Integrated microfluidic platform for multiple processes from microalgal culture to lipid extraction

For economically viable biofuel production from microalgae, it is necessary to develop efficient analytical platforms for quantitative evaluation of different lipid productivities of numerous microalgal species. Currently, microalgal culture, lipid accumulation, and lipid extraction depend on conventional benchtop methods requiring laborious and time-consuming processes. A poly(dimethylsiloxane) (PDMS)-based integrated microfluidic platform was developed to perform multiple steps in sample preparation on a single device for efficient and quantitative analysis of lipid from various microalgal strains. To achieve this goal, a simple microchannel with a micropillar array was integrated to connect the cell chamber and output reservoir, which act as a filtration unit that enables medium change and solvent extraction by fluid injection using a syringe pump. Multiple processes of cell culture, lipid accumulation, and lipid extraction were successfully accomplished using a single device without time-consuming and labor-intensive steps. Various conditions of solvent volume and temperature were investigated to optimize lipid extraction yield in the microfluidic device. The lipid extraction efficiency in the microfluidic system was higher than that in bulk using the same solvent. The lipid extraction efficiency achieved using less toxic aqueous isopropanol on the integrated device was 113.6% of that obtained with the conventional Bligh-Dyer method. Finally, lipid productivities of different microalgal strains grown in the microfluidic device were analyzed and compared. These results demonstrate that this simple integrated microfluidic platform can be applied as an alternative to conventional benchtop methods for efficient sample preparation in microalgal lipid analysis.