Microfabrication methods for the study of chemotaxis

Abstract

We have developed a system for studying chemotaxis in a microfabricated system. The goal was to develop a system capable of generating spatially and temporally stable concentration gradients of a chemotactic molecule while providing a viable environment for the cell. Numerical models were generated to investigate fluid flow in microchannels for given geometries. Through computational modeling and experimentally-driven iteration of the design, features of the chamber were determined and geometry was established. Prototypes of the system were fabricated using soft lithography and multi-layer soft lithography techniques. Three fluid delivery methods for establishing gradients in the system have been studied: gravity feed system, dual-syringe pump feed system, and integrated individually-controlled peristaltic pump feed system. We were able to create spatially and temporally stable gradients using the dual-syringe feed setup. Two syringes were used to pump a chemokine and a buffer in parallel channels that are connected by a cross-channel and terminated to a single output. Microbeads in the flow were used to confirm the lack of movement in the cross-channel. Human neutrophil viability over the course of several hours and directed cell movement was demonstrated in microchannels.