Lipid estimation of microalgae via Finite element simulation using voltage discharging technique

The impending global energy crisis, coupled with the depletion of fossil fuel reserves within the next half-century, can be tackled by microalgae, which stand out for their ability to accumulate high lipid content for biofuel production. In this study, a microfluidic-based approach is proposed for single-cell analysis and real-time capacitive measurement using DC voltage discharging technique for the first time to estimate lipid accumulation in Chlorella vulgaris, a species capable of accumulating substantial amounts of lipids such as triacylglycerol (TAG). Numerical simulations using COMSOL Multiphysics® Software demonstrated that variation in lipid content leads to a significant capacitance difference, with highest value of 72.07 % when discharged to 50 % of its initial value voltage, compared to the highest value of 11.36 % when discharged to 13.5 % of its initial value voltage. Furthermore, the capacitance values at different discharge levels were integrated as a ratio, revealing a clear correlation between the capacitance ratio (0.11 ∼ 0.44) and lipid content (0 % ∼ 50 %). Polynomial fitting of the data achieved a coefficient of determination (R²) of 0.996, confirming excellent agreement between the fitted curve and simulated results.. The polynomial fitting yielded a coefficient of determination R² of 0.996, indicating an excellent agreement between the fitted curve and the stimulated data. The proposed DC voltage discharging technique provides a simple, cost-effective, and label-free method for lipid estimation in single cells while introducing a practical platform for advancing microalgae research and offers new opportunities for scalable bioenergy applications through rapid lipid quantification at the single-cell level.