. Significance : Selective plane illumination microscopy (SPIM) is an emerging fluorescent imaging technique suitable for noninvasive volumetric imaging of C. elegans . These promising microscopy systems, however, are scarce in academic and research institutions due to their high cost and technical complexities. Simple and low-cost solutions that enable conversion of commonplace wide-field microscopes to rapid SPIM platforms promote widespread adoption of SPIM by biologist for studying neuronal expressions of C. elegans . Aim : We sought to develop a simple and low-cost optofluidic add-on device that enables rapid and immobilization-free volumetric SPIM imaging of C. elegans with conventional fluorescent microscopes. Approach : A polydimethylsiloxane (PDMS)-based device with integrated optical and fluidic elements was developed as a low-cost and miniaturized SPIM add-on for the conventional wide-field microscope. The developed optofluidic chip contained an integrated PDMS cylindrical lens for on-chip generation of the light-sheet across a microchannel. Cross-sectional SPIM images of C. elegans were continuously acquired by the native objective of microscope as worms flowed in an L-shape microchannel and through the light sheet. Results : On-chip SPIM imaging of C. elegans strains demonstrated possibility of visualizing the entire neuronal system in few seconds at single-neuron resolution, with high contrast and without worm immobilization. Volumetric visualization of neuronal system from the acquired cross-sectional two-dimensional images is also demonstrated, enabling the standard microscope to acquire three-dimensional fluorescent images of C. elegans . The full-width at half-maximum width of the point spread function was measured as 1.1 and in the lateral and axial directions, respectively. Conclusion : The developed low-cost optofluidic device is capable of continuous SPIM imaging of C. elegans model organism with a conventional fluorescent microscope, at high speed, and with single neuron resolution.

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