In the fiber-sensing gas detection system, characteristic of near infrared absorption spectrum of the detected gas is greatly significant. The volatilized gasoline vapor is a mixture rich in various components, of which near infrared absorption spectrum shall be determined by means of experimental measurement. In this paper, an experimental platform is constructed by analyzing absorption characteristic of liquid composition in gasoline within the range of near infrared spectrum, which achieves measurement of the volatilized gasoline vapor with different concentration. In addition, reliability of this measurement method is inspected, a comparison between features of absorption spectrograms of liquid and gas is made, and linear relation of absorbance and concentration of gasoline vapor is verified. The result shows that the experimental data is acceptable and may be used as the basis of further analysis and for design of the online detecting system of gasoline vapor concentration in the hazardous environment.

A novel micro-machined out-of-plane resonant accelerometer with a differential structure is presented. The micro-machined accelerometer consists of two identical torsional structures with asymmetric mass distribution, torsion beam and two different-height resonant beams. Due to the asymmetric mass distribution, the two mirror-symmetrical-placed torsional structures turn an angle under an out-of-plane acceleration, which makes the different-height resonant beam connected to the structures bear different axial stresses, outputting a differential resonant frequency shift. A multi-layer mask etching process based on silicon-on-glass micro-machined technology was employed to fabricate the differential structure and the different-height resonant beams. Primary experiment shows the differential sensitivity of out-of-plane acceleration is 32Hz/g at the resonant frequency of 21.41 kHz.