Articles techniques et présentations

This study presents a novel microfluidic chip integrated with biosensors and capillary microfluidics, specifically designed for target screening and precise fluid control. The capillary pumps facilitate spontaneous fluid delivery to the sensors, eliminating the necessity for external pumps, while the stop valve regulates flow, ensuring dependable operation in field environments or resource-constrained settings. The sensor array can be functionalized with various biosensors tailored to specific targets, enabling the chip to screen and identify targets in unknown samples. By consolidating multiple functions on a microfluidic platform, the operations of sample transmission, rapid response, accurate detection, and timely cleaning are automated, significantly enhancing analytical efficiency. The chip's fluid control mechanisms are influenced by the geometries of the capillary pump and stop valve, channel width, wetting angle, and liquid surface tension; even minor variations can impact the chip's functionality. To verify the feasibility of these functionalities and refine the design, we conducted simulations of fluid movement using computational software. Initially, we introduce the governing equations for fluid flow, including the control equations and the Navier-Stokes equations, with a particular emphasis on two-phase flow simulations to investigate factors affecting fluid dynamics. Subsequently, we modeled the microfluidic chip using AUTOCAD and employed the CFD (Computational Fluid Dynamics) module within COMSOL Multiphysics to simulate fluid dynamics and perform finite element analysis (FEA) to evaluate flow field distribution, velocity variations, and the operation of the stop valve. Through comprehensive numerical simulations and analyses of fluid flow, solution mixing, and cut-off valve control within the microchannels of the chip, we validate that the capillary pump can autonomously transport liquid to the biosensor module, while the cut-off valve effectively regulates liquid flow. Furthermore, the geometry of the capillary pump has been optimized to enhance flow rates. Simulation results indicate that the flow characteristics of droplets post-microfluidic chip passage are closely correlated with the dimensions of the capillary array and the wettability of the pump wall. Consequently, the design of the capillary pumps’ dimensions and channel widths has been carefully tailored. This research provides a robust theoretical foundation and technical support for the future advancement of microfluidic chip technology, particularly in applications requiring independent and field-deployable solutions.