Fluorescence quenching technology is used to detect dissolved oxygen concentration.Dichlorotris(1,10-phenanthroline)ruthenium doped in sol-gel as an oxygen indicator is described;plastic optical fiber is used as sensor head to transmit light,in order to increase sensitivity the sensor head is bent into U shaped;the fluorescence lifetime is detected by using phase modulation technique.The experimental results show that the oxygen concentration is linear with fluorescence lifetime when the dissolved oxygen co...