基于自聚焦光纤操控的高性能光微流流速传感机理与技术研究

Microfluidic chip is a widely-used tool for investigating living cells, drug screening as well as chemical synthesis and analysis. Among these application, the microfluidic flow rate is of great importance, e.g., it influences the accuracy of cell counting, the generation frequency and size of micro droplets. Therefore, high-performance flow rate sensing is essential. Previous flow rate sensor did not meet the requirements on the measurement range and sensitivity. In this proposal we plan to develop a novel flow rate sensing technology based on graded-index fiber optical manipulation of microsphere. The content includes: (1) Perform non-contact, long-range tunable optical manipulation by using the graded-index fiber, changing the laser wavelength, using different kinds of microspheres and investigating the balance between optical forces, photophoresis forces and flow force on the microsphere. (2) Perform flow rate sensing with large measurement range and high sensitivity by combining the open- and closed-loop detection methods via detecting the manipulation length and the injection electric voltage of the pump laser. Also the lateral distribution of the flow rate is to be detected by locating the microsphere via a transverse optical scattering force. Based on the proposed method, the optical, thermal, and force interaction processes between laser and microparticle can be investigated in the microfluidic environment. Further, it provides universal tool for the cutting-edge research of optofluidics and various of lab-on-a-chip application.

微流芯片是研究细胞、药物筛选以及化学合成与分析的主流技术，其中微流体流速的影响广泛。因此，高性能流速传感十分必要。现有流速传感技术在测量范围、灵敏度等方面尚不能满足实际需求。本项目在前期研究基础上，提出基于自聚焦光纤操控的高性能微流流速传感新技术。思路与亮点：（1）基于自聚焦光纤，采用不同波长和微球类型，研究微球在光力、光泳力及微流力共同作用下的位移特性，实现非接触、长距离可调光操控，基于微流力与流速的Stokes关系，实现流速传感。（2）结合开环和闭环传感模式，探测操控距离和泵浦激光补偿电信号，同时实现大测量范围和高灵敏度；通过横向光力操控微球，实现流速的截面分布传感。该技术可研究微流环境下激光与微粒相互作用的光/热/力学过程，并为微流应用提供普适性的流速测量工具，适用于光微流前沿研究及各种微流芯片应用。

微流芯片是研究细胞、药物筛选以及化学合成与分析的主流技术，其中微流体流速的影响广泛。因此，微流体的流速控制及其精确测量十分必要。现有流速传感技术在测量范围、灵敏度等方面尚不能满足实际需求。. 针对上述背景，项目组在首次提出了基于光纤的高性能光微流传感技术，研制了基于光微流操控和光微流激光两种原理的光微流传感器。首先，项目组研制了自聚焦光纤微流操控技术，实现了非接触、超长可调控距离，研究了光纤操控的距离、可调范围、稳定性等方面；基于上述技术，项目组还实现了高性能的流速传感、温度传感和浓度检测等；同时，项目组还研究了基于光纤的光微流激光传感技术。. 本课题执行期间（2016-2019），共发表学术论文29篇，其中期刊论文22篇，EI会议论文7篇；授权发明专利4项，申请发明专利5项。其中，在《Biosensors & Bioelectronics》、《Lab on a Chip》、《Journal of Materials Chemistry C》、《Sensors and Actuators B》、《IEEE Journal of Selected Topics in Quantum Electronics》、《IEEE/OSA Journal of Lightwave Technology》等影响因子>4的国际知名刊物发表论文共15篇。项目成果入选国际著名期刊《Journal of Materials Chemistry C》和《Lab on a Chip》的Back Inside Cover；入选为国际著名期刊《Lab on a Chip》的Top 10%和Hot Article；入选第26届光纤传感国际会议（OFS-26）和亚太光传感会议（APOS2016）的Postdeadline Paper。项目负责人龚元教授担任光纤著作《Handbook of Optical Fibers》的Section Editor、国际知名期刊《Journal Optics & Laser Technology》的客座编辑，并参与组织国际会议3次，国内外会议特邀报告12次。人才培养方面，通过本项目已培养2名博士和7名硕士。