Development of an optically induced dielectrophoresis (ODEP) microfluidic system with a virtual gel filtration chromatography (GFC)-inspired mechanism for the high-performance sorting and separation of microparticles based on their size differences

Size-based sorting and separation of microparticles is critical for many applications. Conventional techniques might not be suitable for this task particularly when sample is limited. Integration of optically induced dielectrophoresis (ODEP) in microfluidic system for the task is believed promising. However, its utilization can be limited by the influence of the friction force acting on microparticles. In this situation, the microparticles might not be effectively sorted and separated. To address this challenge, this study presented an ODEP-based virtual gel filtration chromatography (GFC)-inspired mechanism. By mimicking the concept of GFC, this study proposed to use a circular light image array to maximize the retention time difference among various microparticles when they flowed through such an array. In this study, the array design and its operational conditions were determined. Additionally, its performance for sorting and separation of polystyrene (PS) microbeads with 4 different sizes was evaluated. Results demonstrated that the proposed method was capable of sorting and separating microbeads in a high-performance manner (e.g., purity range: 92-100%). This could be beyond what is currently possible using the current ODEP-based method. Overall, this study presented a new ODEP technique that could solve the problems commonly encountered in ODEP-based microparticle sorting, and separation.