Silica glass-based single-phase liquid flow passive control microfluidic chip: Simulation analysis, femtosecond laser fabrication, and performance development

Silica glass, known for its excellent chemical stability, physical properties, and biocompatibility, is an ideal material for microfluidic chips. However, its brittle nature makes precise microfabrication challenging. Femtosecond laser technology, with its high processing precision and minimal thermal impact, provides an effective solution to this issue. Single-phase liquid flow in microfluidic chips is widely used in applications such as biological monitoring and chemical analysis, where flow characteristics, including flow rate and pressure drop, have a significant influence on system performance. Therefore, precise control of liquid flow is essential. In this work, a passive control method for single-phase liquid flow based on the microchannel cross-sectional geometry is proposed. First, numerical simulations were carried out to investigate the influence of different microchannel cross-sectional shapes on liquid flow behavior. Under the same flow rate, the results indicate that V-shaped microchannels exhibit the highest average flow velocity, followed by trapezoidal and rectangular channels, and the pressure drop shows the same trend. Subsequently, femtosecond laser processing was employed to etch microchannels, where the channel geometry was tailored by adjusting the processing parameters. After chip packaging, the liquid flow behavior was experimentally characterized. The experimental results show that the trends of flow velocity and pressure drop are in good agreement with the simulation predictions, with an average deviation of approximately 10%. These results confirm that passive regulation of liquid flow can be effectively achieved by modifying the microchannel cross-sectional shape. This approach provides a practical strategy for liquid flow regulation and femtosecond-laser-fabricated microfluidic chips, with potential applications in biological monitoring, chemical analysis, and related fields.