Spectral intensity mapping and analysis of dyed microflows

The objective of this work is to develop simple reliable software to observe and quantify diffusion phenomena in microfluidic devices. One of the great advantages of microfluidic technology is that it permits the flow and diffusion of multiple streams in a single channel. The accurate control of a diffusion-based process has applications in bioanalytical chemistry, production of organic compounds and combinatorial chemistry. This method has been discussed in the literature as laminar fluid diffusion interface technology. It is heavily dependant on the controlled and reproducible introduction of several fluids into one channel and enables the design of separation and detection systems based on laminar fluid diffusion interfaces. A method of analysing and interpreting the diffusion behaviour of multiple microflows using the MATLAB programming language as an image analysis tool is presented here. This paper considers two dimensional brightfield and time series images but the method can be applied to other forms, including fluorescent and three-dimensional images. The approach taken relies on the fact that a digital image stores its colour information in signal channels. The information contained in the channels depends on the colour method being used to define the image. Software-based spectral filtering is performed, yielding three-dimensional intensity maps of dyed and clear microflows. These maps can be used to monitor diffusion behaviour in a number of different areas simultaneously. Spectral noise reduction techniques are also incorporated without significant reduction in original data quality. The technique is used to determine the aqueous diffusion coefficient of the dye Green S by processing digital images taken at 2 s time intervals in a stopped-flow experiment. The approach is applied to microflows in straight, two-dimensional serpentine, and three-dimensional serpentine channel configurations.