FBG嵌入型光纤Sagnac环的窄道空间微流速和温度测量系统

A narrow channel microflow velocity and temperature measurement system based on FBG embedded in Sagnac ring

提出了一种光纤布拉格光栅(FBG)嵌入型光纤Sagnac环的窄道空间微流速和温度测量系统,其由传统光纤Sagnac环和嵌入光纤Sagnac环中的FBG组成。光纤Sagnac环中的保偏光纤(PMF)受到的侧压力会随着微流体流速的不同而发生变化,通过监测光纤Sagnac输出干涉峰的漂移实现对微流速的测量。此外,嵌入光纤Sagnac环中的FBG对温度有较高的响应灵敏度,可以实现环境温度的监测。实验过程中,用毛细管模拟窄道空间,将光纤Sagnac环中的PMF置于毛细管内部,用微流泵获得一定范围的微流速。实验结果表明,当微流体的微流速在0~450μm/min范围内变化时,光纤Sagnac环输出的干涉谱向短波方向漂移;由监测波长1 522.47和1 544.64nm处的谐振峰可知,测量的微流速平均灵敏度分别为5.59和5.98pm/(μm/min);实时监测环境温度的结果表明,在20~45℃范围内,FBG的温度灵敏度为9.74pm/℃。本文传感器具有测量范围大、灵敏度高、结构简单和成本低等优点,特别适用于微通道如生物血管等方面。

In this paper,a narrow channel microflow velocity and temperature meas urement system based on FBG embedded in Sagnac ring is proposed.The lateral pressur e of the polarization-maintaining fiber （PMF） sustained varies with the microflow rate,a nd the microflow velocity is achieved by monitoring the output wavelength shift of the fiber Sagnac ring.I n addition,the fiber Bragg grating （FBG） embedded in the fiber Sagnac ring is sensitive to the temp erature,which is used to achieve the environmental temperature.In experiment,the narrow channel is simulated by capillary,and the polarized fiber in the fiber′s Sagnac ring can be fixed by the capillary.Then,the range of microflow rate can be obtained by microflow pump.The experimental results show that the lateral pressure for PMF will change with the microflow velocity, resulting in the Sagnac interferometer wavelength shift.When the microflow v elocity changes in the range of 0-450μm/min,two resonance peaks at 1522.47nm and 1544.64nm are monitored and the average sensitivities are 5.59pm/（μm/min） and 5.98pm/（um/min）,resp ectively.In addition, the temperature sensitivity of the sensor is 9.74pm/℃ with the ambien t temperature increases from 20℃ to 45℃.The sensor owns several advantages,s uch as wide measurement range, high sensitivity,simple structure,easy manufacture and low cost,and it has gr eat practical value.