(422c) Digital Imaging, and Subsequent Quantification, of Mixing in Bioreactors

Traditional mixing studies use single point measurements at a specific location to measure mixing. While this approach presents a single location information of the mixing conditions it does not represent the entire mixing performance in the vessel. To overcome these difficulties protocols have been developed that include more than one probe in order to obtain more representative measurements that allow a better estimate of mixing performance. Those studies have shown that measurements in different positions are notably different, reinforcing the need for data from multiple locations and further introducing the concept that one has not investigated enough locations. An alternative to a single point location has been the addition of dyes, or other similar type of indicators, that allow visual observations of the mixing in the whole vessel. However, these techniques tend to much more qualitative in nature. In this study we applied a commercial, digital image processing software which allows a ?region of interest?, ROI, to be identified, and the subsequent distribution in pixel intensity for all the pixels in this ROI to be recorded frame by frame. This technique was used on several vessels; with at least one vessel the ROI represented approximately 40% of the total volume of the vessel. Such large volumes allow a much more rapid evaluation of a range of agitation speed, impeller designs, and energy dissipation.