Programmable microfluidic device for dynamic concentration gradient generation

Abstract

Concentration gradients are essential in fields such as cell biology, analytical chemistry, and material synthesis. However, achieving stable gradients with precise spatial and temporal control within microfluidic channels remains a significant challenge. This study presented a novel multilayer microfluidic chip that integrated a concentration gradient generator with micro-mixing structures. The system utilized air pressure-driven deformation of microvalves to modulate flow resistance, enabling fine-tuned control over gradient profiles. The incorporation of herringbone-like microstructures enhanced the efficient mixing of small sample volumes with diluents. By dynamically adjusting the closure of microvalves, the device provided precise control over flow resistance at multiple points within the channel network, enabling the generation of both linear and nonlinear concentration gradients. The flow resistance of the deformed valves was studied both numerically and experimentally, and an empirical model for valve flow resistance was developed. Furthermore, the system supported rapid switching between gradient profiles, facilitating time-sensitive studies of cell-chemical interactions. This programmable, dynamically controlled gradient generator shows significant potential for applications in drug screening, analytical chemistry, and cell biology, where precise modulation of chemical environments is critical.