Development of an integrated microfluidic device for evaluating of in vivo chemo-sensing of intact Caenorhabditis elegans

Conventional macro-scale methods are not appropriate for in vivo neuronal analysis at a single neuron level when experimental subject is small model organism Caenorhabditis elegans. In this paper, we demonstrate a powerful microfluidic device that allowed investigating in vivo chemo-sensing of intact C. elegans by integrating functions of automated manipulation of worms, effective immobilization without damages and well-controllable stimulations. Live C. elegans were effectively immobilized in microfluidic channels by a comb-shaped microvalve without physiological damages. A well-controlled sample introduction system was used to deliver chemicals to the chemosensory cilia at the worm's nose tip. In vivo neuronal responses of the animal to the chemical stimulations were monitored using calcium fluorescence imaging. Dynamic calcium signals related to varying concentrations and durations of stimuli were investigated using this integrated microfluidic device. We anticipate this immobilization approaches can have an impact in a variety of applications, such as neuron responses investigation before and after laser ablation upstream or downstream neurons for studying olfactory or gustatory neural circuits in individual healthy worms, in this high-throughput system.