Embodiments are described for treating a fluid, e.g., a biological fluid. The embodiments may include systems, apparatuses, and methods. Embodiments may provide for a flow cell, with a plurality of manipulation elements, through which a fluid is flowed. The fluid may be treated (e.g., exposed to energy) as it moves through the flow cell. In embodiments, the flow cell may be used to inactivate pathogens in the fluid.