Fig. 1.

Microfluidic EPG recording device (chip). A. In this image (modified from Weeks et al., 2016b; https://creativecommons.org/licenses/by/4.0/), microchannels were filled with a red dye to aid visualization. C. elegans were loaded into the input port (filled arrow) and distributed via a branching network of channels into 8 recording modules, each with a distal (blue) electrode wire. A hollow metal electrode (not shown) inserted into the input port delivered perfusate and served as a common electrical reference. Solutions flowed past worms and exited to waste reservoirs (*, waste reservoirs for recording module 1). Open arrow indicates expanded region shown in B. B. Recording modules were modified from an earlier design by adding bilateral side channels parallel to the worm channel to enhance access of perfused solutions to worms. Feature height in the PDMS layer of the chip was measured relative to the glass substrate. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)