Graded-Index Fiber Enabled Strain-Controllable Optofluidic Manipulation

Controllable optofluidic manipulation of a microsphere is achieved by tuning the strain applied onto the graded-index fiber (GIF) for the first time. Instead of fiber-optic tapers, the GIF with a flat endface, which is simple to be fabricated with low cost and high repeatability, is employed for enhancing the performance of optical manipulation. By exerting strain onto the GIF, the manipulation length can be periodically controlled and tuned up to 1314.1 mu m. Furthermore, we use the force microbalance on the microsphere as a new way to measure the microfluidic flow rate down to 30 nL/min.