Ultra-sensitive fluorescence detection based on helical micro optical fiber

A simple fabrication method of helical micro optical fibers (HMOFs) with controllable diameters and pitches based on micro-Weissenberg effect is proposed in this Letter. Single fibers with minimum diameter and pitch of 5 μm and 15 μm were directly written by near-field electrospinning of molten poly(methyl methacrylate) (PMMA). The morphology and transmission characteristics of single PMMA HMOFs were experimentally measured. The results showed that HMOFs have periodic modulation effect on transmitted light and show its potential as a micro-displacement sensor. Then a fluorescence detection structure based on HMOF is proposed, where HMOF was used to incoming the excitation light and collecting fluorescence. Experimental results show that for the fluorescence sensing of R6G aqueous solution, the fluorescence collection efficiency of HMOF was 4 times that of the micro optical fibers of the same diameter.