Shen Changyu, Lian Xiaokang, Kavungal Vishnu, Zhong Chuan, Liu Dejun, Semenova Yuliya, Farrell Gerald, Albert Jacques, Donegan John F
Opt Lett. 2018 Feb 15;43(4):751-754. doi: 10.1364/OL.43.000751.
In microfluidic chip applications, the flow rate plays an important role. Here we propose a simple liquid flow rate sensor by using a tilted fiber Bragg grating (TFBG) as the sensing element. As the water flows in the vicinity of the TFBG along the fiber axis direction, the TFBG's spectrum changes due to its contact with water. By comparing the time-swept spectra of the TFBG in water to that of the TFBG with water flowing over it, a spectral sweep comb was formed, and the flow rate can be detected by selecting a suitable sweeping frequency. The proposed sensor has a high Q-value of over 17,000 for the lower rate and a large detectable range from 0.0058 mm/s to 3.2 mm/s. And the calculated corresponding lower detectable flow rate of 0.03 nL/s is 3 orders magnitude better than that of the current fiber flowmeter. Meanwhile, the proposed sensor has the temperature self-compensation function for the variation of the external temperature. We believe that this simple configuration will open a research direction of the TFBG-deriving theory and configuration for lower flow rate measurements for microfluidic chip applications.
在微流控芯片应用中，流速起着重要作用。在此，我们提出一种简单的液体流速传感器，它使用倾斜光纤布拉格光栅（TFBG）作为传感元件。当水沿光纤轴方向在TFBG附近流动时，TFBG的光谱会因其与水接触而发生变化。通过比较TFBG在水中的时间扫描光谱与水在其上方流动时的TFBG光谱，形成了一个光谱扫描梳状信号，并且可以通过选择合适的扫描频率来检测流速。所提出的传感器对于较低流速具有超过17000的高品质因数，并且可检测范围大，从0.0058毫米/秒到3.2毫米/秒。计算得出的相应最低可检测流速为0.03纳升/秒，比当前的光纤流量计好3个数量级。同时，所提出的传感器对于外部温度变化具有温度自补偿功能。我们相信，这种简单的结构将为微流控芯片应用中基于TFBG的低流速测量理论和结构开辟一个研究方向。
