Cell collection based on deterministic lateral displacement (DLD) and cell circulation with a loop channel are two component technologies for stressless cell retention which have been developed with a view to working toward suspension culture in a microfluidic channel. DLD devices with low array angles collect floating S. cerevisiae through an array effectively. The DLD device with an array angle of 2.6° showed an efficiency of 91.7%. Two types of loop channels with a piezoelectrie pump make a stable two-phase laminar flow of a pre-filled fluid and supplied fluid. A loop channel with a connection between an inlet and outlet on the opposite side replaces a filled fluid in the channel with a supplied fluid, which is essential for supplying nutrient rich medium to cells in microfluidic channels as well as retaining cells in a microenvironment without external stresses.