Flexible and disposable paper- and plastic-based gel micropads for nematode handling, imaging, and chemical testing

TL;DR

This paper introduces a low-cost, disposable microfluidic paper-based device for handling, imaging, and testing nematodes like C. elegans, enabling simple, on-site chemical testing and automated behavior analysis.

Contribution

It presents a novel microPAD platform on paper and plastic substrates for nematode studies, including fabrication, loading, imaging, and automated locomotion analysis.

Findings

Successful nematode loading and visualization on microPADs

Automated recognition and analysis of worm locomotion

Effective chemical testing with levamisole on the device

Abstract

Today, the area of point-of-care diagnostics is synonymous with paper microfluidics where cheap, disposable, and on-the-spot detection toolkits are being developed for a variety of chemical tests. In this work, we present a novel application of microfluidic paper-based analytical devices (microPADs) to study the behavior of a small model nematode, Caenorhabditis elegans. We describe schemes of microPAD fabrication on paper and plastic substrates where membranes are created in agarose and Pluronic gel. Methods are demonstrated for loading, visualizing, and transferring single and multiple nematodes. Using an anthelmintic drug, levamisole, we show that chemical testing on C. elegans is easily performed because of the open device structure. A custom program is written to automatically recognize individual worms on the microPADs and extract locomotion parameters in real-time. The combination of microPADs and the nematode tracking program provides a relatively low-cost, simple-to-fabricate imaging and screening assay (compared to standard agarose plates or polymeric microfluidic devices) for non-microfluidic, nematode laboratories.