Femtosecond laser-fabricated microfluidic PCR device with graphene microheaters for DNA amplification

Polymerase chain reaction (PCR) is an essential technique used to amplify specific deoxyribonucleic acid (DNA) fragments. This study presents the design and fabrication of a microfluidic PCR device using a femtosecond laser (FS-laser) process, integrating microheaters and microfluidic structures. The device integrates graphene, offering high electrical conductivity, with silica glass, providing comparatively higher thermal conductivity and excellent biocompatibility, to enable rapid thermal cycling (RTC) for efficient and reliable DNA amplification. The microheater, fabricated through laser ablation of graphene films at a required laser fluence of 2.02 J/cm², demonstrated a heating rate of 82 °C/min. Additionally, the laser-fabricated microfluidic device incorporates micropillar arrays and narrow sections designed to ensure uniform sample distribution and stable capillary-driven flow. The study also investigated the FS-laser parameters for silica glass processing to optimize the fabrication process. Finally, the PCR device was validated using Porphyromonas gingivalis (P. gingivalis) DNA as a model, achieving amplification of a 404 base pairs (bp) target sequence over 36 thermal cycles. This work reveals the potential of FS-laser technology to improve PCR devices by providing high precision, stability, and efficiency in DNA amplification.