Fabrication Method for Optical Tweezers Using a Single-Mode Fiber and Dual-Photopolymerization

This article presents a novel fabrication method for single-fiber optical tweezers (OTs) with a lens-like tip using a single-mode fiber and dual-photopolymerization that eliminates the need for unique curing light fields and involves no fiber micromachining process. Quantitative analysis of axial and transverse trapping forces applied to transparent spherical microparticles with different diameters and refractive indices demonstrates that the lens-like tip is significant for efficient trapping. Experiments show that the fiber OTs can manipulate yeast cells in various directions. Then, we evaluate the capture stabilities of five fabricated probes with different tip lengths, which are achieved by using various 532-nm laser curing times and powers during the second photopolymerization. The axial and transverse displacement standard deviations are less than 0.16% and 0.17% of captured yeast cell diameter, respectively, proving that the fabricated probes all have superior stability. Additionally, the length of the lens-like tip has negligible effects on capture stability. This robust and easy-to-operate fabrication method is promising for the mass production of photopolymer-based single-fiber OTs.