CO2 and compressive immobilization of C. elegans on-chip.

We present two microfluidic approaches for immobilizing the roundworm C. elegans on-chip. The first approach creates a CO(2) micro-environment while the second one utilizes a deformable PDMS membrane to mechanically restrict the worm's movement. An on-chip 'behavior' module was used to characterize the effect of these methods on the worm's locomotion pattern. Our results indicate that both methods are appropriate for the short-term (minutes) worm immobilization. The CO(2) method offers the additional advantages of long-term immobilization (1-2 hours) and reduced photobleaching, if fluorescent imaging during immobilization is required. We envision the use of these methods in a wide variety of biological studies in C. elegans, including cell developmental and neuronal regeneration studies.