Research on microchannel fabrication in UV curable resin using combined beam processing

Abstract

Abstract To break through the limitations of traditional rectangular microchannel processing methods for microfluidic devices, this paper proposes a processing technique based on a holographic combined femtosecond laser beam. The phase and topology of the hologram are adjusted by SLM to flexibly control the spot width and energy distribution of a generated Bessel beam, thus realizing high-precision and multi-size processing. To achieve high-precision microchannel sidewalls and bottom surfaces, the positive first-order Bessel beam is shifted at an appropriate position after the zero-order light by using a blazed grating to obtain the suggested holographic combined beam required for processing. At a laser power of 0.98 W, compared with using only the Gaussian beam (bottom roughness Ra of 0.361 μm, MRR of 882.219 μm³/s) and the Bessel beam (Ra of 0.377 μm, MRR of 3490.590 μm³/s), processing with the combined beam reduces Ra to 0.128 μm, a reduction by factors of 2.8 and 2.9, respectively. Meanwhile, the MRR increases to 6786.362 μm³/s, representing improvements by factors of 7.7 and 1.9, respectively. Under this power, when the phase value s increases by 4 pixels, the microchannel width increases by 3.2 μm, and when the topological charge n increases by 4 pixels, the microchannel depth decreases by 0.7 μm. This novel method, which enables smooth surfaces without the need for post-processing, offers a new option for the high-quality, efficient, and flexible fabrication of curable resin microfluidic devices.