Diffusion-based concentration control in microcavities during long time period by programmed syringe pumps

We propose a programmed syringe pumps system for diffusion-based concentration control in microcavities. Fluorescein is used to demonstrate the influence of different durations of unvarying injecting speed and different sizes of microcavities on the concentration control and distribution in the microcavities. With longer duration of unvarying injecting speed and smaller size of microcavities, the concentration control of the microcavities will be more consistent with the input signal. Using this system, we can precisely control sudden as well as gradual change of the microenvironment of cells within a period from several minutes to days by re-setting parameters of the program. As a demonstration, we apply this system to culture budding yeast cells in the microfluidic device and follow the growth status in precisely controlled nutritional environment. This system will be useful for high-throughput cell stimulation and differentiation studies. (C) 2009 Elsevier B.V. All rights reserved.