Research on cavity-driven control methods for concentration gradient microdroplets with high precision and stability

Abstract

Microfluidic chip technology, an emerging interdisciplinary field, enables precise control of fluids at micro- and nano-scales and is widely applied in biomedicine, chemical analysis, and drug screening. This study investigates the effect of the parameters of chip geometry and the flow rate of fluid on the performance of the droplet concentration gradient generator using a cave-based microfluidic chip structure through numerical simulation and experimental verification. Finite element simulation software, equipped with laminar flow, phase field, and dilute substance transfer modules, was employed to analyze the impact of geometric parameters (cavity number, cavity radius, contact length between the cavity and the central channel, and cavity interval length) on the concentration gradient curve. Additionally, the effect of the fluid flow rate on the frequency, size, and concentration of the generated microdroplets was explored. Results indicate that the number, radius, and contact length of cavities significantly affect the concentration gradient curve, while the interval length has a minimal impact. Precise control of droplet concentration, generation frequency, and size can be achieved by adjusting the flow rates of the dispersed phase and the continuous phase. This study provides a theoretical basis for the design and optimization of concentration gradient microfluidic chips and promotes the application of concentration gradient microdroplet technology in high-throughput drug screening, biological detection and chemical analysis.