Cell transfection by electroporation is a biological assay that has been utilized to inject exogenous molecules (e.g.: RNA, DNA and protein) into live cells. Recently, electroporation has been utilized in developing cell therapy for cancer (e.g., CAR T-cell). One of the major drawbacks in current electroporation methods is the cell death during the process. These dead cells can be detrimental, if injected back to the patients. Current cell filtering methods are unable purify T-cells following electroporation, this is due to the lack of unique biomarkers that target the apoptosis and necrosis of T-cells. To address this issue, we have developed a method using dielectrophoresis and microfluidics, where no prior labeling is needed to isolate dead cells from live cells. Upon electroporation, the cell sample has to be flowed through the microfluidic chip where a selective electric field is applied through specially designed electrodes so that the dead cells are trapped on the electrodes, and the live cells are able to flow through and are collected at the end. Results after purification of the cells using our method reveal that it is possible to achieve ∼100% of purity in filtering of the live cells. This method presents a viable solution to a critical concern regarding CAR T-cell manufacturing. This paper presents an extended study of the variation of efficacy in the design with the time from the electroporation.