Hydrogen Sulfide Surface Acoustic Wave Gas Detector

Abstract

A surface acoustic wave (SAW) hydrogen sulfide (H S ) gas detector has been designed, fabricated an3 tested. The detector consists of twin SAW delay lines fabricated on a single LiNbO substrate. Each delay line i s confi uredas an i s coated with a sputfered f i l m of activated tungsten trioxide (WO$ while the other i s uncoated and used as a stable reference. Phase dela changes due to the mass loadin stress and elecrric field effects induced by the 82s gas sorbed on the WO3 film result in corre ponding frequency shifts which are directly proportional to the as concentration. Gas detector properties time and shape of the response curve gignature). The detector was found t o be quite stable and s stematic responses to concentrations less than 18 parts per billion were observed.oscillator. The propa ation path o 9 one delay line stu 2 led include selectivity, sensitivit , response

Subsurface H2S Detection by a Surface Acoustic Wave Passive Wireless Sensor Interrogated with a Ground Penetrating Radar

“…Indeed, 3 kHz frequency variation of a 60 MHz SAW device with a gap between IDTs of 2.5 mm, leading to an equivalent phase shift of 900 degrees was reported. [20] The origin of this phenomenon is explained as follows: the exposure of a lead(II) acetate derivative to H2S leads to the formation of PbS and carboxylic derivative (Figure 7). The formation of PbS explains the color variation in the well-known lead(II) acetate test paper [16,21].…”

Applications of surface acoustic and shallow bulk acoustic wave devices

“…In this case, the sensing SAW delay linewas coated with a film of activated tungsten trioxide. This sensor was found to respond to concentrations of H 2 S of less than 10 parts per billion [286].…”

Advances in SAW-based gas sensors

“…In recent years there has been growing attention to surface acoustic wave (SAW) devices for the detection of various physical and chemical parameters including temperature [1,2], acceleration [3][4][5][6][7][8], force [9], pressure [10][11][12][13], DC and AC high voltages [14][15][16], electric fields [17], magnetic fields [18], weight percentage in solutions [19], ionic concentration [20], gas flow [21], dew point [22] and gas and vapour concentration [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Table 1 gives an idea of the research work done since 1981 on SAW chemical sensors.…”