A droplet-based gradient microfluidic to monitor and evaluate the growth of Chlorella vulgaris under different levels of nitrogen and temperatures

Algae are potential sources for different industrial products. However, biofuel production from algae still needs to reach valuable economical approaches. Select algae and optimize culture conditions considered main challenges for biofuel production. Traditional batch cultures' techniques are time and labor consuming. PDMS-based Microfluidics is time-and labor-saving technique with high throughput single cell analysis. We present gradient-based microfluidics as tools for studying algal growth under different cultivation conditions. Applying our device provides the opportunity to generate droplets with different concentrations of medium nutrients' in 200s which keeps reagent and time for preparing such solutions using conventional techniques. Chlorella vulgaris was encapsulated inside uniformly droplets with different NO3−-N concentrations of 2.46, 6.69, 10.91, and 15.14 mΜ/L. separated devices were exposed to different temperatures of 20, 27, and 37°C. The photosynthetic energy conversion for each cell per droplet was calculated. It was observed that the higher the NO3− concentration, the higher the growth kinetics. According to the presented results, the optimum nitrate and temperature conditions were 15.14 mΜ/L and 37°C. Our device is considered the third effort for applying a gradient chip in algal biotechnology field. It is unique and simple in use with high competence results.