FBG-based monitoring of solidification strain development in a microstereolithography photocurable resin

The shrinkage characteristics of photocurable resins are critical factors in final three-dimensional microstructures fabricated using micro-stereolithography. In this work, an approach in measuring in situ solididification strains in a photopolymer, frequently used for the fabrication of micro-parts, is presented. The photopolymer used in the present investigation is a multifunctional acrylate-based resin with 1% photo-initiator used in the past for single and two-photon stereolithography. The resulted strain profile build up is monitored via the use of an embedded fiber Bragg grating (FBG) into a cylindrical test specimen as the photopolymer is exposed to stepwise applied UV-light irradiation. The obtained results demonstrate the potential of strain levels monitoring as a function of laser light exposure and scanning conditions in microstereolithography photocurable resins.