Enhancing Scalability and Consistency in Pulsed Electric Field Processing of Microalgae: Integrating Single-Cell Suspension Rheology and Multiphysics Simulation

Emerging extraction technologies such as microsecond pulsed electric field (μsPEF) offer an energy-efficient and gentle method for downstream processing of single cells. However, attaining consistent processing outcomes in continuous PEF systems across different scales is challenging due to variations in cell residence times caused by cell concentration and flow-dependent rheological behavior. This study employed COMSOL Multiphysics® simulations to model rheological changes in high-density heterotrophically grown Auxenochlorella protothecoides microalgae suspensions. The model was designed to precisely estimate residence times for consistent μsPEF treatment and increased processing capacity at high flow rates and cell concentrations. Implementing the simulated residence times into experimental validations achieved consistent treatment outcomes, resulting in 86 ± 4% of cells being permeabilized and increased processing capacity from 21 to 300 mL min-1. Higher cell concentrations led to increased energy input and decreased protein extraction yields, indicating complex underlying permeabilization and diffusion processes during and after treatment. This work advances scalable and consistent μsPEF technology for single-cell downstream processing by applying cell suspension rheology and residence time simulations.