On-Demand Isolation and Manipulation of C. elegans by In Vitro Maskless Photopatterning.

Caenorhabditis elegans (C. elegans) is a model organism for understanding aging and studying animal behavior. Microfluidic assay techniques have brought widespread advances in C. elegans research; however, traditional microfluidic assays such as those based on soft lithography require time-consuming design and fabrication cycles and offer limited flexibility in changing the geometric environment during experimentation. We present a technique for maskless photopatterning of a biocompatible hydrogel on an NGM (Agar) substrate, enabling dynamic manipulation of the C. elegans culture environment in vitro. Maskless photopatterning is performed using a projector-based microscope system largely built from off-the-shelf components. We demonstrate the capabilities of this technique by building micropillar arrays during C. elegans observation, by fabricating free-floating mechanisms that can be actuated by C. elegans motion, by using freehand drawing to isolate individual C. elegans in real time, and by patterning arrays of mazes for isolation and fitness testing of C. elegans populations. In vitro photopatterning enables rapid and flexible design of experiment geometry as well as real-time interaction between the researcher and the assay such as by sequential isolation of individual organisms. Future adoption of image analysis and machine learning techniques could be used to acquire large datasets and automatically adapt the assay geometry.