A Study on the mechanism of precise control of microfluidic droplets using PMMA

Polymer microfluidic chips, such as those made from polymethyl methacrylate (PMMA), are currently widely used in the pharmaceutical and biological fields due to their stable performance and ease of fabrication. However, many existing methods for fabricating PMMA-based microfluidic chips are costly and offer poor precision in controlling microfluidic droplets. Research into the mechanisms of low-cost, precise droplet control in PMMA-based systems offers a solution to these challenges. This study utilizes COMSOL software to model and simulate a T-junction microchannel, investigating the effects of the flow rate ratio ( η ) between the continuous and dispersed phases and the channel width ratio ( λ ) on droplet diameter and spacing. A T-junction microfluidic chip is fabricated on a PMMA substrate using a CO₂ laser at low cost, and experiments are conducted to precisely control droplets using a syringe and a constant-flow pump. The results indicate that as η increases, the average droplet diameter increases while the spacing decreases; conversely, as λ increases, both the droplet diameter and spacing first decrease and then increase. The experimental results are highly consistent with the simulation patterns, with a deviation rate of less than 15% in all cases. This study provides a theoretical basis and technical reference for the low-cost fabrication of PMMA microfluidic chips and the precise control of multiphase flow.