Maskless 3D Ablation of Precise Microhole Structures in Plastics Using Femtosecond Laser Pulses

Femtosecond laser ablation is a robust tool for the fabrication of microhole structures. This technique has several advantages compared to other microfabrication strategies for reliably preparing microhole structures of high quality and low cost. However, few studies have explored the use of femtosecond laser ablation in plastic materials because of the lack of controllability over the fabrication process in plastics. In particular, the depth profile of microhole structures prepared by conventional laser ablation techniques in plastics cannot be precisely and reproducibly controlled. In this paper, a novel three-dimensional femtosecond laser ablation technique was developed for the rapid fabrication of precise microhole structures in multiple plastics in air. Using a three-step fabrication scheme, microholes demonstrated extremely clean and sharp geometric features. This new technique also enables the precise creation of arbitrary-shaped microwell structures in plastic substrates through a rapid single-step ablation process, without the need for any masks. As a proof of concept for practical applications, precise microhole structures prepared by this novel femtosecond laser ablation technique were exploited for robust resistive-pulse sensing of microparticles.