nerves and muscles.The device used in the experiment has advantages of small in size, portable, easy preparation, operation at room temperature, low power consumption etc. This system exhibited the potential value of application of on-line analysis for gas detection, and provided a reference for the determination of the gas and the metal ions.